Keylock-era Smith & Wesson revolvers

[fourarmed]

Hi guys, haven't been on the board in a while. Glad to see it's still golng strong.

I traded for a 625-8 "Performance Center" revolver a year or two ago. It is not an impressive shooter with anything I've tried so far. I had an opportunity to try it in a Ransom rest last week. The best groups were around 6" at 50 yards, the worst over a foot.

I finally did what I should have done long ago: I slugged it. The groove diameter is .454. The chamber throats are all .452.

The only other "new" Smith revolver I've slugged was a M69 that had exactly the same problem: .429 throats and .431 grooves.

Once is happenstance, twice is coincidence, etc. Is this a common state of affairs with the MIM Smiths?

[rintinglen]

I cannot speak with exactitude, but I had .428 throat and .429+ groove diameters on the M-69 that I had. Despite having the throats put right by Doug Guy, It still never would shoot cast without severe leading. S&W ignored my letter, and were not too helpful in response to my e-mail. It left such a sour taste that I haven't bought another new S&W since.

I do have a couple of Hilary-hole Smiths, a 21-4 and a 342 that shoot OK, though neither are bug-hole accurate.

[david s]

I have one of the 625-8 45 ACP revolvers. I have no idea if what I'm about to post is correct or just bad gossip. I heard quite awhile ago (can't even remember where) that these revolvers had two types of rifling. The standard broached rifling and EDM (electrical discharge method) rifling. The EDM style was supposed to not handle cast bullets well. Again not a clue if this is true or not. I'm not the biggest 45 ACP fan, and having said that my two most accurate centerfire handguns are both chambered in 45 ACP. A SIG 1911 is my most accurate centerfire semi auto and this S&W 625 is the most accurate centerfire revolver. The revolver gets a Lee 45-230-TC cast or occasionally the RCBS 45-270-SA put up in auto rim brass. It will also see the Speer 200 grain hollow point. The cast Lee bullet and the Speer jacketed will both shoot lights out. I never slugged the bore as it has always been a superbly accurate pistol and will shoot the cast Lee in either the ACP brass or auto rim with out complaint.

[Reverend Recoil]

My S&W 69 has a 0.429 bore and 0.430 chamber throats and shoots quite well.

[Beecherkid]

I also own a Smith & Wesson 625-8 Performance Center 45acp revolver.

After reading this thread I slugged the bore and it measured .4535 using a micrometer. The cylinder throats measured .453 using a M2 Minus pin gauge.

The accuracy was never what I expected from this revolver and I suspect the problem is the small cylinder throat diameter vs larger bore diameter. I wouldn't think that .0005 difference in the larger bore size would make a difference but, the cast bullet size is only .452 diameter.

I would like to get the cylinder throats honed out to .454, then use that diameter bullets, if I could find them.

Does this sound reasonable, or just a waste of time and money? The revolver currently groups approximately 2.5" at 25 yards, arm rest from a sandbag.

[marlin39a]

I recently bought a S&W 638 revolver. It had the dreaded lock, and a bear of a trigger pull. I installed the lock delete, and the Apex duty spring kit. Now it works for me. Why can’t the manufacturer make the gun work like this?

[FergusonTO35]

I deactivated the lock on my 637, added Wolff Springs, and lightly honed the rebound slide. It is definitely an accurate and reliable little companion, and I honestly would not trade it for an older one.

[35remington]

Given the Smiths have an odd number of lands and grooves I’m curious how you measured the interior barrel dimensions with a micrometer.

[fc60]

Greetings,

5-flute Micrometer...

https://m.media-amazon.com/images/I/...L._SL1500_.jpg

Cheers,

Dave

[david s]

I deactivated the lock on my 637, added Wolff Springs, and lightly honed the rebound slide. It is definitely an accurate and reliable little companion, and I honestly would not trade it for an older one.

I have two of the key lock S&W revolvers. The above 625 in 45 ACP and one of the 329 44 magnums. I personally didn't care all that much weather these two had the key lock or not. The locks were never an issue. Last October at the beginning of rifle season during lunch a bunch of us were making some noise and I was shooting the 329. About half way thru the second cylinder the 329 just wouldn't cycle. It took me forever to figure out what was wrong. Finally I noticed the little "Locked" flag by the hammer was up. Not having ever actually engaged the lock before it wasn't something I looked for and I sure didn't have the silly things key with me. I forget exactly where I got them from but these two pistols got lock replacement plugs post haste. Oddly enough the 625 has been fired quite a bit more than the 329 and never had any issue with the lock.

[fourarmed]

My PC 625-8 has a 6-groove barrel.

[Jtarm]

Two of the most accurate revolvers I own (and I own a bunch) are Model 66-7s built around 2005. With the lock.

The tensioned barrel and uber-tight .003 b/c gaps are not only accurate, but fast to boot. One had some very tight throats, but a trip to Doug fixed that.

I haven’t shot my 625-8 (PC edition) at 50 yards, but a soft slug driven through the bore will drop through the .4525 throats. I haven’t fully explored loads with it yet.

[murf205]

My 629-6 was born with a .429 groove dia and a couple of tight .428 throats with the rest were tight .429. It was not the most accurate gun in the safe but after I reamed the throats to .431, it is a lot better accuracy wise and does not lead at all. Unfortunately for my arthritic hands, it's favorite load is a 310 gr Lee loaded warm-very warm. It also shoots a Lyman 429421 @1016 ave about as well as the Lee and a LOT more comfortably. My late model 24 has the Hillary Hole and it had the same problem so while I had the Manson reamer, I did the cylinder throats on it too with the same improvement. The late model S&W revolvers are geared for jacketed rounds and they don't want to listen to us casters so thank goodness we have Doug Guy.
Now with all that said, I believe the EDM barrels are accurate but they are a bit persnickety about what they like even after the throats get tuned up. The smoothest of barrels is going to lead and not be accurate if you stick a boolit down them that is too small and the tight throats from the factory are doing just that. IMHO

[M-Tecs]

I have no idea if what I'm about to post is correct or just bad gossip. I heard quite awhile ago (can't even remember where) that these revolvers had two types of rifling. The standard broached rifling and EDM (electrical discharge method) rifling. The EDM style was supposed to not handle cast bullets well. .

It's a different process than EDM. It's Electro Chemical Machining.

https://firearmshistory.blogspot.com...-chemical.html

https://www.firearmsid.com/Feature%2...calrifling.htm

Since 1993, Smith & Wesson has been using an electrochemical machining technique to rifle most of their revolver barrels. The only revolver barrels that are still broach rifled are .22 caliber barrels and ported barrels. The manufacture of electrochemically rifled (ECR) barrels begins with the same steps as conventional broach rifling. The barrels are drop forged from bar stock, annealed, and wheel abraded to remove scale. During the annealing process the barrels have a tendency to bend and are therefore put through a straightening operation. The barrels are next drilled and reamed using conventional machining tools and the forcing cone is made with a tapered reamer. The barrels are then ready for rifling.

The electrochemical rifting machines arc made by Surftran and were specifically designed for Smith & Wesson. Each machine runs two independent workstations, each one with a single electrode manufactured by Mechanical Plastics. They are constructed of a two-inch long plastic cylinder with metal strips spiraling down its exterior. The metal strips are in the desired dimensions of the grooves, are at the appropriate rate of twist (1 turn in 18.75 inches for .357 Magnum), and are slightly inset in the plastic cylinder. The barrel is placed in the machine and is held stationary. The electrode is placed into the barrel and both are submerged in an electrolyte (sodium nitrate). The electrode travels down the barrel and rotates at the desired rate of twist. As current passes from the negatively charged electrode (cathode) to the positively charged barrel (anode), the metal is removed by electrolysis to produce the grooves by duplicating the shape of the electrode. During this operation the electrolyte flows through the barrel under pressure to remove the reaction products. This prevents the build up of reaction products on the electrode. Because the metal strips on the electrode never come in physical contact with the barrel and reaction products are not given the opportunity to build up, the electrode does not require any cleaning or maintenance. In fact, electrodes are only retired when the plastic core, which contacts the barrel to provide proper spacing and centering, wears over time. An electrode will usually remain within the tolerance of 2 thousandths of an inch concentricity tier approximately 3000 inches of barrel. During our tour of the Smith & Wesson factory, they were rifling six-inch .357 Magnum caliber barrels and the ECR process took about 60 seconds per barrel.

[Thumbcocker]

I have never had good luck with boolits in an EDM barrel.

[david s]

M-Tecs thanks for clearing that up. The conversation was so long ago I must have miss remembered the details (EDM vs ECM) and been thinking it was something like what Mag-na-port use to do.

[murf205]

M-Tecs, thanks for the clairification. I was under the impression that this process made a smoother barrel. Maybe yea, maybe no but I have had success with the newer method although it is sinful to admit in some circles.

[Cosmic_Charlie]

I have a newer 686+ deluxe and it is a fine shooter. My throats are tight at .357" and that is what i size to. No leading at all and very good accuracy. My alloy is softer, usually 20/1 or close to it. Loads up to 1,200 fps. Never bothered to slug the barrel but i would have if problems arose.

[murf205]

I have a newer 686+ deluxe and it is a fine shooter. My throats are tight at .357" and that is what i size to. No leading at all and very good accuracy. My alloy is softer, usually 20/1 or close to it. Loads up to 1,200 fps. Never bothered to slug the barrel but i would have if problems arose.

PC or lube? I have the same results with my 625-3 @.452 throats but sized to .4505 powder coated or lubed and a .451 barrel. My concoction is range scrap + 2% tin. Like the old saying, "fit is king". I have not clocked the load that really shines but MY load is 6.7 grs of
accurate #5 in 45 auto rim cases and a 253 gr Accurate Molds boolit so I might be bumping it up a mite when it hits the forcing cone. At any rate, it is a good shooter in the newer rifled barrel at least.

[35remington]

For historical perspective my 625-3 is five groove with very shallow grooves for a revolver. This allows for a fair amount of skidding with heavier bullets and they have to be hard or they won’t shoot if the bullet is heavy like a 452423. Lighter lead bullets shoot best and it shoots jacketed very well.

A very satisfactory but slightly odd revolver. Has to be catered to but a very accurate and useful gun. Throats are .4515.”