38-55 chamber questions

[milsurpcollector1970]

I am building a 38-55 rifle on an Enfield action and I am to the point where I will be renting the reamer.

4D offers two, A .395 neck and a .400 neck.

Which one do I get? I bought a bunch of Starline brass so that's all I will be using. I have the RCBS cowboy dies.

I have not gotten a a boolit mold yet. I will have Accurate make me one when the time comes.

The barrel is a McGowen 1-16 the other choice was 1-22 which I though was a little slow.

I will post pics when its done

[Scharfschuetze]

Do you have dies yet? If so, I'd load up a round with the diameter of the boolit you plan to use and then measure the outside diameter of the loaded round's neck around the boolit. Use that measurement as a guide for which reamer to rent for the brand of brass you intend to use.

That sounds like an interesting project so please keep us updated. That might be something that I'd like to try down the road.

[rbertalotto]

You need to slug that barrel to determine what diameter bullets you will be using. Some grooves are upwards of .381. The reason for two neck sizes is to compensate for this wide variation in groove diameter of the 38-55.

If your groove diameter is large, you want the .400 neck reamer. If you go to the smaller reamer with a large groove diameter the rifle will not shoot and lead up badly.

Hope this helps.

[Mk42gunner]

Sounds like good advice so far to me.

Knowing for certain what the groove diameter is and the neck diameter of a loaded round will allow you to make an informed decision, instead of guessing; or even worse saying "I should have rented the other size reamer."

Robert

[TXGunNut]

McGowan site lists bore dimensions of .375 groove/.368 bore.

[captaint]

If I were in your shoes, here's what I would do. It would be pretty common to cast a boolit at
.377 for a .375 groove diameter. Brass + .020. Now you're up to .397. Yes, I would go with the
.400 reamer. You're gonna love the 38-55. Mike

[NVScouter]

Single shot or think it'll feed from the magazine?

[Mohillbilly]

If your building , look into chamber length as well as neck dia. Starline also makes different lengths brass .

[milsurpcollector1970]

Well I slugged the barrel and it measures .373 in the grooves. I went with the .395 reamer. I guess I will rent the other one too If I cant get the rounds to chamber.
I got the long brass from starline. Not sure what the reamer is.

Right now its a single shot. im not real good at metal fab. I would love to at least have a 4 shot