I just returned from the range where I shot my first box of ammunition through my relatively new Winchester 25 WSSM. The ammunition was Winchester 120 PEP. Upon examining the cases I noticed considerable power residue around the neck, what looks like a very slight casing stress fracture (on 2 of 20) around the neck and casing expansion at that base on most of the twenty. I do not reload, I purchase manufacturered ammunition so I am not completely sure what I am seeing. The rifle for the first time out seems to be shooting good, fairly accurate as I would expect in that caliber and size bullet.

My question to the above is: Does this seem abnormal and is there concern as to the chamber tolerances of the rifle or is more likely I got a batch of crappy ammunition with maybe lousy brass (too brittle)?

I am thinking about trying a few boxes of Conley Precision 115 grain TSX's.

Thanks for the insight.

Winchester/Olin WSSM brass is very thick/heavy and is factory loaded very close to the maximum safe pressures. It takes a maximum load to expand the thick/heavy brass against the chamber, so smoked case necks are pretty common in all of the WSSMs.

I reload for my 25 WSSMs using Federal 243 WSSM brass that has been reworked to the 25 WSSM configuration. The Federal brass is slightly thinner/lighter than the Winchester/Olin brass, so it expands more easily and doesn't smoke the necks.

I have had excellent results with all 4 styles of Winchester/Olin factory ammo; 85 grain, 110 grain, 115 grain, and 120 grain. I built a dedicated 25 WSSM varmint rifle with a Winchester/USRA 70 Super Shadow action, Shilen 1 in 14" twist varmint contour stainless barrel, and McM Compact stock. This rifle is intended to shoot 75 grain bullets and will do less than MOA groups with the 75 grain VMax, Sierra HP, and original Barnes X. When I head to SD armed with this rifle, pdogs need to be worried!

Jeff

Yes it's pretty common. The WSSM brass Olin makes is made from sizing down WSM brass and that's it, no other process but cutting it off shorter. That makes for very thick brass in the body and the neck. Instead of changing this process to eliminate the problem, Olin has just made us "deal with it". That means pressures have to stay very high and brass performance is poor.

I have had the same problem with my brass. I found the factory brass neck thicknesses all went between .020 and .022 thick. To give you an idea, my 257 Wby brass is .014, which is about what you'd expect to see from a bottleneck rifle case. Basically the WSSM brass is nearly TWICE as thick as it should be. Leads to pressure problems and reloading nightmares. I turned the necks of my brass down to .014 and don't get smoked necks and hard bolt lift anymore, but this shortens case life. I also use a neck bushing die to size the brass necks. This is less than ideal, since the necks are now "undersized" for the chamber, but pressures are stable and accuracy is better. I also don't have the heavy bolt lift issues anymore.

I have not tried the Federal brass, but I do hear that it is made better, by that I mean thinner and doesn't exhibit the same pressure problems as the Olin stuff.

260remguy,

Time permitting, could you measure some of your neck thicknesses on your Federal brass and post the measurements for me? I was intending to buy up some Federal brass when my current horde of Olin brass is spent. Thanks.


I was originally contemplating setting my barrel back and rechambering with a tighter neck, but with the demise of the Berger .257 varmint bullets, I'm seriously considering a rebarrel to 243 or 264 with a tight neck chamber.