I havent cast the chamber. I have forced a "dummy" round in to get an idea of how much additonal freebore is needed:



This was before the first and second reaming pass. I need to do a new test like this and see where I am.

Quote from: sqlbullet on September 01 2016 08:17:40 PM MDT
The reamer recuts the throat as it extends the freebore.  The concern I have is the longer the jump for other bullet profiles, the more time for the bullet to enter the rifling out of true.

Thanks for the feedback.  I think I will stew on it a bit more.  Perhaps I will just wait until the gun has a couple thousand rounds thru it and the throat is getting eroded and then clean it up.

Revolvers have a long free-bore, and they are accurate.


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Wow. How deep is that groove? Is your 225 JSP a tangent or secant ogive? If secant, you may have to choose one or the other, as the JSP won't likely ever normalize if you correct for the thumpers. Maybe if it's tangent. What's your COAL and pull length? Are you committed to the 225 JSP? There may be much better options available to maintain the versatility.

I am not really committed to jcaketed bullets at all.

I have a new mold inbound that is a 280 grain spire point plain base from NOE.  I will probably see how it does, then decide if I am going to push the freebore on out.  I really intended this gun to shoot powder coated lead, not jacketed.

So....I guess i have answered my own question. Keep cutting.  If I have to choose between jacketed and cast, I will choose cast.

I have used both dedicated throat reamers (tapered lead into the rifling) and chucking reamers (almost a 90 degree step into the rifling from free bore) to lengthen the throats in my barrels and have no issue on cast bullets with either.  I did shoot about 200 jacketed bullets on the chucking reamed barrels before I went to cast in an attempt to smooth the surface a bit.