Twist rate for 500 grain 45 caliber?

[oldred]

Unless I am mistaken 1-18" to 1-22" seems to be the most popular for BPCR rifles chambered in 45/70, 45/90, etc but how would a 1-14" twist work with 500+ gr cast at BP velocities? The reason I ask is that I have the opportunity to acquire a Shilen bull barrel blank at a really good price but it's a 1-14" twist, I think this is for the likes of the 458 WinMag, 458 Lott and such. Apparently this twist rate must be about ideal for 500 grain jacketed bullets at Magnum velocities but since I have no interest in such high powered rounds and if that rate is too fast to work well at BP velocities I probably would just pass on it if it's not suitable for BP cartridges, any thoughts on this?

[ColColt]

My browning 1885 BPCR 45-70 has a 1:18 twist and does superb with bullets like the Lyman 457125 and a Brooks' Postell 530 gr. In fact, it does better with those two than with lighter ones so, it seems to me a somewhat faster twist would do great with even heavier ones. A 1:16 should work fine but, 1:14 I couldn't guess.

Just my 2 cents.

[Gunlaker]

From what I understand, the fast twist in those rifles is to help ensure good penetration. i.e. to help prevent the bullet from tumbling after it's penetrated the game animal.

With respect to accuracy, I have a 1:16 twist .45 cal rifle that is very accurate. Maybe 1:14 would be too.

Chris.

[John Boy]

any thoughts on this?

Yes, put this link in your references and in case you have a question on stability in the middle of the night, you can do your own calculating ...
http://www.jbmballistics.com/ballist...culators.shtml

[kokomokid]

I know several Texas boys shoot 16 twist by 525gr postel and are very accurate at the ram line but have problems with pigs.

[oldred]

I called him back just a bit ago and told him I decided that with that fast twist the barrel probably didn't suit my purposes, it's just too much work to fit the thing only to find out it was a bad choice just to save a few bucks. He told me he was having second thoughts about the swap anyway so I guess at this point I will never know for sure how well it would have worked.


BTW John Boy, thanks for that link I have been playing a bit with the calculators there and I found it to be VERY interesting!

[rfd]

i believe that a 1:18 for a .45-70 can cover a fair range of boolit weights (400-530) for real long range shootin'.

[Tackleberry41]

It would depend on the bullet. I have been using the Lee 500gr, long and pointed, out of an H&R. I plugged it into jbm ballistics computer and at the subsonic velocities I was using, it was right at the edge of stability, at range you would probably have issues. I put a faster twist green mountain barrel in a stub, have 2 barrels, the fast twist for the heavy slow 500, and the regular barrel for everything else.

[JSnover]

Nose profile matters. The twist rate is determined by caliber, velocity, and projectile length. A wadcutter would be shorter than a 3r ogive of the same weight. Fired through the same barrel, best velocity would differ for each one.

[rfd]

in the long run, it'll always come down to trialing a whole buncha cartridge ingredients - bullet, brass, primer, powder, charge weight/volume, oal, neck tension, etc etc etc. change one parameter and it could be a whole new and challenging ballgame.

i don't generally like lee moulds, but have also had good results with their 459-500-3r ...

[Tackleberry41]

^^^^ This what I use, alot of lead tho throw at something. But will only work in a single shot.

[rfd]

dat's my medium size 500 grain boolit ... for reaching waaaay out i use a 532 grain postell, lyman #457132. rolling block & sharps, each with 34" barrels, 1:18 twist.

[oldred]

Rfd, that Lee is the one I use mostly because I got impatient waiting on a Sharps chamber 45-90 reamer to become available and just settled for a Winchester chamber, this chamber requires most 500 gr+ bullets to be seated too deeply but the 3R seems to work quite well. I have heard a lot of negative and not much good on the Lee design so would be interested in any impressions you might have on it, I shoot it in a 32" 1-18" twist Green Mountain cut rifled barrel.

I have intended for a while now to rechamber this rifle to 45-110 in order to correct the mistake I made by using the Winchester chamber that was meant for a shorter COL, might get around to it some time soon but as for now I am getting decent results with the Lee design.

[rfd]

i have best casting results with the 500-3r by using one of the double cavities, the front one - it should never have been offered as a double cavity mould, imho. with 1:20 or 1:30 alloy it drops at .459", i just dip lube and it's ready for loading.

[ColColt]

My most accurate bullet is the Brooks' 530 gr Postell with 64 gr of Swiss 1.5 with a .030" wad. If I'm seeing good that day and do my part it's given me some sub 1" groups. The Lyman 457125 is next in line for accuracy. That's in a Browning BPCR with 1:18" twist.

[brad925]

I have a 1-20 twist in my Cimarron hi-wall and it loves everything. Lees 405 HB, Lymans 530gr, saeco 528, and even the 405hb I modified to a flat base that weighs in at 418gr. All with wws. And all will shoot one ragged hole with imr 3031, 4198, and pyrodex. Not tried black yet but I will if I ever run across any to try. Its nice in these times of having trouble finding powder to have a few options. Would like to try lees 500gr mold too.

[montana_charlie]

I called him back just a bit ago and told him I decided that with that fast twist the barrel probably didn't suit my purposes, it's just too much work to fit the thing only to find out it was a bad choice just to save a few bucks.!

Probably would have fouled more, too.

CM