New 627 PC Performance Center accuracy question...

[PotShotter]

Hi,

I am completely new to this forum which I only joined recently because I finally got my very first S&W revolver – it is a S&W Performance Center 627 stainless .357 magnum “8-times” (the 5" barrel version). I should add that it is NOT the V-comp compensated version which did not really appeal to me.

In any case I have so far had it at the range only once and I was wondering if anyone here could help me to understand what appears to me to possibly be an accuracy issue:

When I first took it to the range I took a selection of ammo with me including some boxes of expensive home defense hollow point .357 magnum, some cheaper target FMJ .357 mags and also some cheap .38 special target ammo.

I got some wildly varying accuracy accuracy results that surprised me – generally my groups with the .38 special ammo were all over the paper (and it certainly wasn’t due to me flinching because I thought the .38 Special recoil was pretty tame and the trigger on this thing is silky smooth).

But I had much better and much tighter groups with a couple of the home defense rounds however the cheap FMJ .357 magnum rounds also seemed to have fairly poor accuracy in my tests.

What is going on here? I know that I’m an OK shot and that the huge differences I was seeing were <1” groups vs over 6” groups at only about 15 yards were not because of my bad shooting.

For the record my other main pistol is a Glock 36 and it seems that I always get very tight groups with it regardless of what I choose to shoot with it.

Thank you for any advice and any tips that you can offer me…..

Bob

 

[colt_saa]

First question......Did you purchase this revolver new or 2nd hand?

Second Question......Does the revolver exhibit these same issues with other shooters?

Third question......Did you jiggle the front and rear sight to make sure they are not moving?



If it is a NEW revolver and under warranty, I would send it back to S&W presuming that other shooters have had the same experience with it and you already checked the sights.

 

[XTrooper]

I don't know if this is your problem or not, but .38 Special ammo will often be more inaccurate when fired from a .357 Magnum revolver because of the longer "leap" the bullets must make from case mouth to rifling. If you're looking for match accuracy, firing .38 Special ammo from a .357 Magnum revolver is not the way to attain it.

 

[Sevenshooter]

I'll take a shot at an answer.

Were you shooting single action or double action, meaning do you think there is a chance you "may" have flinched? That could be a cause for bad groupings. I'm just sayin'.

Also, if you did everything right, meaning no flinchin, and a nice smooth trigger pull (you are correct, the 627's have a nice trigger) there were issues with the barrel crowns on a lot of 627 Pro models which had rough irregular finishes on the barrel crowns, and had to go back to S&W for repair.

Mine was one of them, and at first with the poor crown, (it was really rough and uneven... I don't know how it left the factory like that), my groups were all over a paper plate @ 25 yds no matter how careful I tried to do my part. I was shooting jacketed and hardcast 158's in .357mag cases. I don't shoot the .38's in my .357's.


After sending the gun back and the crown repaired, now the groups are as tight as I can make them.

If your gun has a crown that is not smooth it "might" be a cause for the bad groupings if your doing all you can do.

Good luck with her.

Ss

 

[PotShotter]

First let me say thank you!

So, to try answer your questions….

First, this is a brand new pistol. When I was trying to get good groups I was shooting the revolver single action (as always) – and I must say that the trigger on this thing is very sweet! I am (so far) the only person to have shot the pistol. I shot about 150 rounds of different types of ammo that evening (but mostly very cheap ammo).

I don’t generally flinch as I understand the problem very well – I can get very tight groups with my .45 Glock 36. I found the .357 recoil to be quite vicious though (it ended up removing some skin on my left hand). But the .357 ammo seemed the most accurate in general.

I bought the pistol really to try to do some very accurate revolver shooting and everything that I had heard about the 627PC gave me some high expectations. I’m hoping that you gentlemen are going to tell me that the gun is OK and to get different ammo. I guess that .38 is never going to be really accurate then? That would be a pity because the recoil makes for longer more pleasant target sessions.

I did get one very tight group – I think that it was with the Golden Sabre HP .357 mags. But the cheap .357 FMJ target stuff that I bought at the range was not nearly as good.
The .357 groups were all better than the .38 Specials. I’ll accept that I might have been flinching here as the .357 recoil is much more vicious than my Glock. It feels like someone whacking the end of the pistol with a hammer.

It is brand new so there is a S&W warranty with it I’m sure – but I’m hoping that it won’t come to that. So… how much of a variation between different ammo types is “normal” ? Could this just be crappy cheap ammo? I guess that I can’t use .38 for accurate shooting as I’d hoped.

I couldn’t figure out though why .38 special rounds shot so badly though – I’d take a long time over each shot and I’m usually “above average” with a pistol. I’m quite steady and I certainly wasn’t waving it around. If anything shooting with the .38’s I was even steadier as the weak recoil and little pops had me grinning.

Because it was not convenient to “bench” my elbows at this particular range all of these shots were taken while standing.
Finally, I’m not sure of the barrel crown – thanks for the tip. I’ll get the gun out of the safe this evening and examine it closely. What would it look like if bad?

I do recall seeing that it had been recessed like a rifle barrel.

Bob

 

[PotShotter]

By the way - the picture here in this thread matches my revolver exactly. I still think that it is prettier (and slightly cheaper) than the V-comp.

Bob.

 

[colt_saa]

If it is doing this exact same thing with other shooters it NEEDS to go back to S&W.

No Performance Center revolver should shoot one brand of factory ammunition into 6" and another into 1".

I have more than a dozen of the Performance Center 8 shot 357 Magnum revolvers. Each and every one is a Fantastic shooter. It does not matter if it is a 27, 327 or 627 they are top notch firearms. If your is not, something is wrong and you have to let the factory make it right.

 

[.357magger]

Couple of thoughts if I may. It seems from your posts that you're doing lots right, but you might be skipping a step imo, or not seeing full picture to explain your circumstances.

a) Check the recessed barrel crown as per the previous post. This has been noted here several times and it is my/our hope that your gun is not so affected. If you search for "627 Pro" in this forum you ought to get hits and pics to describe the issues others had. Have not heard of the PC guns having this problem though.

b) Check that the sights are not loose. Might sound like "Duh" statement, but you'd be suprised how often this happens. Particularly if YOU haven't set them.

c) Any cylinder play? Meaning, that when you cock the gun for SA fire, does the cylinder move an excessive amount?

d) Check the barrel rifling too. Slow steady examination with a borelight. Do you see any burrs or damage to rifling? Would be a rare thing but...hey...they're made by humans.

e) Find a range where you can "bench" the gun. Not talking about a Ransom Rest, but where you can either rest the gun on a sandbag or other rest, or at minimum where you can rest your elbows for most stable testing.

f) Start very close in in testing. Be specific in your loadings too. For example, one cylinder load of Load A, fired at 7 yards produces group size X. Do that at same distance for several loadings, THEN move it out to 15 yards and beyond. Don't worry about if you're hitting point of aim. What you're looking for initially is group size. THEN you can move the sights to change POA/POI. Shoot at the EXACT same place, EVERY shot at the same distance. Maybe I'm being overly cautious on distance, but you can uncover any shooter errors first, particularly if the gun is rested.

I've never owned a Smith that delivered 6" groups at 15 yards, more like 2-3 " at 25 is the norm if I can do my part. But starting close then moving back can expose ANY type of flinching or motion with a new firearm type. The only reason I say this is your refernce to "vicious" recoil in an N frame Smith in .357. I shoot a lot of them, in N frames almost exclusively, and don't recall, even in REAL stiff loadings having my hand torn up. L frame? Maybe. K frame? Maybe plus and forget about the J's cause they ARE vicious imo. But the .357 in a 5" N frame shouldn't be more "vicious" than your G35 in .45acp.

Try these steps and holler back as to the cause (I too HATE to send guns back to maker, but sometimes...like I said...they're made by humans).

Good Luck and hope this helps.

 

[Sevenshooter]

"IF" you have to send it back, contact S&W serv. dept., get them to send you a return label and describe your issues on a note with the gun.

You most likely will get the gun back in top shape probably in 2 weeks or less. They will do a good job. Don't put it off, it is no fun owning a weapon that has issues, when a small amount of time without it can get it in top shape.

About shooting .38's, the only reason I don't in a gun chambered for .357 is so I don't have to clean the powder crud ring from the cyl. after firing the shorter .38 cases. Other than that, .38's shoot fine from my stuff.

Ss

 

[colt_saa]

About shooting .38's, the only reason I don't in a gun chambered for .357 is so I don't have to clean the powder crud ring from the cyl. after firing the shorter .38 cases. Other than that, .38's shoot fine from my stuff.

Ss

100% agreed

 

[keithherrington]

Well, I had similar results with mine.

My PC 627 (exactly like shown) was similarly inaccurate when compared with my other 38 and 357 revolvers. The reason really surprised me. When I cleaned the gun after the first and only range session (it was a long one), I found the bore was significantly tighter where the barrel joined the frame. In my opinion, the barrel was over tightened in the frame and in doing so the bore was squeezed slightly. When using a brush or a tight fitting patch the constriction was very noticeable. The dynamic of what would happen during a shot was pretty straight forward: the bullet squeezed down to fit the bore at the forcing cone and was therefore slightly undersized for the remainder of its travel in the barrel. I never got any ammo to shoot worth a darn except 148 match wadcutter. I believe that bullet was soft enough to upset into the bore and provide a good seal even after squeezing through the forcing cone.
Keith

 

[PotShotter]

Thank you all again - you guys are really helping me out here. Most people that I know own automatics and not revolvers.

Lot's of things for me to check out now. I have not set the sights on it yet or even checked to see if they are loose - I will also do that this evening. I do know that they are adjustable.

I will also inspect the crown and the barrel (I have a bore light) and I'll try the bore diameter tightness check.

I remember noticing previously that the cylinder was not quite "rock solid" as I'd expected it would be when the gun was cocked - that surprised me a bit given what it is about to occur (but this is my first revolver so I am really not sure what is normal). For the record it did have a very tiny amount of play (I would not describe it as loose though).

Now I think that another more careful study is needed at a different range with the pistol sitting on sandbags.

I'll get back later with a report.

If the worst happens here I guess that it will need to go back to S&W for a check-up/fix. It certainly was not a cheap pistol.

Bob

 

[scooter123]

First, IMO ANY AND ALL accuracy testing should START from a bench rest. In addition, with the 1 piece barrels such as that in your 627 it's absolutely imperative that NOTHING touch the barrel during firing. This means YOU DO NOT support the barrel on a sandbag or something similar. One piece revolver barrels will "ring" in response to the bullet transitting the barrel and having something in contact with the barrel will cause a variation in the "ring". As a result you'll see group size double or triple. Take the gun in a combat hold and plant the heals of your hand on a sandbag or the bench. Then aim at the center of the target and slowly increase the pressure on the trigger until it releases. You'll also want to make sure that you aim at the exact same spot on the target for each shot, where the bullets actually hit don't matter a bit, what you are testing for is Group Size, not how well the gun is sighted in. I would stongly suggest that you do a bit of shooting from a rest before you make any assumptions about accuracy.

As for the bullet jump from shooting 38 spl. in a 357 Magnum hurting accuracy, IMO that is WAY WAY overblown. I have a model 620, which is a 357 Magnum set up with a reflex sight for longer range shooting. Currently I am getting 1.75 inch groups with it from a rest using 130 grain American Eagle 38 spl. at 35 yards. I've also seen enough 3 shot cloverleafs to believe that if I were to mount a 2X scope on it I could probably get it between 1/2 and 3/4 inch at that distance. Note, that American Eagle is a cheap range load, it's not a premium accuracy load.

Now, a couple of notes on some details that can degrade accuracy and how to spot them.

One is inconsistent ignition, which can rear it's head if the trigger has been lightened to a point just above the point where misfires start to take place. What you will see in this case is that your groups look like the letter I, meaning you'll see vertical stringing due to variations in velocity from shot to shot. The solution is to increase the power produced by the mainspring or to install an extended length firing pin. For a short term increase in mainspring power placing a 0.010 - 0.015 inch thick piece of shim between the mainspring and the strain screw will provide enough increase in mainspring power to normally eliminate the vertical stringing.

Second thing to look for is horizontal stringing. This is a symptom of poor trigger release skills, usually "snatching" the trigger. What's happining is that your trigger release is causing the end of the barrel to "nod". The solution to this is to concentrate on a slow steady increase in pressure on the trigger until the gun fires in a "surprize" event.

BTW, I've been there done that, meaning that I've learned by making mistakes and figuring out how to correct them. You may think you're a decent shot, I can tell you from personal experience that spending a bit of time shooting at 25 to 50 yards from a benchrest will reveal every single flaw in your trigger release.

As for flinching, I've also been there done that. I can tell you from personal experience that even a basic range load of 357 Magnum can build a flinch if you overdo it. One quick way to test for a flinch is to put a snap cap in one chamber, give the cylinder a spin, and then close it without looking. If you've grown a flinch, you'll see it as soon as you hit that snap cap. The solution for a flinch is to concentrate on a relaxed release of the trigger without anticipating the shot, work on this skill often enough and in time you'll learn to "feel" a flinch coming. Spend a bit more time and you'll then learn to "listen" to your body during each shot and gain the ability to call where the bullet will impact. BTW, these are skills that I've found easiest to learn initially by shooting from a rest, not by shooting offhand. IMO too many handgunners ignore shooting from a rest to their detriment, if you are one of those shooters you really should give it a try.

Now, as for the functional accuracy of your revolver, first you do need to run a controlled test to determine where you are. There are many mechanical features of a revolver that can effect accuracy that will require a trip back to the factory, however a 6 inch group at only 15 yards would require a rather major flaw that should be clearly visible and pretty unlikely. It also wouldn't allow the gun to exhibit that variation that you are reporting between the 2 caliber. My experience is that stepping down from the magnums will ususally just result in about a 4 or 5 inch change in the POI at 15 yards and the groups will stay about the same size. Personally, I have a hunch that you had the gun sighted for the 357 Magnum and with the large change in POI with the 38 spl. you started "chasing your hits". Yeah, something pretty dumb to do, however I've also been there done that.

 

[PotShotter]

Excellent - I really like this reply as it implies that the gun is OK which I am very happy (hoping) to believe at this point.

At the very least it should get a more serious trial - my first session was really just having fun and trying things out. I'm happy to accept that I really don't know what I'm doing yet with revolvers.

Thank you too for these great tips. I now have tons to things to try out (and also to remember), I will post again later with what I learn. I do know of a different range that will be perfect for the kind of tests that I want to do next.

Bob

 

[What the]

In your first post you seem adamant about not "flinching" but in your second post you seem to say you were flinching. That makes all the difference in the world when it comes to accuracy. Even if the crown is perfect on your gun you won't get good groups if you are flinching.

You say recoil is vicious which tells me without a doubt you are flinching.
Have someone else load your gun and skip a chamber...you'll see if you are flinching or not. Checking the crown is very easy to do,if it's good you have some work to do.

As far as shooting for group goes,unless your made of concrete you Have To Bench! Rest your arms on sandbags and start at no more than 10 yards. You have to take your time for each shot...same sight picture same trigger pull...make sure you take notes with every ammo used and don't adjust your sights until you are getting consistent groups even if they aren't in the bullseye.

Have a known revolver shooter look at the crown and shoot the gun a few times. Quick feedback one way or the other. Finally don't give up,it may take time but you will get there.

 

[Stainz]

To see if you are flinching, leave two or more empty chambers - oddly spaced - and don't look when you close the cylinder. Shoot normally - you'll see if you flinch when you fire an empty cylinder.

Another check - the even nature of the barrel/cylinder gap - check it with an empty gun, of course. The normal range is .004-.010", but they should be consistent - and .004-.007" as a PC gun. Something to test.

Good luck.

Don't forget - call S&W (1-800-331-0852) for a pre-paid overnite FEDEX label if the problem is the gun.

Stainz

 

[PotShotter]

So FYI, I got the 627 PC out last night and got a magnifier and my bore light.

Nearly everything looks perfect on it: The sights were not adjusted I noticed and they (the rear) has some very slight play but it is the normal kind that doesn't really change your aim at all.

The bore also looks perfect, the cylinder locks up tighter than I had remembered and the forcing cone area looks very good and clean.

(I have it all shiny again after learning about stainless revolver cleaning and those lead removal cloths).

On close inspection there is however one very tiny imperfection on the crown/barrel edge at one tiny spot. It looks like a really tiny ding and I'm not sure if it really matters as it is really very small - about a millimeter (or less) in size and not at all deep (just really on the surface). I'd have a tough time believing that it could have much effect on a bullet being that it is so small. I needed a magnifier to really see it clearly. The rest of the crown/barrel area looks quite perfect.

Everything else checked out (I forgot to do the tightness check).

I reckon that the cylinder to barrel gap is probably about .010" although I did not measure it (that is just by eyeballing it and based on my previous engine experience).

The cylinder gap does not change at all as the cylinder is fully rotated.

So, another session at the range is now needed with the gun in a more stable position....

Bob

 

[PotShotter]

Thank you for the tips on flinching - again I don't think that I was doing that but I'll try that test with random empty chamber(s) to see.

I shot hundreds of .357 rounds and the new grip (I used the wood one) took a bit of skin from the crook of my hand in the process - so I ended dribbling blood onto my new gun) I might have been flinching a bit then (but was more concerned with avoiding getting blood in the mechanism). Next time I'm going to use the supplied rubber grip.

Sorry - but I just don't have the hard skin on my hands that I used to have in my younger days.

Bob

 

[EvenStephen]

I've got the same revolver and it's very accurate. No problem shooting small groups with 38 spcl range ammo either.

 

[PotShotter]

I've got the same revolver and it's very accurate. No problem shooting small groups with 38 spcl range ammo either.

Thanks! Yes, I had heard great things about this pistol in the accuracy department and that is why I snagged this one as soon as I found it for sale.

It looked good, felt great in my hand and the trigger pull was like silk - I just had to have it. I'm also not a fan of the v-comp look.

By the way, does yours also have about a .010" cylinder/barrel gap? (That looked a little bit on the wide side to me).

Are there any tiny marks on your bore/crown edge? I have one very small mark (a tiny nick) on the edge with the bore - but it looks quite insignificant to me although I am not a firearms expert.

My goal is to achieve high levels of target accuracy with this pistol and maybe even take it hunting. And of course it would always be a great option to use in a home defense situation.

Bob