Maximum Accuracy of Plain Based Bullets in Fixed Ammo

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John Alexander posted this 5 weeks ago

I know a lot of people shoot cast bullets in rifles without gas checks.  I can see from past articles in the Fouling Shot that reasonable hunting and plinking accuracy is possible (2 to 4 MOA).  However, I have never seen or heard of anybody showing up for a CBA match with plain based bullets in fixed ammunition.  Probably some have, but if so they don't seem to won many matches or set any records.  The few times I have compared appropriate low velocity loads with and without gas checks the loads with gas checks shot much better than those without.

Breech seated plain based bullet shoot about as well as shooters in heavy and unrestricted class.  High grade rimfire ammo and rifles can average 0.5 moa.  So we know that a gas check isn't always needed for great accuracy. The BPCR shooters may achieve great accuracy without gas checks, if so, I hope someone  will tell us how they do it. 

With gas checks at scalper prices this may be a good time to learn to do without them.  What does it take to achieve excellent accuracy with plain based cast bullets in fixed ammo?

John

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Spindrift posted this 5 weeks ago

I don’t consider myself an expert on this subject. But I have dabbled a bit with plain based, lubed bullets. Particularliy in .308win/ .30-06.  

I have a couple of augmentations available, in the form of polymer coating, and tools to make plain base gas checks (PBGC) from beverage cans. I have some bullet designs available in both GC and PB design- like the NOE #315- clone, and the MP Hunter (both excellent designs!).

 

My best PB, lubed bullet loads are similar in accuracy potential to my best GC loads with the same bullet design. But the PB load is much more sensitive to wind drift, so I would choose the GC load if entering a competition.

Neck tension is very important with PB loads; less is more. 0.002in is too much. 0.001in is much better. Over-sized bullets in unsized brass might be best? Don’t know, haven’t tried. 

 

Adding a PBGC to your lubed PB bullet fortifies your bullet to the point where load preference is very similar to the same bullet, in a regular GC-design. I’m not talking about extreme high-velocity loads here, but about 1700 fps.

Adding polymer coat to your PB bullet also reinforces the bullet, and load preferance is usually +5% compared to the same bullet design with lube and regular GC. The resulting velocity is very similar, despite the slightly larger amount of powder in the PC load. As to accuracy potential of PC’ed vs lubed PB bullets, the jury is still out.

 

Adding both polymer coat and PBGC only increase load tolerance very slightly as compared to one of the augmentations alone. 

 

 

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Tom Acheson posted this 5 weeks ago

There are a handful of differences between the use of fixed ammunition smokeless cartridges vs. black powder cartridges. Here are a few...

Large pistol primers are gaining widespread use instead of large rifle primers.

Over primer wads are inserted into the case before the powder is entered into the case or are punched into the primer pocket at the same time that the primer is inserted

All bullets (for competition) must be plain base cast, which limits the muzzle velocity

There is a trend that sees the use of paper patched bullets instead of grease groove bullets

Many of the cases are straight wall, but there are a few bottleneck cases being used

There is a limited range of projectile diameters in use, 38 to 50 caliber

The BPCR shooting distances are longer than smokeless matches. Those distances are 200, 300, 385 and 500 meters, as well as 600, 800 and 1,000 yards.

They have iron sight and scope sight categories with some limits on magnification.

And of course....the differences in behavior of the two powders during ignition

Want to learn more about the performance of BPCR? Go visit the Shiloh Rifle forum.

Tom

 

 

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Tom Acheson posted this 5 weeks ago

One other thing....

Quite a few shooters run two wet patches and then a dry one down the barrel, after each shot. Fouling control is critical to good accuracy.

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John Alexander posted this 5 weeks ago

Thanks for good information so far.

We know:

Breech seated PB bullets and 22 LR are capable of 0.5 moa accuracy.

Plain based bullet with the right poly coat can be shot at jacketed velocities with near match accuracy from Dan Lynch's extensive experiments reported here.

Paper patching allows plain based bullets to be shot at fairly high velocity -- some claim with accuracy.

Putting a metal gas check on a bullet meant to be shot PB (PBGC) makes it essentially a gas check bullet.

Would like to know:

BPCR shooters attain accuracy to hit some size target at long range. I am personally not interested in black powder but would like to know the accuracy (aggregates not single sometimes groups) the best shooters, guns, and scopes in BPCR are capable of.  I assume the matches are score matches but what kind of groups are they capable of?

What special techniques, lubes, or bullet design are needed to get plain base to shoot as well as gas checked bullets at 1,400 fps or less.

 

 

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John Alexander posted this 5 weeks ago

Spendrif says: 

"My best PB, lubed bullet loads are similar in accuracy potential to my best GC loads with the same bullet design. But the PB load is much more sensitive to wind drift, so I would choose the GC load if entering a competition."

That is good news.  Is this true of many bullet designs or only with special designs?

What do you do other than light neck tension?  When I simply leave off the gas check, groups are always  bigger, even at, or below the velocities needed for plain based bullets

Is the sensitivity to wind drift just because of higher velocities of the gas checked bullets? If not what caused it?

Any information will be appreciated.

John 

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Tom Acheson posted this 5 weeks ago

John,

Their matches are for score. In silhouette if you knock it over you get a point, you miss, no point. For BP target rifle, the target is paper with scoring rings, out to a max of 1,000-yards.

It is often said that you need a gun/load/shooter to attain 1.5 MOA to be competitive. At 200-meters that's a group of about 3.237", iron sights or low power scopes.

I'll watch for some groups they shoot and try to post them. When they do load development, they always shoot groups.

Tom

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Ken Campbell Iowa posted this 5 weeks ago

wind drift :  remember that match 22rf is below 1200  fps ... not 1360 ... because wind drift is less at that lower velocity.  

it could be that pb cast bullets would have less wind drift at 1100 fps than a gas checked bullet at 1850 ...

 

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Little Debbie posted this 5 weeks ago

I’ll weigh in here. From the original poster the question was about accuracy with fixed plain based bullet ammunition. My standard for all cast ammunition is that it can be fed from the magazine (tube, detachable magazine, internal box etc) and be carried in a pocket without damage, so the lube needs to be inside the neck. I find the keys to PB accuracy’ are as follows; perfect bases, perfect fill out, finding the right amount of lube, (Either Ben’s Red or LBT blue soft have been best for me) use one lot of brass, trimmed and uniformly annealed, primer pocket uniformed, flash hole uniformed, inside of neck polished with 00 steel wool, neck or collet sized (with graphite or other dry lube), expand neck to .002 smaller than bullet diameter, bullet base wiped free of lube, bell case mouth just enough to prevent shaving, seat in a straight line seater (I use a Herter’s)

I’ve found that Bullseye and Red Dot are best for plain base in .30 and .32 caliber, don’t exceed 1500 fps, primer is what I have these days, but I tend to favor large pistol for plain based. Store rounds nose down to keep powder out of flash hole, tap nose lightly on bench when accuracy shooting. Powder in the flash hole creates stringing on the target. Despite some people’s belief, Red Dot and Unique do migrate through flash holes. Bullets should not be the type that extend below the case neck.

I’ve shot plain based bullets in CBA competition, I’ve not set any records; my current project involves a Pre-64 M70 Featherweight in .30/06. The load is 9.0 gr of Red Dot, NOE copy of the Saeco #315 and Federal large pistol primers. The bottom two lube grooves are filled with Ben’s Red, the bullet is sized .311, case neck expanded .309. Bullet is seated to just cover the second grease groove. Bullets from my 5 cavity mold are visually sorted. In July I shot in a 100 yard match. My 4 5 shot groups averaged 1.39 inches, my two 10 shot groups average 1.84 inches. I’ve fired an additional 18 5 shot groups at home under calm conditions that averaged 1.13 inches, 5 10 shot groups averaged 1.48 inches. I shoot better at my home range, I don’t accuracy test unless there is no wind. (I don’’t use CBA targets either) My rifle is as it came from the factory, and has been out of the stock twice in the 50 years I’ve owned it. The scope is a Leupold 2.5 x 8. This accuracy represents the best this rifle is capable of. All with scrap lead and no gas checks.

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rhbrink posted this 5 weeks ago

I'll weigh in a little on the BPCR shooting groups at 200 yards. I had a Browning BPCR chambered in 40-65 with a Badger barrel as this was the best available at the time.  Shooting a Brooks .410 diameter, 420 grain bullet lubed with DGL, with a .060 LDPE under wad, a compressed load of GOEX Cartridge Powder (this was before Swiss became available) Federal 215 Mag Primers. Using iron sights shooting from a bench rested position on a good day I could keep five shots inside of 2 inches at 200 yards most of the time. This was 25 years ago and my eyes were much better then! 

But I was determined to make the rifle shoot as good as possible so I mounted a 20X scope on the barrel and did some more testing mainly to develop the absolute best load possible. Tweaking on the load and using the scope on really good days I was able shrink my groups to 1.5 inches at 200 yards at times. I suppose that if a guy shot  lots of groups and hand selected the best of the bunch I might have had a few that were under 1.5 inches but most ran for 1.5 to 2 inches. And I can assure you that a lot of lead, powder, and primers went down range doing this!

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Tom Acheson posted this 5 weeks ago

I got sucked into this BPCR "experience" after watching the movie "Quigley Down Under" way too many times. The co-star of the movie was a Sharps Model 74. I decided that I wanted to experience shooting a rifle similar to that. So the do this to "get the most accurate load" played second fiddle to just enjoying shooting, trying to hit a far distant target. I committed to no smokeless, no jacketed or gas checks and no scope.

For a while our local gun clubs that are hosting CBA matches had an Open category. It was intended to try to attract first time shooters to try shooting in a match. We used the CBA Military targets and the only equipment rules were that iron sights needed to be used. One shooter tried this and he has stayed with us for over 15-years, now shooting Military or Hunter categories but his match he used a Shiloh Model 74 in .45-70 and factory jacketed ammo.

So your obedient Match Director shot in the category a few times with his Sharps and I really enjoyed it!

When I got started someone said to me..."welcome to the world of mold and rear sight collecting". So far only one rear sight (they are not cheap) but several molds. The best greaser mold I have is a Paul Jones and I have only one paper patch mold, by Steve Brooks. I've tried Goex, Swiss and Old Eyensford black powders, settling on the latter. A book by Mike Venturino got me started with CCI BR2 primers but after some 200-meter testing, I settled on FC large pistol match primers. 200-meters is the longest distance I have routine access to.

I have a Remington Block that I enter in the CBA matches in the Plain Base Bullet category. Next season I may try pistol primers and the over primer wad. It is fixed ammunition in .38-55. One of the things I learned this summer is softer bullets, 25:1 or 30:1, performed better than harder bullets....and trying to have square "perfect" bullet bases is a common goal at the casting bench.

FWIW

Tom

 

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beltfed posted this 4 weeks ago

Here are a couple examples of plain base bullet BPCR shooting:

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beltfed posted this 4 weeks ago

More from my 38-50

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beltfed posted this 4 weeks ago

another one, I called #8 at 10.   .

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beltfed posted this 4 weeks ago

Last but not least, an 800yards group in BPTR competition at Lodi with my  371 gr Elliptical Minigroove 

40-65 Hi Wall, 

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Tom Acheson posted this 4 weeks ago

Arnie,

Good to see you checked in here. Your groups should expand everyone’s impression of the possible groups in this “field of study”.

Tom 

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Spindrift posted this 4 weeks ago

A bit more details on my process. I’m not a competitive shooter, but I shot quite a lot. I try to keep my reloading routines simple, and avoid steps that increase workload unless I find meaningful improvements in results.

I use almost exclusively range pick-ups, and gravitate towards cartridges where I can expect to find free brass (in Norway, that means .223 rem, 6,5x55, .308win, .30-06 and derivatives). Brass is sorted by head stamp, and FL resized for the first cycle. From then, I use the Lee collet die for all cartridges for which I have such a die available. Some brands tend to be long, and I trim for length. Other brands of brass (like Norma), I often skip the trimming process. No weight sorting, uniforming, neck turning, cleaning (unless absolutely necessary).

 

I use (mostly) the NOE expander plugs designed to fit the Lee universal flare die, after slightly lubing the inside case neck with a nylon brush, and imperial sizing wax. My general standard for all GC and PC bullets, is 0.002in neck tension, while lubed PB bullets seem to work better with 0.001in.

 

I mostly use large rifle primers (CCI or WLRP), but I should really try some LPP in the future.

 

For lube, I use a home-made concoction with rather a lot of ingredients. I discovered this lube as I mixed 3 home-made lubes together (for practical reasons, as they seemed equivalent) and experienced a sustained improvement in accuracy. If this is of interest, maybe I could drop a link to a detailed description I made on another forum?

For lubed .30-cal PB bullets in .308/.30-06 I use around 8,5 grs of pistol/shotgun powder (Universal, IMR PB, Vectan A0, Vectan Prima V, Vihta N32c, Vectan Ba9). 

 

I seat the bullet using standard bullet seaters, and leave the flare (unless loading for a tubular magazine). I think of a concentric flare as  an adjunct in centering the cartridge in the chamber (just a thought).

 

The PB, lubed bullet that has been most consistently accurate for me, is the NOE copy of the #315. In my Howa .308, my 5-shot groups at 100m are in the 18-40mm range, shot from prone with support on a bag. Most groups just above 1MOA. This is one of my most accurate loads, actually. 

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Tom Acheson posted this 4 weeks ago

Arnie,

What was the basis of thought to use a greaser in the 40-65 @ 800-yards, and I assume 600 and 1,000, instead of a PP round? Wind impact?

In the bench rest world we often see reference to the practice of neck turning case mouths. In the PB world, is neck turning a rare practice or is it a common case prep procedure?

Tom

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beltfed posted this 4 weeks ago

Tom, 

That 800 yds group was shot with my 371 gr Elliptical Minigroove bullet for the 16 twist 40-65 in 2011.

I have after that gone to DDEPP(DualDiameterEllipticalPaperPatch) bullets for all my BPCR shooting. First one was a

371 gr DDEPP version of that as seen in my first PIC showing the 100yds group. The other pics are of my 38-50/10 twist

shooting my DDEPP bullets in the BACO catalog:  JIM371345E and JIM3712360E

arnie

 

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