S&W Mountain Gun Forcing Cone Angles

[DougGuy]

I have had a few Mountain Guns on the bench, and I knew they weren't cut on 11° but I didn't know what the angle was. I found out today from S&W that the 44 Magnum is cut on 8° and the 45 Colt is cut on 10° and that set me to thinking.

We know that using a Taylor Throat Reamer reduces pressure because it lessens the resistance against the boolit entering the bore. I am speculating that S&W used 8° on the 44 because the barrel stub is thicker due to the smaller bore, and they used 10° on the 45 Colt for two reasons. One, the threads on the barrel are the same OD between the two calibers but the barrel stub is thinner on the 45 because the 45 bore is larger, and using 8° would weaken the barrel, and second, they also know that the 45 Colt is typically loaded to lower pressures than the 44 magnum, even at the "Ruger Only" level it is generally less than the 44 magnum. This is S&W's way of reducing the pressure at the barrel/frame juncture.

Irregardless, I am not aware of a manufacturer that would make the D-shell style forcing cone cutter that is sold in the Brownell's chamfer kit in anything less than 11° Might get away with using the 11° angle on the 45 Colt Mountain Gun, but that won't work for the 44.

[megasupermagnum]

Those are interesting thought's, but I'm not sure they are accurate. If a forcing cone is going to crack, it's going to happen right at the entrance, and the angle of the forcing cone isn't going to effect that thickness. It's only going to effect how far the cone progresses into the barrel. I think what is more important is how large they cut the cones. If the 44 mag has an entrance of .455", there's all that strength right out the window, and there's no way it's helping accuracy. If you look at guns that are known for really good accuracy like Dan Wesson or Freedom Arms, their forcing cones are very small and short. They are no bigger than needed to accommodate whatever slop there is in the cylinder.

Why S&W cuts to two different angles, who knows. I have my doubts it has anything to do with putting out a superior product.

[M-Tecs]

Pacific goes down to 5 degrees

https://pacifictoolandgauge.com/488-...g-cone-cutters

[DougGuy]

Pacific goes down to 5 degrees

https://pacifictoolandgauge.com/488-...g-cone-cutters

5° is a standard cutter for 38/357 a lot of Ruger 357s use this angle.

I am LOL'ing at the 9° cutter on their page for sale, I'm probably the one that got them started on this angle b/c they didn't offer it when I had one custom made. I had this one made to use on a Mountain Gun. The problem with it (and I can see they haven't learned much from past failures) is that they needlessly grind away metal that leaves the front of the cutter horribly thin, and mine shattered the first time I used it.

Pete Folk refused to stand behind it, he quit returning any of my calls and quit responding to emails. They handed off my request to some numb nuts that ground a cutter 9° on each side, for an 18° included angle. This thing is just hideous. It looks EXACTLY like a countersink bit for countersinking holes. I couldn't find it for a photo, maybe I tossed it, I don't have any positive memories about working with PT&G. Never again.