barrel/cylinder gap

[Brutus]

Just out of curiosity I checked the gap of my revolvers. Always set my Dan Wesson at .004 thousands which works great, but my fixed barrel guns are as follows:

1978 Colt Python (My most accurate revolver) .006
Colt King Cobra Target .004
2022 Colt Python .005
Colt Cobra 38 Special .005
Colt Agent .003
Smith & Wesson 629 .004
Smith & Wesson 625 .45 Colt .005
Ruger single six 22lr. .004
Ruger single six 22 Mag. .004

 

[Alan0354]

My experience is 0.004 is good, when goes to 0.006, you lose accuracy.

I had a S&W 19, 6" barrel, it was very accurate at about 0.004"(don't recall the exact). But from long day of firing, the cylinder started to bind. My stupid mistake thinking widen to 0.006" should not make a difference, WRONG!!! I widen it a little, I lost it.

I also have a few tiny Freedom Arms and one NAA mini .22 Magnum revolvers. I chronograph them. I got about 1,300fps with 1 3/4" Freedom Arms, 1,100fps with 1". The gap are all about 0.003". The bigger longer barrel NAA has a bigger gap(don't remember, but it was wider) barely got 1,000fps with at least 2"barrel( I don't have it to confirm).

To me, it's very important to keep the gap small, 0.003" if you are willing to clean the gun very often. It loses velocity and accuracy if the gap is even 0.006"

I am not surprised one of your Colt has 0.006", I have their Gold Cup 45. It's the most expensive at the time. You should see the crappy workmanship inside. It is a Series 70 bought in 1989. I will NEVER buy another Colt again.


Unrelated to the subject, do NOT buy S&W Model 17!!! It is NOT accurate. We bought two, both are garbage. They are all 6", the gap are OK. It is just not accurate. The worst one is my wife's, it has flyers randomly. I did sandbag and all. I even sent it back to S&W, they shot 5 shot with good grouping(1") and sent it back to us. We finally gave up. For target and competition, I use my Ruger MarkII bull barrel and the Gold Cup. Both are so much better than the 17. Don't ask me why, the size and shape of 17 is exactly the same as 19, only different in caliber. 19 was so accurate until I ruin it. Even after I ruined the 19, it's no worst than the two 17.

 

[JohnKSa]

I've never seen any careful testing showing a correlation between accuracy and cylinder gap size. In fact, did you notice that the OP's most accurate revolver also has the largest cylinder gap?

What method did you use to widen the gap on your 19?

 

[Alan0354]

I've never seen any careful testing showing a correlation between accuracy and cylinder gap size. In fact, did you notice that the OP's most accurate revolver also has the largest cylinder gap?

What method did you use to widen the gap on your 19?

A file. Very careful, making sure it's even.

Regarding to the velocity, I did not file anyone of those mini revolvers. The Freedom Arms just a lot faster with the same rounds. The only difference is the gap. I have 3 of the Freedom Arms, they all fast. It's actually quite amazing.

One has to specify the length of the barrel. Of cause a 6"barrel even with wider gap is going to be more accurate than a 3" or 4" NOT just because of the length, likely because of the sight of aiming. It is always easier to be accurate the bigger the distance between the front and the rear sight.

Also, it depends on the shooter how good one is. If one shoot less than 50% into the black at 25yds, they will likely NOT see the difference. Only way is to sand bag in order to tell the difference.


EDIT: Now, I did not use match ammo, I just bought reloads from the same shop. The rounds are ALL bought from the same place and no difference on my Colt Trooper 8". I don't know whether it will make a difference if I try different bullets. The Model 19 was very impressive before I ruined it, it's just as good if not better as the 8" Colt Trooper. I really regret monkeying with it. I never sand bag them, but my guess they are all within 1 1/2" grouping at 25yds or even better with no scope.

 

[jmstr]

I had an interesting interaction with Ruger regarding one of my revolvers [but I forget which one right now. I am pretty sure it was a super blackhawk- but it might have been a regular blackhawk].

They told me that their acceptable/within tolerances/no repairs to be done BC gap was somewhere between .003 and .011, IIRC. I could have been a width of .010 though- but it was one of those two. I am pretty sure it was .003 at the tight end though.


Just throwing this out there. Of course, their concern is reliability- not precision or avoiding power loss.

I prefer gaps of .003-.004, when possible.

 

[Alan0354]

0.01" is crazy wide. Like I said, I lost my M19 at about 0.006".

Of cause, the tighter the better. But at 0.003", the cylinder will start to bind after 50 to 100 rounds even after a good cleaning before that. That was the reason I widen to about 0.006" thinking it won't affect anything, I was WRONG, I lost my most favorite revolver.

 

[JohnKSa]

0.01" is crazy wide.

S&W claims that if the gap is anywhere from 0.004" to 0.010" then it's in spec.

Ruger says more or less the same thing--anywhere from 0.003" to 0.010".

So, at least for a S&W or Ruger, 0.01" is most certainly not "crazy wide". It's within spec. At the top end of being in spec, but still in spec.

That was the reason I widen to about 0.006" thinking it won't affect anything, I was WRONG, I lost my most favorite revolver.

There is absolutely no reason that a revolver with a barrel cylinder gap of 0.006" should be inaccurate.

I don't know why your revolver suddenly stopped shooting accurately after you filed the gap larger, but it's not simply the result of the gap being 0.006". That's well within spec. and there are plenty of revolvers out there with gaps that large and larger that shoot very, very accurately.

 

[Alan0354]

S&W claims that if the gap is anywhere from 0.004" to 0.010" then it's in spec.

Ruger says more or less the same thing--anywhere from 0.003" to 0.010".

So, at least for a S&W or Ruger, 0.01" is most certainly not "crazy wide". It's within spec. At the top end of being in spec, but still in spec.There is absolutely no reason that a revolver with a barrel cylinder gap of 0.006" should be inaccurate.

I don't know why your revolver suddenly stopped shooting accurately after you filed the gap larger, but it's not simply the result of the gap being 0.006". That's well within spec. and there are plenty of revolvers out there with gaps that large and larger that shoot very, very accurately.

That's what my experience, only thing I did was that and that change the accuracy.

Like I said, accuracy is relative. I said before, if anyone only average shooings 50% or less into the black at 25yds, they will never notice the difference. I did shoot better than that average high 70 to low 80% consistently in the black with 38 and 45 reloads bought from shop cheap and just Winchester Wild Cat .22LR. with different guns including Colt Trooper 8", Colt Gold Cup, Ruger MarkII. I know what I am talking about.

I might get better result with match rounds, but with the reloads I bought from the same place for years, there's a DISTINCT difference. I don't believe in paying for expensive match rounds. I buy the cheapest ones like 50 of 38 reloads were only $6.50 ( in 1988) and Winchester Wild Cat was 99cents a box of 50. I bought thousands at a time!!!

I own plenty of S&W, NEVER have I seen one over 0.006".

AND like I said, I chronograph the Freedom Arms and compare to North American Arms mini revolvers, I reported the speed in the above post. The only difference is the gap. This is from measurement, not speculation. I know gun smithing.

 

[GeauxTide]

My experience has been the forcing cone has to be properly cut and the diameter of each cylinder hole must be uniform to the bullets I'm using to get great accuracy. I've never worried about gap.

 

[Alan0354]

My experience has been the forcing cone has to be properly cut and the diameter of each cylinder hole must be uniform to the bullets I'm using to get great accuracy. I've never worried about gap.

When I increased the gap of the M19, I did not touch the cylinder hole and the force cone. So none of the others you mention had been changed. Still I lost accuracy.

 

[Alan0354]

I have to be more specific.

1) I want to emphasize my M19 is 6" barrel that is built for accurate shooting. If the barrel is shorter than that like 4" or under, you never get much accuracy. I have a few M36 and M37, they cannot be accurate no matter what, forget about the gap. I bet you won't notice the difference between 0.003" and 0.01".

2) Like I specified, I use store bought RELOADs only. You can see some the casing is not even perfectly cylindrical even before firing. They are for CHEAP, not precision. It might be day and night difference if you use competition or precision rounds. Then maybe the bigger gap might not make any difference. That's beyond my comment.

I can only speak within the parameters above. I stand by what I said. My two M17 with 6" barrel were never accurate, I never measure the gaps as it's not even that accurate. One had fliers, it's strange. I have a friend that laugh at me when I told him. He blame me instead.......UNTIL he try shooting it. Then he admitted the gun has a problem of flyers. I don't even talk about that two M17, they are a lost cause

I sent one back to S&W, but they came back with a tight group target and said there's no problem. Problem is they shot 15 shots in 3 groups of 5. The problem with that gun was it has flyers one every so often. I gave up on the two. One thing I can think of now is I use cheap Winchester Wild Cat that was 99cents/50. Maybe if I use standard speed match round, it might eliminate the problem.

I stopper worrying about those revolvers after I went into semi autos. My acurized Colt Gold Cup and the cheap Ruger MarkII bull barrel easily out shot all the revolvers. I really never looked back to dig any deeper why. I got better result with 45 reloads and cheap Wild Cat 22s with the gold Cup and Ruger MarkII.

Hell, I just thought of this again from talking on this thread. I might do better in competition IF I spent a little more to use competition rounds!!! I was being generous using the CCI Blazer rounds with my Gold Cup for competition instead of reloads!!! But that's still the cheapest of factory rounds with aluminum casing. Maybe I should spent a little more at the time. But I can't help it, I am born cheap!!!

 

[Bill DeShivs]

Barrel length has nothing to do with inherent accuracy.
Any reasonable cylinder gap has nothing to do with accuracy.

 

[Alan0354]

Barrel length has nothing to do with inherent accuracy.
Any reasonable cylinder gap has nothing to do with accuracy.

Could be, the sight radius might be the issue that it's hard to aim. I am just talking about the result. Just the same as anyone that shoot 50% or less average into the black from 25yds likely won't see the difference.

I just tell my result, it's very consistent. Take it however which way. I think the reasonable gap is 0.003 to 0.005. Not 0.01"

 

[Drm50]

I don’t believe barrel length has anything to do with accuracy of the revolver. It may have direct effect on person shooting it. Also reasonable gap has little effect and would only be in velocity. Now messing on forcing cone and getting it out of square could possibly effect accuracy.
I’ve put 19s on Ransom Rest and snub shot as well as 4” & 6”. Did this more than once with same model but different pieces. Have done it with N frames too, but samples were 4” to 8 3/8” didn’t have a N snub.

 

[RoyceP]

My experience is 0.004 is good, when goes to 0.006, you lose accuracy.

I had a S&W 19, 6" barrel, it was very accurate at about 0.004"(don't recall the exact). But from long day of firing, the cylinder started to bind. My stupid mistake thinking widen to 0.006" should not make a difference, WRONG!!! I widen it a little, I lost it.

I also have a few tiny Freedom Arms and one NAA mini .22 Magnum revolvers. I chronograph them. I got about 1,300fps with 1 3/4" Freedom Arms, 1,100fps with 1". The gap are all about 0.003". The bigger longer barrel NAA has a bigger gap(don't remember, but it was wider) barely got 1,000fps with at least 2"barrel( I don't have it to confirm).

To me, it's very important to keep the gap small, 0.003" if you are willing to clean the gun very often. It loses velocity and accuracy if the gap is even 0.006"

I am not surprised one of your Colt has 0.006", I have their Gold Cup 45. It's the most expensive at the time. You should see the crappy workmanship inside. It is a Series 70 bought in 1989. I will NEVER buy another Colt again.


Unrelated to the subject, do NOT buy S&W Model 17!!! It is NOT accurate. We bought two, both are garbage. They are all 6", the gap are OK. It is just not accurate. The worst one is my wife's, it has flyers randomly. I did sandbag and all. I even sent it back to S&W, they shot 5 shot with good grouping(1") and sent it back to us. We finally gave up. For target and competition, I use my Ruger MarkII bull barrel and the Gold Cup. Both are so much better than the 17. Don't ask me why, the size and shape of 17 is exactly the same as 19, only different in caliber. 19 was so accurate until I ruin it. Even after I ruined the 19, it's no worst than the two 17.

That's pretty weird. I had to try various kinds of ammo in my Smith Model 17. When I tried Remington it was dead nuts accurate. I don't buy anything else now. Apparently you are buying some lackluster reloads too.

 

[Alan0354]

That's pretty weird. I had to try various kinds of ammo in my Smith Model 17. When I tried Remington it was dead nuts accurate. I don't buy anything else now. Apparently you are buying some lackluster reloads too.

Could be, I might have to try it one day. I used Winchester Wild Cat and another Winchester I forgot the name. The reason was I got those on sale. I bought over 10 big box each time, (now each box is 10 brick, each brick is 10 box of 50). It was from Service Merchandise back in the 80s. They were popular chain store in the bayarea back then.

ha ha, honestly, I never even gave it a second thought until this thread!!!

But my Ruger MarkII bull barrel did well with the cheap Winchesters.

Now this really made me question I stuck at high 70 to low 80% into the black at 25yds for years and never improved after that. Now I wonder is is because I was too cheap and kept using cheap reloads and those Winchester 22s. Those reload 38s and 45s are quite ugly, some of the casing is NOT even perfect cylindrical before the rounds were fired. they were cheap!!!

I quit in early 90s, I was going nowhere, and I saw my friend punch a big hole in the black!!! So I said forget it!!! My friend was scary, one time I looked at his target, 3 or 4 distinct groups of like 5, all in the black. He used a Browning 22 with like a bull barrel.

 

[tlm225]

It sounds like your frugality and poor choice of ammo is the problem, not the guns. In .22 rimfire it's well known that different ammo will yield different levels of precision depending on the gun in use. Experimenting is the key. BTW the S&W K frame .22 (AKA K-22/model 17) is widely regarded as one of the most accurate revolvers ever made.

 

[RoyceP]

Cheap stuff is great if it works. If it doesn't work you haven't saved any money.

 

[Alan0354]

Thanks guys, I just NEVER think of this one. I bought so much of those Winchesters I never even give it another thought!!!

At least I did not do anything to that two M17 other than smooth out the DA inside, so it should be still factory regarding to the precision. Too bad I ruin the M19, or maybe it would still work with better ammo. But it did work with cheap ammo before I ruin it.