Split Necks / 6.5 Grendel

[Rootshot]

I've been splitting necks on about 2-5% of my Lapua 6.5 Grendel brass. I did some measurements to try and figure out what was going on.

Average fired neck diameter = .2950"
Average sized neck diameter = .2872"
Average loaded neck diameter = .2884"
Average neck tension = .0012"

Bullets used were Sierra 107gr Matchkings. Rounds were fired in a 16" Alexander Arms tactical Grendel upper. Dies are Forster Ultra dies.

If I interpret these numbers right, the most amount of brass movement occurs when the round is fired (.0076" assuming .001" springback). This would indicate that the 6.5 Grendel chamber throat diameter is about .2960".

Interestingly, the .264LBC reamer dimensions indicate a tighter .2948" throat.

So, my questions are: Do any other Grendel shooters have similar issues? Is a neck clearance of .0066"-.0076" excessive? Is the answer "this is normal, just get over it"?

--Rootshot

 

[vman]

Re: Split Necks / 6.5 Grendel

Annealed brass?

 

[jackit]

Re: Split Necks / 6.5 Grendel

Morning sir,

I had just received my built AA(Alexander Arms) 6.5 grendel. I am in the process of still breaking it in with the AA ammo my friend who built the gun gave me. Of course it is Lapua brass. My question is this after some time searching......is the Hornady brass worthy to feed through my AA upper and how does it hold up to repeated reloadings in a mild to medium load? I know you get what you pay for but at nearly half the cost of Lapua perhaps I was thinking Hornady might be worth a shot. Just don't want to screww my weapon up is all.

Thanks and have a nice day.

Sid

 

[country888]

Re: Split Necks / 6.5 Grendel

he said it was lapua brass. it should be annealed... i would think.

 

[armorpl8chikn]

Re: Split Necks / 6.5 Grendel

If I missed the answer I appologize I read it 3 times to make sure. How many times has this brass been fired? .006-.007 is not too much clearance in an autoloader. Even the mighty Lapua brass needs annealing from time to time.

 

[Tactical30]

Re: Split Necks / 6.5 Grendel

I have 15 reloads on some of my 6.5 grendel lapua brass and they are still going strong. Most of my Grendel Lapua brass has 10+ reloads and have yet to have any type of problem besides maybe trimming here or there but no split necks on any.

I FL resize with normal prep after every firing.

 

[Rootshot]

Re: Split Necks / 6.5 Grendel

The brass is about 6x-8x fired. I agree that it may be time to anneal it since it is probably strain hardened. That being said, it does appear to be an anomaly since others who have reloaded the Grendel more times than this have hod had the same problem.

I have a call in to Forster to speak with a tech about this problem. They have been very responsive so far. I'll post a diagnosis / solution if I find one.

Thanks for the help.

--Rootshot