Home Forums Reloading Big Game Rifles RL-15 7mm-08 and cratered primers

Worked up to 42 gr of RL-15 and started getting cratered primers. Book max is 44 gr. Seems like everyone but me can make it to 44 gr with their guns.

Bolt face looks fine. I've only registered about 200 rounds on it. I did have two loose primer pockets blow gas back on the bolt face when I was using a different load.

Accuracy is good...

Any thoughts?

Rem M700
Win Brass
Rem 9 1/2
120 NBT
.010 jump
Air Temp: 80 F

Velocity?

That may be max in your gun. Drop a couple grains and chronograph the load.

Firing pin fit....?

Don't have a chrono. Firing pin fit looks to be fine. I said that about my 17 Rem though and now it's in the process of being bushed. I'm starting to think that Rem has some sloppiness in their firing pin holes. At least the ones I have. I don't want to have to do five of them.

Hoping to get ahold of some Big Game soon. If I had this issue with RL-15, is there a good possibility it'd happen with Big Game too?... or any other powder for that matter?

You really should invest in a chrono. I shoot 44gr of RL-15 in my Remington 700 7-08 with the 120 BT and my primers are cratered also. Velocity however is where it should be. I would bet its just your firing pin fit. Remingtons are kinda famous for that.

Dooger

This very same subject came up in another forum I was in and I was having cratered primer problem also. They were all talking about oversized holes in the bolt face and having a gunsmith bush the firing pin hole to make it smaller.

I broke out a magnifying glass and said WTF when I saw the tapered hole. "WE" are not the only ones who have this same problem, I contacted Remington and they said this is normal and not to worry about it. BUT my older 700 rifles were not made this way. So take a close look at yours and get back to us, no one is having any luck getting Remington to fix it. It seems "modern" cost saving manufacturing methods are how companies save money.



Also you need to keep your shoulder bump to minimum to help prevent the ruptured primers. The further the primer can move back to meet the bolt face when fired the greater the chance of a ruptured primer. Meaning if you have .002 shoulder bump you will have .002 head clearance, so remember excessive resizing makes the problem worse.

The Rem 700 is well known for over sized F-pin holes producing "cratered primers" and false pressure signs.

Thanks guys!!!! Good stuff!

I'm buying a chrono for next year, already planned on it.

I have a Remington M700 in 30-06 that craters primers badly. On close inspection, the firing pin hole looks as if it was deliberately chamfered. This had to have come from the factory as I bought it new in the box at J.C. Penney when they were closing out their sporting goods stuff along with all the other non-yuppie stuff back in 1981. One hell of a discount as they were trying to get rid of it as fast as possible and as my wife worked there at the time I get her 10 percent discount as well as the sale price. IIRC, it was something like $110 tax included out the door. I also bought a Winchester M94 for $95 and a Marlin 336 for $100. So for the price most places charged for an M700, I gor the M700 plus two more rifle for an additional $95.
FWIW, even a cast bullet gallery load (5.0 gr. Unique and a110 gr. cast bullet) with produce a cratered primer.
Paul B.

Been years since I've given cratered primer's a though. Really flattened primer's and ejector mark on the cars head. If you had some blowing gas back at you, I'd definitively take a look at that.

I think the blowback was due to loose primer pockets. It was with a min load of 4320. Only two of 50 did it. Those cases were trashed and then it hasn't happened since.

I'm boxing up a 700 bolt to go to Gre-Tan tomorrow for a bushing job. Only one I've had to do, but probably not the last.

See below:

Same rifle, same load, same brass before & after bushing. (Not my pics, just pilfered from another thread)

I had the same issue & looked exactly the same; had the firing pin hole bushed by GreTan with exactly the same results.

FWIW, 42 gr of RL-15 as a max with a 120 in a 7-08 would be abnormally low; every 7-08 I've seen will go between 44 & 45 grains w/o issue, a couple of brave souls even go more than 45 gr.

MM

Thanks. Might have to send it away once the snow flies.

OK, I am having this same issue with a 700 also in 7-08. Velocities and loads are in line with expectations and below max. Is this cratering not really a sign of high pressure? Am I good to go as long as no other signs appear? Would a change in primers possibly help? Getting really good groups and would like to stay with this load if it is safe.

Thanks,

bludog

Not necessarily. As mentioned before is could be the result of the interaction with the firing pin. Winchesters are famous for it, especially with softer primers.

^^^^^^^^^^

This is the cure. Bush the firing pin.