Two chamber sizes

[noone]

I have two Grendels. When I measure fired cases at a datum line on the case shoulders, there is .007 inch difference between the two chambers.

One rifle had a bolt replaced because a lug had broken. The upper was returned to the company who made the bolts, so they could make sure they got the fit they wanted. The tight chamber is the 264 LBC/6.5 CSS, it isn't the Alexander Arms reamer chamber. I am aware that the AA chamber was made a bit looser by design so it could have more reliability in the field.

I'm wondering if I should have either have the chamber of the shorter rifle deepened up a few thousandths so there isn't as much brass stretching, or if I should just leave them alone. Both rifles shoot great.

I have considered having the bolt deepened a few thousandths, but don't think that would be a really great idea.

Am I worrying unnecessarily about brass stretching too much? If I size the brass so that it has the shorter shoulder pushed back .002, then when that brass is fired in the longer chambered rifle, it will stretch .009, and that seems like quite a bit.

Any input will be appreciated.

[CoolBarrelBill]

I would have the barrel with the 264 LBC/6.5 CSS chamber rechambered for the A.A. 6.5 Grendel chamber. Keeping every thing the same would solve your problem.

[Stormrider]

I'm wondering if I should have either have the chamber of the shorter rifle deepened up a few thousandths so there isn't as much brass stretching, or if I should just leave them alone. Both rifles shoot great.

I can think of at least two reasons why that wouldn't be a good idea...

[mjh30]

Noone I would keep the 264LBC chambered rifle, talk with your builder ask his advice.

[noone]

Both rifles shoot great, and when fed proper ammo, are absoutely reliable. The AA rifle is the one I used to win a precision rifle match, so there isn't going to be anything done to a rifle that works that well.

My first thought was to have someone with a chamber reamer deepen the 264/6.5 CSS chamber to match up with the AA chamber. The AA chamber is properly done, and was done by the factory at AA, so I don't want to mess with it. The 264/6.5 CSS has a Lothar Walther barrel. The rifle had a broken bolt, so the bolt that is in it now, is the replacement bolt. Perhaps I need to contact the maker of the bolt and ask them for advice...

[noone]

What problems could come from having a gunsmith use the proper reamer (from Pacific tool and gauge) to deepen the short chamber by .007? Of course, the proper reamer would also move the throat forward an equal amount. The Lothar Walther barrel is the one that is .007 shorter.

My friend also has two Grendels. His Lothar Walther barrel is also .007 shorter than his other Grendel rifle. (I am using Grendel/6.5 CSS/ 264 LBC interchangeably, even though I realize there are subtle differences).

[Stormrider]

I quoted the wrong part of the post.

This is what I meant to quote:

...I have considered having the bolt deepened a few thousandths, but don't think that would be a really great idea...

[noone]

So no problems perceived with having the chambers and throats deepened a few thousandths so they are the same depth?

[bwaites]

Noone, I understand your concern. This would be a good question for Bill Alexander or maybe Steve Satern. I personally would hesitate to do anything on a rifle that is shooting well, though. I would just separate brass and keep them like I would for separate calibers, just like I would for two match rifles in the same caliber. A little bit of a hassle but manageable.

[philmurphy]

Both rifles shoot great, and when fed proper ammo, are absoutely reliable. The AA rifle is the one I used to win a precision rifle match, so there isn't going to be anything done to a rifle that works that well.

My first thought was to have someone with a chamber reamer deepen the 264/6.5 CSS chamber to match up with the AA chamber. The AA chamber is properly done, and was done by the factory at AA, so I don't want to mess with it. The 264/6.5 CSS has a Lothar Walther barrel. The rifle had a broken bolt, so the bolt that is in it now, is the replacement bolt. Perhaps I need to contact the maker of the bolt and ask them for advice...

Noone,

If the barrel with the tight chamber is from Lothar Walther, I would advise you to call them. Speak with Woody. He is aware of the 6.5G chamber issues. The problem with my LW barrel was with Hornady 6.5G ammo from the first lots. The problem was that the ammo was .001 - .002 over the max head space, and the neck to shoulder radius was/is too wide. Hornady shortened their ammo and LW relieved the neck to shoulder radius of my chamber. This is an ongoing issue with 6.5G & ETC chambers. I suggest that you purchase PTG Go & No Go gauges and L.E. Wilson cartridge gauge. My barrel is now chamberered to tightly chamber the old Hornady 6.5G & .264LBC and easily chamber the new Hornady 6.5G. The answer to how all this happened is known by BA and Hornady. Neither of which are speaking on the record. If SAAMI certification happens, then we'll have correct and publically available chamber and cartridge drawings

Phil

[pinzgauer]

If SAAMI certification happens, then we'll have correct and publically available chamber and cartridge drawings

From memory on the 3-4 dozen other times this has been brought up, Bill has made it clear multiple times that the prints provided to SAAMI were the same as the prints provided to Lapua, Hornady, PTG, etc.

"Nothing to see here, move along."

[philmurphy]

From memory on the 3-4 dozen other times this has been brought up, Bill has made it clear multiple times that the prints provided to SAAMI were the same as the prints provided to Lapua, Hornady, PTG, etc.

"Nothing to see here, move along."

Pin,

If that is indeed the case, how is it that Lapua got it right and Hornady did not? How is it that Prvi Partizan got it right and Hornady did not? I don't believe that anyone on this thread referred to AA's chamber print. I have seen the print and my gauges were made by 6.5G licensees. The neck to shoulder radius is not specified, and Hornady ammo is .001 -.002 over the specified max headspace. Another key point is that there is not an offical 6.5G cartridge drawing!!!! So, if your rifle easily chambers Hornady 6.5G and 6.5LBC ammo from last year's lots and chambers the "new" Hornady 6.5G ammo then I would guess that you have a chamber that does not conform to the 6.5G or 6.5LBC chamber drawings.

Phil

[pinzgauer]

Not going to debate this (again).

Seems Hornady only got it "wrong" for rifles without Grendel chambers. Both old and new Hornady work fine in my grendels. (One AA barrel, one licensed) Both pre-date the alleged changes. I'm getting excellent accuracy from them as well.

Regarding the missing radii, seems the PTG LBC print for their gauge does not have them, is that what you are referring to? All the other diagrams I've seen did list the radii. I don't see how you'd make a reamer without that! Now that they have dealt with Usama and found Obama's birth certificate maybe we can focus on the alleged (and apparently magic) changing of the AA chamber prints.

Maybe old joe will post his two (alleged) incriminating prints and we can put an end to the conspiracy?? Oh wait, that was over a year ago and never surfaced.

Joking aside: I am glad your custom chamber is now working with the Hornady ammo. Your project sounds interesting, and I'd like to see how it turns out.

[philmurphy]

Not going to debate this (again).

Seems Hornady only got it "wrong" for rifles without Grendel chambers. Both old and new Hornady work fine in my grendels. (One AA barrel, one licensed) Both pre-date the alleged changes. I'm getting excellent accuracy from them as well.

Regarding the missing radii, seems the PTG LBC print for their gauge does not have them, is that what you are referring to? All the other diagrams I've seen did list the radii. I don't see how you'd make a reamer without that! Now that they have dealt with Usama and found Obama's birth certificate maybe we can focus on the alleged (and apparently magic) changing of the AA chamber prints.

Maybe old joe will post his two (alleged) incriminating prints and we can put an end to the conspiracy?? Oh wait, that was over a year ago and never surfaced.

Joking aside: I am glad your custom chamber is now working with the Hornady ammo. Your project sounds interesting, and I'd like to see how it turns out.

Pin,

The reason that your chambers "work" is because they are oversized, and they have .300 necks, that compensate for incorrect neck to shoulder radius. Hornady's neck is effectively .292, due to the burr. But, it is really a .290 neck. That gives .010 wiggle room, that allows Hornady's wide neck to shoulder radius to settle into. The offical 6.5G and 264LBC drawings, that I have seen, do not contain radius specs. The radius specs would look like this ".030R or .075R." The numbers that you've seen are degrees of angle, not radius. I've spent a year sorting it out, and I have Hornady's data. I'll be happy to discuss this ad nauseam. Once and if SAAMI settles on the cartridge/chamber spec, I suspect that all pre-spec chambers will be "custom."

Phil

[rasp65]

Pin,

The reason that your chambers "work" is because they are oversized, and they have .300 necks, that compensate for incorrect neck to shoulder radius. Hornady's neck is effectively .292, due to the burr. But, it is really a .290 neck. That gives .010 wiggle room, that allows Hornady's wide neck to shoulder radius to settle into. The offical 6.5G and 264LBC drawings, that I have seen, do not contain radius specs. The radius specs would look like this ".030R or .075R." The numbers that you've seen are degrees of angle, not radius. I've spent a year sorting it out, and I have Hornady's data. I'll be happy to discuss this ad nauseam. Once and if SAAMI settles on the cartridge/chamber spec, I suspect that all pre-spec chambers will be "custom."

Phil

The reason why Grendel chambers work is because they are GRENDEL chambers. That is the way they were designed and that is why they work with 6.5 Grendel ammunition. The problem with your chamber is that it is not a 6.5 Grendel and ant prudent owner of a weapon should only use the ammo that id stamped on the barrel. It is not BA's fault that you bought a barrel that is not a 6.5 Grendel and he owes you nothing. I suppose that I would be bitter too if I bought a rifle for which no ammo exists( especially if I did not posess the skills necessisary to reload) and would do everything in my power to put the blame on someone else rather than blame myself for my own mistake.