flattening primers

[loteksw]

purchased a used 110 in 270 win. and a box of Hornady American Whitetail 130 gr bullets
A little more kick than I expected, 1 casing a little sticky coming out, so I checked the primers and they were flattened out pretty good. first thought was 85 degree temps. Is it possible with preloaded ammo for the neck to be too long and be pinching the bullet, or the rifling is jammed against the bullet.
I cleaned the barrel and it was dirty so maybe that contributed some. and Ill try a few more shots when the weather cools.
any thoughts?

[Bolthead]

If it is not a head space issue, I would be tempted to try a different brand of ammo just to see if it makes a difference. I shoot 150 grain Federal in my .270 with no problems, even with temps well into the 90s. Barrel heats up fast though. How is the accuracy?

[Robinhood]

What indicated that there was a headspace issue? I was under the impression that if headspace was an issue it would be on bolt closing. Primary extraction maybe but it sounds like a pressure issue. I hope thorough cleaning will help.

[loteksw]

there is no real evidence that its a headspace issue, just a possible reason why a factory load would be so hot.
to the best of my ability, after measuring with my calipers, ( I don't have the right equipment)there seams to be about 1.5 to 2 mm clearance. Does that sound right?
As to accuracy, perhaps the high pressure is affecting it. with the limited number of rounds I shot at 100 yrds I could only maintain 1.1"
I thought the American whitetail round was a little milder round than the superformance. and it doesn't flatten out in my model 11 243. Maybe I just got use to .5 moa

[J.Baker]

I hope you meant 1.5-2 thousandths (of an inch) difference. If there's 1.5-2mm difference in the shoulder you clearly have a headspace issue. 1.5-2 thousandths of an inch (0.0015-0.002") shoulder bump is petty much perfect headspace.

As Bolthead suggested, try some different ammunition before doing anything to the gun as it could be the American Whitetail ammo. Just because one gun likes it doesn't mean this one will - especially when you're talking a different cartridge all together.

[Nor Cal Mikie]

Could be a headspace issue. Loaded ammo being too short for the chamber and not a problem with the actual headspace. Firing pin hits the primer, case gets pushed forward in the chamber, round goes off and in turn gets pushed back against the bolt head and you are getting flattened primers. As suggested, try different ammo. Wouldn't think ammo was too hot. Most factory ammo is on the milder side compared to some "home built" ammo.
Good reason to roll your own.

[Robinhood]

Nor Cal, Wouldn't he be seeing primers backed out also?

[FW Conch]

What Mikie said. Flattened primers can mean next to nothing, except that they may have a thin case.

If you think heat may be having an affect you can put your ammo in a small cooler with ice.

[Bunky-Shooter]

I agree with the rest of you that he should try some different ammo in a differ brand. If the problem continues it more than likely a head space issue as Mikie stated.. Too much head space can even flatten out primers with low pressure loads.. Another flattening issue is if the primers were not fully seated. My thoughts !!

[Nor Cal Mikie]

If the brass is too short for the chamber, the primers can "back out when the round is fired and be pushed back into place" as the case hits the bolt face. (Flattened and funny looking primers) The ideal situation would be to reload that fired brass without pushing the shoulder back too far. But in your case of not rolling your own, your only choice is to try different ammo. Once that brass in fire formed to the chamber, the only time you would be seeing flattened primers would be with high pressure loads. Everybody jumps on a mechanical headspace issue when it's only a problem with brass not fitting the chamber like it should. One step at a time and keep it simple.

Another way to correct the problem would be to pull the bullets out to jam into the lands and a longer OAL before firing. That will keep the case head back against the bolt face when fired.
Again, if you're not set up for modifications to the ammo, different ammo is your only choice.

[earl39]

One key here is sticky cartridge. That along with flat primers would lead me to assume excess pressure first then after trying a different brand of ammo i would look at headspace if the problem continues.

[Robinhood]

Given the OP's issue, I am having trouble with how H.S. is even considered to be an issue. Can someone help me understand.

[FW Conch]

I think what they mean is the Factory Ammo could be on the short side of spec ?

[Nor Cal Mikie]

In this case, headspace relating to the "length of the round" NOT the length of the chamber. Best way to see if it's in spec is to use a go/no go gauge in the chamber.

[Bolthead]

Quick and easy to rule it out, even if it doesn't seem like a HS problem.

[Dewey7271]

Hate to mention something that may not be a factor but are you leaving excess oil in the chamber possibly after cleaning? Realize that's a simple solution but have seen exactly what you describe occur with oil left in the chamber or oil that came down from the barrel into the chamber after a cleaning and having the gun leaning against something.