But I finally found time to get back to it (knock on wood). Let's hope this time I can stick with it long enough to get some of my gunsmithing projects more or less done.
To review: I want a TC carbine chambered for 357 mag, to use for both pressure measurement and bullet testing. The TC factory 357 barrels usually have a craptastic throat that makes them useless for serious bullet testing. Hence a custom barrel is in order.
Likewise, most standard 357 mag reamers are SAAMI spec with a "funnel" throat instead of a proper rifle throat. Hence a custom reamer is in order.
My previous attempts at chambering barrels with homemade reamers haven't gone well. The reamers required a lot of force to cut, one broke (it had not been tempered), and several dulled quickly. But the main problem was that they gouged the chamber and the gouges made it difficult to extract the case.
I often laid awake at night wondering what was wrong with my reamers.
I decided that 1) maybe I should try boring a 357 chamber rather than reaming. I'm not very good at making reamers but I've got lots of experience with boring stuff.
2) Maybe the gouging and difficult cutting was due to inadequate relief. In fact, my "D" reamers usually didn't have any relief at all, because I had been told by numerous sources that D reamers did not require relief (i.e., I believe Roy Dunlap's gunsmithing book recommended D reamers without grinding relief).OK, so I set back my $20 357 barrel, refit it to the stub, bored the chamber portion (not the throat) with a boring bar, then polished the chamber with fine emory cloth. That turned out well.
I didn't bore the throat because 1) I didn't have a long enough boring bar on hand and 2) I was afraid the rifling would make the boring bar chatter.
So I used a homemade throating reamer. This time I freehand ground relief to within 1/16" of the cutting edge. Freehand grinding is "iffy" but I got lucky and it turned out as intended. I'm not sure if it was due to the relief, but this reamer cut effortlessly, unlike my previous "D" reamers.
FYI the throater was made from O-1, heated to 1600F, quenched in water, then tempered at 300 degrees in the kitchen oven. It has a 1 degree included angle, which in theory should be cast-friendly.
My $20 rifle barrel started out as 18 1/2" but because I had to set it back several times, it has shrunk to 14 1/2".
TC pistols can be very accurate and some people love them, but for this project I want a rifle, not a pistol, so another 35 rifle barrel is waiting in the wings and this was just a practice run to get the kinks worked out of my chambering process. I didn't bother to "clock" the barrel and I'm not going to bother to attach a forearm.
I did fire a few rounds to verify functioning -- the empties extracted effortlessly, YEA!
As long as I have the barrel set up I might as well mount a scope and see what the barrel will do on paper. First I'll have to load some ammo for it since the chamber (0.3795" ID) is too tight for the 357 ammo that I use in my other guns, which have 0.380"+ chambers. Hopefully I can get that done within the next week (knock on wood).
I don't know why -- the lack of a forearm? The 357" size instead of 0.358"? Short barrel awkward to shoot? Off-center chamber? Cold weather (it was 25 degrees)?
