Strange looking primer marks. Too much pressure? Pics

[joe]

Hey guy I got a new rifle & went to the range for a break in process. I noticed that the primers had strange looking strike marks after firing.

It is a brand new Remington 700 5R. It did it with two different types of ammo & I am concerned. I do not remember the bolt being more difficult to open after shooting. I do need to pay more attention next time to be sure. The gun seemed to shoot well.

Any help will be appreciated.

Pics next to a 308 so you can see the difference easier. Notice the circle around the firing pin indention.

 

[Wildcardace]

I believe it is over pressure.

 

[joe]

Thanks.

I went & found some old 7-08 cases with similar looking strike marks & it was from Rem 700 as well. So I wanted to get some opinions if its pressure or just the way Remington 700s strike.

My 5.56 out of my Ar do not look like this, they look like the 308.

 

[joe]

I may have just answered my own question but would appreciate any feed back.

I found some old 7-08 casings shot from a remington I do not own anymore & they appear a lot like the 223 out of my new remington.

7-08 & 223 shot from Remigntons, 308 & 5.56 from other brand weapons.

 

[flyandscuba]

Definitely NOT over-pressure. It is just a trait with that particular firing pin design -- no worries. If you were seeing extremely flat primers or pierced primers, along with bulging brass at the bass -- that would be a sign of over-pressure.

Glock pistols always leave strange looking marks on the primers as well -- more of a rectangular striker mark instead of round.

 

[Little Jack]

Agree with scuba. Xcrs had that issue. The fix was to chamfer around the firing pin hole on the face of the bolt.

 

[Daezee]

If you examine the bolt face under magnification, you should see a bevel around the firing pin hole. Some makers do that in some calibers to help prevent a circular disk from the primer from being punched/blown out of the primer and going into the bolt interior and causing problems with the firing pin movement. Robinson Arms XCR's are built like that. No problem.

 

[joe]

Thanks guys!

I was shooting it along with the 308 & noticed the difference. Better to be safe then sorry.

 

[M.O.A.]

It's a little more obvious ( probably due to close up camera angle ) but normal for new manufacture REM 700's. Savage will do that on some rifles as will howa. Those are fine. Load em up and shoot them again.

 

[Wildcardace]

Sorry I was just talking to my buddy with a 700 and he says his does the same thing.

 

[JohnAL]

Yeah, my first thought was overpressure but the rest of the primer does not show the signs. My Model 700 from 1971 nor my Model 7 do not do that but I guess the new ones are different.

 

[M.O.A.]

Essentially what these specs say is there's some free space around the firing pin .

. Ensure the firing pin hole is true to the centerline and is .065 +/-.010 inches in diameter. Firing pin diameters must match their associated hole diameter as close as possible without sticking or binding. Hole diameters of greather than .075 inches pose the danger of pierced or cratered primers while hole diameters of less than .055 inches produce unreliable primer ignition.

 

[M.O.A.]

A little follow up to that earlier post. In 1982 I believe remington launched the NBAR project which changed a few aspects of the trigger mechanism to address a safety concern related to the possibility of a rifle firing when the safety was moved to the "fire" position. At the same time some of the internal dimensions were changed. The firing pin hole was enlarged at the same time to prevent the possibility of a round firing on bolt closure due to a stuck firing pin which was also a somewhat known issue though it is still pretty much denied by REM.