Home Forums Hunting & Shooting Ask The Gunwriters long barrel, small case

Has anyone read of a rule of thumb to predict when a jacketed bullet is likely to halt in the barrel due to too little pressure?

I have on order a small Uberti rifle in .357 with a 26" barrel. In looking at Hodgdon's data for the .357 in a rifle, I was surprised to see 3.7 gn of PB under a 158 gn XTP. I have to wonder if that's marginal.

In the same vein, I've been considering a .300 AAC in a long barreled single shot, and here one has a similarly small case but with bullets of longer bearing area against the bore.

Assuming a reasonable powder (one that nearly burns completely), it seems that grains of powder per cubic inch of bore and chamber behind the muzzle might be a figure of merit, in that it would roughly indicate the pressure at the muzzle. Many years ago I read a Dept. of Defense paper on the web about engraving and friction forces of bullets in a rifle bore, but I can't find anything in my notes. Certainly, if the gas force on the bullet's base falls below the friction to the bore, the bullet begins to decelerate.

I'm probably worrying about nothing here. That charge of PB was measured at 19 ksi, which works out to about 1900 lb accelerating the bullet at peak, and I doubt bullet drag in the bore near the muzzle can fully reverse such an acceleration.

Karl

The bullet won't stop accelerating in any rifle barrel short enough for a person to carry, even with a small case like the .357. There is a max length where it would stop accelerating and friction would start slowing it, but it's would require an extremely long barrel before that came into play.

I wouldn't even consider a jacketed bullet for light loads. Speer used to warn of the jackets on their half jacket bullets sticking, with the core slipping out and hitting the target. The next round would be a kaboom. Anyway, cast or swedged lead would be a much better choice.

I ran QL on this just to see what I would see. Unfortunately, PB is not in the powder database so I used VV N320 and AA No.2 which are nearby on the burn rate chart. Muzzle pressure appeared to be down around 400 to 500 psi. That doesn't seem like much, and it isn't relative to chamber pressures, but when the bullet is sliding down the bore it is enjoying the dynamic coefficient of friction AND should have quite a bit of momentum having been accelerated to near 1000 fps. It does cause a guy to wonder about it, though, just how slow we could get away with...diametrically opposed to the way we collectively tend to think.

Do a littlr research into suggested dc bullets for 38 loads. This gun may be a 357, but you are not treating it that way. The etra lenghth is a concern.

P.S. When I say suggested, I dont mean by internet opinions, inclucing mine, but real lliad data from ballistions.

I just want to add, I don't plan to use PB, I just got to wondering how slow was safe.

RiverRider, I, too, ran QL as you did and got the same pressure. That's about only 40 lb on the bullet, so I have to think deceleration is possible.

Dillonbuck, I've read (but can't recall where) some load book warning about jacketed bullets not exiting a .38 Spl if you reduce the starting loads too far. Even those PB loads are hotter than that, though.

Just wondering...

I checked, my Speer #13 advises against jacketed bullets over 125gr for 38 standard loads. Their minimum load for 125 jhp with pb in a 38 case was over 4 gr. Your load was a heavier bullet but a bigger case, not sure how that compares. That charge weight was max, but for min it was marked do not reduce. Not sure what the 357 loads were. The book is in the bedroom and I don't want to wake the boss. Can't sleep, just took two glugs of 10 Wild Turkey for sleep medicine, 0415 is coming fast.


Karl,

Just guessing but your rifle probably has more pressure than a .22 short, and they never get stuck in rifle barrels.

In shotgun reloading it sometimes happens that one gets a shell without any powder. I have seen wads get stuck in barrels and also have seen them exit and fall a few teet from he muzzle.

The .22 short uses a bullet which is short, soft, and lubricated, in comparison to a jacketed 158 gn in the .357 Mag. I'll guess you're right, though, that I wouldn't have a problem. (I wonder when that rifle will ever get here. Uberti makes some models infrequently.)

Dillonbuck, that Speer 13 must be what I recalled. A friend who passed away recently had an older Speer manual I borrowed now and then. Modern Hodgdon data has no such cautions. Regardless, I won't be loading so low as those PB charges, probably nothing faster than 800X, or just maybe Unique.

Paco Kelly wrote an article on shooting huge bullets out of very long barrels at low velocity, for sound reduction purposes. Its been a while since I read it but near as I can recall it was something like a 500g 45-70 or somesuch shot out of an h&r buffalo rifle with a 32 inch barrel the method used was to use as heavy as possible cast lead bullet and a small charge of fast burning powder. I want to say he was using bullseye but again it was a few years back I read it, But they would start at so many grains and work backwards until the bullet wouldn't exit then increase the charge slightly and go from there. It was really quite interesting and I have looked but can't find the article again. Anyways I dont remember how much bullseye it was but a jacketed bullet causes way more friction and I would think it would require quite a bit more powder. I have heard of jacketed 38's getting stuck in a rifle before tho, so would definitely be a little cautious.

When working up cat fart loads in my 35 whelen I had drop down to a load under 2 gr of powder before sticking a 148 gr wadcutter in the bore of a 24" barrel. A small case will produce more pressure than a larger case (expansion ratio)

I wouldn't be the least bit concerned about sticking a bullet using published loads. You'll have to throttle down even more to stick a bullet, but if you really want super mild loads stick with soft cast bullets as they are easily removed.

Okay, so I wasn't paranoid. Thanks, half_wit -- and to 458_Lott for some empirical data.

Even just a primer alone will get some bullets all the way down the barrel but don't count on it. Read somewhere and don't recall the exact number but even with a 22 short it is somewhere over 30 inches of barrel when the bullet starts to decelerate. I have had it happen on a Ruger Mk. II pistol with a target barrel, first shot probably had no powder next shot split the Bull barrel like a banana. Never under estimate how powerful a 22 really is. I have also had dud reloads in my shot gun and even the primer alone will push an ounce and a half of pellets into the choke.

Stuck a 45 grain jacketed bullet in a 26" Hornet barrel with a load of about 2 gr of Bullseye. Lead bullets come out of the same length barrel with lesser charges and .22 RF standard velocity performance.

So, scaling those by the bore cross section, to proportion the gas volumes and the inertias, that's a 115 gn .357 over 5 gn of powder. Bullet construction details won't scale, nor exactly will the burn, but now I'm certain I won't try the lighter Hodgdon loads in this rifle.

Curiosity satisfied; thanks, all.