Ideal bullet weight?

[Johnny bravo]

Gents:),
I am thinking of making a custom mould for a 1:26 twist barrel. The calibre is 45-70. I would appreciate your thoughts on what weight bullets would work best for the barrel I have before I waste more money.

ATB:drinks:

[felix]

That would be my choice of twist for the 460 diameter boolits. My reason is that I am NOT a hunter and like to shoot 2100-2400 fps for ALL loads in all rifles for a consistent trajectory amongst the guns. Boolit weight should be between 250-350 grains for a general purpose boolit, and it would be fun to play with the ACP boolits with filler. Even with the 250 grainer, the recoil will be substantial at 2400. I do not know what powders you have, and for that matter, which one would be preferred. I would start with an 4198 equivalent, maybe N130 over there. V-V powders are my personal favorite because of their consistency between lots. ... felix

http://www.youtube.com/watch?v=g9Dz5yui0Rc

[Johnny bravo]

Felix, thanks for the quick reply but I am shooting with BP and have no intention of using nitro. There’s no way that I am even going to hit 1350fps with BP much less 2000+fps. Any ideas of a BP bullet in the 1250fps range that will travel 1000yds in that 1:26 bbl?

ATB

[405]

Your twist rate is slower than anything I have in 45 cal BPCR. The closest are a couple of trapdoors with 22" twist. At the lower velocities your planning, Felix is right with the 460 grainer. The Greenhill tables show the 45 cal 460 gr. at the iffy top end of stability in that twist. My best guess for a good, stable, versatile 45 cal bullet within the blackpowder velocities in the 26" twist would be a short roundnose or short flat point bullet in the 350-425 grain range. Since a major part of the stability function is bullet length... you could go a little heavier with the stubby front end or have to go a little lighter with a longer nose.

[felix]

1000 yards is too much for a 26 twist to be "competitive" in any kind of wind. The 400-500 grainer boolit would be required for those distances to "win" consistently, and the twist should be closer to 18 for that. Your best bet is to make that gun a short range (200 yards/meters) monster with flat trajectory potential using 250-350 grainers with gas checks. That 26 twist should shoot way less than an inch at a hunnert in a gale. Now, that would be competitive group wise if you can handle the recoil at 2100 plus. ... felix

http://www.youtube.com/watch?v=g9Dz5yui0Rc

[RayinNH]

Sorry for the hijack, but, Felix what's with the Monster Mash link, someone you know in the video?:-D...Ray

[felix]

No hijack, but quite appropriate for my way of thinking. I would be the monster mashed at the bench shooting that thing as a target gun. I am referring to the recoil at 2100 fps. No way could I do that caliber/twist justice. ... felix

[RayinNH]

Aha, now that I follow you, I have to agree that would be punishing, at least for an afternoon of fun...Ray

[montana_charlie]

Gents:),
I am thinking of making a custom mould for a 1:26 twist barrel. The calibre is 45-70.
That would be my choice of twist for the 460 diameter boolits.
Boolit weight should be between 250-350 grains for a general purpose boolit,
Felix is right with the 460 grainer. The Greenhill tables show the 45 cal 460 gr. at the iffy top end of stability in that twist.
Felix did not recommend a 460 grain bullet. Rather, he suggested using bullets between 250 and 350 grains with a diameter of .460".
Since the 460 grain bullet IS so iffy, it makes sense to avoid it altogether.

With such a slow twist, the bullet must be fairly short in order to be stabilized. That brings to mind the popularity of the 405 grain bullets, but I don't know their actual length. Once that is learned, they should be run through Greenhill to see if they are 'better enough' to fool with.

In any case, anything much under 500 grains is not going to be a thousand-yard bullet. It will fly far enough to reach the target, but it probably won't stay 'on' target.

In order to get the longest usable range capability, the design should probably be something like the 500 grain Government bullet, shortened to the length that the 26-inch twist will stabilize. That would pack the greatest amount of weight into the available length...without going to a pure wadcutter shape.

Out of curiosity, how did you determine that you have a 1 in 26 twist?

CM

[405]

MC, you're right on. I missed it, doh! I was looking at Felix' post while looking at the stability table. It's .460 diameter not weight :-D
Coincidentally, the Greenhill table does show about a 460 gr "generic?" bullet as the upper limit of stability in a 26" twist. The lower BP velocity can also mean two things working against each other with the goal of 1000 yard range. With that slow a twist and the possible required shorter or lighter bullets, it'll be at the margin no mattter which way.

JB, you might try to get ahold of a few of the fairly common 405 grainers (mine out of the RCBS mold with a soft 30-1 alloy drop closer to 420 grains and are 1.06" long) Shoot them or better yet a variety of bullets at the longer ranges and see how they do. Might be the best help with the decision on a custom mold design.

[Johnny bravo]

Out of curiosity, how did you determine that you have a 1 in 26 twist?

CM

MC,
I measured the twist with the old cleaning rod technique. Did it a few times to make sure I got the measurements right; it did measure approximately 1:26. Just to make sure I was doing it right, I measured my Pedersoli as well and it came to approximately 1:18. So, the technique was correct.

Well, whoever originally ordered this rifle with this twist had specific plans to mind, which obviously is not mine. Shooting such light bullets as suggested by Felix and many on the other site is not going to do me any favours beyond 2-300yds I am thinking. And if it’s going to cause that much recoil, forget it. I shoot for fun and relaxation, not for pain[smilie=1:.

Thanks 405 for the advice. The problem that I envisage with the shorter/lighter bullet is it 'jumping' in that darn barrel of mine. This particular bbl also has a huge freebore and a shorter round will be several thousands on an inch away from the rifling. Thus, this may be another issue to contend with. Wish I had provenance for my rifle. Atleast I would have had a clue as to why it was made this way:roll:

ATB

[felix]

Now, that brings up a different picture. That freebore shows the thing was reamed with a standard 45-70 reamer when it should not have. That would indicate why the gun was "affordable" to you. 26 twist barrels were made extensively by or for the winnie lever gun in 45 colt. Because you already have a standard 45-70 for 1000 yards, why not get rid of that freebore in this gun just for 300 yard shoots? Thataway you could have it reamed properly for a shorter case length as well as getting rid of that freebore entirely. Another consideration, what is the land/groove dimensions in that barrel? The newest Winnie 45 colt barrels are 451 with chambers meant for 456 boolits. Those chambers are too large for 45 colt cases, and won't be for 45-70 cases when chopped off to 45 colt magnum length (454 Casull). ... felix