Revolver Headspace

[KCSO]

I can't remember where the question was but someone was asking why the ctgs were loose in his revolver. The rims on all ammunition are a plus or minus dimension and they can vary as much as 15 thousands.

I recently got in a Uberti Smith and Wesson copy that worked fine with Remington ammo but wouldn't shoot Starline at all... the gun had 0 headspace... the thicker rims on the Starline brass either dragged or locked up the gun. I had to dress off the recoil shield to provide the headspace. Now Starline brass has .002 clearance and Remington brass is running .010. So if you hold your gun up to the light and see a gap between the rom and the recoil shield it is there for a reason and your gun is just fine.

But this brings to mind an associated problem with revolvers...If you shoot very light or way bullet loads the primer holes need to be enlarged and the cases marked because with a small primer hole the primer will back out into the headspace and will lock up the cylinder. Again this is nothing to worry. It is just a function of the normal tolerance needed to operate the gun properly.

[Silver Jack Hammer]

The Schofield is being revisited by shooters and cartridge manfucturers. I'm shooting nickel Schofield in my 3rd Gen Colt's at matches with various low pressure loads with no problem.

Headspace is term that the proper definition has eluded me somewhat. Having been raised in a rifle family, with older siblings and Uncles students of Jack O'Conner and being the black sheep Handgunner fluke of the gene pool. I've come to define headspace as that place which Holds the cartridge firmly in place when the firing pin strikes. On some Jack O'Conner cartridges that place is the shoulder. Some magnum rifle cartridges that place is the belt. On most shell schuckers that place is the case mouth. On true guns (revolvers) that place is the cartridge rim.

I suspect your issues are the thickness of the rim of your cartridges being different between the Starline and Remington. Couple that with a gun made in Italy after a model which has been largely out of production for over 100 years. Even when it was being produced they were not as widely popular. So Uberti did the best they could with the space between the cylinder and the recoil shield.

Ive got a dual cylinder Colt's 3rd Gen SAA. The .44-40 drags the back of some of the cartridges against the back of the recoil shield.

I'd suggest you alter the back of the offending cartridges or only use a brand of case your gun prefers. Tom Stargis has a note on his website he won't work on Schofield handguns, there must be a reason behind that.

The only primers I've had back out were fired with no powder or boolit, primer only. Firing primer only backs the primers out and ties up the gun.

[Outpost75]

In revolvers headspace is affected by end-shake movement of the cylinder on its center-pin or crane arbor, and the mechanical limits of such movement governed by the cylinder bushing and extractor bearing pad of a DA, or head clearance of an SA revolver.

In SA revolvers during the blackpowder era guns were built with as much as 0.005" end shake being possible, being determined by forward movement of the cylinder being stopped by the front bushing, ensuring adequate gap to prevent blackpowder fouling from binding the cylinder, and to ensure the front of the cylinder could not hit the barrel. In the hammer down, trigger held back firing position the hand or pawl would push the cylinder forward, taking up any end-play, and leaving maximum head clearance to ensure free cylinder rotation. The common tolerancing convention was for head clearance to be +0.005" greater than maximum rim thickness, with the "Go" dimension in a cartridge like .45 Colt being 0.065" and the NoGo 0.070"

The .44-40 has a thicker rim, as much as 0.065" being allowed by current SAAMI prints.

In modern smokeless, magnum caliber revolvers they try to limit cylinder end-play to about 0.002" during initial assembly.
If it is appreciably more than that the cylinder slamming back against the recoil shield tends to set back the recoil plate and stretch the topstrap, increasing cylinder gap also.

[Silver Jack Hammer]

The thicker rim of the .44-40 is something we are all aware of, yet my second cylinder which is a genuine Colt's fitted at the factory still causes rubbing on the recoil shield. You'd think Colt's would get this simple dimensions right. I read where Jeff Milton, famed Indian fighter traded away his .44-40 because the cartridges caused the fun to hang up.

[Piedmont]

You'd think Colt's would get this simple dimensions right. I read where Jeff Milton, famed Indian fighter traded away his .44-40 because the cartridges caused the fun to hang up.
Yeah, you'd think. But you would also think they might be able to get the chamber dimensions right and the cylinder throat dimensions right. Also, how hard would it be to case harden the hammers and put the black powder chamfer on the front of the cylinder? None of the post Gen One guns look right-- that squared off cylinder and white sided hammer, yuck. We're talking about a $1,500 handgun!! I'm all for the Gen Two change that brought a better sight picture but everything else was a step backward.

I bought two Ubertis two years ago. They do these things better (at least my two examples) than Colt does and cost roughly 1/3 as much.