Need advise on unstable bullets.

[chuebner]

Rifle: Numrich Arms Buffalo Rifle 45-70 .451 X .456 bore, 1:22 twist, 28" barrel

Boolit: Rapine 460500 sized .459 50/50 beeswax/EVOO lube

Load: BP, 50-65gr. GOEX 2F, .030 wad, boolit seated .525 into case.

This rifle shoots OK at 100yd. with this bullet and load but sometimes I notice an oval hole in the paper indicating the bullet is unstable and maybe starting to tumble. Same thing observed at 50yd. Same thing observed with Lee 459-405HB boolit and Lyman 400gr. RNFP. Any ideas or suggestions?

charlie

[45 2.1]

I have one of those rifles and it was very frustrating and less than accurate until I found what it liked. I think you are running into the problem that the boolit is not asleep or stabilized at 100 yards. Try the load at over 200 yards and see if it shoots as tight of groups with round holes. The problem will probably go away when you do. I shoot the Saeco 881 (Trapdoor springfield 500 gr. boolit) in mine with smokeless powder.

[chuebner]

45 2.1,

The 460500 mold is a Rapine which is the same as the Saeco 881 and the Lyman 457124. Unfortunately I am limited to 100yd. range. Sure wish we had a longer range down here.

charlie

[Don McDowell]

Given your numbers that bullet is .003 over groove, might be getting into some finning problems,try sizing down to 458 or .457. Bump that powder charge up to 70 grs and see if stops the keyholing. That slow twist you might need to drive the bullets pretty hard to get them stable.

[chuebner]

Could barrel length have anything to do with the oblong boolit holes. Reason I ask is that the same load combination shoots great out of my M1888 trapdoor.

charlie

[Don McDowell]

No keyholing is more a function of bullet/bore size, or wrong twist.

[montana_charlie]

The 460500 mold is a Rapine which is the same as the Saeco 881 and the Lyman 457124.
The Saeco 881 is advertised as a 500 grain design. The Rapine seems to be a 500 grainer, as well. The Lyman 500 grain design is their 457125...not 124.

Actually, that 457124 might answer your problem. It is considerably shorter than the others, and might be more comfortable in your slow twist rifling.
CM

[chuebner]

The Lyman 500 grain design is their 457125...not 124.
CM

m_c,

Your right, my oops. IIRC Springfield Armory did considerable testing of different twist rates before settling on 1 in 22 for the M1873 trapdoor and subsequent models. They also found that twist rate stabilized the M1881 design 500 grainer quite well. The Rapine 460-500, Saeco 881 and Lyman 457125 are all copies of that arsenal design bullet. I have had this rifle now for a little over 3 years and am still fiddling with load development but I guess that is half the fun. I plan on getting a Pedersoli Sharps in 45-70 in the next couple of months and can then start all over again. WOO HOO!!!

charlie

[August]

Most BPCR rifles set up for 500 meters to 1000 yards have 1:18 twist to stabilize 500 grain, and heavier, boolits. However, since you report that you are seeing the same OCCASIONAL result with 400 grain boolits, it seems the twist rate is not the problem.

One thing you do not mention is the alloy, which should be in the 1:30 to 1:20 range of tin to lead.

Also, I do not recall a lube formula with that much olive oil in it, rather it seems most folks use about 10% olive oil with half bees wax and 40% crisco.

Since the tumbling is occasional, I'm gonna guess you have a fouling problem. Try whipping after ever shot and see if the problem stops. You might want to invest in a chunk of SPG, which is a proven product and will help with fouling. Use 63 grains (to 65 grains) of goex and use a powder compression die to get the powder column to the correct height -- i.e. do not use the boolit to compress the powder.

Finally, as has already been mentioned, you might have to try different boolit diameters to get things to run smoothly. However, using a soft boolit will usually compensate for dimensional issues in the bore.

I hope something here helps.

[RMulhern]

Yes sir.....I'd whip it to death!! Best go cut you a big ole piss elm club and beat that sonofagun slap to death!![smilie=w::bigsmyl2:[smilie=s:

[hyoder]

Don McDowell and August have you on the right track.
.457-.458 size, 65-70 grs powder, 1:20 - 1:30 alloy

If you haven't already done so, make a blow tube and at least give a couple of good breaths dow the barrel after each shot. Be certain that the tube fits tight in the chamber throat - don't wet the chamber.