6.5 Grendel brass look ok?

[Space Jam Darimon]

Hello,

I just finished my 6.5 Grendel build and took it to the range this morning for a function test. The brass in the pictures are from the four rounds that were put through it. Not familiar with how brass usually looks after coming out of an ar15, usually run bolt actions. Does anything look out of the norm on these?

Thanks!

 

[6.5SH]

The proper fix for the dinged case mouths is to shorten the ejector spring a coil to coil and a half. The band-aid method is put a piece of heavy duty loop side Velcro on the shell deflector and replace as it wears.

The 2nd pic looks like you may be unlocking a little early. Where was it ejecting the brass on the clock scale?

 

[Space Jam Darimon]

The proper fix for the dinged case mouths is to shorten the ejector spring a coil to coil and a half.

Ok I’ll give that a try and see what happens.

The 2nd pic looks like you may be unlocking a little early. Where was it ejecting the brass on the clock scale?

The 5 o’clock area. For learning purposes, do you believe that to be the case, due to the marks on the rim?

 

[6.5SH]

5 o'clock points towards under-gassing, which is the opposite of what I was expecting.
The shiny ring on the body near the top of the web is what I was looking at.

The ejector swipes on the base can be from sharp edges on the ejector face or the ejector hole on the bolt face.

What's the rest of the story; is this factory ammo or reloads? What is the rest of your build info? What were the conditions when fired?

 

[Space Jam Darimon]

Alright,

What's the rest of the story; is this factory ammo or reloads? What is the rest of your build info? What were the conditions when fired?

Factory ammo, 123 Hornady Black. Barrel is a 16.1” Cmmg with a RLGS. Low Profile Grendel Hunter gas block. Grendel Hunter Bolt. No Name Bolt Carrier that was from a build before. Carbine buffer, unsure of the spring, I’m sure it’s just a standard. Was approximately 27 degree Fahrenheit.

If you need more details I can get that, I just listed the stuff that I thought would be useful.

 

[6.5SH]

Not trying to bash you or your build but you are likely going to be chasing your tail a bit to find the right combination to make that work reliably under varying conditions.

I'm guessing that barrel was intended to be used with a suppressor, and even then it's still an odd duck. Even 18" with rifle length gas on Grendel is problematic due to short dwell time, 16" is going to make that even shorter.

Since is a new bolt it can just require some breaking in or careful hand finishing if you can see where the brass is shaving/smearing on the bolt face. I'm not familiar with that brand so no idea how good or bad they are.

The biggest problem I see is the ring on the case. Given it's Hornady, it is thicker in that region so it shouldn't be doing that, doubly so with low pressure and a too long gas system. It's not so bad that the brass will fail at next loading but life is going to be shorter and it's not "right".

What exactly your going to need to change or adjust I can't definitely say given the visual symptoms are contradictory.

Perhaps @bill alexander might have some sage advice here.

 

[Space Jam Darimon]

Alright, well thanks for you input. Guess that deal that’s too good to pass up, should be passed up on sometimes.

 

[Jsp556]

Not trying to bash you or your build but you are likely going to be chasing your tail a bit to find the right combination to make that work reliably under varying conditions.

I'm guessing that barrel was intended to be used with a suppressor, and even then it's still an odd duck. Even 18" with rifle length gas on Grendel is problematic due to short dwell time, 16" is going to make that even shorter.

Since is a new bolt it can just require some breaking in or careful hand finishing if you can see where the brass is shaving/smearing on the bolt face. I'm not familiar with that brand so no idea how good or bad they are.

The biggest problem I see is the ring on the case. Given it's Hornady, it is thicker in that region so it shouldn't be doing that, doubly so with low pressure and a too long gas system. It's not so bad that the brass will fail at next loading but life is going to be shorter and it's not "right".

What exactly your going to need to change or adjust I can't definitely say given the visual symptoms are contradictory.

Perhaps @bill alexander might have some sage advice here.

I’ve had an 18” rlg Grendel that I’ve been shooting for years and never any malfunctions suppressed or unsuppressed. My 18” 6 ARC ran fine also.

 

[Greg Langelius *]

The middle photo looks a bit like mine when I started load development. My cases displayed soot all the way past the shoulder, which definitely translated to early extraction. The barrel was 24" and apparently, the extended dwell was really putting a lot of strain on my extractor by attempting to extract a case that was still under significant internal pressure. Soon after, the extractor broke in two.

The issue is that the AR bolt face needs to be subjected to a lot of surgery in order to accommodate an appropriate extractor, and this results in a weak extractor. In the end, the extractor is not really brawny enough to handle higher pressure loads, especially in longer barrels where extra dwell time prolongs the stress. The quick remedy is a stronger extractor; I employed the J-P Enhanced Grendel Extractor. It works, but for safety sake, I restricted the 24" barrel to 90 grain Varmint loads. I have two 6.5G AR's and the other is a 20".

For reasons that weave in and out of these conditions, I feel that reading pressure signs off the fired cases may be unreliable, and urge new handloaders to stay within the load ranges shown within the popular loading manuals, and to resist hot loading, especially when the cases don't show much in the way of pressure, and especially so when the barrels are longer than 20". It's as if the damage is being done at pressures that are significantly below those which put readable signs on a fired case.

The 6.5G can be a very effective upgrade to the AR, but I would prefer mine with 20" barrels, and being run at more sensible pressures.

...And I am just one person speaking here, there are many others...

Greg

 

[TonyTheTiger]

.Even 18" with rifle length gas on Grendel is problematic due to short dwell time,

 

[37L1]

Your brass is normal for an AR-15 Grendel.

 

[Space Jam Darimon]

I’ve had an 18” rlg Grendel that I’ve been shooting for years and never any malfunctions suppressed or unsuppressed. My 18” 6 ARC ran fine also.

Anything vastly different between are builds? You seeing any issues?

The middle photo looks a bit like mine when I started load development. My cases displayed soot all the way past the shoulder, which definitely translated to early extraction.

Are you referring to the streaks on the right sides the cases? If so I do believe that’s from a shadow. I can confirm for sure when I get home.

Your brass is normal for an AR-15 Grendel.

Does the brass tend to get beat up a little more than 556?

 

[Jsp556]

Just the barrel length.

 

[37L1]

Anything vastly different between are builds? You seeing any issues?

Are you referring to the streaks on the right sides the cases? If so I do believe that’s from a shadow. I can confirm for sure when I get home.

Does the brass tend to get beat up a little more than 556?

Depends on feed ramps, extractor and what it hits upon ejection. Still, there's is nothing unusual about your brass. Reload and shoot 'em.

 

[hlee]

I think a lot of reloaders around here are accustomed to looking at brass out of custom chambered barrels. Lots of factory barrels will yield brass with that line at the web. It’s not, necessarily, from case stretch, but from the chamber being on the high side of the spec for diameter. The thinner case walls expand to the chamber walls, but the case head (being solid brass) does not. Run a pick down one and you won’t feel a lip indicative of separation. Cut one in half if you must. Keep an eye on them, and don’t ignore any sign, but that line around the base is not abnormal…

 

[Dildobaggins]

You could always try putting a piece of Velcro on the brass deflector. Or get one of these.
I have a 22" with a rlgs and it happens quite often. Run em through the FL die and all is well.

 

[krw]

I really really tried to get excited with my Grendel uppers and Grendel bolt action. I have a 20” upper w Lilja bbl left. Do not shoot through a chrono, that always put me in sellin mode

 

[hlee]

I really really tried to get excited with my Grendel uppers and Grendel bolt action. I have a 20” upper w Lilja bbl left. Do not shoot through a chrono, that always put me in sellin mode

Then you’re not shooting at targets that are sufficiently far away to appreciate the Grendel. Or, you’re comparing to the wrong cartridges…

 

[Space Jam Darimon]

Run a pick down one and you won’t feel a lip indicative of separation. Cut one in half if you must. Keep an eye on them, and don’t ignore any sign, but that line around the base is not abnormal…

I stretched out a paper clip and ran it down in there, couldn’t feel a lip.

Sounds good @Dildobaggins , thanks!

I took a few measurements on them today while I was looking at the brass.

Fired Measurements:
Headspace - 1.237
Case Head - .439
Shoulder - .430

Loaded Factory Cartridge:
Headspace - 1.233
Case Head - .435
Shoulder - .427

 

[supercorndogs]

Then you’re not shooting at targets that are sufficiently far away to appreciate the Grendel. Or, you’re comparing to the wrong cartridges…