Headspace????

pyscodog

Active member
I found a Grendel barrel that I'm interested in. But I have questions.

The gas block should work off mine but it needs a Gen II bolt. Gen II bolts measure .136 deep off the front of the bolt to the bottom. Mine is .145, a little deeper for some reason. Is this going to cause headspace issues? If yes, can a smith fix it? Or do I need a different bolt? I know about bolt rifles and headspace, not so much with AR's.
 
Originally Posted By: pyscodogI found a Grendel barrel that I'm interested in. But I have questions.

The gas block should work off mine but it needs a Gen II bolt. Gen II bolts measure .136 deep off the front of the bolt to the bottom. Mine is .145, a little deeper for some reason.
Is this going to cause headspace issues? If yes, can a smith fix it? Or do I need a different bolt? I know about bolt rifles and headspace, not so much with AR's.
You would need a different bolt if yours doesn't check out when you put a headspace gauge to it.
Because of the way an AR barrel mounts to the receiver, headspace is set when the barrel extension is installed on the barrel.
Then it's Legos after that.
 
I found a really good deal on a new unfired Saturn barrel and they come with a bolt from Saturn. This one doesn't. Mines a cheap rifle that a local store in Tulsa builds with their logo on the lower. Decent rifle but doubt the parts are high quality as their rifles aren't exactly high end. I'm sure mil-spec at best.
 
I just looked and for a few dollars more I can order direct from Saturn and it comes with a bolt. This will be my best bet.
 
Originally Posted By: pyscodogI just looked and for a few dollars more I can order direct from Saturn and it comes with a bolt. This will be my best bet.
Like.
If it's that 20" for $279, that's a good deal.
 
Not only have I spelled it wrong, some of what I read was wrong also. LOL! Satern sells two different barrels. They offer their barrel which is cut rifling and a Liberty barrel that is button pulled. The Satern barrel is $500+ and the Liberty is $279 both includes a bolt. A few reviews on the Liberty barrel puts it in the ER Shaw category while the Satern falls along the line of Bartlien or Krieger. Some said accuracy for the Liberty barrels was in the 1-1 1/2 inch range and the Satern much better. I think with a little more load work the barrel I have will do better than 1 1/2 inchs. Its hovering around there now. My problem is I don't see inch and a half as groups, more like patterns. I guess that's why I've never been an avid AR guy.
 
Having talked with Bill Alexander about his Grendel at the SHOT show, I might be bale to shed some light on this. By the way, he was very generous with his time and information to a young gun builder.

First of all, there is no such thing as Grendel I and Grendel II. When Bill Alexander submitted his print to SAAMI he had every intent of releasing the print to the public when SAAMI approved it. Somehow, that original print got out to the public. But the print had an error. When Mr. Alexander realized the error, he resubmitted the corrected print. But it was too late to put the genie back in the bottle. Now true to his word, Mr. Alexander did release the print to the public but it was too late.

Many of the manufacturers who got their hands on the first print, found that they had to use a 7.62x39mm bolt to work on their barrels. When you use an actual Grendel bolt, it is common to shear the lugs off of the bolt. This appears to be because the extra headspace allows the bolt to move rearward, gaining momentum and shearing off the lugs.

There is a go-no-go gauge that you can use to see what dimensions your barrel has been cut to. You can also use a cartridge and a disassembled bolt to see if you have a mix and match situation. Take your bolt down, pulling out the extractor and ejector, and drop a cartridge into the chamber and see if your bolt will drop in and that you are able to close it with a bit of drag. If it will not close you have the wrong combo. If it will close and rattle, you have the wrong combo.

So, as many of the other guys have previously stated, you might be best off buying the bolt with the barrel.

Hope the info helps.
 
Originally Posted By: pyscodogNot only have I spelled it wrong, some of what I read was wrong also. LOL! Satern sells two different barrels. They offer their barrel which is cut rifling and a Liberty barrel that is button pulled. The Satern barrel is $500+ and the Liberty is $279 both includes a bolt. A few reviews on the Liberty barrel puts it in the ER Shaw category while the Satern falls along the line of Bartlien or Krieger. Some said accuracy for the Liberty barrels was in the 1-1 1/2 inch range and the Satern much better. I think with a little more load work the barrel I have will do better than 1 1/2 inchs. Its hovering around there now. My problem is I don't see inch and a half as groups, more like patterns. I guess that's why I've never been an avid AR guy.
It is not very hard to get an AR with champagne accuracy on a beer budget.
Just be wise about what barrelmaker to go with.
1) Find an AR barrelmaker with an accuracy guarantee like Ballistic Advantage.
2) Find a seller with good product and a no-bull return policy like Brownells.

AR's are not AK's
They can be made to be very accurate.
 
Originally Posted By: SnowmanMoHaving talked with Bill Alexander about his Grendel at the SHOT show, I might be bale to shed some light on this. By the way, he was very generous with his time and information to a young gun builder.

First of all, there is no such thing as Grendel I and Grendel II. When Bill Alexander submitted his print to SAAMI he had every intent of releasing the print to the public when SAAMI approved it. Somehow, that original print got out to the public. But the print had an error. When Mr. Alexander realized the error, he resubmitted the corrected print. But it was too late to put the genie back in the bottle. Now true to his word, Mr. Alexander did release the print to the public but it was too late.

Many of the manufacturers who got their hands on the first print, found that they had to use a 7.62x39mm bolt to work on their barrels. When you use an actual Grendel bolt, it is common to shear the lugs off of the bolt. This appears to be because the extra headspace allows the bolt to move rearward, gaining momentum and shearing off the lugs.

There is a go-no-go gauge that you can use to see what dimensions your barrel has been cut to. You can also use a cartridge and a disassembled bolt to see if you have a mix and match situation. Take your bolt down, pulling out the extractor and ejector, and drop a cartridge into the chamber and see if your bolt will drop in and that you are able to close it with a bit of drag. If it will not close you have the wrong combo. If it will close and rattle, you have the wrong combo.

So, as many of the other guys have previously stated, you might be best off buying the bolt with the barrel.

Hope the info helps.
There is no doubt that Bill Alexander is the authority on all things Grendel.
However, there may not "technically" be a Grendel I and Grendel II, there is a Type I bolt and a type II bolt in Grendel's history.

A Type I bolt, also known as the 7.62×39 bolt, has a bolt face depth of . 125” and is used with some Grendel variants. The Type II bolt is the bolt originally designed for the 6.5 Grendel and has a bolt face depth of . 136”
 
I've had a very accurate AR. I've also had the not so accurate AR as well. That is what turned me into a "not much of an AR guy". If it won't shoot, it won't be around long. That's the reason I hate buying a barrel and bolt to end up with what I already have.
 
Originally Posted By: DirectDriveOriginally Posted By: SnowmanMoHaving talked with Bill Alexander about his Grendel at the SHOT show, I might be bale to shed some light on this. By the way, he was very generous with his time and information to a young gun builder.

First of all, there is no such thing as Grendel I and Grendel II. When Bill Alexander submitted his print to SAAMI he had every intent of releasing the print to the public when SAAMI approved it. Somehow, that original print got out to the public. But the print had an error. When Mr. Alexander realized the error, he resubmitted the corrected print. But it was too late to put the genie back in the bottle. Now true to his word, Mr. Alexander did release the print to the public but it was too late.

Many of the manufacturers who got their hands on the first print, found that they had to use a 7.62x39mm bolt to work on their barrels. When you use an actual Grendel bolt, it is common to shear the lugs off of the bolt. This appears to be because the extra headspace allows the bolt to move rearward, gaining momentum and shearing off the lugs.

There is a go-no-go gauge that you can use to see what dimensions your barrel has been cut to. You can also use a cartridge and a disassembled bolt to see if you have a mix and match situation. Take your bolt down, pulling out the extractor and ejector, and drop a cartridge into the chamber and see if your bolt will drop in and that you are able to close it with a bit of drag. If it will not close you have the wrong combo. If it will close and rattle, you have the wrong combo.

So, as many of the other guys have previously stated, you might be best off buying the bolt with the barrel.

Hope the info helps.
There is no doubt that Bill Alexander is the authority on all things Grendel.
However, there may not "technically" be a Grendel I and Grendel II, there is a Type I bolt and a type II bolt in Grendel's history.

A Type I bolt, also known as the 7.62×39 bolt, has a bolt face depth of . 125” and is used with some Grendel variants. The Type II bolt is the bolt originally designed for the 6.5 Grendel and has a bolt face depth of . 136”



I measured my bolt face depth after talking to the guy that has the Satern barrels for sale. Mine measured .145. That has me really confused and he suggested buying a new bolt as well.
 
Originally Posted By: pyscodogOriginally Posted By: DirectDriveOriginally Posted By: SnowmanMoHaving talked with Bill Alexander about his Grendel at the SHOT show, I might be bale to shed some light on this. By the way, he was very generous with his time and information to a young gun builder.

First of all, there is no such thing as Grendel I and Grendel II. When Bill Alexander submitted his print to SAAMI he had every intent of releasing the print to the public when SAAMI approved it. Somehow, that original print got out to the public. But the print had an error. When Mr. Alexander realized the error, he resubmitted the corrected print. But it was too late to put the genie back in the bottle. Now true to his word, Mr. Alexander did release the print to the public but it was too late.

Many of the manufacturers who got their hands on the first print, found that they had to use a 7.62x39mm bolt to work on their barrels. When you use an actual Grendel bolt, it is common to shear the lugs off of the bolt. This appears to be because the extra headspace allows the bolt to move rearward, gaining momentum and shearing off the lugs.

There is a go-no-go gauge that you can use to see what dimensions your barrel has been cut to. You can also use a cartridge and a disassembled bolt to see if you have a mix and match situation. Take your bolt down, pulling out the extractor and ejector, and drop a cartridge into the chamber and see if your bolt will drop in and that you are able to close it with a bit of drag. If it will not close you have the wrong combo. If it will close and rattle, you have the wrong combo.

So, as many of the other guys have previously stated, you might be best off buying the bolt with the barrel.

Hope the info helps.
There is no doubt that Bill Alexander is the authority on all things Grendel.
However, there may not "technically" be a Grendel I and Grendel II, there is a Type I bolt and a type II bolt in Grendel's history.

A Type I bolt, also known as the 7.62×39 bolt, has a bolt face depth of . 125” and is used with some Grendel variants. The Type II bolt is the bolt originally designed for the 6.5 Grendel and has a bolt face depth of . 136”



I measured my bolt face depth after talking to the guy that has the Satern barrels for sale. Mine measured .145. That has me really confused and he suggested buying a new bolt as well.
The final say would be checking your bolt with a Grendel headspace gauge.
 
.125,.136 .145 Face depth? Lets say you are screwing a barrel extension onto a Mil-Spec barrel shank, you will have .xx clearance between the end of the barrel and the front of the locking lugs. Now comes the dept of the bolt face. So, now you have two factors to consider, before going further. First is the dept of the face on the bolt in hand and the clearance between the bolt and barrel. The numbers will dictate the amount of case that is Unsupported outside the chamber. I never mess with anything more than .125, your mileage may vary, and your cases may swell more than mine at the base.
 
Originally Posted By: Icedtea.125,.136 .145 Face depth? Lets say you are screwing a barrel extension onto a Mil-Spec barrel shank, you will have .xx clearance between the end of the barrel and the front of the locking lugs. Now comes the dept of the bolt face. So, now you have two factors to consider, before going further. First is the dept of the face on the bolt in hand and the clearance between the bolt and barrel. The numbers will dictate the amount of case that is Unsupported outside the chamber. I never mess with anything more than .125, your mileage may vary, and your cases may swell more than mine at the base.
.125 Grendel ?
You're in the minority, then.
The .136 bolt was developed by Colt for their 7.62x39 to allow for a stronger extractor. (see drawing in link)
Bill A. followed those bolt specs for Grendel.
https://www.65grendel.com/forum/showthre...ll=1#post182217
 
Originally Posted By: DirectDriveOriginally Posted By: Icedtea.125,.136 .145 Face depth? Lets say you are screwing a barrel extension onto a Mil-Spec barrel shank, you will have .xx clearance between the end of the barrel and the front of the locking lugs. Now comes the dept of the bolt face. So, now you have two factors to consider, before going further. First is the dept of the face on the bolt in hand and the clearance between the bolt and barrel. The numbers will dictate the amount of case that is Unsupported outside the chamber. I never mess with anything more than .125, your mileage may vary, and your cases may swell more than mine at the base.
.125 Grendel ?
You're in the minority, then.
The .136 bolt was developed by Colt for their 7.62x39 to allow for a stronger extractor. (see drawing in link)
Bill A. followed those bolt specs for Grendel.
https://www.65grendel.com/forum/showthre...ll=1#post182217

You're right about me being in the minority. But, we did build them before the type II or the MK135 came about without any warranty returns. Colt needed the extra strength as they have a history of over gassing their carriers.
The pictures in the article you posted the link to, are not to scale and do not show a real cartridge to chamber to bolt relation.
 
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7.62x39 Bolts are 0.125"
To make sure, I just measured my Grendel bolts again: 0.136"
If you are in doubt, just buy a new bolt, they are not expensive right now.
 
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