OK< i've always wanted to know this, even though i have 2 .357s and 2 .38s, i have never gotten a straight answer.
personally, i shoot .38s a LOT better in my model 10 than in my model 66., which surprises me a lot as the 66 is heavier, and has better grips and sights, so there must be something to this.

how much accuracy is lost shooting .38s in a .357 chambered revolver?

The accuracy loss is due to the extra lenth of the 357 chamber. A 38 special will have .100 of an inch more of free travel than will a 357 round, before it get to the chamber mouth. How well does your 66 shoot with 357s?

Quoted: The accuracy loss is due to the extra lenth of the 357 chamber. A 38 special will have .100 of an inch more of free travel than will a 357 round, before it get to the chamber mouth. How well does your 66 shoot with 357s?

i'll be honest with you, i can't hit shit with it!!
.357s in the 66 are a little better than the .38s in the 66 but not as good as .38s out of the model 10, that make any sense?  i think i confused myself.

its odd, cuz i shoot distinguished expert with autos, but suck ass with wheelguns which are supposed to be inherently more accurate, go figure?

I've got a couple of 10s, very old, very smooth actions. Only shoot HBWC at about 700fps.Single action they're accurate as hell,double action I can't do too well either. I blame it on old age and bad eyesight.

Well, the M-10 and all the Pre-10's that preceeded it are just about the best 38spl revolvers ever made. The balance, pointability, return to POA and consistency are near perfect, so I'm not surprised that you shoot them well.

I've never found any difference in accuracy when shooting 38 in a 357 vs 38 in a 38 spl and it sounds like are seeing the same. You say that you can't shoot the 357 well in your 66 either. So my guess is that the balance of the M-10 suits you better.

If I were you I'd start experimenting with different grips on your 66. Does yours still have the Uncle Mikes fit no one grips? That would certainly be the first thing I'd change.

Also, what about barrel length? Is your 66 the same barrel length as your M-10?

Quoted: If I were you I'd start experimenting with different grips on your 66. Does yours still have the Uncle Mikes fit no one grips? That would certainly be the first thing I'd change. Also, what about barrel length? Is your 66 the same barrel length as your M-10?

actually, the first thing i did was swap those shitty grips out with pachmayr grippers, and they're both 4" barrels.
it just really frustrates the hell out of me that i can't shoot this revolver worth a damn, as i can shoot 100% better with any other gun in my "arsenal"
i was just wondering if the crap accuracy was the result of the longer chamber/short bullet, or it was me?  
i guess i'll just stick with the model 10 if i want to use a 38 revolver......

Well seeing as nether round shoots well in the 66 maybe the cylinder is not indexing properly, or there is a problem with the cylinder locking up properly. Take it to a good pistolsmith and have checked.

Quoted: Quoted: If I were you I'd start experimenting with different grips on your 66. Does yours still have the Uncle Mikes fit no one grips? That would certainly be the first thing I'd change. Also, what about barrel length? Is your 66 the same barrel length as your M-10? actually, the first thing i did was swap those shitty grips out with pachmayr grippers, and they're both 4" barrels. it just really frustrates the hell out of me that i can't shoot this revolver worth a damn, as i can shoot 100% better with any other gun in my "arsenal" i was just wondering if the crap accuracy was the result of the longer chamber/short bullet, or it was me?   i guess i'll just stick with the model 10 if i want to use a 38 revolver......

There are a couple simple things that I'd check, things you can simply do on your own. First, check timing. Make sure that the cylinder is lined up with the bore. The easiest way to do this (make sure that it's empty or this can get exciting) is to look down the barrel while the trigger is pulled fully to the rear. Shine a light, (may want to have someone help on this part) across the headspace area. This should give you a good view and let you see if all is lined up properly.

Next, check the timing. These test should all be done while the trigger is pulled all the way to the rear. There should be no side to side or fore and aft play in the cylinder. A slight rotational play is okay.

Check the yoke and see if there is any play there.

Get someone else to shoot the 66. See if they have the same problems.

If they have the same problems, send it back to S&W. It does carry a lifetime warranty. Enclose a nice letter explaining what symptoms you're seeing and what tests you've done. i think that you will be down right amazed at the response you get.

o.k., i do get some fore/aft play.
not sound uneducated, but seriously, what is the yoke? (i'm primarily an auto guy)
i did notice that i can fire the weapon just before the cylinder catches if i put light pressure on the cylinder while turning it (a slight fraction of the cylinder face is visible) is this normal.
BTW, it's a new model 66 (firing pin in frame)
there also appear to be small notches, approx 1/8 mm where the cylinder latch is nicking the side of the recess for the latch on all of the cylinders.

The yoke is the part that holds the cylinder and swings out. And never feel bad about asking questions. It's the questions you don't ask that will get you hurt someday.

A 4" 66 should be dead on accurate with either 38spl or 357Mag, so I really think you have a legitimate complaint. The symptoms that you describe sound like you have a timing problem.

Here is what I suggest you do. Call Smith & Wesson (see www.smith-wesson.com for numbers), tell them that you have a sick 66 and ask them if they can send you a shipping package. Their handguns carry a lifetime warranty so they should be able to fix whatever is ailing it.