Twist Rate?

[Hylander]

So thinking of getting a GM drop in barrel in 50 cal.
These are 1:70 twist and 32" long.
I am thinking this might be a tad slow for 50 cal. for best accuracy.
Your thoughts?

Also I like a 28", so I was thinking cutting it down a few inch's.

 

[Greasecookie]

I have one in my T/C Hawken, great for round balls, too slow for conicals.

 

[Hylander]

I have one in my T/C Hawken, great for round balls, too slow for conicals.

Any idea what kind of consistant repeatable accuracy you get at 50 and 100yds.

 

[longcruise]

Now, I'm not sure about this, but I think the gm 50 drop ins are 1:66. The 54s are definitely 1:70.

 

[Hylander]

Now, I'm not sure about this, but I think the gm 50 drop ins are 1:66. The 54s are definitely 1:70.

Not sure, TOW advertises 1:66 but GM says 1:70 for a 50 cal.

 

[Loyalist Dave]

So thinking of getting a GM drop in barrel in 50 cal.
These are 1:70 twist and 32" long....,Also I like a 28", so I was thinking cutting it down a few inch's.

Well if you do then you're pushing towards less accuracy...though it should not matter if you're shooting at 100 yards or less. Plus there is a difference between the accuracy needed for hunting, vs. cutting the 10/9 ring at 100 yards on a target.

With that slow a barrel, you're also probably not going to find a "light" load that gives you a good group, but recoil will be "felt" less by you with a good hunting load.

LD

 

[TreeMan]

Well if you do then you're pushing towards less accuracy...though it should not matter if you're shooting at 100 yards or less. Plus there is a difference between the accuracy needed for hunting, vs. cutting the 10/9 ring at 100 yards on a target.

With that slow a barrel, you're also probably not going to find a "light" load that gives you a good group, but recoil will be "felt" less by you with a good hunting load.

LD

I have a 42” slow twist GM barrel on my 45 mountain rifle. I tried light loads for target shooting. I shot a 100 rounds experimenting with patches and lube and never could get it to group for spit. When I worked up to 75 grains of 3f Goex she shot one hole groups at 50 yards. I use Dutch’s dry patch system too.

 

[Grimord]

Slow twist barrels with deep rifling generally require stouter powder charges to get their best accuracy, but once you find the sweet spot, they generally are tight shooters. I have found that once I find the sweet spot on my slow twist rifles that 1/2 of the accuracy load usually makes a good plinking load out to 25 yards or so.

 

[ugly old guy]

1:60 to 1:70 is "correct" for patched round ball, regardless of caliber, and will deliver fine accuracy - so long as you are shooting PRB and do your part.

If you intend to shoot conicals or sabots, you will not be happy with the accuracy of a slow twist barrel, again, regardless of caliber..
A 1:66 to 1:70 twist is not fast enough to stabilize a conical bullet.

In 1987/1988 I had a CVA .45 caliber (percussion) "Kentucky" rifle, 33.5 inch barrel, 1:66 twist. With 120 grains Fg (1F), it would put a .440 patched round ball inside 1 inch at 100 yards all day long, with the standard iron sights.
I never should have sold that one.

 

[Loyalist Dave]

1:60 to 1:70 is "correct" for patched round ball, regardless of caliber, and will deliver fine accuracy - so long as you are shooting PRB and do your part.

If you intend to shoot conicals or sabots, you will not be happy with the accuracy of a slow twist barrel, again, regardless of caliber..
A 1:66 to 1:70 twist is not fast enough to stabilize a conical bullet.

USUALLY.... OR most commonly

See There are exceptions to the rules. For example 1:56 works quite well with bores from .45 to .54...and Colerain makes them that way. Plus most of your .40 caliber barrels for round balls are 1:48, and a lot of states allow .40 for whitetail.

THEN you have the 1857 Wurttembergischen with 1:55, the 1861 Springfield and the 1862 Richmond with a 1:72, and the 1854 Lorenz with a 1:78 and the reproduction the Enfield 1853 "three band" muskets, which are used for NSSA target shooting competitions...with a 1:78 twist rate barrel. and all of them use conical Minie balls.

LD

 

[nkbj]

Been wanting to try a paper patched .454 hollow base in the .46 bore flinter with 56" twist, not that it could take the place of revolver ball that the rifle was bored for.

 

[Bad Karma]

USUALLY.... OR most commonly

See There are exceptions to the rules. For example 1:56 works quite well with bores from .45 to .54...and Colerain makes them that way. Plus most of your .40 caliber barrels for round balls are 1:48, and a lot of states allow .40 for whitetail.

THEN you have the 1857 Wurttembergischen with 1:55, the 1861 Springfield and the 1862 Richmond with a 1:72, and the 1854 Lorenz with a 1:78 and the reproduction the Enfield 1853 "three band" muskets, which are used for NSSA target shooting competitions...with a 1:78 twist rate barrel. and all of them use conical Minie balls.

LD

Generally... usually, gotta love those words. Really like the 1 in 60 twist in my .54 and .58 Hoyt rifles. Both are accurate with modest powder charges while a slower twist such as 1 in 72 or 90 or some such, might require a much heavier charge for best accuracy. My combo twist Thompson Centrr rifles can also be accurate with lighter powder charges under a patched ball and much heavier charges under a longer bullet. Dedicated bullet shooters have similar rules of thumb depending on the length of the projectile, the speed at which it’s intended to be fired, and possibly the phase of the moon. And then of course smaller projectiles require more spin than than larger. Usually...

Sam Fadala has an excellent treatise on the subject in one of his Black Powder manuals.

 

[Loyalist Dave]

Generally... usually, gotta love those words. Really like the 1 in 60 twist in my .54 and .58 Hoyt rifles. Both are accurate with modest powder charges while a slower twist such as 1 in 72 or 90 or some such, might require a much heavier charge for best accuracy...

Yes it's odd since those rifled muskets mentioned in my reply and shooting Minie Balls with like 400+ grain projectiles are accurate at long ranges with something like a 60 to 70 grain load. My 1:56 Colerain barrel with a .530 round ball weighing a mere 224 grains shoots really well at 70 - 80 grains. Some of the folks like using loads around 90 grains for their round ball rifles....

LD

 

[rich pierce]

My .58 has a 1:56” twist (custom) so I can shoot it accurately with a comfortable load.

My over the log .50 heavy rifle has a 1:72” twist and likes 120-140 grains. But at 25 pounds it’s more of a shove than a kick.