Factory Cylinder Throat & Bore Specs - Your Findings & Experiences?

[Bigslug]

Hoping for some self-enlightenment here. If I pull off a forum public service coup, better still.

I'm curious to know what those who have thoroughly gauged out their revolvers have found. With regards to:

Make
Model
Caliber
Approximate production date

And what did you find, with regards to:

Throat diameter
Bore diameter
Problems & solutions to them (such as tightness at frame/barrel junction, needing to bore throats, replacement of cylinder etc...)

My purpose in this? We get a lot of threads with regards to causes of leading, or asking about formulas for best accuracy, or getting started with a minimum amount of bother and equipment. We also have folks who are newcomers to reloading boolits; looking to feed a multitude of same-caliber guns; or trying to find an easier, less technically-involved answer.

Entering into this with an understanding of that each gun has its own individual quirks that may put it outside any norm, I'm hoping this thread will start to show patterns. These patterns may be useful in determining diameters when ordering custom molds or sizing dies, outlining what to expect from a new purchase, or may illustrate certain production ranges that should be eagerly sought or desperately avoided.

Take it away, Village Elders!:drinks:

[Ron Williams]

Hi Bigslug I've got a colt SAA 45 I bought about ten years ago. The barrel slugged .451 and I just slugged the cylinder at .457. Even with soft bullets sized .454 I get leading. Thinking about rebuilding to 44WCF.
Ron

[Outpost75]

I can tell you that with Rugers they can vary all over the map, dependinf upon when they were made.

My .45 New Model Blackhawk convertible has .4505" groove diameter and .443" bore. Cylinder throats on the. 45 Colt cylinder are .452" exactly and those on the .45 ACP cylinder are. 4515". Revolver shoots 1-1/2" groups with Saeco #954 in. 45 Colt sized. 452" with 6.5 grains of Bullseye, or in.45 ACP with H&G68 sizsd .451" with 4.5 grains of Bullseye. I'm very happy with the gun.

[Catshooter]

In my experience, and I've measured about 50 -60 short guns of mine over the years, you never know what you get until you measure. With a large enough statistical universe you may get patterns. But you can never tell from a general pattern just what you have without measuring it.

For a while I was into 357s. I've measured them from .355 Smith 686s (two of 'em) to a Ruger Blackhawk at .3598. Throats go from tiny to huge, regardless of caliber.

Not trying to rain on you idea, this is just what I've observed.

Ron Williams,

I have a Smith 25-5. Known for mismatched throats/bore and mine is no exception. Throats .456, bore .451. I bought an old Ideal 454424 and it drops .457 to .458 boolits, depending. I size mine to .457 and they chamber just fine and shoot with fine accuracy and zero leading.

Welcome to the forum too.


Cat

[Harter66]

The 76' RBH I had , had cylinder throats .454,.4535,.4535,.453,.453,.452 . The bbl was 452x445 w/the longer forcing cone and lead and next to zero thread choke.

With the chambers matched up via manual lapping to .4535+ the extreme flyers went away and groups closed w/o having to be certain to not load ''that'' chamber and be sure ''that'' chamber is 1st up.

[bbqncigars]

S&W 1917: .451" groove, .452" throats. Bowen 25-20 Blackhawk: .257" groove, .258" throats.

[Char-Gar]

1I have records on a hundred Smith and Wesson and Colt sixguns made over the past 100 years. In general this is what I have found.

1. Smith and Wesson 38/357 throats run .357 - .358 and bores .357 with a few going .356 and one going .355.

2. Smith and Wesson 44 Special and Magnum throats run .432 - .434 with bores of .429 on the older ones and throats of .430 - .431 with bores .430 on the newer ones.

3. Smith and Wesson 45 ACP sixguns run .455 - .457 in the throats and .451-452 in the bores.

4. Smith and Wesson 45 Colt sixguns run .457 - 458 in the throats and .451-452 in the bores. Beginning with the 25-7 Smith and Wesson tightened the throats to .4525 - .453.

5. Colt 38/357 sixguns are pretty uniform running .359 in the throats and .354 - .355 in the bore.

6. Colt 45 ACP (1917) sixguns run .456 - 458 in the throats and .452 in the bore.

7. Colt 45 Colt DA (New Service) sixguns run .456 - 458 in the throats and .452 in the bore.

You will always find individual handguns that will fall outside of these parameters.

I have not measured enough Colt SAs or 44s to offer an opinion.

I defer to Outpost75 for all things Ruger.

[bones37]

I agree with this statement wholeheartedly. I bought a New Model SuperBlackhawk last year(2012) with the intent of shooting my Accurate 432-250K boolit. Funny thing was, the barrel NEVER leaded once, However, the cylinder throat leade was what gave me problems. and FYI, graywolf, a member here had the exact same problem. Nevertheless, after contacting Ruger, they told me the newer production revolvers are chambered for use with J-word ammuniton, and NOT cast lead. I tried many different things to correct the problem, none of which worked. I eventually traded the SBH for a Smith 29-3 and magically the leading problem disappeared using exactly the same cartridges. I also used the exact same cartridges in a co-workers SBH produced circa 1997 with NO leading whatsoever. So it would seem to me that the older guns are more cast friendly.
I can tell you that with Rugers they can vary all over the map, dependinf upon when they were made.

My .45 New Model Blackhawk convertible has .4505" groove diameter and .443" bore. Cylinder throats on the. 45 Colt cylinder are .452" exactly and those on the .45 ACP cylinder are. 4515". Revolver shoots 1-1/2" groups with Saeco #954 in. 45 Colt sized. 452" with 6.5 grains of Bullseye, or in.45 ACP with H&G68 sizsd .451" with 4.5 grains of Bullseye. I'm very happy with the gun.

[Bigslug]

I also used the exact same cartridges in a co-workers SBH produced circa 1997 with NO leading whatsoever. So it would seem to me that the older guns are more cast friendly.

Comforting to hear, as the RH, SBH, and GP of my current / upcoming science projects are all children of the late '80's to early '90's when the old man was still in charge. We still miss you Bill.:cry:

Curious to hear from the Cowboy Action crowd to see if this holds true with the Vaqueros. Not a lot of jacketed going through those.

[Mal Paso]

Late S&W Cylinders are cut for jackets as well. The 2 629 revolvers I measured were .4275"-.4285" over a .429 groove. Common issue on the S&W Forum and not just 44s. Saw a thread here, a guy shooting a S&W 38 for years buys a new S&W 38 and the rounds won't chamber the last 1/8 inch. For those of us without a machine shop but some ability there are Manson Reamers.

'08 Redhawk has .432" throats .429 groove. .4325" is SAAMI Spec for throats in 44 Mag.

[C. Latch]

I have a very accurate 686 smith that put thousands of rounds downrange and I never thought to measure any barrel dimensions. It just flat-out shoots most anything I feed it.

I've been playing with a new (march 2013 production) Blackhawk lately, a SS bisley Blackhawk 5.5", and instead of going off of memory, I stopped and measured it before replying here. The front of the barrel measures .4490 to .4495 for all 3 measurements around the slug, the rear measures .4475 to .4490 (just in front of the forcing cone; the tightness in the last half-inch of barrel is obvious as you slug it).

Throats were tight and inconsistent when I bought it. Had cylindersmith.com fix them to .4525 before I ever fired the gun.

[bones37]

Mal Paso,
I'm glad You brought that up about the Smiths, I have a 629-6 that was doing the same exact thing as the Ruger SBH. The measurement I got from mine mirrored Your findings. I didn't know it was a common issue with late production Smiths, but good to know. I used a Manson reamer to "correct" mine, as very little metal was removed. However, it did correct the 'leade' angle enough that it stopped leading. I wish I had access to the reamer before I traded the SBH. Nevertheless, it's part of the process of learning, or so I keep telling myself.


Late S&W Cylinders are cut for jackets as well. The 2 629 revolvers I measured were .4275"-.4285" over a .429 groove. Common issue on the S&W Forum and not just 44s. Saw a thread here, a guy shooting a S&W 38 for years buys a new S&W 38 and the rounds won't chamber the last 1/8 inch. For those of us without a machine shop but some ability there are Manson Reamers.

'08 Redhawk has .432" throats .429 groove. .4325" is SAAMI Spec for throats in 44 Mag.

[Bigslug]

EDIT ON 8/27/13. Pin gauged all the throats last week. Going to give the oddities a serious scrubbing a try again. Got the friends together for a "slug fest" with all the bores. All the .357's and the Smith .44 have offset lands and grooves, so I'm waiting for the USPS to bring me a V-block micrometer from the People's Republic of China

Two recent S&W 640-1's: .358" throats
1988 GP-100: .357" throats
Webley MKIV "War Finish": .360" throats. Bore grooves .359"-362" (yes that is strange, but it's clearly got one groove hitting farther back on the slug).

1993 Ruger SBH: .432" Fire lapped back in the day. .430" grooves
Mid-late '80's Ruger RH: .432" Also fire lapped back in the day. .4295 grooves.
1991 Ruger RH: Scrubbing all the chambers and running the pin gauges from the back shows a gun that WANTS a .432" slug, though complete pass through currently not possible on all holes. .4295" grooves.
S&W 629-6: .428" throats.

S&W 1917: .454" throats, .4505" bore
Cimarron Peacemaker clone: .452" throats. .453" pin very snug in two holes. .4505" bore.
Freedom .454": .452" throats. Not sure there's really a reason to slug something that well made. . .
Pair of 1917-dated Webley MKVI's: .449" throats on both. The unmodified .455 bore fired a slug into a collection trap that was .4515 on the grooves. The .45ACP modified one gave a groove spec of .447-ish" Got more studying to do on that one to see if the powder charge was too gutless to flare or if that really is the bore diameter.

[Kent Fowler]

Colt
Early Trooper with Python lock work (pre-MKIII)
All throats at .359. Measured using a Starrett #829C small hole gauge. (I prefer these gauges over a bunch of pins)
Groove Diameter, surprisingly, at .354.

Fire lapped 100 rounds as thread area was a tad tight. Then sent measurements to Veral for a 160 gr. FNGC mold.
He cut the mold to drop at .357
Have run some real heavy loads using water dropped ww's , WW296 and LBT Blue lube. Haven't experienced any
leading or accuracy problems.

[Bigslug]

Bump. Added some new data to the last post. Sized a NOE 429421 to match the .432" throat in the Redhawk. Sucker slip fit right in there like buttah. This learnin' stuff is COOOOOOOOOOL!