20 Grains

[Gary Owens]

I am going to a match in a couple of weeks that requires a 20 grain max load because of location. My question is will my 50 cal even be able to spit the ball out well enough to shoot with that load.The rifle has a 1/48 twist and I am using 2f. Thanks

 

[jethro224]

It'll spit out pretty hard. Don't try and catch it!

It'll probably shoot a lot lower than you're used to so try and get a little practice in first. I hope the targets are close.

 

[Stumpkiller]

Be glad you're not shooting a .62 cal rifle.

Yeah, it will spit the ball out. But you'll want to range check it ahead of time to see where.

 

[William O.]

Sounds like the max load should be determined by velocity potential and caliber rather than an arbitary limit. A .32 propelled by a 20 grain charge is going to have a distinct advantage over a .50 using the same amount of powder. At any rate, 20 grains will shoot a 50 caliber ball out of the barrel with deadly force but limited distance.

 

[BrownBear]

... and I am using 2f. Thanks

That's one thing I might change. I shoot a lot of reduced loads for smacking bunny heads, and in every gun I own 3f is more accurate (and flatter shooting) than 2f with reduced loads.

One thing to consider- If you're using a Lyman GPR, the patent breech holds between 30 and 35 grains of powder, while the ball will stop at the top of the breech. I stopped dropping my loads at 30 grains in GPRs so I had a minimal or no air space between the ball and powder. A conventional flat breech is no problem, but even at 20 grains I'm a little too twitchy about leaving an airspace under the ball.

 

[Gary Owens]

I thought about going with 3f , the air space thing I did not. The rifle is a pedersoli hawken.

 

[paulvallandigham]

Be careful about what Kind of backstop you will be shooting into with those light loads. We had a ball bounce off the knot in a RailRoad tie, and come back about 50 feet to cut a spectator's ankle.

After that, we bought a 1/4" plywood sheet of wood to put in front of the railroad ties, to place our targets on, and to act as a "splash-back guard" if a ball bounced off the Ties. No further accidents.

We also required our guys to use full loads, and stay away from the very light powder charges when shooting against railroad ties.

Ties, FYI, are usually of Pine, filled with Pitch, and Creosote, after cutting, to weather well, and resist wood eating insects. Old ties tend to have had most of the creosote bleached out of them by the sun and rains, freezing and thawing cycles. The wood gets soft, and "Spongy", and can be dangerous for bouncing RBs back off it, rather than let them penetrate. Examinations of each "splash-back guard" 4 x 8 foot panel of plywood indicates that several balls fail to penetrate the RR ties at each public shoot.

We also banned pistols and revolvers from being shot at these public demonstrations, where a backstop was improvised from Railroad ties.

As noted above, I would not use a "20 grain" charge in a gun with a powder chamber at the breech, that holds more than 20 grains. No, I am not worried about the breech exploding, or bulging, but It can't be good- even that small amount of powder-- to be firing repeated loads that small and Leave an air gap between the powder and PRB.

At the very least, I would use Farina, Cream of Wheat, Corn flour, corn meal, corn muffin mix, etc as a filler on top of the small powder charge in that powder chamber to fill the air gap that would exist behind the PRB when such a small charge is used.

Just a safety thought. :thumbsup:

 

[BrownBear]

The rifle is a pedersoli hawken.

I've formed the impression that the Pedersoli patent breech holds less powder than the Lyman. It's sure a lot skinnier any way. Wish I could tell you I've tried 20 in mine, but I haven't got around to it yet.

Let us know what you learn! :thumbsup:

 

[CoyoteJoe]

... and I am using 2f. Thanks

One thing to consider- If you're using a Lyman GPR, the patent breech holds between 30 and 35 grains of powder, while the ball will stop at the top of the breech. I stopped dropping my loads at 30 grains in GPRs so I had a minimal or no air space between the ball and powder. A conventional flat breech is no problem, but even at 20 grains I'm a little too twitchy about leaving an airspace under the ball.

Are you sure about that number BB? I haven't a GPR but have checked a dismounted T/C breechplug. I poured the powder chamber overfull, carded it off level at the top and dumped the powder into my scale pan. Five charges averaged just 13 grains, and that's level full, a seated ball would intrude at least somewhat into that space. I concluded a T/C rifle could fire 15 grains and still be a compressed powder charge.

 

[BrownBear]

Are you sure about that number BB? I haven't a GPR but have checked a dismounted T/C breechplug. I poured the powder chamber overfull, carded it off level at the top and dumped the powder into my scale pan. Five charges averaged just 13 grains, and that's level full, a seated ball would intrude at least somewhat into that space. I concluded a T/C rifle could fire 15 grains and still be a compressed powder charge.

I'm guilty of repeating what I saw and read here on the site. A couple or three years back someone pulled the breech on a GPR and measured its capacity, also providing photos. I'd been using 25 grains till I read that, then upped my load.

One clue about the GPR that seems to lend credibility is Lyman's recommendation of using a 35 cal brush for cleaning the breech. It doesn't take a very tall stack of powder, 35 caliber in diameter, to add up to 30-35 grains, especially with the flash channel added in.

 

[ohio ramrod]

I once thought I would "catch " a shot ball to check for rifling engraving/patch pattern on a patched ball. I put a pile of wood chips on a sheet of 3/8 plywood and loaded a 45 caliber with 5 grains FF. Shot it straight down into the plie of wood chips. The ball penetrated the wood chips, the plywood ,and six inches into the ground!So yes twenty grains will shoot a fifty caliber ball to a paper target! I would recomend a little corn meal on top if you have a patten b reech to make sure the powder chamber is filled with no gaps. :idunno:

 

[BrownBear]

I would recomend a little corn meal on top if you have a patten b reech to make sure the powder chamber is filled with no gaps. :idunno:

Good suggestion, I think.

 

[tiger955]

Another suggestion... pour 20gr of powder down the barrel, tap it down gently with a bore-sized jag on your rod, see if you hit metal. If you just get a dull thud you know the breech is full and powder is in the bore. If you get a sharper hit then you need more powder, or some filler to compress the charge.
As another stated, an arbitrary 20gr limit is silly. A 32 or 40 cal with 20 gr is going to have some velocity and range, a big bore, not so much.

 

[roundball]

I would recomend a little corn meal on top if you have a patten b reech to make sure the powder chamber is filled with no gaps. :idunno:

Good suggestion, I think.

Everyone should do as they like of course, but IMO, there's no need for worry...there's not enough powder / pressure involved to consider the situation a 'bore obstruction".
The few times I've "blooped" out a dry ball I've remove the liner, set the 3grn pan primer's plunger on a thread and actuated it several times...20-25grns 4F.

 

[Rhett Griffith]

I've never chronographed my .50 with 20 grains of powder, but 30 grains of FFFg is giving me a shade over 1200 fps about 20 feet from the muzzle. :shocked2: Given the fact that a roundball in .50 caliber weighs about 177 grains, that would put this load in about the same power category as a .357 magnum out of a handgun. Definitely deadly!

 

[Gary Owens]

I also think 20 grains is silly ,this shoot is in the city complex in kind of the center of town. I think the better way to go would be a few more grains and a real good backstop.Just my opinion , I may just go and watch this one. Thanks for all the information.

 

[CoyoteJoe]

Are you sure about that number BB? I haven't a GPR but have checked a dismounted T/C breechplug. I poured the powder chamber overfull, carded it off level at the top and dumped the powder into my scale pan. Five charges averaged just 13 grains, and that's level full, a seated ball would intrude at least somewhat into that space. I concluded a T/C rifle could fire 15 grains and still be a compressed powder charge.

I'm guilty of repeating what I saw and read here on the site. A couple or three years back someone pulled the breech on a GPR and measured its capacity, also providing photos. I'd been using 25 grains till I read that, then upped my load.

One clue about the GPR that seems to lend credibility is Lyman's recommendation of using a 35 cal brush for cleaning the breech. It doesn't take a very tall stack of powder, 35 caliber in diameter, to add up to 30-35 grains, especially with the flash channel added in.

A .38 special cartridge case is just over one inch long and holds 22 grains of 2f. The powder chamber of that T/C breechplug was just shy of 3/8" diameter and about 7/16" deep with a hemispherical bottom. A powder chamber to hold 30 grains would have to be either very much larger diameter of an inch and a half deep.
I don't know who provided you with that information, much less how they measured, but I very much doubt that number.