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Lyman Rifle Accuracy

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pepebml

32 Cal
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What accuracy can I expect from a percussion 54 Lyman Deerstalker or GPR at 100 yards with PRB using medium to max loads for hunting? Does the twist rate make that much of a difference? Would going to 50 cal make much of a difference?

I am not interested in what the best accuracy is if you spend hours and hours and tons of money finding the perfect load combination and hold your mouth just right. I am interested in what the typical accuracy is from the bench for hunting purposes. For example, in an area I am familiar with, a typical M1 Garand rifle should shoot 3-4” groups at 100 yards with common ammo. Worse than that, there is a problem with the rifle or shooter.
 
Been a while, but I am pretty sure sub-three-inch groups were the norm with a patched round ball in a .54 GPR at 100, rest with somewhere in the neighborhood of 100-110 grains of FFg. Lyman did the ballistics chart in their old classic Black Powder Handbook using FFFg. Page 118 shows a .535 PRB under 1110 grains G-O FFFg getting 1731 fps from a 30-inch barrel. Note the use of musket caps in their tests.
image_16886785.jpeg
 
pepebml said:
What accuracy can I expect from a percussion 54 Lyman Deerstalker or GPR at 100 yards with PRB using medium to max loads for hunting? Does the twist rate make that much of a difference? Would going to 50 cal make much of a difference?

I am not interested in what the best accuracy is if you spend hours and hours and tons of money finding the perfect load combination and hold your mouth just right. I am interested in what the typical accuracy is from the bench for hunting purposes. For example, in an area I am familiar with, a typical M1 Garand rifle should shoot 3-4” groups at 100 yards with common ammo. Worse than that, there is a problem with the rifle or shooter.
Click to expand...
I shot sub 3" groups off the bench with my percussion 50, and flint .54 about anytime I wanted to show off.

My eyes don't work that good anymore.

But I bet my rifles still do.
 
BillinOregon said:
Been a while, but I am pretty sure sub-three-inch groups were the norm with a patched round ball in a .54 GPR at 100, rest with somewhere in the neighborhood of 100-110 grains of FFg. Lyman did the ballistics chart in their old classic Black Powder Handbook using FFFg. Page 118 shows a .535 PRB under 1110 grains G-O FFFg getting 1731 fps from a 30-inch barrel. Note the use of musket caps in their tests.
[snip]
Click to expand...
That's very interesting. In the manual they shipped with the GPR (not sure of manual vintage), it lists the max loads for .54 Cal as 120gr for 2Fg, and 100gr for 3Fg.

The jumps in pressure between 90gr and 100gr, and then between 100gr and 110gr are counterintuitive, especially given only negligible increase in pressure between 110gr and 150gr (possibly relate to odd scale of CUP and switching from LUP to CUP). Yet, the velocity increases much more linearly (~90fps per 10gr of powder) from 90gr to 130gr.

...so I looked in the Lyman 2nd Edition Black Powder Handbook, and the closest they have is 32" 1 in 60" twist. In the new edition, they only go up to 120gr, but test multiple powders available in ~2005. They use PSI in this chart, but there is still a pressure spike from 100gr to 110gr for the 3Fg.

The velocities are all about 100fps slower in the new tests. Maybe that is partially the difference between a 30" bbl and a 32" bbl, but 2" of barrel shouldn't make that big of a difference, should it?

In any case, I am saving the pic you provided. I like those numbers better.

...let me see if I can get a pic:
54RoundBall_LymanBPHandbook2ndEdSm.jpg
 
BillinOregon said:
Been a while, but I am pretty sure sub-three-inch groups were the norm with a patched round ball in a .54 GPR at 100, rest with somewhere in the neighborhood of 100-110 grains of FFg. Lyman did the ballistics chart in their old classic Black Powder Handbook using FFFg. Page 118 shows a .535 PRB under 1110 grains G-O FFFg getting 1731 fps from a 30-inch barrel. Note the use of musket caps in their tests.
View attachment 293856
Click to expand...
Pretty sure 110 grains of FFF is an overload for the Lyman GPR.

If memory serves me correctly, 120 of FF is maximum and 100 Grains of FFF is maximum.

From the Lyman PDF.
 

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.54 deerstalker has been my main hunting gun for years. 3 inch or better groups at 100 from a bench. Hunting accuracy judged by leaning on a tree or free hand i can hit a 6 inch plate at 100 all day. Load is 90 gr 3f behind .530 ball. Your milage may vary.

I've also used 60 gr 3f in spots where shots were limited to no more than 50 yards.
 
pepebml said:
What accuracy can I expect from a percussion 54 Lyman Deerstalker or GPR at 100 yards with PRB using medium to max loads for hunting? Does the twist rate make that much of a difference? Would going to 50 cal make much of a difference?

I am not interested in what the best accuracy is if you spend hours and hours and tons of money finding the perfect load combination and hold your mouth just right. I am interested in what the typical accuracy is from the bench for hunting purposes. For example, in an area I am familiar with, a typical M1 Garand rifle should shoot 3-4” groups at 100 yards with common ammo. Worse than that, there is a problem with the rifle or shooter.
Click to expand...
I have two GPRs in .50 caliber. One in flintlock. With my old eyes even with cataract surgery, I keep my shots 75 yds or less. Both rifles get good results for hunting. My .54 custom Hawken with a Green Mountain barrel gives me 3 inch groups at 50 yds with 85 grains of 2f powder. The barrel is still new and only has about 100 rounds through it and I can only get 2 shots off before I have to swab.
All in all, I find the GPR barrels good and never had a problem with them.
 
ETipp said:
Pretty sure 110 grains of FFF is an overload for the Lyman GPR.

If memory serves me correctly, 120 of FF is maximum and 100 Grains of FFF is maximum.

From the Lyman PDF.
Click to expand...
I shoot 110 Grs Graff FFFg with a patched ball all the time in my Lyman Plains Rifle .

My feeling is a 2 or 3 inch group at 100 is possible if your eyes are good enough. I usually don't shoot farther than 75
 
I know you're interested in 100 yard accuracy but I've yet to shoot my .54 Lyman Trade Rifle at that distance. I have shot it quite a bit at 50 yards from the bench using an improvised rest that doesn't support the butt stock. I'm still playing with patch materials however using a .530 ball, spit lubed patch of about .017 and a 90 grain charge of Schuetzen FFG I've shot several 1.5" five shot groups, most shot cutting each other. These guns have a 1:48 twist, same as yours, but the barrel is a few inches longer. I'm guessing with a double set trigger it might do better although as single triggers go it's not bad.

Not exactly the info you requested but I hope you find it helpful.
 
pepebml said:
What accuracy can I expect from a percussion 54 Lyman Deerstalker or GPR at 100 yards with PRB using medium to max loads for hunting? Does the twist rate make that much of a difference? Would going to 50 cal make much of a difference?

I am not interested in what the best accuracy is if you spend hours and hours and tons of money finding the perfect load combination and hold your mouth just right. I am interested in what the typical accuracy is from the bench for hunting purposes. For example, in an area I am familiar with, a typical M1 Garand rifle should shoot 3-4” groups at 100 yards with common ammo. Worse than that, there is a problem with the rifle or shooter.
Click to expand...
Accuracy is in the hands of the one holding the rifle.
 
pepebml said:
What accuracy can I expect from a percussion 54 Lyman Deerstalker or GPR at 100 yards with PRB using medium to max loads for hunting? Does the twist rate make that much of a difference? Would going to 50 cal make much of a difference?

I am not interested in what the best accuracy is if you spend hours and hours and tons of money finding the perfect load combination and hold your mouth just right. I am interested in what the typical accuracy is from the bench for hunting purposes. For example, in an area I am familiar with, a typical M1 Garand rifle should shoot 3-4” groups at 100 yards with common ammo.
Click to expand...
Typical accuracy ‘from the bench for hunting purposes’ (are you actually hunting from a bench?) with minimal effort will likely be 6” or less groups at 100 yards with patched roundballs with either gun. It will all depend on if you are lucky and ‘choose wisely’ when selecting your common shooting components and your shooting ability. One thing you may want to spend just a bit of time on, particularly if you are starting with a gun not previously shot (Lyman has been out of the muzzleloader business for some time now, and NOS doesn’t come up that often) is cleaning up any sharp machining edges you may find at the muzzle (they tend to be rough on patches) by hand or running a couple hundred rounds through the barrel. If any burrs are present either method will typically improve accuracy once removed.
 
I have three 54 cal rifles. I’ve never loaded more than 80 grains of either 2F or 3f for targets or hunting. I used to have a Great Plains. Great shooter. Getting in the black on a NMLRA target at 100 is good for anyone. Most who say they get 1” groups consistently at 100 yards are liars. Have I done it? Yes. Does it happen often? Absolutely not. I shoot matches and have for decades. Those tiny groups at 100 are rare for anyone. Worry about 50-75 yard distances for hunting and don’t stress over getting cloverleafs at 100.
 
Here’s what I know with certainty;

Open sights are the obvious limiting factor at play here.
At 100 yds even the young eyes experience about a 2 inch sighting error with post and notch system…if the ball shot perfectly the same every shot, this margin of error is 4 inches.

Add a peep and hooded globe front sight under ideal conditions at a round black bull and sighting error is now around 3/4 inch …consistent 1inch groups @100 are slug gun or scope sight territory.

If I can realistically and consistently hit a 6 inch bull at 100 yds with notch and post sights from an improvised rest, I’ve met my round ball expectations….just adding a rear peep and using the front post improves things to around 4 inches….and this is all after proven load development….
minute of mule deer out to 150 yards.
 
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Thanks for all the good info.

I am getting 16-18” groups with my 54 Deerstalker. Every third shot or more is a flyer. This is with both PRB and TC maxi hunter bullets. I have tried many loads and patch sizes/type with PRB. I have also had both my neighbors shoot it with the same results.

The rifle has a Lyman rear aperture sight. The bore is good. The crown is good. The barrel is tight in the stock. I can shoot really good with irons.

20 years ago I had a 50 cal GPR. I recall it was a 3-4” rifle with no effort of load testing. I wanted to ensure my memory was not that poor.

I also wanted info if I consider getting another Lyman. I have a mule deer hunt this fall that I need a fairly accurate rifle for, 3-4” at 100 yards would be ideal and 6” would work. I will also use the rifle for elk hunting. I may consider getting a GPR in 54 or 50.

I don’t have interest in in-line rifles or conical bullets. I know they can be really good. I just like the simplicity and long term availability of round balls.
 

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