Home Forums Hunting & Shooting Gunsmithing HELP! Case separated.in new brass

Rifle is REM 722.257 Roberts that I had reamed to AI 5 yrs ago.I've fired,counting fire forming,maybe 400 rounds max thru it.<P>This afternoon I loaded 6 rds with one gr. under max[ Barnes data] of RL 22.I had bought 100 new rem cases and fireformed them.This was first loading after fire forming.I had full length resized in RCBS dies which is same procedure I always follow.Second loading I neck size only.<P>I fired three over chrono and velocity was consistent with data.BTW,yesterday I had fired three with one less gr.of powder.The 4th shot today was not remarkable except that a little more than half the case came out when I worked the bolt.The break was fairly smooth in that the length of the extracted piece varied only 1/16 in.<BR>I put two patches on my cleaning rod and the rest of the case pushed right out.<P>It seems I can see a ridge of some sort in the chamber when I hold the muzzle toward the light.I have been scrubbing the bore per Barnes instructions,and I may have a gunk build up in the chamber.The rest of the cases in this batch that have only been fire formed dont show any marks at this point on the case.With cartridge head being sta.0,the separation was at sta.1.200,the shoulder is about sta.1.800.<P>I been doing this a while and aint seen this before.Any ideas?

Gene/ Just a thought. In PO Ackley's Vol.#1,<BR>he states that if light loads are used in fireforming standard cases, the shoulders can<BR>form with excessive headspace. This can cause<BR>separations on sucsessive firings.<BR> FL sizing can produce these results as well<P>On a second thought, most separations or stretching occurs in web area. If there were any oil or sizing lube, in rearward portion of chamber or case, combined with headspace on case,upon firing, this could allow the rear portion of case to move toward bolt, while the front portion of case adhered to chamber wall. Thats my 2 cent budget spent