I had the same problem when I started loading for my 375 Ruger I backed out the die a little and it worked great. But then I had to get the crimp right. That took me some time. But I had been spoiled with the Lee factory crimp die. . I finally got it right with the seater/ crimper and I was able to make great ammo. But I wrinkled a bunch of cases before I got it. I was able to recover most all the cases I wrinkled
WOW. that definatly exceeded the 20 minute attention span. But, that's OK. . . If we always shot in a dead calm, no mirage condition then the machine advantages we have in modern bolt actions would prevail. However. Real world conditions play a major part. I firmly believe that most factory rifles can far out shoot their shooters when shot from field positions. Not including short bipods on benches for pdog shooting. That doesn't detract from the discussion but does lend itself to how much accuracy can be utilized.
My factory Ruger Hawkeye 6.5 Cm is a half inch or less rifle. And that's using a MTM plastic rest with a 4-12 Nikon Pro Staff. At 30 below zero. I get real sick of guys dishing Ruger. NightForce Scopes sure are nice.
Stainless Ruger Hawkeye. Thats the reason I got a Creedmoor. It was in the action I use. I wanted the 28" barreled VT model but one wasn't available when I was ready for the rifle. The 6.5 Creedmoor, like the 260 and 6.5x55 is about the ideal winter rifle. But rotating extractors and plunger ejectors can have big problems in the cold. As can complex trigger systems when the rifle takes a dunk in overflow at 30 below. Ruger's are just plain bone tough. Mine wants to shoot sub half inch groups. I'm the problem in it being accurate. I look at it like I saved lots of money to put in my new 570 Bearcat fund.
I've had some McGowan barrels. I really like them. Harry McGowan was a great guy to talk to. I'm planning on getting a 28" 6.5 Cm in the 8" twist from them in stainless. I think their barrels are Cryonized. As I shoot my rifles in the cold, like down to 50 below. I like that the barrel has already spent plenty of time in the cold. Steel does funny things in the cold . I've read of too many guys that had high dollar barrels that don't shoot any better than the factory barrels on the rifles I have. I like McGowan barrels.
Lee dies are my favorite. Tho My 6.5 Cm dies are RCBS as soon as I can I will get a full set of Lee 6.5 dies with the factory crimp die. I Don't have anything against the other dies I have. Reefing,RCBS, Lyman .Pacific and Hornady. But I like Lee best. Been loading with them for almost 40 years now.
On the Hogdon site they list quite a few powders. Most of them faster than H4350. I have been thinking of an 18" barreled 6.5Cm for my wife. Shooting 120 gr bullets. I think H4895 would work to give 2700 fps. It would make a nice little general purpose caribou truck gun. good for fox- wolf and bou.
If I can get my lunch hooks on a can of RL17 I will do a cold weather temp test. Right now its pretty warm out, around 15 above. But we get lots of cold. 50 below cold. I did some testing with Varget. It lost 30 fps when the ammo and rifle were stood outside for a half hour at 40 below. The Superformance 129 gr factory ammo was very close to advertised vel when it and the rifle were stood outside for 2 hours at 40 below. . I did feel a bit tighter chambering from the chamber and barrel contracting in the cold.
My load is the 120TTSX with 39 gr of Varget. From my Ruger M77 Hawkeye SS 26" I'm getting 2875 fps so far but I'm going to Molly tumble the next batch I get. I haven't killed anything with them yet but hope to be using them on caribou next weekend. the X and TSX have been the most consistent 1 shot killers in all the calibers I shot them in. I think I'll get 25-75 fps gain in velocity when I moly tumble them. I think it will kill good but not destroy much meat.