Why all the lube grooves in cast bullets?

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  • Last Post 28 November 2014
John Alexander posted this 22 November 2014 

             I recently finished a series of tests to see the effects of filling the lube grooves in a multi-groove bullet in addition to the small gap ahead of the gas check on the gas check shank. A full report will be in a future Fouling Shot describing the test, reporting the results, and discussing the possible implications of the results.

One of the conclusions was that lube in the additional grooves ahead of the gas check “groove” did nothing positive that I could tell.

Does anybody have any results from a planned test showing that lubing additional grooves provides any benefits in accuracy, consistency, etc? If such testing has been done and the extra lubing showed that it is worthwhile, it would be nice to know of it and in what type of situation was it found necessary for best load.   Unless there is good evidence that lube in the forward bands is beneficial, the obvious question is why are we still designing bullets with multiple lube grooves when the space they take up might be better used to increase the length or either the driving bands or the part of the bullet that aligns it in the throat and bore. It is also unlikely that all those grooves improve the ballistic coefficient compared to a smoother bullet at least as some velocities.

John     

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Ed Harris posted this 22 November 2014

The surplus of grease grooves is a carryover from blackpowder days when lots of grease was needed to keep the foyling soft. Prior to WW2 little science had been paid towards bullet lubes, aside from ease of applcation during manufacture and economy of production. The various draw die lubes and waxes normally used un the ammunition plants were applied as bullet lubes. Refinements were mainly to improve shelf life and to avoid picking up dirt and lint when carried in the pocket. Lead bullet factory ammunition did not exceed blackpiwder velocities and highly efficient lubes weren't needed.

Some experimenters tried to improve accuracy and velocity of cast bullets, but most of this work bordered on voodo and hokum until Col. E.H. Harrison published his series of articles in American Rifleman from 1957-1960. That changed everything.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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onondaga posted this 22 November 2014

http://www.castbulletassoc.org/view_user.php?id=6375>John Alexander

It seems simple to me, John. but I think many will disagree. You are on the edge of agreeing with the tumble lube method being a superior lube method to traditional pressure lube into grooves.

I don't need any convincing and I tumble lube everything as it works without fail for me in every application of my shooting cast bullets. I get bullets to fit and the better the fit is, the less important lube becomes. Rough barrels are a  major deal breaker as they scrub any kind of lube off and you get a balancing game going to have enough lube to not get scrubbed off and do the job before the bullet leaves the muzzle.. That is another reason I polish my bores too, it makes lube less critical and reduces the abrasion factor of barrel finish upon bullet lube.

Gary

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Ken Campbell Iowa posted this 22 November 2014

reminds me of some of the most excellent saeco designs with only one lube groove near the base.

wonder if ” lots a lube ” is a hold-over from black powder residue days.

and it has been mentioned here that the grooves may help in storing material displaced by the grooves... where does that material go in metal jackets ? some solid turned bullets ( barnes ) have grooves.

and yep it would seem that a no-groove cast bullet would approach a little ways toward a jacketed bullet's resistance to deformation.

ken

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RicinYakima posted this 22 November 2014

Ed's response is excellent and right on the money. The other use is, for those of us you prefer a driving band closer to the nose, is to have some place for the displaced metal from the driving band. Without having a “lube” groove to be squished into, it forms fins or deforms the bullet body. There is a reason all of those bore sized lube groove designs fail. IMHO, Ric

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Lee Wiggins posted this 23 November 2014

Many years ago at a CBA national match Tom Gray was competing. He loaded between relays and with his thumb nail removed the lube from the front lube groove of all his rounds. I don't know if there was a rear groove that was still lubed or if the only lube was between gas check and rear driving band. Tom said he was doing that to reduce ” lube purging fliers, to much lube is not a good thing". Maybe Tom could weigh in on this thread. He is a good CB shooter and makes a good bullet lube as well (TG24). Tom,if I got anything wrong here please correct me. Lee Wiggins

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John Alexander posted this 23 November 2014

RicinYakima wrote: Ed's response is excellent and right on the money. The other use is, for those of us you prefer a driving band closer to the nose, is to have some place for the displaced metal from the driving band. Without having a “lube” groove to be squished into, it forms fins or deforms the bullet body. There is a reason all of those bore sized lube groove designs fail. IMHO, Ric Ric,

You can have the driving part of the bullet as close to the nose as you want without a groove after it. 

I am aware of the theory explaining the need for grooves to avoid forming fins and/deformations in the bullet. It sounds reasonable but has anybody ever found the fins or the deformation?  Even if fins/deformations are formed, additional work would have to be done to show that the fins/deformations have an effect on accuracy. Has anybody done that?

Ken raises an interesting question about fins on JBs.

Ric, I am totally ignorant of the bore size lube groove problem you mention.  What designs have them and how have they failed? I obviously am in need of education of this and would appreciate it. You have become our unofficial historical consultant with you knowledge of old loading tools.

John

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Brodie posted this 23 November 2014

Ken said:"and it has been mentioned here that the grooves may help in storing material displaced by the grooves... where does that material go in metal jackets ? some solid turned bullets ( barnes ) have grooves.

and yep it would seem that a no-groove cast bullet would approach a little ways toward a jacketed bullet's resistance to deformation."

The grooves in turned solid bullets like the Barnes have been put there to reduce pressure.  When Barnes started with the solid heavier jackets it was found that pressure spiked like crazy the grooves were put there to reduce the force of engraving and relieve the pressure spikes that happened during load development.  Brodie

B.E.Brickey

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Paul Pollard posted this 23 November 2014

<url=/view_user.php?id=6375>John Alexander wrote Ric, You can have the driving part of the bullet as close to the nose as you want without a groove after it.  I am aware of the theory explaining the need for grooves to avoid forming fins and/deformations in the bullet. It sounds reasonable but has anybody ever found the fins or the deformation?  Even if fins/deformations are formed, additional work would have to be done to show that the fins/deformations have an effect on accuracy. Has anybody done that? John John, I drove a couple 25:1 LBT bullets through my .256 win barrel. The untapered bullet showed metal being pushed ahead of the bullet. There is a little bit of fin pushed to the rear also. Photo attached, I hope.

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Paul Pollard posted this 23 November 2014

Here's another photo of the gas check groove with a REAL close up view. You can see lead trash in the groove ahead of the gas check. The bullet looks bent because of the lens.

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RicinYakima posted this 24 November 2014

John, Paul Matthews in his book Forty Years with the 45-70, revised edition, has his experiment with lube grooves only as deep as the bore. He never could get the concept to work. Col. Harrison also discussed this theory in some of his articles in the AR in the 1970's.   Yes, Yes, I know some things are style; like the “dirt catcher groove” in front of the first driving band on Ideal bullets from the 1890's. Like #311284 compared to #311290, I can't tell any difference in the shooting and scoring.   I look at bullets that win accuracy matches. No where do I see the Mann/Neidner style of bullet that is all bore riding body with just one short driving band in the rear. Even the breach seating guys don't use that style. Winning bullets have a groove behind each driving band. The only bullet that doesn't have a driving band and groove is the paper patched. They have not been used in matches for over 125 years. There is a reason for that, bigger groups.   Ric

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RicinYakima posted this 24 November 2014

Paul,

Excellent pictures!

As the bullet is being compressed by all that pressure in the rear, it has the physical structure of bubble gum. As it is being reshaped, metal has to go some where, and it is not being compressed like air.

Ric

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John Alexander posted this 24 November 2014

Ric, Thanks for the education. I had never heard of Mathews' experiments.  I wonder what he though the advantages of the very shallow lube grooves might be. Although I knew about both Mann and Neider, I had forgotten the two diameter bullet if I ever heard of it.    It looks like the RCBS “SIL” bullets, the bullets Merrill Martin favored, and the bullets I have been using like the NOE80SP have only one lube groove and thus are pushing pretty close to the Mann Neider two diameter concept and all have been more or less successful.  I am just wondering if I can go the extra step and eliminate the last dedicated lube groove, leaving only the gap ahead of the gas check. Simpler is sometimes better. I will perhaps find out if I can get such a bullet mold made.  I have paid for one but never received it.  I will try another mold maker.     Your strategy of looking at what has been successful in matches is a good one but it has limitations.  One limitation is that some of the stuff being done by successful match shooters may not be contributing to their success and they could do just as well without it.  The second limitations is that if we only try what has been successful before we will never learn if there is something better that we haven't tried.  Trying new stuff will result in lots of failures but maybe we will find an improvement as well. Searching is half the fun.   John

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RicinYakima posted this 24 November 2014

John,   Matthews said he was looking for a non gas checked bullet he could drive faster and more accurately. The idea was that the bottom of the lube groove would be a “bore rider” instead of the nose.   The RCBS SIL have a groove size section in front of the lube groove, the dedicated driving band and the gas check. Enough to hold the bullet together so it can be forced to rotate and be centered in the throat. I think your idea of an enlarged groove sized section, lube space in front of the gas check and then the gas check would shoot just fine. The question will be can you deliver it to the throat on center line and hold it there mechanically? It is not going to straighten itself up after the primer goes off.    "Searching is half the fun.” I didn't explain myself well. I look not only at the winners, but what others are doing down the listings. I would never tell some of the stuff I have tried! Looking back at it, it would never have worked, but it seemed “logical” at the time.   Ric

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Ken Campbell Iowa posted this 24 November 2014

harrison said that paper patch shoots better with grooved bullets.

about 10 years ago _ rifle _ magazine mentioned that the barnes designers had to put grooves deeper than bore diameter to solve fouling and accuracy bugs.

also i wonder why we don't see more winners using the LBT idea of long throat at full groove diameter ....although maybe the ardito tapered chambers are sort of the same idea.

i thought the loverin designs were like that but all my lyman-loverin molds have undersized noses ::: 2-3 inch groups again.

i have been laying awake at nights thinking that 1/8 ^ taper per side throat would be terrific ... sort of a tapered dimension barrel for a few inches. a pretty long reamer, i suppose .. ( g ) ..

ken

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John Alexander posted this 24 November 2014

RicinYakima wrote: John,   I think your idea of an enlarged groove sized section, lube space in front of the gas check and then the gas check would shoot just fine. The question will be can you deliver it to the throat on center line and hold it there mechanically? It is not going to straighten itself up after the primer goes off.   Ric Maybe it wouldn't make much difference but if the SIL type bullet has enough groove diameter driving band to do the job then the length wasted with an unneeded groove could be used to lengthen the bore riding nose.  The nose would give a lot of guidance to the front of the bullet and the slightly over groove diameter rest of bullet fitting into the ball seat/start of throat should position the rear.    If the geometry of the bullet was such that this position of the bullet before firing had only a minimum length in the case (maybe gas check only) any misalignment of the chamber would have minimum effect of the bullet before firing. Concentricity of the loaded round would mean nothing because the long bullet would align itself with the bore as it was seated.

This is close to what I have been doing with my MOS bullet and NOE80sp and is getting fairly close the the effect that breach seated bullets acheive.  I think trading off the one lube groove for an even longer nose and a single driving band might be better yet. 

Unless I am missing something, designing molds to cast rifle bullets with two, three, or more lube grooves as needed for BP in the 1890s is the wrong way to go and a waste of bullet length that could be used to better force the bullet into alignment before firing. However, this may be splitting hairs and not worth worrying about.

John

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R. Dupraz posted this 24 November 2014

"If the geometry of the bullet was such that this position of the bullet before firing had only a minimum length in the case (maybe gas check only) any misalignment of the chamber would have minimum effect of the bullet before firing. Concentricity of the loaded round would mean nothing because the long bullet would align itself with the bore as it was seated".        I can tell you from experience that that approach works very well with a paper patched 550 gr. smooth sided bullet in my 45x2.4 Shiloh Sharps. They will shoot just as good and more often than not, much better than GG bullets

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LWesthoff posted this 25 November 2014

Just looked at the Nat'l records. Looks as though the only classes that can equal Plain Based bullet are heavy rifle and Unrestricted. Most PBB shooters seat their bullets separately in the barrel, before they chamber the loaded case - thereby going one step better than chambering a round with only the gas check in the case. Since most PBB rifles can be picked up with one hand, which is not exactly the case with Heavy and/or Unrestricted, it looks like John A's theory holds water. (Those monster Heavy and Unrestricted rifles certainly help do away with a lot of those 'operator error” fliers.)

Maybe I'll have to buy one of those pretty PBB rigs after all.

Wes

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RicinYakima posted this 25 November 2014

Joe Gifford won more than his share of Mod-Iron postal matches in the late 90's and early '00's with that idea. His 1891 Argentine Mauser had the early straight sided throat at 0.313” inches about 1/4” deep. He put a 0.313” Lyman #311284 with just the gas check in the case. The bullet would self center with the nose riding the lands and the front driving band just touching the front of the throat. If he could keep the skinny barrel at the same temperature, it was the first sub-minute military rifle I ever saw.

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bjornb posted this 25 November 2014

LWesthoff wrote: Just looked at the Nat'l records. Looks as though the only classes that can equal Plain Based bullet are heavy rifle and Unrestricted. Most PBB shooters seat their bullets separately in the barrel, before they chamber the loaded case - thereby going one step better than chambering a round with only the gas check in the case. Since most PBB rifles can be picked up with one hand, which is not exactly the case with Heavy and/or Unrestricted, it looks like John A's theory holds water. (Those monster Heavy and Unrestricted rifles certainly help do away with a lot of those 'operator error” fliers.)

Maybe I'll have to buy one of those pretty PBB rigs after all.

Wes Do you know of anybody having tried breech seating of gas checked bullets? 

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frnkeore posted this 25 November 2014

I've BSed the 323471 in one of my 32/40's, back in the early 90's. The chamber has to be throated with a freebore and a shallow leade (.120 x 1 deg) in my rifle. You also need a heavy duty BSer. I had to make a special sizing die to get the bullet from .326 down to .322.

The load was 32 gr 2520 and the velocity was about 2150.

It worked fairly well with my smallest group at .430 for 5 shots @ 100 yd.

Frank

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RicinYakima posted this 25 November 2014

I tried seating WW + 2% tin bullets with gas checks in a Springfield with a plug seater. I am not man enough to do it and the short closing stroke of turning down the bolt handle was less than 1/2 the length of a driving band. It will take a really well designed mechanical seater to do it. FWIF, Ric

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LWesthoff posted this 25 November 2014

Bev Pinney has been shooting PBB matches with a bolt action rifle - and winning. Of course, there's no gas check. He does breech seat the bullet. I don't think his bolt action is quite as pretty as a lot of those other PBB actions, though.

Wes

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frnkeore posted this 25 November 2014

A few other things regarding BSing GC bullets.

  1. A tapered GC bullet would be a good start. I believe some of the Egans are tapered.

  2. A bore rider, such as the 311299 would also be a good bullet to use with it's realitively narrow bands. I have a NEI 190 gr, PB with two driving bands (.080 each) that will do 1 1/4” groups at 200.

  3. There is a big wind drift advantage to be had with a hard bullet and a GC, traveling at 2000+ fps.

  4. The older twist rates are perfect (15 & 16) for GC bullets at higher velocity. That 323471 I shot was in a 15 twist and it is almost 1 1/4” long. A well designed spitzer, 1.1 long with a GC, will stabilize in a 16 twist and you could get at least .400 BC with it.

The alloy that I used in the above 2150 fps load was WW with 5% tin, with the long cylinderical body, it wasn't easy to BS. I didn't have a good, high leverage seater and it's was hard to get even pressure on the bullet. It has to be seated with one continous even push or the base can distort.

I used to shoot with Bev, back in the 80's and 90's in the Springfield Schuetzen matches. I don't know why he gave up traditional single shots but, I don't think he's gained anything in accuracy with them, not based on what he used to do in Schuetzen and what the top N/W Schuetzen shooters are doing now. 250's are now common place. Bev has always been at the top of the final scores.

I would love to see how he constructed his BSer. Any pics out there of it?

Frank

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bjornb posted this 25 November 2014

The reason I asked is that we are experimenting with breech seating in my 30XCB rifle (some of you may have read about the cartridge on the other CB forum), and to that end Goodsteel (the gunsmith who built all the XCB rifles) has fabricated a guided breech seater (FN Mauser action) that I'll have in my hands sometime this week. The idea is to seat the bullet far enough to have it fully engraved (ie. all the way to the gas check), and to fire with a charged case using a small tuft of dacron to prevent powder spillage. The goal is high velocity, in the 26-2700fps range.

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frnkeore posted this 25 November 2014

As you probably well know, I'm NOT a advocate of Dacron. I would use what we've been using in ASSRA & ISSA, the green floral foam (I don't even use that but, my wife has to in her 32/20). I cut it into 3/16 slabs on my radial arm saw. You then just push it into the case mouth and NOT down onto the powder. Much easier, faster and cleaner than trying to stuff that Dacron into the case.

Post a pic of Tim's seater, if you can.

Frank

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bjornb posted this 25 November 2014

Floral foam sounds like the way to go in this application.

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bjornb posted this 25 November 2014

Another pic

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bjornb posted this 25 November 2014

And another

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frnkeore posted this 26 November 2014

That's a great guild and now you need a adjustable piston and a way to push it smoothly into the throat.

I'd suggest taking the bolt stop off and using that as a anchor for a toggled lever to do the pushing.

Frank

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bjornb posted this 26 November 2014

We are working on that now. Tim with the actual seater in Arkansas, myself with a “chamber neck mock-up” that Tim made to exact rifle throat measurements (same reamer). So far it looks like it will work just oiling the bullet lightly and tapping it to a predetermined position (as measured from the mock-up) with a dead blow hammer. Pushing/levering was a lot harder than I had thought.

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bjornb posted this 26 November 2014

This bullet was tapped through the chamber mock-up and 2 inches of barrel. Bullet was sized .310.

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frnkeore posted this 26 November 2014

"Pushing/levering was a lot harder than I had thought."

That's why I said that it needs to be done smoothly with even pressure.

Frank

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bjornb posted this 26 November 2014

Well, Tim took your idea and ran with it. Not completely done yet but here's the start of a levering device anchored in the bolt stop screw hole:

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nimrod posted this 26 November 2014

I have been wondering when somebody was going to do this? I have thought about a long body the end that would go into the action chamber area to be shaped like the bolt head with opposing locking lugs. You would then have a shell casing made to screw in to the breech loader to insert into the chamber holding the bullet then you could turn it 90 degrees or probably less and have the compound lever on the back just like the normal breech seater. I would think that you have to make the connecting rod as heavy as possible because of the length involved but I don't see that much of a problem because of the diameter of most bolt bodies are around .700. Hope that this is clearer than mud?

RB

RB

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bjornb posted this 26 November 2014

This seater is being completed as we speak. I'll have the final pictures up here shortly. There is a camming lever attached to the channel piece, driving the bullet into the rifle throat in one motion.

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bjornb posted this 26 November 2014

Jam nut to control seating depth:

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Paul Pollard posted this 26 November 2014

This year for the season benchrest postal match, I breech seated gas checked bullets in my .256 Win. The rifle is a Savage Model 12. The first match had a good agg, but it went downhill from there. 

I made a breech seater which uses a camming lever which is a commercially available clamp. I thought there was a photo of it in my trash heap. If I can't find one, I will take another and post it.

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bjornb posted this 26 November 2014

Lever handle:

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bjornb posted this 26 November 2014

Handle in all its glory:

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frnkeore posted this 26 November 2014

This might be something like Nimrod is suggesting? I made this one for my wifes HW but, if made longer, with a case or case shape on the end, the ears could side in the bolt raceway, then rotate the handle, up or down, just a little, to catch the bolt lugs and pull back or, put the toggle on the other side and push as your lever would do. I suggested the bolt release as a anchor, because you had no provision for for anything on yours. Frank

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frnkeore posted this 26 November 2014

I can't find a way of posting mulitple pics in one reply

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nimrod posted this 26 November 2014

Yep that's about what I had in mind.

RB

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frnkeore posted this 26 November 2014

This is the one I made for my Borchardt, same idea with the push lever style. Here I use press fit and slip fit dowel pins for the pivots. Frank

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frnkeore posted this 26 November 2014

Note the button head screw, it isn't taped quite all the way through, used simular to a lock nut, that is a second BS adjustment. Frank

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DR Owl Creek posted this 26 November 2014

Bjornb,   Thanks for posting those pictures. That really helps.   Dave

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jhalcott posted this 26 November 2014

I tried several different lubes in the Loverin .30 caliber bullet years ago. I also tried filling ALL the grooves and only SOME of them. The type and amount DID make a difference in accuracy. I was more interested in minute of ground hog than X ring accuracy. The groups with ALL grooves filled were always larger than when only SOME grooves were filled. I cleaned the bore after each test and fired 3 shots to season the bore before the next test.

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tlkeizer posted this 26 November 2014

Greetings, UMMMM, I'm missing somptin.  Isn't this chain about lube in grooves and is it required for all grooves or sumpin like that?  How do pistons relate to lube required in grooves?  Could most of these replys go to another track or am I not following the beginning of the thought?  I'm kind of weak minded so I can't quite put the head screws and mock chambers in perspective of lube required in grooves other than the proper lubed bullet should find the bunny at the end of the trail.  Please enlighten my if I am off base.   TK

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bjornb posted this 27 November 2014

You are correct and I shouldn't have started the thread drift but I really don't know how to move posts into another thread. So with a final picture of the MBT Breech Seater I promise I'll leave the thread or wait for a mod to move the breech seating stuff somewhere else.

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John Alexander posted this 27 November 2014

Go right ahead with the interesting discussion on breech seating tools and such.  I have started another thread to pursue the questions about lube grooves and reducing their number so a bullet can be designed that will come close to to breech seating with fixed ammunition.  

Threads the drift off seem to be normal and starting another thread is easier than moving all the posts.

John

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bjornb posted this 27 November 2014

Thanks John, I'm glad you cleared that up. When I first asked the question about breech seating GC bullets I didn't envision the discussion and pictorials that would follow. Goodsteel is shipping the seater to me over the holiday weekend, and I'll be posting more on installing it on my rifle and also on actually loading and shooting with this device once it has been installed. Thanks to everybody for posting pictures and comments.

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goodsteel posted this 27 November 2014

Dang, don't leave out the finished product! Came out looking pretty snazzy I thought.Thanks for the tip Frank. I just started thinking about doing a through the action breech seater Sunday, and was going to try to attach the handle to the body of the seater itself, but then Bjorn texted me and told me about your suggestion of using the boltstop stud as an anchor point. Brilliant suggestion! Made it happen and here she is:

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nimrod posted this 27 November 2014

I was reading through the rules and I don't have any idea what most the guys plans are for all this breech seating but the breech seating allowed would be in the Plain Base Class and the Unrestricted Rifle Class, just saying. Of course in the Plain Base class there would be NO gas checks. I don't know about the Unrestricted Class maybe gas checks would be allowed I really don't know why not?

Rb

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Ken Campbell Iowa posted this 27 November 2014

i am interested in how much leverage you need to seat a bullet to ” fully engraved ” ... looks like you have about 10-1 leverage. i had been thinking closer to 50 to 200 to one was needed. which would point to screw threads or hydraulics. heh or rack y pinion.

based on bolt camming leverage is about 60-1 .

hydraulics would allow the input force source to be clear of the action.

ken

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frnkeore posted this 27 November 2014

Ken, The key to BSing is in throating and as cast bullet size or both.

Typically, a tapered bullet for that use has the first band about 1/2 (or less) of the groove diameter and tapers to ~.001 over groove or throat dia (which ever is larger). With a GC you might get away with size for size. PB needs that extra .001 to make sure we get a seal and don't gas cut.

One other thing to keep in mind with all cast bullet shooting is sizing. The more you do, the more chance you take of things not going as planed. That goes for both sizing before you load and the sizing that occures when the bullet is either launched from the case or BSed.

Custom bullet molds are expensive and hard to get made to your dimensions but, they are the way to go.

Frank

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bjornb posted this 27 November 2014

nimrod wrote: I was reading through the rules and I don't have any idea what most the guys plans are for all this breech seating but the breech seating allowed would be in the Plain Base Class and the Unrestricted Rifle Class, just saying. Of course in the Plain Base class there would be NO gas checks. I don't know about the Unrestricted Class maybe gas checks would be allowed I really don't know why not?

Rb Nimrod,our purpose for this breech seater is High Velocity shooting (why? why not?), and we are attempting to get the bullet started in the throat/rifling as straight as possible, with full support. As muzzle velocity increases, accuracy decreases once you get into the 2500fps+ area, and we are attempting to mitigate this by engraving the bullet fully before launching. 

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RicinYakima posted this 28 November 2014

I like to think of this as “fun” benchrest shooting, and not competitive shooting! Ric

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bjornb posted this 28 November 2014

Ric, you get it!

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goodsteel posted this 28 November 2014

Ken Campbell Iowa wrote: i am interested in how much leverage you need to seat a bullet to ” fully engraved ” ... looks like you have about 10-1 leverage. i had been thinking closer to 50 to 200 to one was needed. which would point to screw threads or hydraulics. heh or rack y pinion.

based on bolt camming leverage is about 60-1 .

hydraulics would allow the input force source to be clear of the action.

ken I figured this would be about right and it was just fine. Took about as much force as it does to cock a break barrel air rifle. Bullets are not soft either. There are now four people who have used the tool. I tested it yesterday, and I think its going to hold up very nicely. 

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