New 18in Liberty barrel and bolt, is this normal for the 6.5G

[alligator]

Cliffs notes: New barrel and bolt, 26 rounds fired, cratered primers and ejector marks with factory Hornady, bolt wear.

This is my first Grendel. I ordered in December and received it in January. It is an 18in medium profile Liberty barrel. It was the whole kit, upper, gas block/tube, bolt and heliport brake. I assembled it with a 12in Larue Tactical rail and a Palmetto State Armory "premium" bolt carrier. I have assembled uppers/complete ARs for the past few years with great success.

I fired exactly 26 rounds of factory Hornady 123 SSTs. This is the only ammo available locally. I used a 3-12 Nikon M223 scope. I have yet to buy a scope for this rifle so I borrowed it off of one of my 5.56s. I got it on target at 165yards shooting clays. Very easy. I then started shooting at an 8in steel plate at 500yards. I hit the plate a few times. I have not shot for groups at 100 yet.

The bullets chambered fine dropping the bolt on them. They cycled the gun with no malfunctions. I did not look at the brass or bolt while out, we were too busy shooting other stuff. When I separated all of my brass at home I started looking at them. They all have some cratering on the primers and most have ejector marks.

The bolt has some marks on it. Mainly the corners of the lugs. You can see the shiny spots in the pics. The metal is slightly deformed on these areas. You can catch your fingernail on it, they are not just rub marks. I am measuring the bolt face depth at .130. These are cheap calipers though, can they be that far off? It was generously lubed with Mobile1 Syn. just like my 5.56s. Wet but not dripping. No oil on the bolt face. Barrel was cleaned before shooting.

Is this normal wear? Im thinking not. Does it just need a good break in? Should I send it in to get checked just in case?

[explorecaves]

Lots of discussion about possible tight throats in this thread: http://www.65grendel.com/forum/showt...hort-chambered.

I would measure your chamber and see what your OAL is. If you don't have the tools to do so, measure a few factory rounds before and after chambering them (remove firing pin first).

[alligator]

I saw that thread. It is now locked. Not a good idea to put BCG in without the firing pin in. The cam pin can turn and jam up bad.

[Kikn]

I think your bolt and bcg may be the problem. From what I understand the face depth should be at .136 and if it isn't a bcg for a grendel the length of the bcg is a shorter length than a standard BC. And the extra length on your can cause the cratering you are seeing.

I'm no expert by any standard but if I'm wrong I'm sure I will be corrected shortly.

[LRRPF52]

Not only do you have cratering, but significant ejector channel extrusion (brass flow into the ejector hole).

Primers start to crater in the mid-high 60,000 psi range. I also load for the .270 Winchester, which is rated to 65,000psi by SAAMI. Start loads and loads in the lower-to-mid range won't show any of the signs I'm seeing on your brass, even when I shoot it in hot weather, and they are at or over 60,000psi easily.

Keep in mind that the Grendel is a SAAMI-rated 52,000psi Maximum Average Pressure cartridge. Something is wrong.

The extreme pressure signs on your brass, combined with the visible damage to your bolt indicate something very wrong. I obviously cannot recommend shooting this anymore, and would advise you to seek guidance from the source of the barrel/bolt combo and ammunition maker.

Just in case, record the ammo lot number. I think I know where the problem is, but record the lot # anyway. If you have a short throat, and the projectile is jammed, these signs would be consistent with that condition.

If you have any of the loaded ammo still, take a marker and color the projectile ogive, while keeping the firearm pointed in a safe direction, carefully chamber a round of the loaded 123gr SST, then remove it. You can slowly close the bolt, then extract it while keeping your finger in the ejection port to prevent the ejector from forcing the ogive against the inside of the barrel extension. Tell us what the projo looks like after performing this.

[NugginFutz]

I saw that thread. It is now locked. Not a good idea to put BCG in without the firing pin in. The cam pin can turn and jam up bad.

Good point about the firing pin. I'd never considered its need to keep the cam pin aligned, when I'd recommended its removal to another member, earlier this week.

[SHORT-N-SASSY]

alligator,

Welcome to the 6.5 Grendel Forum!

Like you, I recently shared my experience on the Forum, with a newly installed AR-Stoner 6.5 Grendel Barrel and Bolt http://www.65grendel.com/forum/showt...ambered/page48 (see Reply #473, third from top of Page). My measured Bolt face depth is 0.135". Fired cases do show some firing pin cratering, but no Ejector marks, nor nicks on the Bolt lugs, such as shown in your pics.

Question: After closing the Bolt on a fresh factory-loaded cartridge, then extracting it, are there any marks on the bullet, a short distance from the case neck, such as shown in my pic in the above-referenced Link?

[45r]

The headspace on my chamber is minimum with my bolt that measures .135 deep and I polished the bolt face and lapped the lugs.
Maybe since your depth is .130 you might have too tight headspace.
The face of your bolt looks to have a lot of copper build up for 26 rounds fired.
You should have at least 4 thou headspace clearance on a new barrel and bolt.
I wouldn't use that bolt anymore until the depth can measure .135 deep.
The lugs have to be right also.

[customcutter]

Alligator, welcome to the forum. Sorry to hear about your problems with the Liberty 18" barrel. I have one also, but haven't been to the range with it yet. Mine is chambering and ejecting easily (not slamming the bolt home) with no marks on the ogive.

Remember when you use your caliper as a depth gauge to set the base on a flat hard surface and open the gauge so that the extension is even with the rest of the bottom of the caliper. It may account for the .005" that you are missing. I saw someone else post this, and had never considered it when measuring depth.

Edit, My bolt is from a different mfg, and has the light rings around it.

2nd Edit, Sorry I just realized that if the caliper were fully closed and zeroed your length would be long not short. Unless your extension is extended past the base, when zeroed.

[alligator]

Remember when you use your caliper as a depth gauge to set the base on a flat hard surface and open the gauge so that the extension is even with the rest of the bottom of the caliper. It may account for the .005" that you are missing. I saw someone else post this, and had never considered it when measuring depth.

Good idea. I will try that. I will also chambering a few and measuring before and after OAL. I will also put some black marker on them. I def wont be shooting it anymore. It will be going back.

Edit: Tried zeroing on a flat surface. No difference. Still measuring .130 bolt face dept. I am going to chamber some in a few minutes.

[rickOshay]

Where did you get your kit?

[MTNmyMAG]

This is what my brass looks like in my BHW barrel when I get close to a warm load, I have been told I have an early unlocking issue, still have not tried a heavy buffer to see if that solves it.

[Aaron_S]

Good idea. I will try that. I will also chambering a few and measuring before and after OAL. I will also put some black marker on them. I def wont be shooting it anymore. It will be going back.

Edit: Tried zeroing on a flat surface. No difference. Still measuring .130 bolt face dept. I am going to chamber some in a few minutes.

Find something else to measure. A bullet diameter or a new coin has known dimensions.

[alligator]

Got the kit directly from Satern.

I colored a couple of 123gr SSTs with a dry erase marker and inserted them by had. After the extractor snapped on they did require a little push to get the bolt to lock. They also required a tug to get out. The normal operation of the bolt being pushed with the buffer spring would be enough to overcome the force to push the bullets into the barrel. Notice the marks circled in green. Both measured 2.248 before and after inserting them.



Measured brand new Hornady 53gr Vmax and 150gr FMJ/BT. Calipers measured .224 and .308.

[BjornF16]

I just measured my Satern supplied bolt (for Spartan barrel) at .136".

It appears you have both a out of spec bolt and short throat.

An earlier email with a Steve Satern attributed quote indicated S. Satern didn't believe the SAAMI spec included throat dimensions...I wonder if Satern or PTG believe they could shorten the throat and still call it SAAMI Grendel?...

http://www.65grendel.com/forum/showthread.php?7828-AR-Stoner-6.5-Grendel-barrel-short-chambered.&p=83844&viewfull=1#post83844

There is no Saami spec or requirement for throats. It's up to the reamer manufacturer to grind it to the print.