Noob question; 357 mag cylinder

[garth64]

I fire only 357 from my revolver; this is a new gun, about 500 rounds through it; the cylinders appear to be stepped at the junction between bullet and case; is this the way it should be or is the step I see a build-up of carbon? Thanks.

 

[diamonback68]

There was always a "step" there as you put it, you just probably never notice it before it started to build up carbon. Give it a good cleaning and you will see it more clearly.

 

[Gun 4 Fun]

I fire only 357 from my revolver; this is a new gun, about 500 rounds through it; the cylinders appear to be stepped at the junction between bullet and case; is this the way it should be or is the step I see a build-up of carbon? Thanks.

Welcome to the forum!

That step is called the throat, and it is supposed to be there. If it wasn't, your gun wouldn't shoot worth a hoot.

The chamber has to be slightly bigger than the outside of the case to allow them to chamber, but the bullet fits inside the case, which means it is smaller in diameter than the case. The throat is normally reamed to be the same size as the bullet itself, or with in a thousandth or so of nominal bullet diameter (.357" diam. bullet= .357-358" throat etc.), which greatly improves accuracy by starting the bullet straight in line with the forcing cone/bore. If it were the same diameter as the rest of the chamber, bullets would come out of the case when fired and would get tipped before starting into the forcing cone at the rear of the barrel, which would ruin accuracy.

You won't see that step in a .22 rimfire revolver because the bullets are the type that are called step heeled, and while they seat inside the case, the overall diameter is the same as the outside of the case itself. Rimfires have a tapered chamber/throat that isn't visibly noticable, but can be felt when pushing a snug fitting patch through while cleaning. The chamber tapers down to the exact size of the bullet (since the chambers naturally have to be slightly larger than the cartridge to allow easier chambering of the case), which aligns it with the forcing cone and bore.

 

[garth64]

Thanks for the info!

 

[diamonback68]

G4F, you are the greatest!
I tend to give the short and sweet answers, but you give them the whole nine yards. Great explaination.

 

[Gun 4 Fun]

That's very kind of you to say Dick.

I just remember when (yea, I can remember way back then still) I was just starting out learning about guns. I would have appreciated someone giving me info on things I didn't understand, so I try to do the same for those that follow. I thought it might help out some others that are new here too.