THE CONCLUSION

  • 4K Views
  • Last Post 05 December 2013
joeb33050 posted this 03 December 2013

WIND, EQPT, SKILL, CHANCE, CAST BULLET ACCURACY

Accuracy is affected by and is the product of: wind, equipment, skill and chance.
One example is 5 shot 100 yard groups.
Average group size is 1.190", and with no wind, or if we learned to compensate perfectly for the wind, would be 1.144", a difference of .046". 
 Equipment differences/improvements such as the difference between Production and Heavy class equipment reduce average group size from 1.190” to .845", a difference of .345".

Shooter skill varies group size so: Average group size is 1.190" Differences First place average group size is .731".
Second place average group size is .871". Second to first =.140" Third place average group size is .974". Third to second = 103" Fourth place average group size is 1.070". Fourth to third = 096" Fifth place average group size is 1.133". Fifth to fourth = .063"

Improving skill one level reduces average group size between .140” and .063".

Differences: Wind .046" Equipment .345" Skill .063” to .140"

Wind affects accuracy least, although much more as range increases. Skill affects accuracy more, but less than Equipment. It's hard to imagine an Equipment improvement, above the Heavy class equipment, that is as great as the difference between Production and Heavy equipment. 
These changes in group size don't simply add. The changes, in inches, must be squared, the squares summed, and the square root of the sum is the combined change. If the effects of Wind, .046", and Equipment, .345” were eliminated, and Skill improved from Second to First, .140"; then the total of the three is .531” but the combined reduction in group size is .375".

I think that meticulous attention to detail will not increase accuracy substantially; that to substantially improve cast bullet accuracy-and I'm not sure that that is a reasonable or sensible goal-the recipe needs changing. I think that the difference in accuracy between jacketed and cast bullets is not in skill or equipment or chance; but is in the bullets. I think that accuracy might be found at higher velocities, with swaged bullets, or with bullets cast of harder alloys allowing higher velocities. Zinc?

Now, is all this statistics stuff true? It's as true as I can make it, with a bucket of assumptions. It's certainly not true in any X.XXX precision sense; it's about approximations and tendencies and relative magnitudes. And, there's a tiny chance that I made a mistake. I know.

Attached Files

Order By: Standard | Newest | Votes
RicinYakima posted this 03 December 2013

FWIW, Joe, I think you are correct:

A, We have not perfected the process of casting and then processing the lead based alloy bullet to the uniformity of the gilding metal bullet jacketed bullet. I don't know what is missing, but it must be fundamental.

B. The gap between “Production” and “Heavy” is always the alignment of the chamber and the throat to the bore centerline. Any good gunsmith can chamber better with a sharper angled and smoother throat than a factory chamber if they will take the time.

Thanks Joe for giving me something to think about, these last three days, up here in the cold north while I am sitting by the fire out of the wind.

Best wishes, Ric

Attached Files

RicinYakima posted this 03 December 2013

Well, no one else has any conclusions, I guess.

Attached Files

John Alexander posted this 04 December 2013

I don't have any conclusions either about why the best CBA shooters haven't been able to improve in the last 14 years -- only speculation. We have obviously hit some kind of ceiling -- but what?

I agree with Joe that the most likely suspect is the bullet since we use essentially the same equipment in heavy and unrestricted class that the jacket BR people use -- except for the bullet

There is no evidence that our beloved practices of precisely weighing bullets and powder will have any effect because some of us are already doing that to a greater extreme than JB shooters. So harder, or faster, or better designed bullets might be the answer.

I would like to suggest a couple of other possibilities.

Maybe the barrels that will produce sub .2 MOA five shot aggregates with jacketed bullets aren't really the right design for cast bullets. We know that in some cases the bullet is deformed a bit by the rifling while getting it started spinning even opening a gap on the back side of the groove in the bullet that may let gas though. Maybe higher lands or more of them would help.

JBs are elastic and spring back from deformation. Lead is closer to a fluid than an elastic solid and springs back little or none after going through a bore constriction (tight spot) and into a bigger section (loose spot) of bore (like those in four of my Savage rifles). So maybe a bore that reduces in bore and groove diameter from throat to muzzle, sort of a choke, is needed. There is some hint in Bill Calfee's writing in Precision Shooting that he lapped in a bit of “choke” for the 22RF guns he built. And the rifles he built (shooting lead bullets of course) dominated the sport for several years.

Tom Gray believes that something he calls lube purging may limit accuracy and makes a good case for it. So maybe we should concentrate on achieving exactly the same bore condition from shot to shot. Any thoughtful CB shooter, who has been paying attention, knows that we really don't know the full story of what role the stuff we call “lube” plays in getting the bullet down the barrel. The late Ken Mollohan proved that lead is naturally “slick” and won't rub off on steel. Why do airguns more accurate than our CB rifles shoot bare lead so well but we have to have “lube"? I think Mollohan and others have made a good cast that our “lubes” aren't for lubrication in the usual sense. Maybe if we could eliminate that possible source of variation we could break through the ceiling we seem to have hit.

I don't know if any of this rambling amounts to anything, but something has stopped our efforts to improve groups and we should try to find out what it is and overcome it.

John

Attached Files

Duane Mellenbruch posted this 04 December 2013

Perhaps since there is believed to be a gap created behind the lands as the bullet is not up to rotation speed, is it time to revisit the Wilkes check again?  That would reduce the likelyhood of hot gas forcing past the front check, which would assist in starting the bullet to rotate, and of course the conventional check on the rear for seal and support. 

Just thinking with my fingers moving.  Duane

Attached Files

Ken Campbell Iowa posted this 04 December 2013

deeper lands ... for youse experimenters out there ... be aware that LILJA makes a 0.213 bore barrel for 22 rimfire ... those barrels are very successful in br rimfire. maybe j. alexander should screw one of those into his Tikka and report back. of course, that would bump him out of hunter class. hey i bet there are enough hunter shooters to take up a donation and buy him a tight barrel.... ( g ) ..

which reminds me ... i contracted an extremely tight bore 22 barrel ( button rifled ) ...which cost me more than my 40X ...geeze ... i chambered it but quit that self-flagellation sport before shooting it. wonder if i should rechamber it for a c.f. ? yeah ! rebated base on a 218 b. case ...

ken

Attached Files

RicinYakima posted this 04 December 2013

Gentlemen,

Lube: I first started writing to Molly 20 years ago, before I use shooting matches, about his lube theory. So I shot two ten shot groups with cast bullets, unlubed, with one damp patch of Hoppe's #9 through the bore before each shot. No leading, but not better groups, with that but there is problabley something better.

Barrels: I think a landless, i.e. Landcaster oval-bore, would be a better step than deeper lands.

Ric

Attached Files

Tom Acheson posted this 04 December 2013

Tagging onto John's comment above with regard to Tom Gray's views,about consistent bore condition.....ever wonder why the BPCR shooters either use a blow tube or a wiping rod between each shot? One reason is residual BP fouling in the chamber area which makes it almost impossible to chamber the next round so “blown-in” moisture softens that crap so the next round can be inserted. But the wiping guys maintain that developing a uniform bore and consistent from shot to shot condition for every shot, is one of the benefits of wiping.

Kind of goes against what we believe and have been taught that we need to “condition” the bore before shooting a string of rounds. But then some of us can be seen cleaning after every target at a match. Maybe we should be..........

Attached Files

R. Dupraz posted this 04 December 2013

Tom:

While I understand where you were going with the wiping, I don't think that your analogy applies to smokeless. As you probably already know, the wiping or blow tubing not only is necessary in the chamber area but also to maintain a consistant bore after a fouling shot or two. . There is so much more fouling that is left in the bore from black because of it's inefficient burn rate. I have read where it's 50% of the initial charge. Not so with smokeless.

Also, in my experience with both smokeless and BP rifles, It still depends on the individual bullet launcher as to what it likes to keep on shooting those bug hole groups.

RD

Attached Files

onondaga posted this 04 December 2013

There is an historical period when cast bullets were outperforming jacketed bullets in accuracy matches noted and described in the book “The Paper Jacket” by Paul Matthews. It was in the early 1900s during the period when American ammunition manufacturers were transitioning to copper jacketed bullets from cast in such venerable cartridges as the 30-30 Winchester. It was a marketing/profit decision to transition to copper jacketed bullets instead of paper jacketed cast or paper jacketed swaged  ( now called paper patched bullets) lead bullets. Match records are confirmed  in the book and the paper jacketed lead bullets were more accurate than copper jacketed bullets but the paper jacketed lead bullets were more labor intensive and less profitable than copper jacketed bullets were to produce at that time.

Since that transition to copper jacketed bullets, there have been hobbyists that have improved and corrected the most  problematic defect of paper jacketed bullets to sportsmen and the military. Secure and durable water proofing of the paper jackets and a secure seal between the bullet and cartridge case to prevent moisture contaminating of the powder charge with complete reliability. This is accomplished with a wetting of the paper jacket with a lube that dries durably and hardens like Lee case sizing lubricant. Patches are whetted with the lube before  rolling the patch onto the bullet then dried before sizing of the paper patched bullet.

This method makes cast bullets more accurate than copper jacketed bullets and the bullets hold that accuracy to copper jacketed bullet velocity levels with cast bullet expansion on game completely selectable by alloy selection that does not effect accuracy at all with this type of paper jacketed cast or swaged lead bullet.

So cast bullet accuracy is proven superior to jacketed bullet accuracy and can be used with  the modernized and weatherproofed  paper jacketed bullet method. The hobbyist can take full advantage of this method with custom cast bullet molds of the proper size for the method, paper patches, Lee case lube and the right bullet sizing die for your rifle,  but commercial use of this method is certainly hopeless at this time.

Gary

Attached Files

John Alexander posted this 04 December 2013

I like Ric's idea of a Lancaster bore. Don't Glocks or one of those German pistols use such barrels? Should be a piece of cake to make with button rifling after the button was made. ????????

Ken, are any of the undersized 22 barrels in a faster twist. Of course for your soft, short, healed bullet a slow twist would do.

Bore condition is worth thinking about. At the Nationals some of the best shooters are: cleaning after each target -- cleaning at some other interval -- not cleaning at all and all may be doing well.

Is there a “right” answer or is the right answer different for different powders, velocities, bore smoothness, lube, humidity, temperature or something else. And if it depends on one or more of these, what can we do to eliminate the effect so we know what the heck we should do?

I will be submitting an article this week to Glenn for the Fouling Shot about a bore condition type situation that was driving me nuts and the solution is even crazier. There is so much we don't know about the issue of bore condition and “lubes". And nobody talks about it much.

John

Attached Files

John Alexander posted this 04 December 2013

Gary brings up an facinating subject. Paper patched bullets are interesting and allow jacketed bullet velocities as Gary points out.

I don't doubt that at one time paper patched bullets were more accurate than the early jacketed bullets and Gary cites match reports to show it to be true.

I do doubt that the same is now true with modern jacketed bullets agging in the ones and twos in benchrest matches. I have never see any reports claiming that paper patched bullets can come close to matching that level of accuracy, but I could have missed it.

I am also skeptical that paper patched bullets are competitive with the kind of cast bullet shooting seen at our matches. However, I don't know that for a fact and only doubt because nobody had done it or come close and it is hard to believe that it hasn't been tried.

However, if the potential is there I hope someone tries it in CBA competition. I think it would be exciting if someone won the CBA nationals shooting paper patched bullets. It would shake up and reinvigorate our sport.

Any takers?

John

Attached Files

Tom Acheson posted this 04 December 2013

Yep, PP bullets can be accurate. There are good shooters using them that expect 1 to 1.5 MOA with their BPC rifles. Admittedly, they shoot at distances of 200, 300, 385 and 500-meters at steel silhouettes or out to 1,000-yards at paper targets. No too bad for slow, heavy plain base CB's.

I have a handful of PP bullets that a friend sent me to try out in my C. Sharps .40-70 ss. Not enough time or decent weather but someday.....

Tom

Attached Files

joeb33050 posted this 05 December 2013

When “Cast Bullets” was published, long before the internet, many of us read about paper patched high velocity bullets and clumb on board. So I used Crane magic paper and onionskin and because Bass told of using it in slug guns-butcher paper. Also masking tape and cellophane tape and teflon plumbers tape. The “Chase” patch? Made those rhombus brass patch outlines. I know that there are people paper patching today, they will go to heaven. Paper patching is more agonizing than trying to get a 223 to shoot cast. Most of us gave up after feeling stupid that we couldn't duplicate Col. Harrison's work. I theorize that the PP commercial swaged bullets were PPd because swaging left no grease grooves-that the PP was replaced by grease groove cast bullets. I encourage you all to try paper patching, and will buy pharma stock if you do so.

Attached Files

Categories
Search
Popular Tags
This Weeks High Earners
Hot Topics
Close