What size bullet?

[justinhip]

After slugging my srh barrel i got .430 maybe ..4305 and the cylinders are slugging about .432. What size should i be sizing my bullets to?

Thanks

[WHITETAIL]

justinhip, The rule of thum for boolet
size is .001 to.002 over bore size.
I would start with .431 and shoot them.
If you get no leading and good groups
then try .432.
And see what shoots best out of your gun.

[44man]

justinhip, The rule of thum for boolet
size is .001 to.002 over bore size.
I would start with .431 and shoot them.
If you get no leading and good groups
then try .432.
And see what shoots best out of your gun.

This is right. I have gotten .430" to shoot great from a .430" groove but it is better to go a little over.
You do not need larger then throat size, just groove.

[mdi]

I have found the easiest size to pick when beginning casting for a specific revolver is to go with the same size as the cylinder throats. If you measure .431", go with .431" sizing. Load some and check results. My Ruger has .431" throats and a .429" bbl. I size to .431" and get no leading and more accuracy than I can shoot. I do this with my other .44s too; a 629, and a Dan Wesson. Contender and Puma are a different story though...

[MtGun44]

Throat diameter or throat +.001 is the place to start, assuming that this is
larger than the groove diameter, which yours is. If smaller than groove, you
need to fix the throats first thing.

Bill

[cbrick]

Size to a mild snug fit in the throats, sizing larger than throat diameter is folly. Why? Because revolver throats are the world's best bullet sizers. I don't care how much over measured throat diameter you decide to size, when those bullets exit the throats they WILL BE throat diameter.

As Bill said, if your measured groove diameter is LARGER than measured throat diameter the throats will need to be reamed to a groove matching diameter or leading and inaccuracy is fairly certain.

Rick

[Frank]

cbrick:

Size to a mild snug fit in the throats, sizing larger than throat diameter is folly. Why? Because revolver throats are the world's best bullet sizers. I don't care how much over measured throat diameter you decide to size, when those bullets exit the throats they WILL BE throat diameter.

If they're too big they may not chamber.

[MtGun44]

If you assume that the boolit is perfectly round and that the throats are perfectly round,
the "fit, not larger" makes perfect sense. However, if your throat is .001 out of round, and
you measure it with a gage pin, you will measure the throat size as the SMALLER diameter.
Using boolits this size will leave unsupported portions. Using .001 larger will totally fill the
out of round throat, and seal it and support the boolit fully. An out of round boolit sized to
throat diameter can make it worse if the narrowdiameter of the boolit happens to line
up with the wider diameter of the out of round throat. NOTHING is actually round if you
want measure accurately enough.

So - I say - fit to throats OR try .001 larger - IF IT HELPS YOUR GUN to be more accurate
or lead less. I have a few that work better with slightly oversized boolits. I'm not sure
exactly why, but know it is true, and the above theory would seem to lend some support.
If you try +.001 and it is worse, then stop it, but to councel someone to never even try it
seems a bit narrow minded.

Bill

[cbrick]

Narrow minded? Perhaps as much so as counceling to make the rounds more difficult to chamber huh? Throats can certainly be measured with pin gages, they can also be slugged and thus know "if" there is an out of round condition and if so, how much. Out of round throats is something I've run across rarely. Though it does happen I doubt a couple of tenths would make much difference one way or the other.

Anyone have a cylinder leading problem? How much over throat diameter are you sizing? Ever notice lead flakes adhering to the outside of the cartridge case? How much over throat diameter are you sizing? Both of these conditions are a possibility when sizing over throat diameter.

Rick

[MtGun44]

All I am saying is that insisting that over throat is always a bad idea is a pretty inflexible
position. I have a couple of guns that prefer +.001, so I always suggest that it be at least
tried. If you never ran across one, well, then your experience is different than mine.

Eliminating possible solutions without trying them seems like leaving a blind spot. If it
doesn't work, then don't use it, but to refuse to try it????

Bill

[LUCKYDAWG13]

if you dont have a .430/ .431 / .432 sizer and would like to try first i can size some
of your boolits for you

[cbrick]

I have sized over throat sized bullets, many times in many revolvers, that's how I learned about leaded cylinders, plating the brass with lead and difficult to chanber rounds. So no, not a closed mind, been there, done that. Just never had any luck with it or benefit from it. If it works for you that's great and of course no reason you shouldn't do it, just not my experience.

Rick

[geargnasher]

I've done it both ways, light push fit and a determined oversize that took HEAVY thumb pressure to push through. Getting lead in my cylinder throats was more of an issue with undersized boolits than oversized, but that's with my guns at my hand, not a scientific truth. The boolits can gas-cut and throw a blast of lead just down the cylinder, gap, forcing cone, and bore before they even move if they don't fit the throats. Ever wonder how that lead dust gets plated on the frame above the gap and all over the cylinder face? Loss of obturation before the boolit even breaks the crimp. I'm gonna have to go with Bill on this one for the most part, especially the part about keeping an open mind and trying different things to see what YOUR gun prefers. Here's my take on it:

First off, production revolver throats can be fairly inconsistent from one chamber to the next in the same cylinder, and even if you ream them they will get a bit out of round with some shooting. Sizing a hair over cylinder throat diameter will assist the seal, keep the lube from being blown out of the groove before the boolit even reaches the cylinder gap, and CAN improve accuracy vs. a boolit that is right at, or a hair under throat size.

Next, boolits that pass through a cylinder throat with an interference fit are NOT throat size afterward. They cylinder flexes some like a snake swallowing an egg, and let's not forget how springy some alloys can be, taking as much as a full thousandth of sizing down and bouncing right back to original size. How much sizing actually takes place with a boolit that's .001" over throat diameter depends on cylinder metal and boolit metal composition, strength of design, etc.

Finally, revolver cylinders have CHAMBERS, BALL SEATS, AND THROATS. Unless you do something goofy like I have with a couple of custom boolit moulds, most of the time over-throat-sized boolits crimped in the crimp groove will chamber just fine because the major diameter of the boolit outside the case is very small, and nestles very nicely in the revolver's ball seat. Upon firing, the front band or nose major diameter socks into the throat and squeezes through it, maintaining a nice, tight, compressed seal the whole way through the end of the cylinder, which also helps get a straight start in the bore even after kicking the cylinder a few thousandths into perfect alignment when the front bearing surface finds the forcing cone. Less slop in the throat=less sideways kick of the boolit base or nose when the boolit transitions into the bore. Here's an illustration of what I mean copied from Accurate Mold's website:




Now about that goofy stuff I did with revolver boolit fit. Since all my .38/357s are reamed to .358" and honed to .3582", I had Tom of Accurate Molds make me a boolit that would fit the throats exactly, only giving a few tenths of clearance, here it is, and I size to .358" in a .3575" sizer with 15 bhn alloy:


Obviously, this ignores any ball seat and pilots the nose right into the minor diameter of the throat.

Here's the same principle in .45 Colt, adding a second front band to mover the bearing surface out far enough to pilot in the reamed and uniformed cylinder throats with only a couple tenths clearance:


Both boolits do what they're supposed to, but about every third cylinder-full the throats have to be brushed out or they start binding when chambering, which is a real pain on a SAA pistol.

With one exception, my 1872 Open Top, these boolits do not shoot any better than a slightly larger-than-throat WFN or RFN, and only marginally better than a SWC. I don't know why the Open Top loves it, but it does. Maybe because it has the tightest chamber of any .45 Colt I've ever seen, it's actually right where it should be with modern brass and .452" boolits.

Gear

[geargnasher]

Justinhip, sorry to derail your thread even more! I figured I'd respond to your OP directly with my two pennies in this post, and hope the revolver chamber illustration in the post above helps some. I'd size some at .432" (prolly require honing the die) or so and see if a dummy round will chamber freely in all the holes. If so, do some load development. If you suspect a larger boolit might work better, hone the sizer about half a thousandth and try again. I say this because you can't put the metal back.

All this assumes your boolit casts round and at least .4325"

Gear

[JIMinPHX]

Just to be different, I'll give a real simple answer. I'd try .431-.4315" boolits in that gun.

If your alloy has a little spring back to it, then a .431 size die should put you right in that size range.

[cbrick]

Since all my .38/357s are reamed to .358" and honed to .3582", I had Tom of Accurate Molds make me a boolit that would fit the throats exactly, only giving a few tenths of clearance, here it is, and I size to .358" in a .3575" sizer with 15 bhn alloy:

Let's see, throats reamed to .358" - Bullets sized to .358" giving a few tenths clearance. That's oversize? That's what I do except my match revolver throats are .357" and I size with a .357" die that sizes to .3568" with my alloy. A mild snug fit, I can hold the cylinder in one hand and place a sized bullet in each throat and they stay there, with the erasure end of a pencil they can be tapped through. Another .357" die that I have sizes the same alloy at .3574" and these bullets cannot be chambered without a good deal of effort.

Here's the same principle in .45 Colt, adding a second front band to move the bearing surface out far enough to pilot in the reamed and uniformed cylinder throats with only a couple tenths clearance:

Again a couple tenths clearance, exactly the same as I size for my revolvers. My 45 Colt Bisley has the most uniform throats in a production revolver I've seen. Right at .452" - .4522" with only a couple of tenths variation across all six holes. I size with a .452" die @ .4522" and when chambered the front driving band is snug in the throats.

Both boolits do what they're supposed to, but about every third cylinder-full the throats have to be brushed out or they start binding when chambering, which is a real pain on a SAA pistol.

Gear

Real pain? I think so, I shoot 40 - 60 - 80 round timed matches. The very last thing I need is difficult to chamber rounds or need to stop to "brush out" the cylinder. Given the years of long range revolver testing I've done, testing about everything I could think of and much of what I've read or heard about I don't think anyone can say I don't have an open mind. Long range revolver accuracy has been my passion for many years. I've won state and national championships with perfect scores in long range revolver, I don't think I'm doing a whole lot wrong in how I size the bullets.

Actually Gear, it sounds very much like you are sizing your revolver bullets very much like I do, a mild snug fit the throats.

Rick

[geargnasher]

Rick, you missed my point entirely. I went down the road of sizing boolits to fit the throats as snugly as possible without interference, and designed boolits that would reach out and fit the throats beyond the ball seats of the chambers, and it didn't work all that well compared to using conventional designs that fit the ball seat and are larger than the throats themselves.

I was merely showing what DIDN'T work the best for me, and the lengths to which I went trying to make it work. I stick with conventional designs that are about .0005" to .0010" larger than cylinder throat diameter and fit the ball seats.

Gear

[cbrick]

I stick with conventional designs that are about .0005" to .0010" larger than cylinder throat diameter and fit the ball seats. Gear

I assume by "fit the ball seats" you mean the front edge of the driving band fitting onto or against the beginning of the throat? Is that correct?

If so that is a distinct difference in how I am doing it. I use a bullet long enough (heavy enough) so that when loaded & crimped a chambered round has the entire front driving band fully inside the throat. Chambering such a round that is much oversize goes from difficult to impossible depending on how much oversize it is.

Rick

[geargnasher]

I assume by "fit the ball seats" you mean the front edge of the driving band fitting onto or against the beginning of the throat? Is that correct? Si', that is correct.

If so that is a distinct difference in how I am doing it. I use a bullet long enough (heavy enough) so that when loaded & crimped a chambered round has the entire front driving band fully inside the throat. that works too, nobody is arguing with you if you're getting good results that way. Chambering such a round that is much oversize goes from difficult to impossible depending on how much oversize it is. Like everything else in good cast boolit loading, the boolits must be made to fit.. Mine are only oversized in relation to the throat diameter. In my case, they are selected by design that fits best to start with (depending on the length of the ball seat), sized appropriately, and seated to the correct depth to pilot in the ball seat, rather than the throat. It's just like you'd do when fitting a boolit to a rifle ball seat and throat. This method has worked with commercial lead boolits for eons, and you won't have chambering issues with any of that ammo even if your revolver has badly undersized throats.

Rick

My wife's S&W M36 had .356" throats and would chamber and fire .358" Keith SWC's all day, in fact the only reason I reamed them was to correct the terrible leading in the .357" barrel. There was a problem after reaming, though, I got throat leading and lead dust accumulation on the frame, forcing cone, and front of the cylinder. Now, we shoot .359" boolits in it and it doesn't lead anywhere and shoots even better. It will group 1-1/2" at 15 yards from the bags, and it has a 1-7/8" barrel!

The philosopy with cartridge revolvers has long been to use the front band/ball seat interface for boolit guidance and clearance, that way production tolerances and cylinder throat diameter or state of fouling is really a moot point speaking strictly of the mechanics of chambering and firing. Call it a "fudge factor" for making production ammo fit everything.

Gear

[mdi]

"Anyone have a cylinder leading problem? How much over throat diameter are you sizing? Ever notice lead flakes adhering to the outside of the cartridge case? How much over throat diameter are you sizing? Both of these conditions are a possibility when sizing over throat diameter."

Rick[/QUOTE]
I agree. I kept my first answer short not wanting to complicat matters. Yes I have had cylinder leading from both under throat size (.428" - .429") and over throat size (.433"). Best IMO is same size as throats...