Light loads in a Lyman GPR 54

[Boomerang]

I was playing around a little today with my new GPR in 54cal and I seem to be getting nice tight groups at 30yds with 25gr of 3f BP. I'm thinking that should work good for head shots on small game. What are others experience with real light loads in there 54?

 

[BrownBear]

You're right on the money. Been mushing bunny heads with mine and a comparable load for years. Best part for me, no need to change the sights from your sight in for heavy loads.

 

[BillinOregon]

Good old GPRs. They do a lot of things well.

 

[will5a1]

They most certainly do, and the lightest load I have tried in mine was 55grs of 2F, I'll have to try 25.

 

[Hunter John]

Wow, I've never heard of anyone shooting a 25 gr load in a 54. In a 50, yes, but never in a 54. Thanks for sharing your results. I always thought the the lightest you could go was 1 gr for every cal size....so 50 gr in a 50 cal, 54 gr in a 54 cal, etc.

Must plan on a "light load" day at the range seeing how low I can go with my 54 Hawken at 25 yards before my groups suffer.

Interesting stuff. :wink:

 

[Boomerang]

I don't know how good 2F would work with 25gr, but 3F worked good in mine. Nice low recoil. I'm not sure how many FPS it was shooting, but if I were to guess, I would say around the 800 mark. Looks like it will do well on small game out to about 35yds or so. I think it still packs enough punch for coyote at that range too.

 

[BillinOregon]

According to my tattered old copy of the "Lyman Blackpowder Handbook," 40 grains of G-O FFFg should give just over 1100 with a .535 ball in a 30-inch barrel. That's the lowest charge they show.

 

[Jim C]

Wow, I've never heard of anyone shooting a 25 gr load in a 54. In a 50, yes, but never in a 54. Thanks for sharing your results. I always thought the the lightest you could go was 1 gr for every cal size....so 50 gr in a 50 cal, 54 gr in a 54 cal, etc.

Must plan on a "light load" day at the range seeing how low I can go with my 54 Hawken at 25 yards before my groups suffer.



I shoot two to three grain loads in my 50 whenever I dry ball it. :grin:

 

[ncmtmike]

Do you mean to tell me,I have a EXCELLENT squirrel rifle in my possession that I did not know about? :cursing: Thanks for the heads-up!! lower powder? sounds like gravy to me :wink:

 

[Boomerang]

Do you mean to tell me,I have a EXCELLENT squirrel rifle in my possession that I did not know about? :cursing: Thanks for the heads-up!! lower powder? sounds like gravy to me :wink:

Exactly! :thumbsup:

 

[Hunter John]

1,100 fps with only 40 gr FFF...that's movin' a lot faster than I'd expect.

Just curious what your 'ol book shows for 80 gr FFF. Bet it's not 2,200 (or double the 40 gr FFF load).

Just goes to show ya that once you reach a certain point adding bp, although you gain fps, you do so at a decreasing rate.

Now that I think about it, I've read threads where the older folks load 20-25 gr in their 50s when teaching the younglings how to shoot. Guess you could pop balloons and bust eggs all day long at 25 yards with those lite loads and keep the kids engaged.

Must definitely put this "lite load testing" down in my 2016 to-do list.

 

[Zonie]

The graph that is shown was developed using the Lyman "BLACK POWDER HANDBOOK & LOADING MANUAL", 2nd ed.

Sorry it doesn't show powder loads down where we are talking about.
It does show the 40 grain powder load though.
Each dot to the right from the low 40 grain load represents a increase of 10 grains of powder.

These ultra-light powder loads are just one of the benefits of using a muzzleloader.
We can customize our loads far beyond anything one of the modern cartridge guns are capable of.



The ".490 BALL" was a typo. It should have said .535 BALL.

 

[BrownBear]

Great presentation Zonie. Thanks.

Light load doubters should step back a moment and think about those velocities. A .530 ball weighs right at 225 grains. Compare a 225 grain projectile at 1100 fps with modern handgun rounds, and you'll see what I mean. I've whacked truck loads of deer over the last 5 decades with handguns launching 240-250 grain slugs at 750-800fps, and not a single tracking job or lost animal. Or a second shot.

The defensive handgun rounds that put stars in the eyes of ardent fans aren't reaching beyond the performance of a 54 cal muzzleloader with 40 grains of powder. My wife's favorite deer load of 60 grains of Goex 3f in her 54 leaves them in the dust.

 

[BillinOregon]

John, the old Lyman Handbook shows a velocity of 1466 fps with 80 grains G-O FFFg. Keep in mind the data are more than 40 years old, and Gearhart-Owen was producing its powder at an antiquated plant in Moosic, PA. Today, with Swiss, Old Eynsford and other much better powders those data would likely change quite a bit.

(And yes, I am a throwback and consider words such as data and media plural.)

 

[Hunter John]

Interesting that when you increase the charge from 40grs to 80grs of FF, you pick up roughly 400 fps, but when you increase the charge from 80grs to 120grs, you only pick up roughly 200 fps. And in each case, you adding an extra 40grs.

Yup those 10gr increments when you're under 80gr really have a noticeable affect pushing the ball faster.

I guess the takeaway here is that it's really not worth the extra powder shootin' over 85 grs or so in a 54. :thumbsup:

Still amazed that 40grs of FF results in a velocity >1,000fps...holy cow.

 

[Zonie]

It is a good example of the Law of Diminishing Returns.

Another interesting graph is shown below.



Although this graph is of a .50 caliber guns velocity, it also applies to any gun shooting a lead roundball.

What it is showing is the increase in velocity of a ball at 100 yards vs the muzzle velocity.

Basically, the faster the ball is traveling at the muzzle, the more velocity (and energy) it looses as it flys downrange.

While the ball with a 40 grain powder load lost about 430 fps at 100 yards, the ball that was shot with a 120 grain powder load lost about 840 fps.

The moral of the story is yes, increasing the powder load does increase the muzzle and downrange velocity but, the gains are not that great when one considers the amount of powder being burned.

Getting back to the original topic, the powder chamber in my Lyman looks like it is about 8mm (.315) in diameter X about 25mm (0.98") inch deep. (I don't have a way to actually check out the size with it way down in the bottom of the bore).

If these guesses are about right, that powder chamber would hold about 19 grains of powder.

If this is true, any powder load over 20 grains should compress when a patched ball is rammed down all the way.

Looking at the steepness of the first graph I posted, I'm guessing a powder charge of 30 grains would produce a muzzle velocity of around 750-850 fps.

When one figures the MV of a .45 ACP is in that ballpark, any small game animal within 60 yards would end up in the pot if the ball hit him.

 

[Boomerang]

Yep. I know I wouldn't want to be standing in front of that ball going 800fps! :shocked2:

 

[BrownBear]

Yep. I know I wouldn't want to be standing in front of that ball going 800fps! :shocked2:

Bud of mine was shooting some 490 balls out of a Wrist Rocket slingshot. Dunno what the velocity was, but lots less than powder.

Took a clank at a knot on a 4x4 post about 10 feet away. Hit it and saw the ball bounding back at his head. What could the velocity have been then?

He instinctively moved his holding hand over in front of his face to catch it. Hit the joint at the base of his middle finger and broke the next bone running up the middle of his hand. "Lucky" shot for sure, but food for thought about how slow is slow when we're talking about a hunk-o-lead.