Sako A7 stiff bolt and leaving marks on the brass
 

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)

They are over pressure for sure. I don’t think that is horribly uncommon in factory WSM loads either.

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.

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?

I don’t know, but it’s hard to chamber and extract a factory round. Usually factory rounds are well within SAMMI specs no?

Could be a dirty chamber? But then you would see marks on the case?

Use a brush and solvent and clean out the chamber area of your rifle real well. Also, strip and clean bolt, bolt face etc and trigger group. Now cycle some factory loads, if they are tight, send gun to Sako for repair. Factory ammo should go in and out slick and smooth. If not, something is wrong with the gun.

If is very hard to diagnose the hard to extract after firing issue until after the gun is feeding and extracting unfired factory ammo properly. From the picture I would not say those rounds are over pressure, or at least not by much. Primers are not flattened, no cratering and just the odd one with extractor marks. Federal is VERY soft brass so extractor marks on it is pretty common.

Thanks for the replies guys. I’ll clean it again really good when I get home and then maybe see if I need to take t into a gunsmith or find out about warranty work. It shoots great, just stiff to chamber a round so I almost hate to mess with it. Thanks!

“Tight chambers” is a term that is misused. You may have a chamber that has tight headspace . You may have a chamber that has been cut with a reamer that has tight radial diameter or a combination of both .

Factory rifles gerenally won’t have a tight chamber radially . Often it is a combo of a chamber having minimum headspace and ammo that is on the maximum headspace that cause stiff bolt CLOSE. Stiff bolt lift and ejector marks are indicators of a hot load caused by ammo , short throat or a tight barrel or a combination of these factors

Sako’s typically have a very tight tolerance. I have an A7 Roughtech and everything you’re saying sounds like you’re above max pressure, or very close to it. I would look at getting it returned to Sako, it should definitely be under warranty.

My tikka t3 also in 270wsm had exact same issue. In fact I bought a box of federal premium and several wouldn't even chamber, couldnt close the bolt. After breaking it in and getting enough brass I now full size reload for it and never had an issue. I think it's a headspacing issue.

It’s the bloody ammunition. This is a far cry from the first case of the WSM factory ammunition exhibiting excessive pressure.

So why wouldn't some chamber at all and lots were hard to close bolt on then if it's just hot loads.when they haven't even been fired yet.

Try buying a different brand of ammo and see if it’s still hard to close. Your rifles head spacing could be a bit to tight though and that could be checked easy with a go or no go gauge.

Minimum headspace is not causing brass to flow.

Chambers have .003 “ (3 thousandths of an inch) tolerance between a go and a no go gauge . Ammunition has Tolerance amount as well. So if you get a chamber with minimum headspace and ammunition at the maximum headspace. You can get difficulty closing the bolt. Some of the ammo in the box will be ever so slightly “shorter “ and will be easier to close than the ammo that is slightly longer .

i noticed this with some factory ammo's on tikka t3 and sako a7, can't remember but recollection was the silver winchester factory ammo's, you couldn't close the bolt on some and if so was real tight...not sure what was out of spec, no issues with federal ammo from recollection

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.