M118LR and primer flow

[Ravenworks]

Have any of you had problems with M118LR in a gass gun?

I have a Creition 308 barrel, the plain JP enhanced bolt that is matted to an Aero precision bolt.

I've shot just about anything you could imagine and have never had a problem until last week

I was at the range last Thursday and decided to use up some older M118LR (a few years old) because I'm getting ready to do a bunch of reloading.

I shot 3 rounds and the first thing I noticed was this stuff is hot.
I picked up my brass and noticed that it had severe swipe marks.
I shot 2 more and noticed daylight through the primer and the primer looked like it got to flowing

I forgot to take pictures of the brass but will post some pictures tomorrow.

I know this is a known problem in gassers with some manufacturers ammo.
I also know JP makes a bolt that helps with this problem,.
But do I even have a problem since this is the ONLY TIME something like this has happened.
I went back to using other ammo that I had with me after I broke the BCG and gun down to inspect it and everything is back to functioning as it should.

I know my headspace is correct and up to now this gun has been trouble free.

 

[8up]

What temp were you shooting in? That ammo shoots real hot in this summer weather. I think your good with the rifle set up. I use a standard JP bolt, no HP bolt, with 118LR. I have slight swipe marks during summer temps, goes away during cooler weather.

Seen some lots shoot extremely fast, and add if it was sitting in the sun warming up then you can see real fast speeds.

 

[eastexsteve]

Have any of you had problems with M118LR in a gass gun?
I have a Creition 308 barrel, the plain JP enhanced bolt that is matted to an Aero precision bolt..
..I know my headspace is correct and up to now this gun has been trouble free.

I have two AR10 clones with tight .308 win target chambers that won't even shoot the stuff. However, my three 7.62x51 gas guns love it. Your going to hear that "Oh, it's the same as .308win.." but I'm telling you, it's not.

 

[Ravenworks]

The temperature was close to 90 degrees.

I am in total agreement with what you guys said.
I've shot a lot of this stuff, just not in this gun and it is most definitely hotter than standard 308 or ball M80 ammo.

Thanks for confirming what I was thinking,I will gets some pictures later

 

[eastexsteve]

The temperature was close to 90 degrees.

I am in total agreement with what you guys said.
I've shot a lot of this stuff, just not in this gun and it is most definitely hotter than standard 308 or ball M80 ammo.

Thanks for confirming what I was thinking,I will gets some pictures later

What can make it hotter in a .308win gun is that the 7.62x51 milspec case length from the base of the neck to the base of the cartridge allows it to be .002" longer than .308win spec. In a tight .308win chamber, this could cause you some extra pressure, if it even chambers at all. As I said, my .308win guns won't even chamber them.

 

[__JR__]

'Touch point' on 308 win chamber a lot closer to m118lr bullet than NATO spec, that with the smaller diameter throat drives pressures up. TP is basically the jump. So yeah, my advice in a gasser is to shoot M118LR in Nato or chamber designed for the round.

Later

 

[Ravenworks]

'Touch point' on 308 win chamber a lot closer to m118lr bullet than NATO spec, that with the smaller diameter throat drives pressures up. TP is basically the jump. So yeah, my advice in a gasser is to shoot M118LR in Nato or chamber designed for the round.

Later

My Criterion Barrel is designed specifically for this round.
Part of the reason I bought the profile was it gave me a longer OAL during reloading

 

[__JR__]

My Criterion Barrel is designed specifically for this round.
Part of the reason I bought the profile was it gave me a longer OAL during reloading

10-4. In that case, rather than tinternet roulette you should call Steve Dahlke up in Cheddarland. If this is showing signs from get go or after 'x' amount of rounds he may recommend a carbon clean.

Later

 

[Ravenworks]

I wil do.
I'm not one to consider just one source of information ,especially from the internet.
It's pretty easy to wade through the bullshit here cause folks that know better call the bullshit out pretty quickly.
I'll probably end up buying a JP HP bolt as I have uses for my other JP and Aero bolt that will never see any hot loads

I sent you a PM

 

[bfoosh006]

Try cleaning you chamber ( not meant "mean spirited" ) ... or look for a carbon ring.

Also, how many rounds thorough the barrel ?... length ? gas system length ?

And what is your gas setup , Adj. GB ? and recoil setup, buffer weight and recoil spring ?

I don't get the precision ( accuracy ) I'd like with M118LR... so I haven't fired a lot of it, but the ones I have fired through my 18" Criterion , mid length gas were fine.

Any thoughts on seating the bullet slightly deeper ? ... in case it is mashed into the jams ?