610 Throat Diameter Question

[kend]

I have a 610 Classic and I checked the throat diameter in the cylinder and it measures .399 with a plug gauge, will this have a negative effect on accuracy? I know there's been a lot of issues with some SAA guns but I don't know if it's common with others or not. Any thoughts? Thanks

 

[Protocall_Design]

Shoot it first with some known good loads. The target is the best judge of how a gun is doing.

 

[kend]

Thanks but there are no known good loads, it's a 10mm Magnum. Just trying to figure it out before I get serious about wasting powder and primers.

Shoot it first with some known good loads. The target is the best judge of how a gun is doing.

 

[racoonbeast]

I know that the diameter of cylinder throats has been discussed a lot and seems to be an ongoing concern for a lot of people. Myself included.

But, for the heck of it, I carefully measured the cylinder throats on all of my Smith revolvers from several eras. I used a set of very expensive pin gauges that I picked up in my travels at some point.

To make a long story short. My .45 ACP Model 25-2 from the seventies does not have two cylinder throats the same size. All too big. At least one is way too big. The gun is a tack driver.

I did the same with my stainless .45 ACP Model 625-6 (Model of 1989) has cylinder throats that are the perfect size. No deviation between the cylinders. All the correct size. It is one of the poorest shooting guns that I own.

I should add that I did not shoot any lead in either gun for my tests. All high quality jacketed factory stuff from various makers. Lead bullets might perform differently. Didn't test any so I can't say.

So, if it is any consolation, my very unscientific tests tell me that there is more to revolver accuracy than the size of the cylinder throats. All other things being up to snuff, it may not be a big deal. If it is possible to somehow get some test ammo, you might find that the gun shoots fine. As has been said, the target will tell you once and for all.

 

[Protocall_Design]

I like the throats to be on size with the bullets. That's (ideally) .001 over bore size for cast, and on size for jacketed. If the bore (grooves) are .400, that would be .401 for cast and .400 for jacketed. With a good forcing cone, good muzzle crown, and no barrel constriction, you would theoretically have a gun that shoots very tight groups. There are other variables, but these are the main ones I look for.

 

[CH4]

As others have said, let your target do the talking. I'd bet it's a total non issue. Most barrels/chambers vary slightly from spec, often more than that.. For this purpose, .001 +/- is common, totally acceptable… to me.

 

[Ackley1952]

The manufacturer of your 610 has some experience in this area. ��

 

[glenwolde]

After measuring many, many S&W revolver throats over the years I've found the more modern guns to be the most consistent. I've seen a lot of variation in 60's and 70's guns but somewhere in the 80's things started getting more consistent. I see a lot of 80's and 90's .38/.357 guns with .3575, which is a perfect compromise for jacketed or lead bullets. The worst I've seen is my late 60's Model 14 that was .3555-.3560. No wonder it was shot very little.

The good news: undersized is super easy and inexpensive to fix. Oversized, not so much. But only shooting it will tell you for sure. I ream all my .38/.357's to .358. I have my own reamer, but it may not be cost effective to buy one yourself for one gun. You can rent them, or send it out.

If you're planning on shooting jacketed bullets it may shoot just fine. If you're the kind of guy that does extensive accuracy testing with a variety of lead bullet reloads and 1/2" at 25 yards matters to you, I'd bet you'll decide to ream it out.

I'd look to see if it leads the barrel first. That's a for-sure sign it needs to be opened up.

 

[kend]

Which means what? You know as well as I do if I did call them as soon as I said I reamed it 10mm Magnum they'd be through talking. I have a lot more faith in the gun guys having a solution to an issue like this than I ever would the manufacturer, they'll never admit something is out of whack.

The manufacturer of your 610 has some experience in this area. ��

 

[BLUEDOT37]

Did you shoot the M610 (-3?) as a 10AUTO before it was converted to 10MAG?

I bought mine new & as a 10AUTO it grouped very well & now as a 10MAG it groups the same. If it shot well before it should be fine now.

My throats are .4000", the bore is .3900" (using pin gages) & the groove is .3998".

I don't think .399" throats are going to cause a problem. Most 40 caliber bullets are nominally .400" diameter so .001" isn't likely to cause a problem.

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[kend]

Never shot 10mm in it, rechambered it as soon as I got it. What's your favorite 10 Mag load, anything with 200 gr bullets? OAL?

Edit...I just noticed your username and the fireball, that's what mine looked like with a Bluedot load I'm out of Bluedot and can't find any now but I have several other powders to work with, hopefully I can get one to work.