Any options for tightening a cylinder throat?

C

Casimer

New member
I've got a S&W 25-2 w/ oversized cylinder throats (e.g. .456"). Are there any techniques for reducing this diameter, like a sleeve of some sort?
 
It's "possible" to sleeve the chambers, but you'd be far better off having S&W fit a new cylinder.

The trouble with sleeving the cylinder is, due to the thickness of the cylinder, you can't sleeve the entire length of the chamber. This means all the problems inherent with a partial sleeved chamber.

A sleeving job would probably cost almost as much as a new gun, if done by a really competent pistolsmith.
Done by a not-so-competent gunsmith and you're accuracy would probably be worse.
 
Thanks. That's what I'd wondered.

I'd love to know why S&W made these so large. From my understanding it's how they were designed.
 
If you are a handloader, you could try .454" bullets, and see how it works. I have a Smith .455 Hand Ejector that's been fitted with a M1917 cylinder. The Chamber mouths are .454" and the barrel groove diameter is .457". Loading .454" bullets, it shoots OK. Lots of post-war Colt Peacemakers have .452" bores and .455+" chamber mouths, and there's plenty of advocacy for loading bullets that sort of split the difference.
 
cylinder throats

Sir;
On that 25 one would almost think it would be old, but no it is probably a .452 groove dia bbl.
You should slug your barrel - if it's .454 your O.K.
We like the cylinder exit to be at groove bbl dia or .001 above. Slug your bbl. and see.
I assume you're shooting cast bullets so as was mentioned you might try that - most moulds throw bullets several thousandths larger than the marked size on your mould.
It all hinges on your barrel groove diameter - if it's .454 or more you're AOK.
If not I'd call S&W and see what they say.
Harry B.
 
Like about every other part of a gun, chambers are made to a +/- tolerance. The reason is that they use reamers and need them to last a while. So they start with the reamer at the outside edge of the tolerance. After it wears, they sharpen it, reducing the hole diameter slightly. When the reamer is worn to the point that the hole is at the minimum edge of the tolerance, they scrap the reamer and start with a new one.

The same is true of the reamers made to cut rifle chambers, ammunition manufacturing dies, reloading dies, etc.

Actually, people get a bit over-wrought about revolver throats. The fact is that a thousandth or two in a .45 won't make any difference. A lot of folks who worry about throat diameter shoot cast lead bullets that can vary more than the amount the throat is likely to vary.

(P.S. I would like to blame the throat diameter when I can't hit anything; problem is that it's me!)

Jim
 
Unfortunately S&W doesn't stock cylinders for the 25-2 any longer - and the cylinder used for the new-issue 45 ACP's isn't compatible. They'd advised contacting Numrich, but they don't have any either.

Any other leads will be appreciated.

I should slug the barrel, per HB's suggestion, and get a better idea of the dimensions I'm working with. But I'm not casting my own bullets, and likely won't, which is why I'm interested in new cylinder.

The revolver is actually decently accurate to 25yds w/ jacketed bullets, and it's OK w/ lead, but doesn't hold groups at 50yds well w/ either.
 
You're about to spend a wad of money and earn yourself a load of trouble.

First, in all likelihood a different cylinder will not cure your problem.
As above, they're made to a specific specification so you won't get a tighter throat.

Second, any cylinder you find will be a used cylinder, so it may have other problems not immediately apparent.

Third, revolver cylinders DO NOT "drop in".
To fit a different cylinder to a frame, you MUST have a cylinder assembly consisting of a cylinder WITH a fitted ejector.
You can't just stick the old ejector in the replacement cylinder since it won't be fitted to THAT cylinder.
A used assembly will have already been fitted to a different frame, so it will not properly fit your frame.
Just because a cylinder will fit into the frame and close does NOT mean it actually fits the frame.

Among other things a replacement cylinder and ejector assembly must be fitted and checked for:
Head space.
End shake.
barrel/cylinder gap.
Barrel/chamber alignment on ALL six chambers.
Timing on all six chambers.

This is no job for anyone but an experienced S&W qualified pistolsmith.
Pick up a cylinder somewhere and somehow get it to fit into the gun and you'll have worse accuracy then you do now, if not an unsafe gun.

In your case, all I can suggest is talking to one of the hard chrome plater services that offer plating of the chambers.
Possibly they can plate the chamber mouths to decrease the size.

Armoloy of Fort Worth offers chamber and bore plating.
 
They also have a thermal spray process for plating the cylinders. After its done, They cut or hone new bores in them to the dimension you want and they come out like new. I have seen it before but done remember where and will look around and try to find it again.
 
throats

Sir;
Caution - if you used a dial caliper to measure your throats I wouldn't trust the measurement unless it was a pair of Starret, Lufkin, brown & Sharp or other precision made dial or digital calipers. Chinese made (and there are hundreds of them) while good quality and give an accurate O.D. measurement will always give about .002 or more on the inside guages.
What you need is some Starret "small hole guages"and precision micrometers to really know what they meausure!
Harry B.
 
I think I'd try some of the Remington hollow based .454" .45 Colt bullets in Auto Rim brass. They might be too soft, rifling in that model is kind of shallow. Next would be some cast .454s.
 
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