Bullseye shooting: Critical parts of the revolver

[helmsp]

Trying to build my "personal" S&W 586 6" barrel for precision shooting comp over here in Vienna and been reading a lot about crowning, barrel length, perfect timing, lock-up etc.
But what is REALLY crucial/important for the precision of a S&W Revolver (not talking about sights, shooter, trigger, etc)? In my opinion it should merely be the barrel and crown, right?

 

[bobbyd]

Trigger pull is critical

Actually, stock factory barrels of all lengths are capable of amazing accuracy.
In my opinion, having a good crisp trigger pull of a proper weight is the most important element to delivering an accurate shot. Mechanical accuracy of the gun will more often than not already exceed the ability of the shooter to deliver it.

 

[Daimler1989]

Actually, stock factory barrels of all lengths are capable of amazing accuracy.
In my opinion, having a good crisp trigger pull of a proper weight is the most important element to delivering an accurate shot. Mechanical accuracy of the gun will more often than not already exceed the ability of the shooter to deliver it.

that's the point. It's nice to have a match grade tuned revolver with all the bells and whistles, and then you can say for asure you have done allt hat ist technically possible to ensure a good match count. BUT: You won't benefit of all those bells and whistles if you don't have a match grade trigger control - so you will first of all need a good trigger. I have 2 S&W 27 that are incredible accurate. All that was done on the 27-3 4" was a trigger job 28 years ago because DA was binding a few times (and a match rear sight with correspondign front sight for my ageing eyes). The 27-2 5" is right out of the box and has a crisp trigger with a SA pull of 3.6 pounds. Both are fine enough for high match counts.

 

[boatbum101]

Timing , lock-up , bore condition , barrel crown , length helps for precise sight alignment , forcing cone angle / smoothness ( Taylor throating ) . Bull or slab barrel , Bomar or Aristocrat sight rib or scope rail if using a red dot sight . Under barrel weights if needed . I'd think a Manurhin MR 73 in 38 special or 32 S&W long would do nicely . If you've already got the 586 most shoot quite well . More accuracy a faster twist heavy barrel for 38 special & 32 wadcutter mid range loads such as 1 in 14" to as fast as 1 in 10" for 50yds . Walther barrels are a good value .

 

[helmsp]

Thanks for the posts so far.
I'm aware that trigger, sights and the shooter are vital. These three things are already "tuned in" and I manage sub 2" groups at 25m without any rest.

What I'm after are true information on whats important for the gun's own accuracy.

 

[keithherrington]

Much more to it actually...

Barrel and crown are important, but so are:
a. alignment of each chamber to the barrel, left/right, up/down.
b. is each chamber aligned the same?
c. does it shoot all six chambers to the same group or are one or more consistently shooting their rounds out of the group?
d. throat size needs to be consistent chamber to chamber, and between groove diameter (barrel .357"/throat .357") or up to .001" over groove diameter.
e. cylinder lockup should not be sloppy but neither should it be tight. There should be a slight bit of rotational movement. This allows the bullet as it leaves the throat to align with the barrel's forcing cone.
f. The forcing cone should be cut and finished properly. A lot of different opinions on this but many agree a 11 degree cut is correct with the tool marks polished out. Deep enough to guarantee a smooth transition into the barrel but not larger than it needs to be.
g. The barrel should not be "choked" or tight where it screws into the frame (just in front of the forcing cone). If tight, it can be lapped out.
h. Last, and very important, grips. Not only to give you the right relationship to the trigger, but to put the gun at the proper angle for accurate shooting. I used Nill Hemphill PPC grips throughout my career to good effect.

In my Bullseye career shooting a revolver I went through MANY revolvers before I settled on having Hamilton Bowen build me a custom gun. He addressed each of the issues above (and more) and the gun is incredibly accurate - 5/8" groups at 25 yards and 1.5" at 50 with Winchester "White Box" 148 grain WC ammunition.

With Nills when competing


With Culina target grips now


Hope this helps.

Keith

 

[helmsp]

Barrel and crown are important, but so are:
a. alignment of each chamber to the barrel, left/right, up/down.
b. is each chamber aligned the same?
c. does it shoot all six chambers to the same group or are one or more consistently shooting their rounds out of the group?
d. throat size needs to be consistent chamber to chamber, and between groove diameter (barrel .357"/throat .357") or up to .001" over groove diameter.
e. cylinder lockup should not be sloppy but neither should it be tight. There should be a slight bit of rotational movement. This allows the bullet as it leaves the throat to align with the barrel's forcing cone.
f. The forcing cone should be cut and finished properly. A lot of different opinions on this but many agree a 11 degree cut is correct with the tool marks polished out. Deep enough to guarantee a smooth transition into the barrel but not larger than it needs to be.
g. The barrel should not be "choked" or tight where it screws into the frame (just in front of the forcing cone). If tight, it can be lapped out.
h. Last, and very important, grips. Not only to give you the right relationship to the trigger, but to put the gun at the proper angle for accurate shooting. I used Nill Hemphill PPC grips throughout my career to good effect.

Great information here, thanks a bunch Keith!
Whats your opinion on barrel length, does longer been more accurate?
Also, is there an optimum angle for the crown? I read 11 degree somewhere.

 

[keithherrington]

Great information here, thanks a bunch Keith!
Whats your opinion on barrel length, does longer been more accurate?
Also, is there an optimum angle for the crown? I read 11 degree somewhere.

I've found 6" the best length for me, but when shooting the 586 I tried, I found the gun just too heavy. The K frame with the full lug barrel, like the Model 14 I shoot now, is far better in terms of weight and balance. My next favorite is a Model 27 with a 6" or 6.5" barrel. I actually like the double action on the 27 better than on the Model 14, not because of how good that action feels once all smoothed up, but because you can work an N frame DA better (in general) than you can a K frame. The L frame is about in between. It has to do with the rotating mass of the cylinder. The higher rotating mass of the N frame smooths out the trigger stroke. Now if you shoot single action for everything, not an issue. But if you shoot DA for Timed and Rapid fire like I do then that becomes a BIG, BIG deal. I spent a fortune discovering the best way to set up an action for me (not necessarily for others) and once set up properly shooting DA in sustained fire is not nearly the challenge many think it is. I stage the trigger by pulling quickly till the cylinder locks, then pressing the rest of the way until the hammer falls like a really long single action trigger. The cylinder has to come up early and consistently chamber to chamber for this technique to work. When it does, it works very well indeed.

As to crown, on a factory barrel the 45 degree crown is fine as long as its cut true. On a custom barrel I like a flat (0 degree) crown that is recessed.
Keith

 

[David R]

I have been told all my life, its trigger control and sights. I agree!

David

 

[epj]

And grips that fit YOUR hand.

 

[jtcarm]

If shooting lead bullets (cast or swaged), the chamber throats need to be slightly larger than the bore.

You can measure both by driving a soft lead slug through each chamber throat and bore. Measuring bore dimensions on an S&W is a bit tricky due to the odd number of grooves. You might want to take it to a gunsmith to get this measurement. Check diameter of everything with a micrometer of at least 1/1000" precision, or whatever the metric equivalent is.

If the throats are smaller than groove diameter, they need to be opened up, though with the accuracy you describe, it doesn't sound like a problem.

Then the bullets need to just barely squeeze through the chamber throats, or even be just a hair larger in diameter.

If you reload you can fire lap the bore. Visit Lead Bullet Technologies web site for a description of the process. They sell a fire lap kit with detailed instructions. Fire lapping smoothes the bore and removes any choke points.

 

[ChuckS1]

I would agree with the others who have said a smooth trigger with as light a trigger pull as is allowed by the rules is what you really want. I seriously doubt that you'll notice the other factors. When I'm shooting NRA bullseye (which, I think, is different than the international rules you have), I'm more concerned about keeping my front sight in focus. Honestly, I've seen a lot of good shooters score well with average pistols than I have with average shooters win with top-of-the-line pistols. My revolver is a 1952 vintage Target Masterpiece with original stocks for any revolver matches using a 148 grain HBWC and 2.8 grains of Bullseye for the shortline, or a 158 grain LSWC and 3.6 grains of Bullseye for the 50 yard line. Otherwise, I'm using my Les Baer M1911A1 with a slide-mounted Ultradot for the centerfire matches.

 

[OLDSTER]

IMO, everything else being equal between, say, a couple of Model 14's, there are 5 things;

-trigger
-trigger
-trigger
-trigger
-forward weighted barrel

 

[helmsp]

Some of you didn't read my first post thoroughly...
Thanks jtcarm and cprher for your posts, been very helpful and informative.

Is there a difference in accuracy when you take a dedicated .38 shooter (10, 14, 64, etc) in comparison to a .357 shooter? Read somewhere that there is more "bullet jumping" in the latter one.

 

[H Richard]

The amount of Bullet jump using 38's in a 357 chamber is negligible. To wring out the last tiny bit of accuracy, you could load using .357 brass. Developing a load that your particular gun likes has a pretty good impact on group size. The exact diameter of the bullet, the exact "consistency" of the quantity of powder, amount of crimp, trimming length of the case, and primer seating can go a long way towards the smallest groups.

 

[rct269]

"bullet jumping"-----Not Otherwise Classified:

I'm going to assume you're referring to the distance the bullet travels in the cylinder before it encounters the forcing cone/rifling. Given that, some distance is bad, and more is worse.

Back in the day, when I was getting my butt kicked by folks with strange looking revolvers, this is what they looked like: The length of the cylinder was the same length as a .38 Special Wadcutter round. There was no "bullet jump". The barrels were, needless to say, custom-----and were set back from the frame to meet the cylinder. This is old news to those of you who are familiar with the ammunition developed for/used in the NM #3 Targets---in the 1800's,(!!) The cartridge case is the same length as the cylinder, Again, there was no "bullet jump".

Looking back to yesteryear once again, the so-called "Olympic Chamber" found in some 3rd Model and Straight Line Single Shots is the same fix---just a different pew in the same church----some throat is bad---more is worse. These single shots have no throat---one must seat the round by forcing the bullet into the rifling. It works!

Those who prescribe messing with the cylinder throats are attempting to overcome the inherent disadvantage of "bullet jump" (long throats)---and it helps. It doesn't fix.

Ralph Tremaine

And a personal note: Any and all who shoot .38 Special rounds in .357 Magnum revolvers are nuts!!

 

[swpc]

While crowning is important, the cylinder lock up ( lining up the charge hole with the forcing cone ) is critical. Also, the forcing cone depth and
concentricity is critical. If the bullet goes into the barrel straight , it will
come out straight. The B&C gap ( barrel & cylinder ) gap should be at
about .0035 to .004 for ideal spec.
Check barrel - cylinder line up with bore plug gage , when hammer is fully cocked this will let you know if line-up is correct , if you get a "plug
strike" , meaning the range rod hits cylinder you will get lead shaving and bullet is not entering barrel straight.