Reaming Cylinder Throats for Accuracy

About 12 or so years ago I bought a used model 14 S&W for about $225 because it had been drilled and tapped for a scope. Typical model 14 with a great trigger and good sights. Now I almost exclusively shot waddcutters out of it and mostly at 50 feet and 25 yards. Last year I decided to try a Distinguished Revolver match and I had never targeted the 14 @ 50 yards with round nose or semi-waddcutter bullets. My initial results were somewhat underwhelming in the 5-6" range. 

Okay to get to the point, I measured the cylinder throats and they were a tight 0.356". I sized a couple of bullets to 0.356" and it actually showed a little improvement in 25 yard testing (due to sub 0 weather here lately I just used my off-the-back-porch 25 yard range). My old 158 RN load was shooting an average of around 2.75" @ 25 but the 0.356" bullets took a 1/2" off of that to around 2.25" groups. I bought a cylinder throat reamer and opened the throats to 0.358". The same 158 RN load now groups just over 1.5" @ 25 yards. I am going to plow some snow off my range so I can do some 50 yard testing as soon as it warms a little. 

I am really surprised how much that helped. Has anyone else played around with throat reaming and, if so, how did it work for you?  I am just trying to find out if that much improvement is normal or this was just dumb luck.

I had Hamilton Bowen ream my model 14 throats too.  It helps to not swage the bullet, in the cylinder throat, below the barrel diameter.

all my k-frame Smith revolvers have cylinders opened up to a consistent .358.

Remington 148gr HBWC's just love them.

Make the throats consistent and larger than the bore.  If they aren't constent how can you expect them to shoot the same.

I am really coming in late on this subject but I am trying to catch up on all the discussion on wheel gun accuracy.Can someone tell me if doing this modification is legal to a DSR revolver? From what I have read that goes above and beyond what the NRA says you can do to the pistol.

Len

The NRA stated limit is "honing of the sear" (if their printing geniuses ever get 3.1.4 put back in the book).  BUt how would you or they ever know what else was done inside, especially if the revolver was pre-owned?

I guess they would never know.And I would never know if I bought it used.But, I would know if I had it done and then planned on shooting it in a DSR match. I guess it is up to the individual...


                         3.1.4  Distinguished Service Revolver.

      "Except for stocks and the honing of the sear or sear notch to make a more crisp trigger,and maintain a 2 1/2 lb. minimum trigger pull,no external or internal modification may be made to the revolver as manufactured and sold by the factory of origin"


There it is,and your right they need to get off their butt and get the 2014 regs in print and actually have 3.1.4 included.

To me it doesn't seem like a modification, but bringing a out of spec throat, into specs.

It's not a modification.  you could send it back to the manufacturers and have it done if you feel guilty..

I think it would be a modification. I am sure that if I sent it back to S&W and told them that I needed the pistol brought to factory specs by reaming the throat out to .358 they would wonder what I was talking about. Factory spec appears to be .356. If I sent them the pistol and asked them to modify the pistol by reaming throat to .358 they would be glad to do the work and charge me for it.The key being, if it is wrong they would fix it for free.Since it is a modification they would charge me for the service.Just like any other gunsmith would.

Len

let me write this s-l-o-w-l-y. it is not a modification.

it's no different than the barrel work done on your .45, oversize fitted hood, upper/lower lugs, etc...

it's blueprinting the gun to the manufacturers specs and tolerances, nothing more.

Lets ask the NRA what they think.And guess what I am trying to say very slowly. Those modifications to the 45 would not have been allowed if they followed DSR rules. No modifications means NO modifications. You may not work on the revolver to improve its accuracy. Period.

I asked, years ago. I must have the letter here somewhere....

I would love to see something that lets me go to work on my pistol.I bought a new 14-8 and what a piece of junk. It needs to have everything inside it thrown away. The gunsmith that I had set the trigger to 2 1/2 lbs has been working on smiths for 40 years and has never seen one this bad. I have it sitting in the safe and every so often I glare at it. Want to buy a 14-8 that needs improved?

Len

OldMaster64 wrote:Lets ask the NRA what they think.And guess what I am trying to say very slowly. Those modifications to the 45 would not have been allowed if they followed DSR rules. No modifications means NO modifications. You may not work on the revolver to improve its accuracy. Period.

I think you should review that rule again.  It says no external modifications.  Triggers are addressed but nothing else which would be relevant to this discussion.  As a side note,  why would Smith's cylinder throat specification be smaller than the bullet diameter?

A revolver that has had its chamber throats reamed has absolutely no visible sign that anything was ever been done to it.  Even after a complete disassembly; I'm not sure anyone could prove anything.  No judgment; just saying.

Jim

Everyone else seems to have figured out how to draw a quote down and discuss it. I haven't yet.So to answer Steve Bs question the whole quote on what is legal is included in a previous post just above this one. 3.1.4 says no external or internal modifications. And I have no idea why they are that size.If they were larger then they wouldn't need to be reamed and we wouldn't be having this discussion. 

So, why is 3.1.4 now vacant in the new rulebook??????

There were several of us discussing that earlier.They just goofed.They missed that whole section in the 2013 regs.Any time I was quoting regs I had to go back to 2012 because that is all you can find in print.They printed last years regs in April so we should be looking for the new stuff with all the changes coming out soon.Maybe...

NRA's application to hold a Distinguished Revolver match reflects what I was saying.
http://compete.nra.org/documents/pdf/compete/tourn-forms/dist-rev-app.pdf

I have been tuning Distinguished Revolvers for Bullseye and PPC for many many years. Bringing the chamber throats into proper relationship (they should be lapped on center)  with the bore is one of the first, basic, operations performed, as is a proper crown and forcing cone/ throat angles and concentricity. Timing and alignment of the cylinder, is another.  As a wise old police court judge was fond of saying.."There is the letter of the law, and the spirit of the law". Going to the line with a properly tuned, safe instrument  is not a violation of the rules.
Old Master obviously has a less than quality S&W. It  happens. Should the rules prevent him from correcting its faults? There is some expectation of success when an individual enters into and pays to shoot a match. If one is required to shoot a piece of junk, and rely on chance/luck, there is no incentive.
Then, we have the inspectors... Shall they be trained to use sensitive precise instruments, remove barrels to compute these measurements, and then, to what decimal place ?  
Of all the guns I have done, I am not aware of any disqualifications. 
Jerry

Thanks everyone. I will take this pistol of mine to someone who can get it back in tolerance.I was in Roddys office today and never thought to ask him about it. He is working on a High Standard of mine that is not a POS but started having feed problems.I will ask him when I pick it up.

Len