Bill Alexander
Unregistered
elkbow Wrote:And there is a reason why other manufacturers are using the 7.62x39 bolt, it has less recess, allowing for greater pressures than the Grendel's 50,000 psi limit...
This is some what incorrect, but not the first time I have seen such internet wisdom repeated. The change of 0.011" of depth of the bolt recess (3 sheets of writing paper) has significantly less bearing upon the life of the bolt than surface finish, let alone the geometry. What it will adversely effect is the extractor strength. The Grendel bolt design is not a simple opening up of the 5.56 bolt as typified by what is now referred to as the 7.62x39 bolt. The bolt is a balance of the extractor and the bolt geometry with the steel type used and the heat treatment. The pressure limit was set to 50,000 psi to provide a wide margin of error and also allow for an exceptional cyclic life. It also balances the recoil generated with weapon controllability in a platform weight conducive to the small platform the cartridge was intended to fit.
There have been a number of variations on chamber supposed to "improve" the Grendel. Most notable is the LBC which is particularly amusing as it was a design tested in prototyping and then dumped, that the reamer maker just regurgitated. The typical improvement may prove fruitful for the individual but it may also create frustration. Loading data may or may not be applicable. The Grendel chamber proper was set up to allow it to be easy to achieve good accuracy in bulk production with only a little attention to the details. It is tolerant to both long ogive target bullets, short flat base varmint loads and long but blunter hunting loadings. The typical set up with a half decent barrel will usually outshoot its owner.
As to case life this seems to be another internet rumor. Unless the shooter uses an appropriate bushing type die set, 0.005" on diameter or 0.003" will have no effect at all. The sizing die will move the brass way beyond this both below and then back up as the sizing button passes. What the "tight" neck does without adequate insight is to relocate the origin for the shoulder/neck radius to a possible bind condition as the various manufacturers produce differing batches.
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elkbow Wrote:yes it will work with the standard extension, their bolt is a 7.62x39 bolt, which works with their barrel headspacing, will not work with the AA 6.5 grendel chamber, but should work with others like the .264 LBC, CCS, etc.
Not necessarily the case. The .264 LBC uses a Grendel bolt, as does the 6.5 CSS, as I understand it. The 6.5 CSS, at one time, could be ordered to be headspaced with either bolt, and you might still be able to do so, but from what I've read, the standard they use is now the Grendel bolt.
In a custom situation, I'm sure any of the chambers COULD be made to work with whatever bolt you want, but the .264 LBC, the 6.5 CSS, whatever Satern is calling their version of the chamber, and others are headspaced to fit the Grendel bolt as a rule.
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt
Would there be any benifit from setiing up a barrel with an ARP "super bolt" instead of a Grendel bolt.
cjgemm Wrote:Would there be any benifit from setiing up a barrel with an ARP "super bolt" instead of a Grendel bolt.
It depends on if the extra mass can make up for the sulfur content in the 9130. Armalite experienced this problem when the sulfur in their barrel liners produced weak veins upon being heated and subjected to pressure during the initial trials of the AR10, and barrels burst.
I would want a Superbolt made from the Milspec steel for an M4 bolt, since I know of some 9130 bolts that have broken. They broke because of an upper that had an extension with a face that wasn't true, and was torquing the lugs unevenly. I've read from others claiming to be metallurgists that Carpenter 158 is the steel used in military contract bolts, heat-treated to a certain standard, but that Carpenter 158 is difficult to obtain in small volumes. I don't know because I'm not a metallurgist, or small shop who orders steel stock.
I guess I'll just stick to the bolt that Satern uses then.
bwaites Wrote:Not necessarily the case. The .264 LBC uses a Grendel bolt, as does the 6.5 CSS, as I understand it. The 6.5 CSS, at one time, could be ordered to be headspaced with either bolt, and you might still be able to do so, but from what I've read, the standard they use is now the Grendel bolt.
In a custom situation, I'm sure any of the chambers COULD be made to work with whatever bolt you want, but the .264 LBC, the 6.5 CSS, whatever Satern is calling their version of the chamber, and others are headspaced to fit the Grendel bolt as a rule.
from what I read on the .264 LBC is that it does not use a standard Grendel bolt, but would have to verify that with them as I don't have one to measure, maybe someone that has one could measure the bolt recess as a start to figure out if it is the same. I know on the ARP superbolt, shooting from the 7.62x39, he has never had to replace one for failure, according to what he wrote, again as Bill said 'internet wisdom' or whatever, just what he reported. On the CSS bolt, again only repeating what I read the and the reason I wrote 'should'. I'm far from an expert on the Grendel, I own two, both AA barrels, one complete upper from AA (which experienced a broken bolt with their ammo) and one I built. About to give the ARP setup a test and see how it does and see about OAL with the 1.5 degree throat and their superbolt, I believe it will allow for more accuracy from a button rifled barrel and less sensitive on loads as far as pressure is concerned from my experience and others posted on this site.
cjgemm Wrote:I guess I'll just stick to the bolt that Satern uses then.
Best to buy the correct bolt with the barrel as it is headspace for that barrel, seems there are so many variations and explanations for variation is is best to buy a bolt/barrel combo and not to swap between unless you varify it will work. But I will have a AA Grendel, ARP version and a Satern version so i'll take some pics when I have all to show any differences and provide some measurements.
I have an order with Satern for a barrel. I assume they use a Grendel bolt. Was just curious what advantage, if any the "super bolt" would offer.
cjgemm Wrote:I have an order with Satern for a barrel. I assume they use a Grendel bolt. Was just curious what advantage, if any the "super bolt" would offer.
Yea if you bought a Satern barrel with the 6.5 Grendel chamber, is definitely a Grendel bolt, just remember they switched to the .264 LBC a few months back, and according to some the bolts are the same as the Grendel and others say they are not, so hopefully someone will post some measurements.. The superbolt made by ARP will fit their chamber, it is a 7.62x39 bolt which I believe has better properties than others bolts, sure I'll be slammed for that statement also. You can do a search on the web and it will show design differences, i'll be posting up some photo's in the future, with measurements, etc. of the Grendels and variants I have. I do wish they were all the same, however even other chambers, bolts etc have evolved from the original specs like the 6.8 from SPC I to SPC II, etc. Things can always be improved upon in my opinion. Forums are a good tool for experiences and feedback for improved design, even if they are controversial in nature, we learn by others experiences, whether positive or negative. I like that manufacturers come on here and other forums and give their explanations, design criteria and experiences.
Bill Alexander
Unregistered
In this forum we do not slam anyone for a statement but do try to correct if there is an error or ask for more data if there is new information available.
BHW barrels are chambered in .264 LBC and they, for whatever reason, have a type 1 chamber and a type 2 chamber. Type 1 uses the 7.62x39 bolt and type 2 uses a Grendel bolt. I bought both bolts to see the difference and the 7.62x39 bolt would not lock into the battery, so I ordered an AA bolt and it is correctly head spaced/recessed and functions great. BTW I am not bashing BHW barrels at all, as I really love mine and I'm getting excellent accuracy and have zero function problems with all types of factory ammo. I just recently got my dies and am just starting to reload for it, so I look forward to my findings and results.
Bill, could you weigh-in on the benefits of Carpenter 158, 8620, and 9130, and maybe others that you know about that would be the best alloys for the AR15/Grendel bolt? I haven't met many people that can discuss the details from an engineering & metallurgy perspective like you, since there are so many machinists out there with different opinions, but not enough engineers who can explain this in the firearms community.
elkbow Wrote:65man, there are really only two bolts out there, the 6.5 Grendel bolt and the 7.62x39 bolt. Only the bolts are not compatible, the factory ammo out there will really shoot in any of the barrels. Because AA had the name copyrighted, people made different variations, usually with a different neck and throat to call it a different name, but the ammo would shoot in any of them.
The ARP bolt is a 7.62 bolt, one of the best in the industry, thats why he used it and only changed the chambering to optimize according to him and I think he did, this gives people the choice to get a good barrel, good price, that will shoot anything reliably and give handloaders the chance to optimize for his barrel, I have one on order and will see what it does, but my experience with his barrels have been great. I do like cut rifled barrels, but this will be a button rifled barrel to keep the costs down, but my other ARP's shoot .5 MOA or better
And there is a reason why other manufacturers are using the 7.62x39 bolt, it has less recess, allowing for greater pressures than the Grendel's 50,000 psi limit...
I have not yet bought a grendel, so if i buy a grendel upper, do i have to check and see if it has the 7.62x39 bolt or the grendel bolt? whats the difference? if i understand correctly it doesn't make a difference? they all shoot the same ammo? also if the 7.62x39 can handle more pressure, my guess is that people would want it because you could load hotter right?
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If you buy a GRENDEL upper, you have no concerns. Its when you buy one of the various other chamberings that you have to be concerned.
The easiest way to make sure you have the right bolt is to make sure you buy a complete upper or a barrel/bolt combo that have been headspaced properly together.
The 7.62x39 bolts do NOT allow hotter loadings. DO NOT LOAD THE GRENDEL above recommended maximums or bad things will happen!
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt
I have had a number of dealings with Ar15Performance. Their customer service is absoutely fabulous, and on par with what I have received at Alexander Arms. I would recommend either company without any hesitation. Both companies have provided me with service that I know cost them far more to complete than what they ended up charging me.
Both companies said the same thing: In essence that good customer service relations have long term benefits that far outweigh charging people a great deal of money in the beginning. People tend to return to places where they got good service. In both cases, it has worked on me.
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If one makes enough changes to the standard AR platform, even a "Grendelized" AR platform as standardized by AA, then it almost becomes a new weapon. To my mind, it's like an experimental chambering in, oh, an FN SCAR or an AK or a SIG551 in 65G. And I'm all for experimentation and innovation, the 6.5 Grendel itself being a premier example of thinking outside the box in order maximize performance within the box, so to speak.
So, having said that, more power to 'em. I hope Elkbow will keep us updated on his project. (Just don't try anything crazy, man! Be VERY careful if you're trying to squeeze 6.5 Creedmoor performance from the 6.5 Grendel case, is all I'm saying!)
John
I just disgusted that another company cranked out another variant (that isn't SAAMI certified) and throws the Grendel name on it and shells them out to the comsumer telling them it better or improved. It just throws out more crap for a person to swim through when they want to buy a Grendel or Grendel parts. Then, thier stuff may or may not function with parts made to the Grendel spec. That's what really p's me off.
I looked at thier website and they basically call it a Grendel and a .264 lbc ...... you can't have it both ways. It's just another knockoff.
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Mutt makes a great point. These companies can do what they want, but if it's NOT a 6.5 Grendel, according to AA's SAAMI specs, then DON'T call it a Grendel. Isn't that basic truth-in-advertising?
John
well can always improve upon things, thats the way I look at it....
i still believe the less recessed bolt, stronger bolt, 1 or 1.5 degree throat is a better choice, just my opinion, as we have seen changed in other calibers....and whether you agree or don't agree with other manufacturers is always your right, we're all going to form our opinions mostly from experience. As for the ARP bolt/barrel, looking forward to giving it a try, I'm always open to new and improved and open minded. Everything they have built has worked, they query the forums for inputs, and try it before offering it. And if you haven't read the news, he has the gun built already, been testing loads and accuracy. And he hasn't come up with a name other than listing it as the 6.5G/.264 LBC, why because those are recognized names and similar to the chamber. I'm not dedicated to any manufacturer, just like in trucks, owned a Ford F250 Powerstroke 7.3L, then went to a Dodge Ram Cummins 5.9L, in my opinion interior and chassis were better on the Ford, the Cummins is a better motor, both had weak transmissions. So my ultimate truck, Ford body/frame suspension, Cummins motor, Chevy Allison transmission.
HANKA Wrote:If one makes enough changes to the standard AR platform, even a "Grendelized" AR platform as standardized by AA, then it almost becomes a new weapon. To my mind, it's like an experimental chambering in, oh, an FN SCAR or an AK or a SIG551 in 65G. And I'm all for experimentation and innovation, the 6.5 Grendel itself being a premier example of thinking outside the box in order maximize performance within the box, so to speak.
So, having said that, more power to 'em. I hope Elkbow will keep us updated on his project. (Just don't try anything crazy, man! Be VERY careful if you're trying to squeeze 6.5 Creedmoor performance from the 6.5 Grendel case, is all I'm saying!)
John
Don't worry John, I've been shooting for 45 years, reloading for 30, I'm open to what things will and will not do. I know I won't be hitting Creedmoor specs, why, I have a DPMS 6.5 Creedmoor that was one of their team members that has a few tweeks. Can't say I like carrying it around.
There are several other members on here going to give it a try, so I think there should be some good reports.
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