Sizing question for revolvers

[Fishman]

I finally took some time to measure dimensions on some revolvers I like to shoot. I selected a chamber mouth at random and measured the diameter of a pure lead slug driven through. Then I slugged the barrel as well. The following are my results.

These are formatted like this:
Gun, chamber mouth diameter, bore diameter

.32 magnum:

Ruger single six 6 1/2" .311 .312
Ruger single six 4 5/8" .311 .311

.357 magnum

Ruger blackhawk 6 1/2" .357 .357

.44 magnum

Ruger super BH 4 5/8" .431 .430
Ruger super BH 7 1/2" .431 .429
Ruger super RH 7 1/2" .431 .429


I would appreciate some feedback on proper sizing for these revolvers. Up until now, I've been running .312, .359, and .430 respectively in these guns. It is my understanding that one should size for the chamber mouth, which would result in me using .311, .357, and .431 in these guns. I also understand that it is best for the chamber dimension to be larger than the bore. As you can see, two are the same size, and one has a bore that is .001 larger than the chamber mouth. Of these guns, I've shot the super redhawk the most and tested a few loads with a 2x Leupold and I have not gotten the type of accuracy I would like. Best groups for a cylinder have been around 4" at 50 yards and have really opened up at 100.

Another question is should I slug all of the chamber mouths for each revolver, or do they often vary?

I appreciate any feedback.

[williamwaco]

I would say unless you are having leading or accuracy problems don't change a thing.

Your sizing should work fine an all those revolvers.


.

[Outpost75]

I have found that driving a pure lead ball or slug through each chamber is the best way. Because all six chambers are not cut at once, there may be some variation. Rugers, if I recall are machined two chambers at a time and indexed three times. Sometimes you may get a single chamber which has a burr or ding in it from being struck with a ranging rod... If so, then you want to know which one that is so you can either fix that chamber or avoid it.

It looks to me that you are sizing to correct diameter, but the proof is in the shooting. If you get fliers with one particular chamber, or leading, those are clues. If your revolver shoots well and doesn't lead, then all is good.

83065

[MtGun44]

What you are calling 'chamber mouth' is, I think, actually the 'throat'. Slugging all
is a good idea if you are looking for best accy. Sometimes reaming the throats
up to same or .001 larger than groove diam is in order.

Sizing to throat diameter or throat +.001 will typically produce top notch results.
Frequently, .001 under throat diam will be pretty good, but often moving up .001 or
.002 will improve things. Each gun is a thing unto itself, so you will have to try it.

I'd try .431 in the .44 for sure. OTOH, those groups look fine, so maybe just stopping
now would be fine.

Bill

[Fishman]

Yes I meant the cylinder throats, still learning. :)

It sounds like I am on the right track with some fine tweaking of my sizing, slugging all throats, and testing accuracy. Then and only then if I find any problems I should seek a remedy. I'll have to either get Buckshot to make me a .431 die, or lap out my .430 since I don't see them listed as available.

[fecmech]

If you have good bench technique and shooting with a 2X scope I think I'd be changing bullets or loads till I started crowding the 2" mark @50 yds for a cylinder full.

[Char-Gar]

When I was 14 (1956), I asked my gunsmith/mentor if a Kar98 Mauser I had acquired was an accurate rifle. He told me to go out and shoot it and find out.

In the end, all that is import is how things perform on your target. What do they look like?

[missionary5155]

Greetings Fishman
That Ruger Single Six 6.5... Throat .311 Bore .312
Not so good. I would definately check those throats. If any other throat is less than .312 I would mark them and not count on them as my first shots on target. A .311 "throat sized" boolit is not going to grip rifling the best as it goes down a fatter bore.
Had a caliber .41 RBH that had a couple "under bore" throats. Always had 3 flyers from three cloverleafs. Reamed them all .411+ and it shoots all cylinders the same.
This is one reason people bad mouth lead boolits. It is the machine not the projectile many times.
Mike in Peru

[9.3X62AL]

I agree with Missionary on the potential to have problems with the .311" throats/.312" groove combination. I would shoot the suspect revolver with a number of loads to assess its accuracy before taking tools to the throats, though. .001" to .0015" could likely be polished out with aluminum oxide paper slowly and judiciously spun on an arbor, if a gunsmith can't be found to do the work. When I opened the throats on my Built Backwards Bisley Blackhawk in 45 Colt, it did not take long AT ALL to polish the .4525" reamed throats to .453" with fine-grit Al Ox paper (400 and 600 grits). FWIW, the grooves are .452" and the OEM throats ran .448"-.449". .003"-.004" reversed differential will cause problems, but even with those conditions one boolit shot pretty well (#454490). I have no experience with a "backwards" revolver with .001" of differential--such a sitch might work well, I dunno.

I have MANY revolvers that show identical diameters at throats and grooves, and all shoot very well.

I an a firm believer in the maxim "If it ain't broke, don't try fixing it."

[Char-Gar]

Yep, never modify and firearm based on theory. Shoot it first and let your targets tell you the story. You will be surprised how often you don't need to modify a firearm. Sometimes you do but mostly you do not. Looking at targets is the only way to know which is what.

I am not going to modify my gun, that I paid good money for, just because some yea-hoo on the internet or in some gun rag tells me that is a good idea. Maybe so and maybe not, but I will find out for myself first. You only have a little ammo and time to lose and much information and knowledge to be gained.

[Fishman]

Thanks for all the advice. More testing is always fun! I hope to get to it this w eekend.

[MtGun44]

+1 on Char-Gar's post!

While I HAVE reamed throats I am appalled at the people that appear to want to do something
irreversible like throat reaming without solid knowledge that there IS A PROBLEM, proven by shooting
with a range of loads under controlled conditions.

Once you establish that there IS a problem, there are ways that might work to solve it.

I agree with Al, too. I had the same issue with a .45 convertible BH and solved it the same
way. It shot OK with a couple of jbullets, but only got three of five in tight with most boolits,
two fliers out to 3" at 25 yds in most groups. It was fixed by reaming and polishing the
throats - there is a very old post somewhere in 'gunsmithing' that covers it.
It may well be that only .001 undersized is still workable with some combo of hardness,
design and powder speed. Until I had established solidly that it would NOT work, I would
not go doing irreversible mods.

Bill

[9.3X62AL]

I fooled and fiddled with that 45 BisHawk for close to 2 years before taking tools to it and cutting metal away. Similarly, I've wandered--pondered--laundered--and foundered for nigh on to three years before doing something to address the ringed chamber in my flatband Win 94 x 25-35 WCF. It left Monday for JES Reboring and conversion to 38-55. I don't rush in to remove metal, haste can really make waste.

[cbrick]

Permanently altering a firearm should always be a last resort. Very easy to take metal out, very difficult to put it back.

Your 6 1/2 inch 32 Mag is the only one I would consider and then only after serious accuracy testing. Revolver Accuracy is a relative thing, what is very acceptably for one person is a mediocre performer for someone else so you will need to accuracy test it for what is acceptable to you. If it is acceptable accuracy for you and it's not leading all is good in the world. If you believe you can do better than that particular revolver is shooting or it's leading then it's time to look for a cure.

As to your question on sizing, my preference for sizing for revolvers is to size to a mild snug fit in the throats. The only reason I bother to slug the bore on any revolver is so that I know it's at or a tick smaller than throat diameters.

Rick

[44man]

Throats smaller then groove will always be a problem with cast.
Sizing over throat is just as bad, like Rick says, just a thumb push and even a little less is best. To make the cylinder into a size die will get you nowhere.
To squeeze a boolit through a tight throat and try to make it expand again in the bore is folly.
The naked truth is even with over size throats, a groove size boolit will shoot as will one a few thou over. There is no advantage into making the bore a size die either. Why eliminate lube grooves at the start of the barrel?

[Char-Gar]

I have reamed the cylinder throats on a Ruger BH (45 Colt), but only after getting very poor results. Later I did send a brand new unfired Ruger BH (45 Colt)to Gary Reeder for a full house custom sixgun and had the cylinders reamed on that one before I fired it. Other than those two, I have not reamed any clylinder throats and I have a butt load of sixguns.

[cbrick]

Other than those two, I have not reamed any clylinder throats and I have a butt load of sixguns.

Wow, That makes me really curious . . . How many sixguns does a butt hold? :coffeecom :mrgreen:

Rick

[offshore44]

One butt-load is less than a metric butt-ton, but more than "a bunch". ;)

[Bzcraig]

Interesting thread but a butt load is absolutely subjective. Butt size determines load, load is determined by the size and shape of the load bearing devices (legs) and the age and mileage of the load bearing devices will ultimately determine how many sixguns will be carried.

[9.3X62AL]

But the pivotal question is THIS--how many buttloads constitutes a SHIPLOAD?

[MtGun44]

Al,

I think it is a bazillion buttloads to a shipload. . . . . . :bigsmyl2:

Bill

[9.3X62AL]

I suspected it was a large figure, Bill. Many thanks for clarifying the nomenclature.

[btroj]

Having seen the number of handguns Charles has posted photos of he truly has owned a butt ton of them. Metric butt ton, not English.

I only altered one gun to shoot better, a BH in 45 Colt. The throats were .449 and it leaded badly. It shot well enough but I grew tired of cleaning lead from the barrel. Split rod, 400 grit paper, all now take a .452 bullet snugly pushed thru. No more leading, better accuracy. Shot it for almost a year before changing anything.

Internet experts never cease to amaze me. Every gun needs tons of work before it can possibly be shot properly, well, or safely. Maybe this is why my Remlin with MIM parts, undersized throats, and thread choke doesn't shoot well?

[MtGun44]

It does seem that the most common gun that truly needed the throats opened up was
the BH .45s. Mine was a convertible and both cyls were ridiculously tight. .449 and .450 IIRC.

Didn't even know that the metric system covered the butt load measurement. Learn something
every day. ;-)

Bill

[9.3X62AL]

If it's a "RemLin" with multiple throats, there's already a problem. :) Most leverguns and bolt rifles only need ONE throat.

But I digress. Most of these dimensional "ills" get cured through component adjustment, usually by sizing the bullets to better fit the firearm they are intended to serve--or altering the tooling to NOT cause diameter reduction of bullets bound for such tasking. As repeated above, the taking of tools to the firearm itself is kind of a "final option", and only to be resorted to when all other resolutions are ineffective. My accumulation of toys has not been beset much by MIM parts, or thread choke--the BisHawk x 45 Colt needed surgery, and that has been the sole example I've modified in that fashion. The improvement was immediate and dramatic, too--the revolver went from being a One Boolit Wonder into a tractable, accurate, and non-leading fun gun with a wide range of casting types.

Since stumbling upon the Built Backwards BisHawk, I've acquired a set of pin gauges for revolver throat-checking. Over time, I've slugged the bores of my firearms, and in the revos did comparisons with their throat diameters. The Ruger remains the only example showing this anomaly. My understanding is that Ruger's few Vaquero variants produced in 44-40 WCF caliber showed similar quirks--frequent .430" grooves mated to .426"-.427" throats. It may be likely that such an arrangement will provide poor performance and/or a comprehensively leaded barrel after extended shooting sessions, but I would STILL confirm that tendency through thorough test-shooting of all bullets intended for the beast.

This goes double for the original poster in this thread. I am not convinced that a backwards .001" offset between throats and grooves will be destructive of accuracy or other performance factors. I have not knowingly seen such a condition in my own experience, so take what I say for what it might be worth empirically......but do consider the following factors.

Lead bullets of tri-metal alloys have the alleged reputation for not "bumping up" under the influence of smokeless powder pressure exposure. I am not so certain that we should view this belief as an "absolute", or that such a small diametric variance (.001") can't be bumped up successfully by the forces at work during the firing sequence. Now, every increasing .001" of clearance around the boolit GREATLY exaggerates the flow potential for hot gases to escape past the boolit sidewall, and for this bump-up to fall short of sealing the bore--and in the ideal world, we should guard against these eventualities as best we can. Keep in mind that .001" of backwards orientation could as easily be found in measuring tool variance, either present in the tool's mechanics--by virtue of the operator's usage habits--or both in concert. I am a reflexive doubter, though--this reinforced by 28 years of cop work. I make no claim of being as adept with micrometers and calipers as a machinist would be, but we are all flawed beings. For this reason, I would definitely NOT take tools to the Ruger revolver cited by the O/P until the gun's performance PROVED the need for this step by way of extensive testing.

[Bzcraig]

One butt-load is less than a metric butt-ton, but more than "a bunch". ;)


Interesting thread but a butt load is absolutely subjective. Butt size determines load, load is determined by the size and shape of the load bearing devices (legs) and the age and mileage of the load bearing devices will ultimately determine how many sixguns will be carried.


But the pivotal question is THIS--how many buttloads constitutes a SHIPLOAD?


Al,

I think it is a bazillion buttloads to a shipload. . . . . . :bigsmyl2:

Bill


I suspected it was a large figure, Bill. Many thanks for clarifying the nomenclature.


Wow, That makes me really curious . . . How many sixguns does a butt hold? :coffeecom :mrgreen:

Rick


Always cracks me up how easily the hamster comes off the wheel!

[9.3X62AL]

Oh, THIS thread has been a mild departure--some can become REAL train-wrecks. Check out some of the past "RPM Theory" threads.

[Mal Paso]

But the pivotal question is THIS--how many buttloads constitutes a SHIPLOAD?

That is a Nautical Question more suited to the Marine Forum but I do know just one of their 18 inch guns is more than a buttload.

[btroj]

I don't on bout that, I have seen some women with awful big butts........

[MtGun44]

"two pigs 'rasslin in a sack" southern view of a northbound female in Walmart. . . . . rush for the eyewash.

Al is right. This is only moderate thread drift. Plus we actually put the good stuff in before we went off the rails, this time.

Bill

[9.3X62AL]

"two pigs 'rasslin in a sack" southern view of a northbound female in Walmart. . . . . rush for the eyewash.

Al is right. This is only moderate thread drift. Plus we actually put the good stuff in before we went off the rails, this time.

Bill

Yeah, it appears that we are collectively maturing here. Or something.