Tight chambers in Ruger .357 / 9mm convertible (9mm cyl is tight)

[Buzz64]

Have not been able to chamber any reloads in my 9mm cylinder. Tried 3 different shapes, rn, tc and cone. All chamber fine In shield and CZ but then semi autos are usually looser. Ruger says if it chambers factory (which it does) then they can’t help - sure they aren’t eager to facilate reloading use.
So, do any of our fine members do chamber reaming/honeing or know of someone who does? I would send samples of cartridges (inert but full length and sized) with cylinder to check fit. All boolets are sized to .356.
Thanks

[DougGuy]

You are welcome to send the cylinder and let me get the pin gages to it and get some hard measurements, then decide what can be done to rectify the problem. Send a PM.

[Wayne Smith]

Doug is the guy. He knows that of which he speaks. Do a search of some of his posts and you will be convinced too. Those of us who's guns he's worked on will probably stretch across a small state!

[tja6435]

I have trusted Doug to throat my Freedom Arms cylinder, I'd send him my Ruger cylinders in a heartbeat. In fact, I just got a new cylinder fitted to my .44 Super Blackhawk and it'll go to Doug if the throats are smaller than the throats in my Redhawks.

[KVO]

Had to open up the throats on the 9mm cylinder of my 9mm/357 convertible flat top Blackhawk as well. Chambers themselves were rough and benefited from polishing. I was thinking the 9mm cylinder would be a pliker and junk ammo disposal system. Nearly pooped myself at the groups that 9mm cylinder shot- smaller with my standard 9mm boolit load (.358" 125-135gr RNFP, 4.5gr Unique mixed range brass) then my carefully worked up .357 loads & Starline brass! Good chance you'll like your new set up once it's properly tuned.

[Ed_Shot]

Doug did a fine job of reaming the throats of my Blackhawk .357/9MM to .3585. I size both 38/357 and 9MM to .358. I'm not saying you would not benefit from having Doug work on your cylinders but I believe you are probably going to have to load to a shorter 9MM COAL than you use for your auto's. Read the excellent article by Mr John Goins / aka beagle titled "Cast in the 9mm Blackhawk Convertable". It may be here but I found it at CASTPICS.COM. YES....I hate to reload specially for a single weapon but the Blackhawk is a real winner with 9MM. As example here are the COAL's I "have" to use in my Blackhawk 9MM cylinder (all sized .358). Like you, my CZ and Glock will take longer COAL's with no problem.

358242 (120 gr) -- 1.060"
356401 -- 1.100"
356-125-2R -- 1.055"
356-120-TC -- 1.050"

[Buzz64]

Thanks all -

DougGuy, PM sent.

Ed Shot - what does the shortened OAL on your 356-125-2R and 356-120TC do to chamber pressures? If I remember right the 356-120-TC is 1.110 in the book for OAL.

[Outpost75]

Best NOT to seat bullets shorter, because Buzz64 is correct, it will spike pressure.

The Ruger revolver is strong enough, but if one of those loads gets into your autopistol it will take it apart.

My Ruger 9mm Black chambers with .358 throats enable me to seat bullets out to standard OAL. Accurate also has some designs which are specific to 9mm revolvers having tight throats, having a reduced diameter forepart with "tolerance negative."

[DougGuy]

Yep the cylinder is just a mechanical guide, a feeding tube if you will, from the case mouth to the bore. It should be "dimensionally correct" to do this job. The proper thing to do, is to size the cylinder to fit the boolit, NOT the other way around. This way, the boolit will be .001" to .002" greater than groove diameter, and the cylinder should be .0005" to .001" greater than boolit diameter.

This arrangement works really well for pretty much any revolver. It benefits everything and detracts nothing. It prevents pressure spikes due to the boolit meeting resistance in the throats, it reduces leading, it GREATLY promotes accuracy because the boolit is delivered to the bore at advertised diameter, NOT throat diameter which regardless of what you size to before firing, boolits fired through tight throats will exit the front of the cylinder at throat diameter. It also helps accuracy to have the round chambered with the boolit snugly in the throat as this lifts the cartridge and holds it concentric with the throat instead of it laying against the side of the cylinder and the boolit being crammed into that sharp ledge that the case headspaces on and possibly becoming somewhat deformed upon firing.

[runfiverun]

if I was gonna send the 9mm cylinder I would also send the 357 cylinder.
it might not 'need' anything but then again it might need cleaned up.
having both cylinders cut the same would sure be helpful.

[Ed_Shot]

Thanks all -

DougGuy, PM sent.

Ed Shot - what does the shortened OAL on your 356-125-2R and 356-120TC do to chamber pressures? If I remember right the 356-120-TC is 1.110 in the book for OAL.

Lyman's 4th Ed CB Handbook spec's 9MM COAL of 1.110" for their 356402. My 356402 is .624" long which means at a COAL of 1.110" there is .264 of the boolit inside a .750" long 9MM case. My 356-120-TC is .560" long and is the same weight and same bearing surface length as the 356402. You can load the 356-120-TC to a COAL of 1.046" (a seating depth of .264" given a .750" long 9MM case) and have the same boiler room and pressure for a given load using data for 356402. The same math applies when comparing Lyman's data for the 125 gr 356637 and the 356-125-2R. The shortened COAL loads for my Blackhawk show no pressure signs in the Blackhawk or in my 9MM autos.

[fredj338]

Best NOT to seat bullets shorter, because Buzz64 is correct, it will spike pressure.

The Ruger revolver is strong enough, but if one of those loads gets into your autopistol it will take it apart.

My Ruger 9mm Black chambers with .358 throats enable me to seat bullets out to standard OAL. Accurate also has some designs which are specific to 9mm revolvers having tight throats, having a reduced diameter forepart with "tolerance negative."

It may or may not "spike" pressures, just depends on the powder & the load range & how much deeper you seat the bullet. It isn't an automatic event. OAL is greatly misunderstood by many reloaders.

[Outpost75]

It may or may not "spike" pressures, just depends on the powder & the load range & how much deeper you seat the bullet. It isn't an automatic event. OAL is greatly misunderstood by many reloaders.

I can tell you from personal experience, and Alan Jones at Speer can confirm, that factory 9mm Parabellum loads which tested 28,000 cup spiked dangerously above proof pressure when bullets were purposely reseated only 0.030" deeper. They mention this in the description of the 9mm Para cartridge prior to the data section in the Speer handbook.

As for my personal experience, running "accelerated endurance tests" on 9mm pistols, which normally is done with 364 M905 High Pressure Test rounds, which we didn't have, it was determined experimentally that by reseating the bullets on M882 service ammunition deeper, by only 0.020", that the sample average pressure was raised to 3050 bar (44,200 psi), but care had to be taken not to exceed 0.025" as pressure increased to 50,700 psi, at the upper envelope for M905 HPT rounds and we didn't want to void our test results...

At .030" deeper pressure soared to 62,000 psi!

The pressure specs for US military 9mm ammunition are:

CARTRIDGE, 9 MM, BALL, NATO, M882
Type Classification:
HQDA (DAMA-CSM), dated 15 April 85.
Use: Pistol, 9 mm, M9. The cartridge is intended for use against personnel.
Projectile weight................................112 gr

Performance:
Case mouth pressure ........................31,175 psi (avg),
36,250 psi (max)
Velocity ............................................1263 ± 5 fps, 15 ft
from muzzle

CARTRIDGE, 9MM, HIGH PRESSURE TEST, M905

Type Classification:
HQDA (DAMA-CSM), dated 15 April 85.
Use:
Proof testing of M9 pistols. The cartridge is intended for use in proofing new pistols and test barrels to
demonstrate safety prior to releasing weapons to the field.

Performance:
Chamber pressure ............................50,000 psi
Velocity ............................................. NA

So seat deeper at your own peril!

[runfiverun]

do it on top of titegroup and you won't need to send the cylinder anywhere....
it'll get there on it's own.

[fecmech]

Ed Shot - what does the shortened OAL on your 356-125-2R and 356-120TC do to chamber pressures? If I remember right the 356-120-TC is 1.110 in the book for OAL

The devil is in the details. The Lee 120 TC has a shorter overall length than the Lyman 356402 due to a longer more pointed nose on the 356402. The bearing surface length and weight are the same. When the Lee bullet is seated to 1.050 you have the same case capacity as the Lyman@1.110 and with the same bearing surface and weight I would expect essentially the same pressure. I see no problem here.

[Larry Gibson]

It may or may not "spike" pressures, just depends on the powder & the load range & how much deeper you seat the bullet. It isn't an automatic event. OAL is greatly misunderstood by many reloaders.

I concur based on having measured the psi's of the 356-120 and other cast bullets seated to various depths in various cartridges. The problem with the Ruger cylinder is the tighter chambers as mentioned by the OP. My experience with Ruger 9mm cylinders is a chambering problem is more related to insufficient FL sizing of the case or insufficient taper crimping to close the case mouth flare. I never had a problem with bullets sized .356. I even shot many 358156s sized .356 and seated out so the case just covered the lube groove.

I seat the 356-120-TC at 1.083 in the 9mm. I've shot I don't know how many thousands of them along with Lyman's 356402 (sized .356 or .357) in numerous handguns and subguns. They were loaded over 4 gr Bullseye, 3.7 gr Titegroup or 4 gr Red Dot. Years back I had a Ruger BH convertible and shot a lot of them through it also. Never had any 9mm go anywhere by itself with those loads......

BTW; "pressure spikes" are either indicative of a problem or are a problem. Merely raising the pressures may be a problem only if the pressures are raised too high. Otherwise "higher pressures" are just that.....higher pressures. If those "higher pressures" are within the normal range of acceptable pressure for the cartridge a "higher pressure" should pose no problem in and of itself. Pressure spikes are distinctly different than higher pressures. Varying seating depth can indeed give "higher pressures" but unless the bullet is seated very deep the rise in pressure with cast bullets is not near what it is with jacketed bullets.

The use of 9mm in a revolver cylinder provides an addition "fudge factor" because the cylinder throat is essentially a very long "freebore" which doubles (+/-) the internal expansion before the bullet enters the barrel and engages the lands. Thus the pressure created by the cartridge will be considerably lower due to the increasing expansion in the revolver "chamber throat". That "chamber throat" area is a lot different than the chamber/throat in a pistol with a jacketed bullet running into the lands after a mere .03 " of travel. The time pressure curve will be much lower and longer in the revolver cylinder vs what it is in the pistol barrel.