Which bullet is more accurate: PB or GC

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  • Last Post 12 January 2009
35Whelen posted this 01 January 2009

  This forum is killing me. I've never found so much useful info condensed into such a small space!! Even as I type this I should be out in the shop loading and at my range shooting! But, here I am again....whiling the time away reading posts here!

  Anyhow, I've been shooting a nice little NEI 155 gr. PB bullet and getting pretty good accuracy in my K-31. I've also shot jillions of the 314299 GC and likewise obtained good accuracy. But I began wondering: which is the most accurate design?

  I've pored over the results here from the various matches and it seems the GC design is almost universally used by competitors. I understand that we can buy really high quality moulds, carefully control our casting methods, and weight sort our bullets in order to obtain the most accurate bullet and loads. But, we have no control over the consistency of the gas check which to me seems to be the weak link in the accuracy chain where a gas check bullet is concerned. With a PB bullet, it would seem we eliminate the variable of the check and are totally reliant on the bullet itself.

But again, everyone here seems to use a GC design for competition. Why? Is it because the GC design is necessary for the desired velocities, or is it because the GC type bullet is typically more accurate than a PB design?

I really want to get more into shooting High Power competition and do so with 100% cast bullets, and I'm mulling over the possibility of having a custom mould made, probably for my K-31, and would of course have to decide between PB and GC design.

'Preciate the help and all the cast bullet intellect here!

  Greg

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billwnr posted this 01 January 2009

I don't know which style is more accurate and in a K-31 don't know if you'd be able to test to find out.

Shooting NMC you'll be limited to shooting pre-loaded ammo,l otherwise you'd have to be very, very fast in poking a bullet up into the rifle throat.

You'll have to use an M die to bell the neck and be very careful if you are using a true flat base bullet not cut for a gas check. You'll want to keep the edges undamaged.

If it was me I'd just try to find the most accurate gas check load I could. To research that I'd just go to the military match records, peruse the tech data sheets and test a few of the combos the better shooters are using. Most of the loads used are in the 1500-1650 fps range so chamber pressure isn't a concern.

Have you shot the 314299 in your K-31? If so you might mention how you got around the limitations of the short throat. Or...did you seat the bullet very deep.

As a bit of an understatement, Wally Enga seems to do fair with the K-31.   You could check the tech data sheets for his load combos.

<I believe the main page of the forum talks about the liability of using tech data sheet info.  The CBA is not responsible.......... >

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CB posted this 01 January 2009

Gregg, I'd say you will not find a hands down difference in accuracy. Look at Wind Hill's match results last year 2008 at the CBA website and you'll find a competitor using a K-31 using a Lee cb without the gas check and turn in really good scores.

Over all results-wise, the CBA records show that the PBB class records are real close to the Heavy and UNR classes. Nothing hands down. Under windy conditions I see the PBB shooters have a little harder time. I most always count on windy conditions on match days, between 9am and 3pm.................Dan

 

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35Whelen posted this 01 January 2009

Shooting NMC you'll be limited to shooting pre-loaded ammo,l otherwise you'd have to be very, very fast in poking a bullet up into the rifle throat.  

 Sorry, I don't quite understand what you're saying here. For what it's worth, our local High Power matches are fired at 100 yds. using the appropriate reduced targets. You'll have to use an M die to bell the neck and be very careful if you are using a true flat base bullet not cut for a gas check. You'll want to keep the edges undamaged.

  Right. My method with the PB bullets is to lube them in my Lubrisizer using a .314” die, which of course doesnt size the bullets. I then size it nose first through a Lee .309” die. The problem I have with using a GC bullet is I shoot quite a lot here at the house, and once I've settled on a load, I'll be shooting even more practicing as I seriously need to work on all my positions. As silly as it may sound, I hate the thought of using a 2.5¢ - 3¢ check for a 100 yd. target load if a PB type bullet is just as accurate.

 I have not tried the 314299 in my K-31's as it casts at .314” and my K-31's have groove and bore diameters of .3065"/.295"and .307/.296". I felt that would  too much sizing for that bullet. But I haven't ruled out the possibility of buying a 311299 for use in my K-31's.

  Bill, I'm having trouble finding the tech data sheets with the load information. Under windy conditions I see the PBB shooters have a little harder time. I most always count on windy conditions on match days, between 9am and 3pm.................Dan   That's kind of what I figured. In fact I just came in from the bench and firing my '53 K-31. I tried 8.0 grs. of Red Dot for the first time and my first group at 100 was right at 1 3/8” for 5 shots. Trotted back into the shop and loaded 5 more. The wind had kicked up a little and this group was nearer to 2 1/2"! :X But, I keep trying.

  Thanks for all the input!

   Greg

 

 

 

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billwnr posted this 01 January 2009

Here's a link to the 2008 match results. Click on some and the technical data sheet info is attached.

http://www.castbulletassoc.org/2008militaryresults.shtml

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Wally Enga posted this 01 January 2009

Greg

For the K31, unless you get into taper dies to fit heavier bullets into the throat, it's pretty hard to beat the RCBS-165-SIL or the Lyman 311672  with a moderate load  at around 1700 fps.

I have done some plain base work with the K31 & quite a bit more in the Finn M39 (7.62X54R). The problem I have had with the plain base bullets is, they will shoot extremely tight groups --- just be taking the center out of the X-Ring and then toss out a wide 8, just about one of every 10 shot string. I have not found a way to cull these crazy ones out.

I use them quite a bit for practice --- I don't trust them for Match use.

Wally

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35Whelen posted this 01 January 2009

The problem I have had with the plain base bullets is, they will shoot extremely tight groups --- just be taking the center out of the X-Ring and then toss out a wide 8, just about one of every 10 shot string. I have not found a way to cull these crazy ones out. I've experienced the same thing, but with me it seems to almost always be the first shot. I'm certain it has nothing to do with powder orientation as I just lay five rounds on my bench, randomly pick them up one at a time and single load them into the magazine as I shoot. Even at that, the flyers are not too bad. As an example the last PB load I shot today put four into less than 1” but slung a fifth out 2” away. I don't know which shot it was as I was having a hard time finding the holes in the black of the target, but I bet it was the first. MAybe it has something to do with warming the barrel??

  I weight sort my bullets to a +/- .6 grs. and that seems to help. I'll soon begin a few tests with 10 shot strings, so that should tell.

  Wally, I really appreciate the recommendations for the moulds for the K-31's. That was going to be my next question here.

Again, I really appreciate all the help. When I get a load nailed down for my K-31, I'll start to work with my 03A3, and I'm feeling an urge to buy a Finn M39!

  Greg

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PETE posted this 02 January 2009

 Greg,

  I think a great deal has to do with where you posted your message. Here on the CBA Forum the users would most likely say the most accurate would be a GC design since most of the people on here are using that type bullet.

  If you were on the ASSRA Forum you'd see very little on GC bullets and almost exclusive talk on PB bullets.

  Other Forums deal almost exclusively with black powder rather than the smokeless used by most on here.

  I fire a lot of both PB and GC bullets, and also use both black and smokeless powder for competition.

  The other equation you have to look at is the gun these bullets are being shot out of.

  So..... If you ask me I'd say a PB bullet is the most accurate by far. But the rifles I shoot these with have custom barrels and are set up just for bench competition shooting, whereas my GC bullet guns are all factory stock and I use them for the CBA Postals, or hunting and plinking.

  The next person to answer your question might very well say the exact opposite.

PETE

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Dale53 posted this 04 January 2009

My serious accuracy experiments with cast bullets have been centered around the PB bullets as they are a requirement of the American Single Shot Rifle Association (as is the use of non-bolt action single shots) where I have competed.

Using breech seated bullets, a competitive rifle needs to be able to shoot ½ minute groups (½” groups at 100 yards and 1” at 200 yards). That is quite difficult to quantify as the number of shooters that can wring this level of accuracy from a cast bullet rifle at 200 yards is quite low.

However, I can say with authority, that in the past couple of years, a small number of competitors, during registered matches, HAVE cracked this level of performance. At my last count, Jim Borton (recently retired Schuetzenmeister of ASSRA), had at least on NINE separate occasions, shot a perfect 250x250 - 10 Centers possible. No doubt, he has raised that number since I talked with him. I was present when some of this fantastic shooting was done. Several others have done the same, on at least one occasion (one fellow, Dale Reynolds, did it twice the same day during the same match)!!

Understand, to do this, you have to have each of the ten shots at least half way into the “25” ring. It only counts the higher value if it is at least half way into the ring. The 25 ring at 200 yards is 1.5” in diameter. Conditions at Beeson's Range, near Etna Green, Ind, are seldom good for very long, either. It is flat, open, and windy most of the time.

If you're rifle has the capability to shoot ½ minute groups, it gives you a little bit of leeway when they impact at 200 yards. Borton has broken the old single shot Rowland record at least once in practice and once during a match. The record made during a match was in the sixes!! Here is a picture I took of his record target when I did the article on his first breaking Roland's record,

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Dale53 posted this 04 January 2009

I would like to add something regarding Jim's accomplishments. Jim has, many times, shared his experience with the shooters around him, freely giving any information asked.

This particular target was shot at one time, in one day on a visit to a strange range in California on a trip. It was not shot in competition, but WAS shot in front of witnesses. However, the following year, Jim had a smaller group during the National Matches at Etna Green (I believe it was in the high sixes).

Roland took two or three days to shoot his famous 10 shot group (.711") and was measured with calipers. Jim's was measured with an optical comparator. Roland shot his target deep into a mine so he essentially had no weather conditions to contend with. This is NOT to downplay Roland's accomplishments at all, but to rather explain that Jim shot his initial “record” target in real world conditions. AND, by improving upon his performance during a registered match, no doubts should arise in anyone's mind about any part of his accomplishments.

Jim's shooting ability did not come easy. He has done extensive ballistic research to reach his very consistent level of competition. He has also been beaten. I remember a score match where he came in third in spite of the fact his group was under the Roland record (it was not quite centered on the target). That gave Jim and all the rest of us a bit of a chuckle (the fickle finger of fate, no less)!':shock:'

One other thing - you CANNOT expect to do anywhere near as good with anything less than perfect bullets. My standard for Schuetzen bullets is plus or minus .2 (2 tenths) of a grain variation. Jim throws any bullet back that isn't EXACTLY on the money. He is a master bullet caster and also a FINE bullet mould maker.

Dale53

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joeb33050 posted this 05 January 2009

35Whelen wrote:     I've pored over the results here from the various matches and it seems the GC design is almost universally used by competitors. I understand that we can buy really high quality moulds, carefully control our casting methods, and weight sort our bullets in order to obtain the most accurate bullet and loads. But, we have no control over the consistency of the gas check which to me seems to be the weak link in the accuracy chain where a gas check bullet is concerned. With a PB bullet, it would seem we eliminate the variable of the check and are totally reliant on the bullet itself.

But again, everyone here seems to use a GC design for competition. Why? Is it because the GC design is necessary for the desired velocities, or is it because the GC type bullet is typically more accurate than a PB design?

  Greg

Review of the CBA match results over the past 8 or so years shows that a few PBB = plain based bullet competitors shoot as well or better than the GC guys.

This suggests to me that MAYBE the majority recipe of hard bullet, GC, higher velocity is the wrong direction for ultimate accuracy.

(Now, the jacketed bench rest guys are tending toward 30BR, slow twist, light bullets, high velocity. Some CB guys are moving in that direction.)

When I mentioned this  on another forum, Pat I. leaped on me like a gecko on a butterfly, mean to the bone. No defense was allowed. A shocking attack. Mention of my sister.

Anyhow, the 2008 National Match results show clear examples of each approach in UnP.

H.L.Yarborough, 2007  grand winner, shot a 30BR with 100 grain GC bullets in 18” twist barrel at 2750 fps.

Clark Ehlers shot shot a 32 CHE in a peregrine SS action with 205 grain PBB bullets breech seated  in 12"twist barrel at 1450 fps.

 My guess is that the PBB approach sees less recoil, maybe less wind drift, less gun torque; and may be the direction many follow in the future.

joe b.

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RicinYakima posted this 05 January 2009

Joe,

I think a smart math guy could calculate the wind drift comparison of a 200 grain 30 caliber at 1400 f/s compared to a 100 grain bullet going 2450 f/s? But it isn't me!

Ric

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linoww posted this 05 January 2009

(Now, the jacketed bench rest guys are tending toward 30BR, slow twist, light bullets, high velocity.)

 

The  Hunter BR score matches where the capacity must be over 45g water capacity and the larger larger bullet "scores” better is where i see the 30 BR variants being used.The usually have to blow out the “standard" BR to make it hold 45 grains though.They still prefer the 6ppc in the Varmint For Score matches out here in the PNW.I shot one match with them with a lever action with cast bullets last year,it was fun.At least i had the only real hunting gun on the line.I was hunting for the 10 ring and rarely found it!!

George

"if it was easy we'd let women do it" don't tell my wife I said that!

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CB posted this 05 January 2009

joeb33050 wrote:  When I mentioned this  on another forum, Pat I. leaped on me like a gecko on a butterfly, mean to the bone. No defense was allowed. A shocking attack. Mention of my sister. joe b. Flattery will get you nowhere.

  Both PB and GC bullets can be extremely accurate and when I was more active I used to get beat on a regular basis by both. I don't have a problem with someone having a preference but to suggest that the other one is doing it wrong is a little out in left field.

I remember the conversation you're talking about and what you said was “the guys trying to shoot light bullets fast in a slow twist (which I happen to be one of) weren't thinking it through” and “The CBA experimenters are like all people just doing what's new and popular without giving it any thought"

But anyway thanks for bringing back pleasant memories.

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linoww posted this 05 January 2009

"Roland took two or three days to shoot his famous 10 shot group (.711") and was measured with calipers. Jim's was measured with an optical comparator. Roland shot his target deep into a mine so he essentially had no weather conditions to contend with. This is NOT to downplay Roland's accomplishments at all, but to rather explain that Jim shot his initial “record” target in real world conditions. AND, by improving upon his performance during a registered match, no doubts should arise in anyone's mind about any part of his accomplishments."

I am glad to see an experienced person in Schutezen rifle history echo my opinion of the Rowland group.Too often somebody with an old single shot rifle has bragged over that group and how my 30 BR with GC bullets is so inferior to their 32-40's accuracy capability.But they forget it was not in match conditions like you stated.I have shot besides a  couple of  good PB guys out in the PNW and it seems about equal in score or group to the Heavy or UNR class shooters on a particular day. I was there when Tommy Mason shot a 10 shot  .400 group for a CBA record @100 a few years back.And let me tell you is was nasty conditions and at least he had the advantage over all others that day.I have a line on nice a Miller set up with Smith barrel in .32 MS and may take the plunge if my wife lets me free up the $2000 for it!

George Damron

 

"if it was easy we'd let women do it" don't tell my wife I said that!

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35Whelen posted this 05 January 2009

  Well, I'm very grateful for everyones response and input. The amount of experience and expertise represented on this site is mind boggling. 

  Our local High Power matches are shot strictly at 100 yds. and the range has very high burms on three sides that pretty much block the wind. So, being the minimalist....OK...tightwad...I am, I think I'll stick to the plain base for 100 matches. It looks like 8.0 grs. of Red Dot is going to be a good load. If nothing else, this load will make for an inexpensive practice load. I'm waiting for Mid-South to get the 311672's back in stock so I can order one of them.

   One more thing....I have a 100 yd. range here at my house, but this time of year I cannot get enough shooting in to satisfy me due to the sgorter days. So, has anyone ever set up a range with lights that will suffice for shooting with open sights??.>  This is a terrible addiction.....

    Greg

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CB posted this 05 January 2009

Greg,

My home town range has a 200yd highpower night match every fall. They use a 110v floodlight at the target. Use a soft light, like a Colman gas lantern, behind you and at the side at your position. Its an experience, the irons show up surprisingly well............Dan

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35Whelen posted this 05 January 2009

My home town range has a 200yd highpower night match every fall. They use a 110v floodlight at the target. Use a soft light, like a Colman gas lantern, behind you and at the side at your position. Its an experience, the irons show up surprisingly well............Dan  

  Dan, thank you! That's exactlt what I was looking for. One more thing....can you recommend a good marriage counselor? Preferably one that shoots? I'm not sure my marriage can survive me shooting after dark!:cba:

    -Greg 

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Dale53 posted this 12 January 2009

Greg; My local gun club hosted area smallbore matches at night for years. They used general lighting at the firing line (not particularly bright) and a FLOOD light directly at each target. Irons were NO problem. Nor were scopes a problem. I shot a personal best of 98x100 at fifty yards offhand at that range after dark during a registered match.

We often shot a full match course (smallbore) at fifty yards on standard and metric targets weekly. Conditions at night were pretty dern good.

Dale53

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Mark Wakefield posted this 12 January 2009

 

So ya say;

                 “Maybe it has something to do with warming the barrel??"

Cold barrel are tight they get warm after as littel as one shot

I had a load that cracked the primer every time on the first shot all of the other 4 did real fine.

On a winter elk shoot brought a B taine gas BBQ lighter along...

I shoved the 4 inch pipe gas BBQ lighter up the chamber that snowy morn. After flipping on the flame for a small bit.

It worked    :)

Mark

 

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