Tuning up a revolver for lead.

[noylj]

TiteGroup burns very hot. Try to hold a case that was just fired and compare to other powders. Must be a lot of NG in the powder.
The slug should be way oversized--I use .360 for .38s and 9mm. Look and see if the high spots look like they were actually dragged through the groove or missed it entirely.
Personally, a .355 groove diameter sounds pretty good for .38 shooting lead bullets.
In general, I found a 0.357-0.358" jacketed and a 0.359" lead bullet are pretty good universal sizes.
The SAAMI spec for .38 special groove diameter is 0.355" +0.004/-0.000", so 0.355" is in-spec.

 

[smovlov]

I have good news...

The good news is I'm consistent. The strange news is the barrel still slugs at .355". I used a lead fishing weight cast in an old .38 case. filled it almost to the top. Hammered it down a little. I got about .330" of engagement with the rifling. I also had a large ring pop off the top after the whole slug got in the bore so I know it filled the grooves. I measured two ways. One was with the aluminum can wrapped around the slug and the other was with rolling the slug in the calipers. I did the aluminum trick first and the rolling second. The calipers are Mitutoyo 505-101 from the 70s. The measurements were within .0005 of each other.

I double checked the bullets and they are uniformly .357" which is what is marked on the box. I asked at the shop why (where they cast and size them) and I don't remember getting a clear answer.

I picked up some HP-38 and loaded some up but haven't gotten the chance to shoot yet.

The slug also slips through the chamber throats without resistance. A bullet will not slip through. My guess is the throats are around .356".

Does anyone have a V-Block Mic? I really want to see if I'm messing up here. I know its within SAMMI spec but it just seems weird.

I'm in grad school now so that's why I haven't updated anything. Busy busy busy. Thanks again for all the help!!!

 

[USSR]

smovlov,

Doesn't really matter what your barrel dimensions are, lead bullets will easily slug down to what they need to be. Instead of doing all this measuring and remeasuring, just get yourself some bullets sized at .358" made of an alloy with a BHN of < 10.

Don

 

[Arkansas Paul]

^ Do like Don said.
Your bullets are either too small or too hard, or maybe both.

 

[918v]

R U measuring with the thin or the thick part of the caliper jaws? If the thin, then you are gonna have errors. I also think your barrel is .357" and your throats .358". It might be slugging smaller due to a constriction near the forcing cone, though. Can u feel one?

A soft bullet will overcome this cuz it will obturate past the constriction. Also, if you cast your own, use the NRA 50/50 formula. It's better for target loads than commercial lubes.

 

[smovlov]

R U measuring with the thin or the thick part of the caliper jaws?

I am measuring with the thick part of the calipers. I couldn't discern a constriction before the forcing cone. Not saying there is not one, I just cant feel it.

Your bullets are either too small or too hard, or maybe both.

Bullets measure out to .357". Probably too hard for .38 velocity.

Instead of doing all this measuring and remeasuring, just get yourself some bullets sized at .358" made of an alloy with a BHN of < 10.

I feel ya Don. If I cant get them to shoot right out of the .38 Ill reserve the ones I have for .357 loads and get some wadcutters for the .38.

Everyone keeps telling me its not .355" so I feel like I'm doing something wrong. Just trying to see if its the gun or me. I have plans on shooting lead out of a few guns so I'm trying to check my methods and get everything right.

Thanks for the input everyone.

 

[918v]

I am measuring with the thick part of the calipers. I couldn't discern a constriction before the forcing cone. Not saying there is not one, I just cant feel it.

If you can't feel it then you prolly don't have one.

Try the softer bullets and the 231. Should solve the leading problem.