I shot my rechambered Swede Mauser rifle. There is discussion of this rifle and its provenance somewhere below, but essentially, I rechambered it in order to get a new (tight) neck and a good throat for shooting 140 gr bullets.
The cartridge choice is a bit flakey, as the Swede chamber is nominally .006" larger at the base than is the -06 "standard". After I did a minor bbl setback, the breech ID was .479"; this means that the actual cartridge will be as much as .018" smaller (depending on whose unfired cases you have) than the breech, leading to worries about excessive swelling at the case web and non-eccentric cases. After a bit of experimentation, I found that a steel shim of .008" thickness, made into a ring and inserted into the breech at the base of the cartridge, would force the base of the case to center in the chamber. NOTE: I am *not* recommending this mickey mouse approach to fireforming to anyone else; just reporting what I did :-)
Anyway, it took 56 gr of Rel22 to get a clean shoulder on the fireformed case; Nosler recommends 52gr as a max load for the 6.5-06 w/140 gr bullets, so this indicates a somewhat larger case capacity than that stalwart round. I calculated conservatively 8% greater capacity.
The shim worked a treat. The bulge at the web was concentric with the case axis and it does not appear exaggerated; AAMOF., it is no more extreme than what you see in cartridge cases fired in many factory rifles. The web measures .4765" as against .4655" for the unfired Rem case, after my "blue pill" proof load. Anyway, in order to give me some security that this system was safe, I loaded one cartridge w/10gr extra powder (66 gr Rel22) and fired it while hiding behind a tree. The bolt handle lift was somewhat sticky, requiring moderate tapping upward with a bit of board, and the primer was blown out, the primer being absolutely flat!!!! Web expansion was the same as w/cases later fired with 53 gr loads, but the base was .0015" larger than those.
All-in-all, the rifle is SAFE when fired with normal-pressure loads. For fireforming the bulk cases, I have made a ring of the shim stock soldered (Sta-Brite) onto a music wire ring which fits into the extractor groove of the case. This keeps me from having to do fiddly adjusting of the shim position for each case. The extractor is removed and the cases ejected through the muzzle with a cleaning rod.
Using 53 gr of Rel22, I tried firing for group size, but it happens that my new Simmons 3.5-14 scope (obtained in a trade... I quit buying Simmons optics a decade back due to 100% trouble rate with the first 5 I tried) had troubles (SIGH!!!) and I couldn't get any valid results. I polan to send this back to test their lifetime warranty. Hope Simmons doesn't send me one that is "just as good as new" :-)
I have since made good loading dies, and mounted an oldie but goodie, a steel-tube Weaver K10, on the rifle. I'll report later on whether this thing will shoot if it interests anyone.
Cheers/buffler