686 PC - accuracy issues

[fuzzymcnab]

Hi gents,

Bought the gun new a few years ago, but it has spent almost all of its life in the safe. Best groups are just over 3". I shoot my groups from a bag rest at 25 yards, and yes, a large variety of ammo. 125 to 158 grain, factory, reload, etc.
If any of you have had similar results and have identified a particular barrel flaw and a correction for it, I would appreciate your input.
Happy Easter,
Fuzzy

 

[Erocksmash]

Hmmm. That sounds unusual....

My 3in .3.5.7 series pulls better groups at 20yds with the craziest handloads...

Maybe a trip back is in order?

 

[BLUEDOT37]

Some common flaws worth checking

...have identified a particular barrel flaw and a correction for it...

Generic items:

- check the crown for good presentation of the rifling.

- check the forcing cone for roughness & a good transition into the rifling.

- using a pin gage set, check the bore for a constriction at the frame/barrel union.

- using a pin gage set, check the throats for diameter & consistency.

.

 

[Protocall_Design]

Bluedot37 pretty much covered it. The only thing left is to make sure the bore is very clean. A leaded barrel won't shoot groups.

 

[smithman]

Most of the time poor accuracy for me is caused by the loose nut behind the trigger.

 

[quaduser]

Granted I don't shoot from a bag rest, but I wouldn't complain too much about 3" groups at 25 yards...

 

[fuzzymcnab]

Thanks for all the responses. Blue, i had considered the crown, never would have thought of the other possible issues. I will indeed get the needed gauges and check these.
Erock, I did that with a 625 I bought a number of years ago and that was a complete waste of time. 3" at 25 yards is well within their parameters, which is actually much more lenient than that.
Protocol, the barrel is very clean, and I only shoot jacketed or plated bullets out of it.
Smithman, I have accuracy tested more than 150 handguns, and I assure you I am quite good at it.
Quaduser, if not from a rest, a 3" group from a 4" .38/.357 revolver would indeed be quite acceptable. From a rest, not so much. The best group from a S&W or Colt revolver should not be more than 2.5" from a rest at 25 yards. This assume a 4" or longer barrel. All of my S&Ws and Colts within the above mentioned barrel sizes will shoot about 2". Of course only one of these is less than 20 years old, and that one (a 625) required a new barrel
to fix poor accuracy . After barrel swap, its best group was 0.75" at 25.
Thanks again for all the input,
fuzzy

 

[dmy]

Have you checked the sight screws and blade for tightness?

 

[fuzzymcnab]

Yes I did, but excellent suggestion. Twice over the years this was the last thing I check. Once a loose front sight, once a stripped rear sight adjusting screw. Learned my lesson since then.
all the best, fuzzy

 

[ultratec00]

When I work up a load for my revolvers, off come the iron sights and on goes a scope. In most cases, it's a weaver 2.5-8X28 which is parallax set at 50 yards and also the distance I group to in most circumstances. This totally eliminates any sight alignment errors. Keep in mind this is just to work up a load and the sole purpose is grouping. Suggest if you have access to at the very minimum a quality red dot, give it a try and see if there is any improvement. This will at the very least eliminate one variable.

Both my 3-5-7 686s (3" and 5") both shoot and love 125 JHPs over a load of Enforcer. Haven't tried other weights simply because the 125s will do what I want them to do.

 

[Protocall_Design]

Fuzzy - I have never got any of my revolvers to shoot a group with plated bullets. I have tried several bullet weights and calibers over time. They all shoot fine with quality cast and lubed, jacketed, and polymer coated bullets. You may be wasting time and money on copper plated.

My Open Class Bianchi 686 will shoot 3/8" groups at 25 yd. and a little over an inch at 50 yards in a Ransom Rest. Revolvers can be very accurate when everything is mechanically to spec.

 

[fuzzymcnab]

Ultra,
Thanks for the tip, but all of my handguns (except .22's) are set up for defensive shooting, so I don't have any use for scopes. Nothing against them, just not my cup of tea. I can shoot reasonable groups with most handguns out to 100 yards with iron sights. Recent example: Early this week took my son's house gun to the range for quick function testing before a complete cleaning. It is a Sig 239. I had two rounds left. I fired both at an 8" plate at 50 yards. Hit it once. Trust me, it's not great skill on my part, just putting all the basics together.
Protocall, you may be on to something. the only 2 S&W revolvers I have (not counting snubbies) that are less than 20 years old, both had accuracy issues. However, all the rest shoot plated bullets with great accuracy, especially the current crop of 130 grain FMC factory loadings. Personally, i think all the problems started with EDM rifling, but I am a collector and a shooter, not a gunsmith. However, I will load a batch of lead SWC's for comparison. That just makes sense.
thanks again for all the input.