I'm looking for a little bit of wisdom from some of you guys that know a lot more about this stuff than I do.
I've got a Sako A7 in 270WSM that I bought new last year. When it was new I noticed that every so often it would be a little stiff to chamber a round and get the bolt all the way closed and once it was difficult to get a cartridge removed after I fired it. That particular one I actually had to pull really hard to get it out but it only happened once so I figured it was either the brand of ammo or just a fluke. I've got probably 100 rounds through it now and the bolt is pretty consistantly stiff to close and open(compared to my old Savage 30-06). I've always just chalked it up to something like close tolerances or something like that but today I saw that some of my brass have small circle impressions on them where the "Fed 270 WSM" is stamped around the outside of the primer pocket. Forgive my lack of terminology here, I've been shooting for almost 10 years now but my brain is not coming up with the name for that part of the brass right now. Anyway, the impressions are bulges that match the small hole in the bolt face where the ejector (I think) sits and I would swear that it looks like an over pressure issue or something like that but these are Federal Premium Factory loads. Not every brass has it but I found 3 or 4 out of a box of 20 that I looked at that had pretty definite circle bulges. I'll see if I can get a picture to load so you can see what I mean.
So I'm thinking maybe the stiff bolt and these are related, maybe someone has a good idea as to how I can figure out what is going on with this gun or if its the ammo or if its anything I need to worry about. Thanks in advance!
(you can see the circles in the three cartridges at in the top left of the picture)
I also have a A7 sako. I have only experienced tighter extractions of brass when I was at or little above reloading max specifactions. Brass also showed flattened primers and slight signs of case bulge.
I have never experienced the tight closure into battery that you speak of with factory loads. Only with my hand loads when experimenting with long over all length.
You purchased a sako......closing into battery with factory rounds should under no circumstance be difficult. I would look into warranty on your riffle or consult with a local gunsmith.
Hope it works out for you.
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Seems like a tight chamber which is causing over pressure issues. The bulges in the cases is called case head extrusion and usually is a sign of high pressure.
Seems like a tight chamber which is causing over pressure issues. The bulges in the cases is called case head extrusion and usually is a sign of high pressure.
How do you know it’s a tight chamber?
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Not saying this is the problem but i have seen the neck separate from a case from a factory round and cause issues with chambering and extraction and id imagine would cause high pressures if someone was to have discharged it
In my experience i have only ever had issues with federal casings splitting. I haven't shot 270wsm but a 300winmag i had seen the casing split or bulge and had slight issues removing the casing. Another thought is that the bullet is not perfectly seated when the bolt is closed and the recoil is actually moving the casing back into the bolt? Have you had the same issue with different manufactured ammo? I am sure there are a number of different possibilities.
I know in my 270wsm tikka it was factory federal ammo that did that especially the premium. The fusions only a few out of two boxes did and a box of Remington core lokts were all good. Like I said I now reload for it full length sizing and have shot hundreds mostly overloaded slighty and never had an issue.
Sako A7 stiff bolt and leaving marks on the brass
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