1973 Ruger Blackhawk chamber length

[Catpop]

Through the course of running some 100k reloads through my .357 Blackhawk I found all the chambers are not the same length. I ran across this recently when loading some Missouri Bullet Co 158 gr LSWC bullets. I found that in order to properly put the crimp behind the front driving band the OAL came out at 1.602 instead of a max 1.590. This did not concern me, but the fact the cylinder became hard to rotate did.
It was discovered the cylinder became hard to turn as the longer rounds were forced forward as they came into line to fire. Funny thing two of the cylinders worked fine. I reduced the OAL to 1.590 and everthing was fine EXCEPT I was crimping into the front driving band and not behind it.
This is not a Ruger problem as it works fine with 1.590. Its just a problem I have with the Missouri bullets.
I could extend the other four cylinders to make them all identical
Or I could use a different bullet. I'm doing a lot of thinking right now.
Is this different chamber length or crimping into the front driving band going to affect accuracy?
WHAT DO YOU GUYS THINK?

 

[murf]

i don't think the problem is chamber length, but chamber diameter. when you load a .358" diameter bullet and insert it into a .356/7" chamber throat, the round will not fully seat and drag on the recoil shield when indexed with the barrel. you probably have a variety of chamber throat diameters in that cylinder.

suggest you measure all the throats for diameter to eliminate this problem. if there is a problem with the throats, you can call ruger and see if they will replace the cylinder. they replaced mine!

murf

 

[rcmodel]

+1

Chamber throat size in too tight in some of the chambers.

It has nothing to do with chamber length.

Try to push a bullet through all six chamber throats.
I bet they will go through some, but not the others.

rc

 

[Catpop]

Tx, I'll try that next and report back. Catpop

 

[Catpop]

I tried that with miked .357 jhp of three different brands I had on hand. They easily passed through, but not sloppily. That was the largest one I had at my disposal.
I then tried the Missouri bullets. They were a no go in any of the cylinders. I then FINALLY miked them. They are .359. And hence my problem as you guys said. Small throat or too big bullet.
Next step is to chamber cast all six chambers to see what the throats actually are.
I'm thinking if it is .358 then Ruger did a good job---correct?
I didn't have this problem with OT bullets, but I don't have any left to mike or test. Anyone have any OT they could mike for me?
I let you know more as it develops----Again thanks for the help!

 

[Blue68f100]

May want to check for a lead ring in the cylinder too. Does not take much to change the length. Normally this only applies to those shooing 38spl in a 357mag. But you can leave lead slivers from the reloading process if your not flaring enough.

 

[Catpop]

Cylinders are clean as a whistle. Tx Catpop

 

[Catpop]

Got chance to chamber cast throats last night.
All measure within a .0001 of .3583, so I feel Ruger did a good job back in 1973 if they were trying for .358.
I guess this exercise provided some good insight into problems that may arise with oversize cast bullets.
My next step is to swage my remaining (100 or so) Missouri bullets to .358 and check those results.
More later and thanks for all the help. Catpop

 

[Catpop]

I swaged up a few .359 to .358 and loaded them up.That eliminated 95% of all problems even loaded out to 1.600, which is as short as I can go and crimp just behind the front driving band. Case is trimed to1.280. Give range report next.