Is my Type 2 chamber not Type 2?

[Randy99CL]

These fired rounds were w/ a .136" bolt when the chamber actually needed a .125" bolt. The shoulder of the cases are "ballooned" out.
The other picture shows how far a fired case sticks out of my case gauge.

Thanks for posting these pics!
Very informative. It's hard to predict where a case will stretch when it is fired in an oversize chamber. Yours is what I would guess to be the less dangerous result?

FWI understand, the firing pin usually pushes the case forward in the chamber until the shoulder hits, so when the case expands the main body is held by the chamber walls and the base has to stretch backward to take up the slack. This can lead to a catastrophic case head separation.

Johnny's Reloading Bench switched out a Saturn barrel for a Faxon and the fired brass length difference was .010". The sized reloads made for the Saturn would not even chamber in the Faxon. He rants about it in this video at about the 15 minute mark: https://www.youtube.com/watch?v=1Ecj...lh4cjTRb-JJmto
The funny thing to me is that his Saturn brass looks to be within spec at 1.224" while the Faxon brass measures a little short at 1.214".

[LRRPF52]

Thanks everyone - allowed me to consolidate my thinking enough to give them a call. Was lucky to have the guy who runs QC answer the phone. Had a nice long chat with the conclusion being that being .01 longer than the JP brass would not be out of the ordinary and being around .01 longer than the Type 1 brass would be expected. Long and short of is: remove the firing pin from a Type1 bolt and see if it locks down on Match Grade ammo. So I got home and did the test with StoneHendge Enterprises 123 gr Scenar ammo that gets fed to the JP and voila!

[ATTACH=CONFIG]12269[/ATTACH]

I might not be too happy with a chamber deep enough to make Stormy Daniels proud if I was using Hornady brass for anything else in 6.5mm, but I'm not so I guess I can live with it.

Other random takeaways:

He gushed praise about JP and his tolerances when I brought up the JP measurements - pretty compelling coming from a QC guy. This is the third company I've talked to that had that reaction. Conversely, he was uncomplimentary of some of the things he has seen in the market, such as bolt faces that could vary by .002 from side to side. Not necessarily a disaster in and of itself, but scary when tolerances begin to get stacked.

With having made close to 10k LBC barrels, they've seen very few problems with Type 1 bolts and don't see any real upside to AA coming out with the Type 2 given the confusion it created since the AR market already had an effective solution. (I'm not starting a debate here - just passing along the view from a respected barrel maker that decided to stop making barrels headspaced to Type 2)

I asked if they would do twist rates that aren't on their website and the short answer is maybe. But the one takeaway was that their 3 groove rifling can have a hard time gripping when long bullets start getting pushed fast at high twist rates. Made me start to wonder if this is one of the problems with the Valkyrie - Sierra says 1:7 isn't fast enough for the 95s, but the barrel makers haven't jumped to embrace 1:6.5 (aside from ARPs run which was a failure). Also makes me wonder if that's why my McGowen 1:7 6mm Grrrr barrel didn't really show promising accuracy (other than the fact that it was a hack job)

Bill Alexander introduced the .136" face depth on the .50 Beowulf after doing a lot of research, which included the Colt 7.62x39 program.

Extractor lip geometry and material thickness is what gets you with the thicker and wider rim.

There is no Type I or Type II relevant to the whole industry. There are bolts that were engineered around the cartridge, and bolts that were engineered around convenience for the after-market, not fully understanding all the details of what it takes to make the whole thing work.

Barrel makers specialize in making barrels.

Firearms manufacturers specialize in sourcing all the components after RDT&Eing their overall design, and holding component suppliers to their standard as part of the TQM process. The firearm manufacturer is the one responsible for whether or not the extractor holds up, not the barrel maker. Same for bolts, springs, carriers, gas keys, gas blocks, tubes, fire control parts, etc.

What I've come to learn is that there are some very gifted people in this industry within their own discipline, but once they step even a little bit outside of their expertise and into another component or process on the gun, they are underwater really quick.

Even within the barrel-making process, that is true. Some places can drill a nice hole and rifle it, lap it, but the moment you ask them to finish profile, thread, attach an extension to it, you get a monstrous abortion sometimes.

The same goes for bolts and extractors. I will rarely place much value in what a barrel maker has to say about components they don't make, other than usual observations about quality and characteristics from different shops they've seen. It doesn't mean I'm trashing their reputation or hating on them, just putting into context where expertise should be recognized.

If I'm a home-builder, I'm not going to ask the plumbers how to do my foundation. The plumbing and drainage will certainly be taken into consideration when pouring the foundation, but the plumber won't be doing the job.

[LRRPF52]

Also, if someone is saying that ".264 LBC" standard is .125", they are left having to explain why the originator of the .264 LBC-AR (the name for Les Baer's chamber) uses .136" Grendel bolts, and has done so before anyone else attempted to chamber in ".264 LBC".

Someone who seemed to have connections with BHW stated on AR15.com that they never have had problems with extractors breaking on the .125" bolts.

Right after that, one of their customers posted a picture of his broken extractor with the .125" face depth.

Even the guys running LMT enhanced AerMet 7.62x39 bolts were breaking extractors on the lobster tail extractor, and it was after 1200-1300 rounds. The LMT AerMet bolts are probably the toughest AR15 bolt for this case head diameter out there. There just isn't enough extractor lip to fit in the spaces and necessary mechanical articulation given the AR15 bolt dimensions, unless you take the face back and allow more lip material on the extractor.

What you'll see with 7.62x39 in terms of real stress testing is those who have registered machine-gun lowers that like to blast a lot of full auto.

They go through x39 bolts regularly, and pop in a new one when they break.

The LMT gave them the option to have a bolt that wouldn't shear lugs or snap at the cam pin hole, but alas...the extractor breaks.

[NugginFutz]

Thanks for posting these pics!
Very informative. It's hard to predict where a case will stretch when it is fired in an oversize chamber. Yours is what I would guess to be the less dangerous result?

FWI understand, the firing pin usually pushes the case forward in the chamber until the shoulder hits, so when the case expands the main body is held by the chamber walls and the base has to stretch backward to take up the slack. This can lead to a catastrophic case head separation.

Johnny's Reloading Bench switched out a Saturn barrel for a Faxon and the fired brass length difference was .010". The sized reloads made for the Saturn would not even chamber in the Faxon. He rants about it in this video at about the 15 minute mark: https://www.youtube.com/watch?v=1Ecj...lh4cjTRb-JJmto
The funny thing to me is that his Saturn brass looks to be within spec at 1.224" while the Faxon brass measures a little short at 1.214".

It was for this reason that I kept my fired brass separated. The BHW brass is .004 longer than the Larue. Not as severe as the .010" difference between JRB's two barrels, but enough to make me notice.

With mixed brass, I would have to choose a compromise on the shoulder setback. If I were to setup the dies to bump the shoulders .003" for the BHW, the brass would be on the long side in the Larue. On the other hand, setting up the dies to bump the shoulders for the Larue would tend to overwork the brass fired in the BHW.

The working solution has been to setup the sizing die for each rifle's fired brass, and keep the brass separated throughout the life cycle of the ammunition.

However - with the new found abundance of cheap loaded ammunition with quality brass, the point may be moot. Brass life may have become a little less critical, given the introduction of the American Gunner ammunition.

[Randy99CL]

To quote Johnny at JRB talking about the type 1 and 2 bolts: "I'm aggravated that the market for a really great cartridge has been confused and muddied and made to be ridiculous."

[grayfox]

It was for this reason that I kept my fired brass separated. The BHW brass is .004 longer than the Larue. Not as severe as the .010" difference between JRB's two barrels, but enough to make me notice.

With mixed brass, I would have to choose a compromise on the shoulder setback. If I were to setup the dies to bump the shoulders .003" for the BHW, the brass would be on the long side in the Larue. On the other hand, setting up the dies to bump the shoulders for the Larue would tend to overwork the brass fired in the BHW.

The working solution has been to setup the sizing die for each rifle's fired brass, and keep the brass separated throughout the life cycle of the ammunition.

However - with the new found abundance of cheap loaded ammunition with quality brass, the point may be moot. Brass life may have become a little less critical, given the introduction of the American Gunner ammunition.

This was the battle I was having with my 18"-Arp, the fired brass was too long for any other chamber so I was doing 2 dies and 2 sets of brass for a while. It happened to be an LBC-style but he used his own name for it... bottom line was it stretched new brass out to the 1.225/6 (new Hornady is more like 1.209 at the datum point) and I had to resize such that it was too long for my other, more (what I would call) normal chambers. Didn't like having to stretch brass like that out of the box. Running 2 sets wasn't really getting me any bang for the buck either, so I sold it to a guy who doesn't reload and doesn't worry about brass lengths.

[rabiddawg]

to quote johnny at jrb talking about the type 1 and 2 bolts: "i'm aggravated that the market for a really great cartridge has been confused and muddied and made to be ridiculous."

exactly!

[bj139]

30-06 rim thickness = .044"
6.5 Grendel rim thickness = .057"
Those Russians make thick rims.

[StoneHendge]

Well, we can throw some instrument error/variation into the equation. Measured 5 virgin Hornady cases with 0.350 collet. Results on left are from the shiny red Hornady Digital Caliper. Results in the right are from an ADT-8657 from NAPA.

1.2085. 1.2075
1.2085. 1.2070
1.2090. 1.2070
1.2095. 1.2080
1.2085. 1.2075

The quandary is which to trust more. The caliper from the company that sold me a digital scale that never worked (it would simply run from 0 gr to 15 gr then back to zero, rinse and repeat), or the chain that's living off its reputation and who sold me a hecho en mecho alternator for an E350 that lasted 3 months and a hecho en mecho starter for a 96 Tacoma that lasted less than 3 years (anyone whose ever replaced a starter on a gen 1Taco will feel my pain in that one!) I'll probably go with the ATD-8657 because it sounds more scientific.

Then there is of course the question of instrument variation in the collet. We can all guess where the factory those come from is..........

[Mad Charlie]

The Hornady tool is only a comparator, not meant for absolute measurement. It is good to have a headspace guage to zero from, (a standard) that is what I do with my .308's.
As long as you are using the same calipers, and same bushing, you should get very usable dimensions. Also depends on how consistent your "touch" is, but as long as one doesn't try to use calipers for a monkey wrench they should be within .001-.002. Won't get much better with calipers.

[StoneHendge]

The Hornady tool is only a comparator, not meant for absolute measurement. It is good to have a headspace guage to zero from, (a standard) that is what I do with my .308's.
As long as you are using the same calipers, and same bushing, you should get very usable dimensions. Also depends on how consistent your "touch" is, but as long as one doesn't try to use calipers for a monkey wrench they should be within .001-.002. Won't get much better with calipers.

Yeah, but the comparison to SAAMI spec is an important one since I'm on the fringe (I don't care about LBC spec - the 1.225 was probably for legal reasons, an inside joke or a combination thereof). Having the NAPA caliper give me a lower reading made me feel better - and that caliper gives me a much "firmer" reading. I'm hoping to get a few rounds through it Monday with the GB bolt, my JP bolt and my old bolt that Midway sold with the Stoner/Satern barrel. My guess is the JP will pull it in .001 or 0.002 and that the headspace is a few thousandths inside spec. I'll just be using 95 gr VMax's I had lying around loaded light. Then I can start convincing myself that the 1.230 outside spec dimension leaves room for tolerance stacking instrument error on top of that. I might be being a bit anal, but it's probably a common side effect from having a barrel blow up in one's face.

[grayfox]

SH, I'd still be leery because regardless of the headspace tool you're going from 1.2090 give or take to, what, 1.230, or?
That's a brass stretch of 0.021... whereas the ones I'm used to (and ones I now keep) are 10 thous or less.

With my 18" Arp brass went from the 1.209 (Hornady comparator) to 1.225/6 -- you're going even further. I didn't like that stretch, not one bit.
Just sayin'.

[StoneHendge]

GF, the virgin brass is for my 243. I'm using brass that was from my 1.225 Stoner/Satern barrel for this barrel with a sprinkle of 1.220 JP thrown in. It's 2 lots that came from factory and about 40% has been through the wringer 6 times and it's holding up fine. An in spec barrel is in spec. Ones gotta have faith that the brass makers who are selling out of spec brass/ammo account for the potential stretch to spec, likely along with room for error with tolerance stacking.

[Mad Charlie]

http://www.redding-reloading.com/online-catalog/37-instant-indicator-headspace-and-bullet-comparator

I don't know if you know about these or not, and I see that our Grendel's aren't listed, but maybe a call to Redding will help. There could be a possibility that one of the other 6.5's may "cross over", or they will make whatever it needs to work with the Grendel. I do not have one of these, and have never used one, but the principle looks sound.

When it comes to absolute measurement, I will take a GOOD travel indicator over any set of calipers any day. Calipers are not considered to be precision measuring instruments in the world of machining, being generally used for low tolerance "quick and dirty" measuring, but for most handloading purposes are considered adequate. The experience I have gained from over 40 years of production and job shop machining makes me dislike digital calipers. I much prefer dial calipers'
or if my eyes could still see, plain old vernier calipers.

Like others in this thread, I have had the issue of "short brass in long chambers". When I built my Satern barreled rifle I measured factory Lapua cases at 1.205 with
the Hornady tool and fired cases at 1.220. I thought "holy crap, this can't be right". I thought I got a bad bbl. or mixed up bolt. I have since learned that 1.220 is supposed to be min. spec. and the chamber is OK. Then there is my AA chamber, fired cases come out 1.214. So I have been keeping fired brass segregated and sizing accordingly. I checked every case fired in the Satern chamber with a feeler wire for a while without finding any incipient separation issues, so now I just bump the shoulders back .003-.005 and call it good. I will be calling Pacific or Forster, since my dies are Forster, about a headspace guage to use for a standard to set up the Hornady tool, as I feel that the shorter the travel from zero with calipers, the better the accuracy, comparatively speaking. Another thing I do when measuring is turn the case 90 degrees and measure twice, sometimes case heads don't come out square and extractor burrs get in the way, if the measurement stays within .001 I call it good. I also like to de-prime with a de-priming tool before measuring fired cases.

Yeah,,I can see why you want to be extra careful with your handloading!