Ruger vs S&W; Throat Diameters

[DrBlackhawk]

I've been a long time lurker here at CB for the most part but I have a puzzling question. I consider my knowledge of cast to be on the low end; my only knowledge is having read Veral Smith's book and quite a bit of stuff from Glenn Fryxell.

I slugged my Ruger Super BlackHawk Hunter cylinder throats when I started casting last year. I got a measurement of .433". I bought an NOE 434421 and have been using a Buffalo Arms sizing die to size to .433" with LS Stuff White Label Lube. I think I use 50-50; unsure as I don't have it sitting in front of me. Anyway, they've shot well with very small/minimal amounts of leading.

Recently I picked up a S&W m69; the L-frame 44magnum at the last fun show a few weeks ago. I slugged the throats for that and got .430". Figured that my loads for my BlackHawk would run fine. My reasoning was that it would be more than plenty to fill up the bore and get a nice seal. Nope. Instead I had little lead ring shavings that dropped down into the crane and bound the whole thing up! So I got some .430" sized bullets from Dardas Cast, ran those and had no leading.

What gives? Is this normal for there to be such a large discrepancy between S&W and Ruger? I've been contemplating ordering some ZZ minus pin gauges from .429" to .432" so that the next .44 I found, I could make sure that I got throats that were closer matching.

Sorry to write a book guys. Hope it isn't an information overload.

-Marc

[Love Life]

Yes, it is common to experience different tolerances between manufacturers.

Also, the fact that you read Mr. Smith's and Mr. Fryxells books puts you way ahead of the curve.

[DrBlackhawk]

A good friend and coworker gave me Veral Smith's book to read when I first started handloading. I understood very little of what I read at the time. It wasn't until I started actually doing all this that I started learning first hand, and as I made mistakes along the way, or had questions, little bits of what Mr. Smith said would click and I'd understand what he was talking about.

Should I consider a set of pin gauges then so the next 44 will work with the same bullets? Or am I considering something that just isn't possible; i.e. casting the same bullet, sizing it the same and being able to run it through either revolver depending on my preference that outing without any issues?

I picked up the m69 for local IDPA and pin shoots, but I like having a long barreled 44 for those days when I like to go try to hit things a little farther out. Yes I do realize that working up loads for one vs the other will give me the best accuracy. More than likely I'd work up something for a long barreled gun, and then as long as I can hit a pin at 20yds with the m69, that'd be good enough for me.

It's just slightly disheartening that the .433"s seem to really not jive with the Smith, but if I were to size lower than .433" to accommodate the Smith, I'd essentially turn my groups from my Ruger into a pattern and lead up the bore.

[Love Life]

Pin gauges won't hurt, you just have to make sure the gun store will let you gauge their merchandise.

Getting uniformity across manufacturers would be sweet!!!

[DrBlackhawk]

Pin gauges won't hurt, you just have to make sure the gun store will let you gauge their merchandise.

Getting uniformity across manufacturers would be sweet!!!

I spoke with them tonight before I hopped on here to ask, I was assured by my LGS it shouldn't be an issue. Using a pin gauge wouldn't marr up the throats of a revolver would it?

[Love Life]

Shouldn't as long as you don't try to beat one in.

[DrBlackhawk]

Shouldn't as long as you don't try to beat one in.

Thanks a bunch, majorly appreciate the help. I've tried posting on my State gunowner's forum in the reloading section but I didn't really get much for information.

Thanks again,

Marc

[Love Life]

Glad I could be of help. You can also look at getting the throats reamed, but there are others more knowledgeable on the subject than I am. I believe DougGuy does that kind of stuff.

[DougGuy]

Hi Marc, What you are running into is an age old problem that's been around as long as they have been making revolvers. First, if you have a Ruger that pins out at .433" I'd say you were lucky, as the majority of those are usually smaller than that, and usually very uneven, meaning 2 throats might measure .432" two more might measure .430" and the others could be in between.

Ruger used to gang ream cylinders with a machine that held 3 cutters. It reamed 3 holes in a triangular arrangement, then indexed one hole over and reamed the other 3. When the reamers wore, they replaced them at random so you could have a cylinder that was reamed with one new reamer, and two older ones with different amounts of wear on them, so now you got cylinder throats all over the place as far as dimensions go.

S&W would be closer to SAAMI specs for their production runs, and the throats would likely be smaller, but much more precisely machined and finished.

Having pin gages is nice to measure the exact size of the throats, -and- to discover egg shaped throats, but on the other hand after you have pinned out a dozen or so revolvers I think your brain would be wrapping around a very confusing set of data because none of them will be as you would expect them to be.

I get a lot of cylinders for reaming because throats are tight, mostly Ruger, very common, I do them day in and day out, sized usually right at .432" in the .44 and send them back out to customers who can now load and shoot the same boolit they use for their leverguns or other revolvers. I also get some because it allows the shooter to commonize loads so they don't have to say "these are for the Smith, these are for the Ruger, these are for the Marlin" and so on.

Late production New Model Rugers are beautiful to look in the cylinders, but almost across the board the throats are too tight for cast boolits sized .001" or .002" over bore diameter, and in the case of the .45 caliber guns, many are .4505" and a few at .450" which is smaller than the groove diameter of the bore. They will never shoot good with cylinder throats that might as well serve as a 6-port sizing die that swages down the boolit upon firing. I get a lot of these for reaming out to .4525" which works very well, and I get a LOT of positive feedback from my customers after they get their cylinders back and start shooting the guns. On average, groups will be cut in half.

Addressing cylinder throat size is fairly common. It comes down to what boolit diameter you want to use, the throats must be at least that size or larger.

If you are going to order pin gages, I would suggest the Z Minus gage, and get the half thou sizes as well. Meyer Gage is great for single pins, very fast and very good company to work with.

[MtGun44]

No really new or unknown things here. Throats vary a lot, from maker to maker and between
individual examples from one maker.

I have a SBH with .433 throats, but my convertible BH in .45 had .450 throats in the Colt cyl and
.449 in the ACP cyl. . . now all are .453.
My S&Ws tend to run .429 to .430, depending on exactly which gun I measure.

I make ammo specifically for the BH, but the others all live with .430 sizing.

As to pin gages, I have a set and will try not to buy a revolver without gauging it, although
sometimes at a gun show, I wasn't really planning on buying and run into a deal without
my gauges. Anything in a gun store - I'll go home and get the gages. Too tight is good -
it can be fixed, too loose. . . . . . MAY be able to fix it, but sometimes this is a real PITA
finding oversized molds and such.

Bill

[ejcrist]

I've been a long time lurker here at CB for the most part but I have a puzzling question. I consider my knowledge of cast to be on the low end; my only knowledge is having read Veral Smith's book and quite a bit of stuff from Glenn Fryxell.

I slugged my Ruger Super BlackHawk Hunter cylinder throats when I started casting last year. I got a measurement of .433". I bought an NOE 434421 and have been using a Buffalo Arms sizing die to size to .433" with LS Stuff White Label Lube. I think I use 50-50; unsure as I don't have it sitting in front of me. Anyway, they've shot well with very small/minimal amounts of leading.

Recently I picked up a S&W m69; the L-frame 44magnum at the last fun show a few weeks ago. I slugged the throats for that and got .430". Figured that my loads for my BlackHawk would run fine. My reasoning was that it would be more than plenty to fill up the bore and get a nice seal. Nope. Instead I had little lead ring shavings that dropped down into the crane and bound the whole thing up! So I got some .430" sized bullets from Dardas Cast, ran those and had no leading.

What gives? Is this normal for there to be such a large discrepancy between S&W and Ruger? I've been contemplating ordering some ZZ minus pin gauges from .429" to .432" so that the next .44 I found, I could make sure that I got throats that were closer matching.

Sorry to write a book guys. Hope it isn't an information overload.

-Marc

Marc,

Just curious, but why don't you buy a .430 die for sizing the S&W? I don't believe I have any two revolvers with the same size throats, and even if I did, it's unlikely they'd both like the exact same load best. If accuracy is a main concern I'd assume each firearm would have a different load anyway. I can see your dilemma though if you want accuracy in one and the other is just for plinking.

[Tar Heel]

Send them off to DougGuy for reaming. He will do you right.

[9.3X62AL]

A look at the SAAMI spec sheet for the 44 Special and 44 Magnum will show that .433" is the high side of "within specs" for 44 throats. Late 1970s and 1980s S&W revolvers commonly run this size. Paired with a .429" groove diameter in its barrel, a shooter may need an 11* forcing cone cut to make the choir sing in harmony. If I know I'm headed on a gun shop crawl, the pin gauge set comes along in the truck. They are Revolver Polygraphs. I got very lucky with my 44s......the Redhawk's throats are .430"-.4305", and grooves are .430". It shoots wonderfully, and has never leaded the barrel. Its long gun counterpart--Winchester/Miroku M-92--is .429" across the grooves and maybe a half-thou wider in the throat. The two can exchange ammo easily, accurately, and without leading.

[Treeman]

FWIW, I have found that a whole lot of less than ideal dimensions actually behave just fine in the shooting. If it isn't working measuring throats ,adjusting bullet diameter and hardness can solve problems.....but if the loads aren't extreme and the bullets aren't dead soft or overly hard things mostly work. I must have ten .38 specials from 5 manufacturers all shooting the same loads with no leading. I haven't slugged them all but odds are they can't all be the same (I'm pretty sure I slugged one that had differing throats in one cylinder) Nonetheless they all shoot fine and the 2 that lead only lead a very little that brushes right out. I have fewer .44s but they all shoot the same loads too.

[DougGuy]

The two most important factors are pressure and hardness. With Tier 2 loads approaching magnum pressures and pressures greater than Tier 2, j words and softer alloy cast boolits will gladly "bump up" in the bore after squeezing through a tight throat or even a mild thread choke. As pressure drops off to standard levels, the less of this swaging you will get, and any problems caused by "dimensionally challenged" throats or chokes will become more obvious. The harder the alloy used, the more obvious problems become because they don't swage and once forced through a tight throat or a thread choke, will remain smaller creating leading and poor groups.

The lower the pressures, and the harder the alloys, the more dimensionally correct your revolver needs to be. In the middle of the pressure curve, with middle of the Brinell hardness alloys, it matters a lot less..

[Treeman]

DougGuy, I'm in total agreement.You stated things more precisely than I.

[Char-Gar]

You are new to the wonderful world of sixguns and have just encountered a fact that all revolver users must contend with, i.e. charge hole throats will vary from maker to maker and even from the same maker depending on when it was made.

This is just a fact of sixgun life and all the wishes that it wan't so, won't make it so, so we deal with it through handloading.

[Love Life]

My S&W with .455 throats shots .452 boolits accurately and without leading.

[MtGun44]

Hah! I wish! My two .45 ACP surplus revolvers, Colt and a S&W have .455 and .456 throats. With light loads
and commercial (rock hard) boolits, either can easily keep them in a 24" circle at 25 yds if you work at it.

Drive harder and use softer boolits and they start to work better - as Doug says - I have yet to try really
soft, being a bit concerned due to the claims of shallow rifling in these models.

The best accy has been .454 and .455 wwt alloy (so about 11-12 BHN) with medium level or so loads.

Still puzzling with them, have some good groups and some spectacularly bad ones. One has
to see a few 20"+ 5 shot "groups" to appreciate how badly a poorly match combo of ammo and revolver
dimensions can really be. Frankly, I was astounded.

I thought I'd have much more time to play with this stuff when I retired. Hasn't worked out that
way yet, too much other house and yard and trees and the barn and floors and the new deck,
and the overseas visitors, and my Dad's house, and ............. stuff. :-)

Treeman - seems like .38 and .357s have a much narrower range of dimensions than the bigger
bores, not necessarily comparing apples to apples.

Bill

[Love Life]

.452 boolits cast of water quenched range scrap. I coat these boolits with HI-TEK coating and quench after the last 20 minute bake at 400 degrees. They make a tinking (the boolits) sound when they bump into each other. They are fired over a dose of AA#7. No leading and groups are no different than the .454 452423 boolits cast from air cooled range scap and lubed with LLA.

I never really understood the whole size to throat thingy mabob when I only needed to be .001-.002 over bore diameter. I've had other revolvers with throats larger than the bore and I just sized the same as normal .001 or .002 over and never had any issues with leading or accuracy.

YMMV, but it works for me.

[DrBlackhawk]

Sorry to revive this post from the dead, but thanks for all the responses everyone. I ended up getting myself a set of ZZ minus pin gauges from .4290 to .4330 and take them with me any time I consider buying. I did recently have the chance to gauge an order of Super Redhawks and a few 629s right next to each other.

What I found was that of the 6 Redhawks I tried, .4320 was a Go in every hole, but .4330 was a no go. This was across the board for all the Super Redhawks that my LGS laid on the table for me. There were two 629s and both were go with .429 and no go with .430". I took one of the 629s home and have been feeding it the same boolits I use for the 69 with no ill effects whatsoever. Thanks again for all the help.

For what it's worth, being able to have the same bullet size has been nice because for some of my needs I just order some cast bullets already cast from Dardas. These are typically for double action practice inside of 30yds as well as informal plinking with family/friends. For when I go hunting or shoot longer ranges, I cast my own.