Rifling depth

[bigmike]

A gun I am looking at is a 1-in-48 twist,and the rifling is cut at .005 deep. Is that deep enough for a patched round ball? I always heard it needed to be deeper than that. Usually around .008 or deeper.

 

[Stophel]

That's pretty shallow... I'd prefer about three times that depth! (or even more!)

 

[jamesthomas]

I think It's too shallow. My G.M. has .12. I don't think the real thin patch you would have to use would hold up enough to give you a decent group to either target shoot or for hunting. What caliber is it?

 

[hanshi]

I have a rifle of extraordinary accuracy with rifling .006" deep. I don't like grooves this shallow but it sure does shoot with prb. I also load it fairly tight.

 

[Zonie]

Both the Thompson Center .50 and .54 caliber rifles have rifling that is .005 deep and their accuracy with a patched roundball is excellent.

Yes, I speaking of a tight ball/patch combination and a 70 grain powder load in the .50 and a 85 grain powder load in the .54 but IMO either of these powder loads are more than enough for most muzzleloading hunting situations.

 

[Ken Rummer]

I have the same experience. My most accurate ML is a Lyman Deerstalker in 54 cal. Twist is 1:48. The grooves measure .004 deep. I was disappointed with Lyman when I first measured it but I hauled it to the range and was pleased with the results.

I use 90 gr Goex 3F with OPW, .530 ball, .018 patch w/ Stumpy's moose snot. This loads easy and shoots three rounds into 1" at 50 yards.

 

[Dean2]

I agree with KV Rummer. Didn't know the grooves on my Deerstalker were that shallow, but it shoots the lights out with any load from 40 to 80 grains and I don't load it all that tight. .495 with .015 patch or .490 with .018 patch both shoot great with a wide range of powder loades. All that changes is vertical, group size doesn't move much.

 

[Stubert]

Traditionally, shallow grooves are for a conical or minnie.

 

[jerrywh]

In my opiniom Zonie is dead on the money. Do what he says. Tight patch and ball. 70 grs.

 

[Rifleman1776]

My preference is deeper.
But, I have used shallow groove barrels, mainly in my early years with CVA and TC rifles.
I was tutored by and old timer to use thin patching. I used airplane cloth quite successfully. Don't know if it can be bought anymore. But there are some thin, tough fabrics available. Get a tight weave. It is a starting over project finding the ball/patch combo that works best, but it can be done successfuly.

 

[nkbj]

As far as collective experience goes the best recipes for success with shallow and deep rifling should be available on this forum if anywhere.

 

[Greenjoytj]

1:45 twist rate look like a total compromise between a fast twist barrel specifically designed for conicals and a slow twist barrel for patched round balls.
I have no doubt it will shoot both types of projectiles well if used at the right velocity.
I care less about the rifling depth although very deep rifling in a prb barrel means more blow by gases due to the required thick patch and smaller ball diameter than a more tightly fitted ball with a thinner patch for shallow groove barrel.
My experence is with a Lyman GPR 54 flinter.
This rifle shot best with a tighter fitting prb combo.
my load is: 90 grs 2fg, .535" pure lead ball I cast in a Lyman mold, .017" cotton twil patch, over size 58 cal over powder wad.
This load is a bit hard to start into the muzzle but can be pushed down easly enough.

 

[Johnny Too-Tall]

Big Mike brother where have ya been havent heard from ya in a bit. Most mine are .012-.016 take care.

 

[Dphar]

A gun I am looking at is a 1-in-48 twist,and the rifling is cut at .005 deep. Is that deep enough for a patched round ball? I always heard it needed to be deeper than that. Usually around .008 or deeper.

I would not want one under .008 for cloth patched projectiles. For one thing it will start hard when loading. Over .010-.012 is not needed.

The best way to get a suitable barrel for a certain application is simply to BUY a NEW barrel specifically cut for that application. This saves an immense number of headaches and wasted money.
The other way is to ask an actual BARREL MAKER what they think.
.005 deep is probably button rifled.
Sounds like a shallow groove TC Hawken barrel.

Dan