Wolf 6.5 Grendel Split Cases

[rmbstyle]

Took my 6.5 Grendel out for the first time and noticed that the wolf steel cases are splitting just below the neck. About a fourth of the cases have some split in them. Oddly enough, I didn't notice any wild variations in accuracy when I was shooting. It wasn't untill after I noticed some splits in the cases. Haven't had the chance to try out brass ammo yet. Any ideas on what's causing it?

 

[warmachine]

.I would try quality 6.5 brass ammo first. Steel case ammo has been known to split like that. If it does it with quality ammo see a good gunsmith

 

[Growler215]

Is this a bolt action or AR? For ARs there are a couple of different chambers which require different bolts (type I and type II).

Might also be instructive to post a pic of one of these standing on a level surface next to an unfired Wolf cartridge.

 

[rmbstyle]

Is this a bolt action or AR? For ARs there are a couple of different chambers which require different bolts (type I and type II).

Might also be instructive to post a pic of one of these standing on a level surface next to an unfired Wolf cartridge.

It's out of an AR and both the bolt and chamber are type II

 

[erwos]

Who made the barrel? Because I've put a fair bit of Wolf 6.5G through my Alexander Arms AR-15 barrel and Ruger American barrel and have never seen anything like that.

 

[Boats]

What is causing it?

Shit ammo and stacked tolerances.

/thread

 

[rmbstyle]

Who made the barrel? Because I've put a fair bit of Wolf 6.5G through my Alexander Arms AR-15 barrel and Ruger American barrel and have never seen anything like that.

It's Satern/Liberty Stainless barrel from Grendel Hunter

 

[Growler215]

The unfired case looks significantly more tapered than the fired case, and quie a bit narrower just below the neck. Could just be the picture though. I would measure the diameter here with a micrometer or calipers at the same distance below the neck. The fired case should be a smidge larger here, but this looks like too much to me. I would only expect a couple of thousandths difference.

Might also try removing the bcg and seeing if a fired case will readily chamber.

 

[Doco Overboard]

Looks like brittle cases and maybe slightly + chamber D's.
Brass cases will do the same thing when work hardened/fire-formed.

Especially when they have been stored for a while or the brass is slightly brittle from the start. (seasoned)
Thin necks work hardened will do the same thing but above the shoulder.

Complete separation is found a little ways up from the head and is best found out with a rimmed cartridge.

 

[Doco Overboard]

Looks like brittle cases and maybe slightly + chamber D's.
Brass cases will do the same thing when work hardened/fire-formed.

Especially when they have been stored for a while or the brass is slightly brittle from the start. (seasoned)
Thin necks work hardened will do the same thing but above the shoulder.

Complete separation is found a little ways up from the head and is best found out with a rimmed cartridge.

 

[Rocinante]

It's out of an AR and both the bolt and chamber are type II

Barrel length and gas system?

 

[Squaregrouper]

Looks like a loose chamber to me.

 

[smokey]

Is the shoulder blown forward?

 

[erwos]

Looks like a loose chamber to me.

This is my feeling, too. The manufacturer is pretty reputable, but everyone has a bad day once in a while.

 

[rmbstyle]

Barrel length and gas system?

It's 16 inches mid length

 

[rmbstyle]

Is this kind of case expansion normal?

 

[Sherman]

Luckily for you I kept some spent wolf ammo, mine measured an average of 10.58mm-11mm. (I've got a faxon 18inch barrel)

 

[Rocinante]

It's 16 inches mid length

Is this kind of case expansion normal?

I believe this is the same problem JB62 had in this thread: https://www.mdshooters.com/showthread.php?t=263674

What's happening here is you don't have sufficient dwell time- the pressure inside the casing is still very high when extraction occurs.
Unlike your split steel cases, the brass cases are much more malleable than steel and bulge at the base (where the casing is strongest), the rest of the casing fireforms to the chamber then contracts to a slightly bulged size. Steel is not as malleable and usually doesn't return to its original size so your cases are splitting as they fireform.
Remember- the moment extraction begins and there is still high pressure, the casing WILL expand to whatever the chamber surface is at that point until the pressure drops (i.e casing is 0.05in OOB on extraction, casing will expand to approx that)

Solution(s):
1. Adjustable gas block to increase your dwell time.
This may make your upper ammo-sensitive though if you finely-tune it.
2. Longer barrel with a longer gas system.
6.5x39 is a mid-long range cartridge and tends to work best in 18in barrels with a rifle gas system. Downside here is you will have to make sure your bolt matches the barrel.
2a. Heavier buffer or switch to A5 or rifle buffer.
Carbine buffers are notoriously light, and the H3+ weights get VERY expensive as you go up in weight. A5 and rifle buffers start at 5oz and go even heavier. The downside here is A5 uses proprietary parts and are moderately more expensive than carbine parts, and rifle buffer you lose the collapsing stock and there aren't many options out there for rifle buffers.

Personal opinion: if you know how to install a gas block and muzzle device and like your current setup, this is the cheapest and most-efficient option.

 

[smokey]

I believe this is the same problem JB62 had in this thread: https://www.mdshooters.com/showthread.php?t=263674

What's happening here is you don't have sufficient dwell time- the pressure inside the casing is still very high when extraction occurs.
Unlike your split steel cases, the brass cases are much more malleable than steel and bulge at the base (where the casing is strongest), the rest of the casing fireforms to the chamber then contracts to a slightly bulged size. Steel is not as malleable and usually doesn't return to its original size so your cases are splitting as they fireform.
Remember- the moment extraction begins and there is still high pressure, the casing WILL expand to whatever the chamber surface is at that point until the pressure drops (i.e casing is 0.05in OOB on extraction, casing will expand to approx that)

Solution(s):
1. Adjustable gas block to increase your dwell time.
This may make your upper ammo-sensitive though if you finely-tune it.
2. Longer barrel with a longer gas system.
6.5x39 is a mid-long range cartridge and tends to work best in 18in barrels with a rifle gas system. Downside here is you will have to make sure your bolt matches the barrel.
2a. Heavier buffer or switch to A5 or rifle buffer.
Carbine buffers are notoriously light, and the H3+ weights get VERY expensive as you go up in weight. A5 and rifle buffers start at 5oz and go even heavier. The downside here is A5 uses proprietary parts and are moderately more expensive than carbine parts, and rifle buffer you lose the collapsing stock and there aren't many options out there for rifle buffers.

Personal opinion: if you know how to install a gas block and muzzle device and like your current setup, this is the cheapest and most-efficient option.

https://suparms.com/products/750-adjustable-low-pro-clamp-on-gas-block-stainless-steel-finish
Aka, Get this

 

[Doco Overboard]

My solution would be to see what happens with brass cases. Make a chamber cast which is easy to do.
Embrittlement with manufacture of steel cases is not uncommon or unheard of.
It happens during the pickling/washing stage.