Problem with 357 Magnum trr8

[Fotis]

Hey guys I've got a Smith & Wesson from the performance center it's a 327 8 shot with a 5-in barrel. No matter what loads I have put into it so far it's always very very slow. I tried the 125 XTP with 19.4 grains of little gun and it gave me 1,200 ft per second. It shoots the 158 close to a thousand feet per second. Any idea what's going on cuz this thing's going to drive me nuts.

Now I do have a Smith & Wesson 686 Plus 6 in and a Dan Wesson pistol pack 2 4 6 and 8" barrels they seem to be shooting these loads just fine at regular velocities. I just shot 16 grains of IMR 4227 with 125 Hornady XTP and I got 960 ft per second

 

[gnappi]

Are you saying that loads in the TRR8 shoot SLOWER than the SAME loads in other .357's? If not try the Lil gun loads in the others and compare apples to apples?

 

[SGT ROCK 11B]

What velocities do you expect? In the Speer Manual a while back they had a great explanation why two identical revolvers may have significantly different velocities. Why a four inch Model 19 post faster velocities than a six inch Model 19.

Do not over think it.

 

[Fotis]

Today I just shot some factory ammo 125 and 158 out of the 5-in 327 and 6" 686 Plus the 686 Plus with one more inch of barrel is yielding a little over 200 ft per second more than the 327

 

[Fotis]

I read something about ECM rifling on the 327 and another guy is having the same problem that I am on another forum never heard of this rifling before

 

[Fotis]

Are you saying that loads in the TRR8 shoot SLOWER than the SAME loads in other .357's? If not try the Lil gun loads in the others and compare apples to apples?

19.4 grains of little gun and 125 Xtp yielded 1550 in my 6-in 686 Plus
Same did 1300 ft per second from my 5-in 327 TRR8

 

[Fotis]

By the way measure the cylinder gap is .006 on the 327

 

[BLUEDOT37]

I read something about ECM rifling on the 327 and another guy is having the same problem that I am on another forum never heard of this rifling before

Hardly any modern S&W revolvers don't have the ECM/EDM (electronically etched) rifling. Only a few have broached (mechanically cut) rifling.

The 686+ definitely has the ECM/EDM (I have a 5" 686+) & in looking at my 327TRR8's rifling it too looks to have the same rifling.

My 627PC, & 625PC, have cut rifling. Notice how the rifling is definitely sharper in the pics below.

You might check the throat size, since the B-C gap is nominal, to see if the 327TRR8 has loose throats. If you don't have pin gages use a quality brand jacketed bullet, like the Hornady XTP, to compare the two revolvers.

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686+ TALO muzzle, after chamfering
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627PC muzzle, after chamfering
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627PC muzzle, before chamfering
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[trulyapostolic]

You might check the throat size, since the B-C gap is nominal, to see if the 327TRR8 has loose throats.

Or see if it has really tight throats. If the bullet coming out of the cylinder is swaged down smaller than the barrel diameter it won't build as much pressure.

 

[Fotis]

Tried a couple of more loads last weekend.

165 Matt bullet cast 14 gr Enforcer I got 1088 fps....should have been 1350 or so.
125 XTP 22.5 MP 300. I got 1250 fps....should have been around 1500.
165 Matt cast bullet with 17 gr MP300 I got 1110 fps should have been in the 1300's.

After thinking on it a while I decided to measure the cylinder gap again. It measured .006.
I pulled my SW 686 out and I could BARELY fit a .003 gap gauge through it.
The 327 has a removable/adjustable barrel like the Dan Wesson pistol kits so I can change the gap.


Can this be the issue?

 

[jaymoore]

Tightening the cylinder gap might help a little. It you really want to try experimenting, make, have made or possibly buy a barrel nut wrench. I carved one out years ago, starting with a flanged 1/2"-13 nut. Mostly because my TRR-8's barrel nut came loose on it's own.

 

[jaymoore]

Here's an old thread with photos:

https://smith-wessonforum.com/s-w-r...urprise-disassembly.html?highlight=barrel+nut

Note Post #9: To get a 0.006" cylinder gap after tightening the barrel, I had to screw the barrel in until it touched the cylinder face before tightening. To get less, you'd have to likely touch off, then open the cylinder and rotate the barrel a little more. Could take a few tries to get a tight 0.002-0.003" gap.

 

[Lou_the_welder]

I think "EWK arms" makes a tool to tighten the 327s barrel. I have it somewhere.....
I did try using it to tighten my then loose 327 barrel. EWK does not sell you the tool to lock in the barrel- because tightening the barrel pulls the barrel out of the frame. You would have to figure out how to keep the barrel from spinning and guess how much pressure to torque.

I do not have an answer for the velocity discrepancies. My guess would be a tight barrel. But I have neither chrono'd nor measured my barrel.

In my experience, using the top factory supplied optic mount and/ or mounting an optic using that steel mount, unscrews the barrel out of the frame. It happened to me a few times. Once I figured this out, and had the factory tighten my barrel using their specs, I haven't had it happen again.

I mount an optic by removing the rear sights for better eye relief anyways.

 

[38SPL HV]

By the way measure the cylinder gap is .006 on the 327

That’s ideal according to S&W. The spec is .004 - .010.

 

[daverich4]

In two separate articles in Handloader 293, December 2014, Brian Pearce mentions that barrels with EDM rifling instead of traditional Broached rifling produced lower velocities.

 

[WR Moore]

That would seem to make sense. Cut/swaged rifling produces directional surface finish. Hammer forged is going to pound the metal flat against the mandrel. EDM is essentially burning material away. It'd be interesting to see magnified images comparing surface finish of the various methods.

 

[Taj]

Hey guys I've got a Smith & Wesson from the performance center it's a 327 8 shot with a 5-in barrel. No matter what loads I have put into it so far it's always very very slow. I tried the 125 XTP with 19.4 grains of little gun and it gave me 1,200 ft per second. It shoots the 158 close to a thousand feet per second. Any idea what's going on cuz this thing's going to drive me nuts.

Now I do have a Smith & Wesson 686 Plus 6 in and a Dan Wesson pistol pack 2 4 6 and 8" barrels they seem to be shooting these loads just fine at regular velocities. I just shot 16 grains of IMR 4227 with 125 Hornady XTP and I got 960 ft per second

There are a lot of factors that play into velocity variations from gun to gun. Ball end of the charge holes can play a big part in that as well as the barrel cylinder gap. Groove diameter and how sharp the rifling is cut (ECM vs cut rifling) can also play into it. I certainly wouldn't get too wrapped up in the velocity variation as long as the guns are shooting well. It's not too uncommon to find large variations from charge hole to charge hole.

 

[SASFixer]

Slug the bore and determine if it is over size. You have only discussed velocity; what size groups are you/it shooting at what distance?

 

[6mmrem]

OK, I read the entire thread and about halfway through I'm thinking "How does it shoot?" I tend to agree with SASFixer, Accuracy is the real measure of how good the load is performing.

 

[67ray]

Slug the bore and determine if it is over size. You have only discussed velocity; what size groups are you/it shooting at what distance?

I'm with him - slug both bores and see what you get. Even 0.001" - 0002" difference can show up in velocity.

And then you need to measure your projectiles. Not just one but say 20 to see how they vary in diameter.