6.5 Grendel ammunition warning

PPU had a recall for their 6.5 Grendel ammo in 2016, as it was causing dangerously high pressure in some rifles. I think ammunition issues like this were more common in the earlier days of 6.5 Grendel as you had Type I and Type II bolts\barrels both on the market and people unintentionally mixed components.

FWIW, I've found the Hornady and Sierra Grendel load data to be pretty conservative. I do use .3gr increments when doing load development with 8208XBR, as it pressure spikes pretty quickly when getting near max load.
 
cr5 said:
Anyone seen this before?
I've read warnings about loading a little lighter than book max for the AR-15 as well but can't remember where I saw that. I'll link it later when I find it. Might explain the broken bolts some people have experience in the Grendel.


https://www.jprifles.com/safety.php?document_id=55
Click to expand...

I would have thought the broken bolts were more a function of the larger case diameter in 6.5G than in 5.56.
 
mileageman said:
I would have thought the broken bolts were more a function of the larger case diameter in 6.5G than in 5.56.
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I'm sure that causes a weakness just like when guys run 7.62x39 in an AR, hot loads would definitely increase the odds of a lug failure.
I'd love to see a non restricted CMMG Mutant in 6.5G with a quality barrel. Would be the best of all worlds if it was built well and affordable.
 
You can not youse a 556 bolt for 6.5 Grendel Alexander made a bolt designed for the Grendel!
 
220 said:
You can not youse a 556 bolt for 6.5 Grendel Alexander made a bolt designed for the Grendel!
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What was meant was that since the rifle was designed for 5.56 and in order to fit the Grendel case into the bolt there isn't a lot of material left around the lugs when it's opened up to fit. No one is taking a 5.56 bolt and putting it on a lathe, but there is only so much material there and it leaves it very thin around the lugs which is probably a leading factor in why these and the x39 AR's have a history of bolt lug failures.
Then factor in that everyone always pushes for maximum velocity and loads on the hotter range of the book charge range and the chances are higher. This is pretty much what the JP warning was saying is that just because it's factory ammo doesn't mean it's safe in your AR. I know from experience that Hornady Superformance is very hot in 6.5 Creedmore, my 6.5CM semi hates that ammo.
 
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cr5 said:
What was meant was that since the rifle was designed for 5.56 and in order to fit the Grendel case into it there isn't a lot of material left around the lugs when it's opened up to fit. No one is taking a 5.56 bolt and putting it on a lathe, but there is only so much material there and it leaves it very thin around the lugs which is probably a leading factor in why these and the x39 AR's have a history of bolt lug failures.
Then factor in that everyone always pushes for maximum velocity and loads on the hotter range of the book charge range and the chances are higher. This is pretty much what the JP warning was saying is that just because it's factory ammo doesn't mean it's safe in your AR. I know from experience that Hornady Superformance is very hot in 6.5 Creedmore, my 6.5CM semi hates that ammo.
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I ran a 223 bolt opened up to work on the 450 bushmaster and that was fine given its low pressure. There will always be people
who cheap out on the bolt thinking they can get away with it. But really a super bolt like ar performance makes or equivalent alloy should be used.

I recently had a discussion about bolts when I was shopping around for a new NR semi in rem 30 AR and after some discussion it was a no go from the manufacturer unless a bolt could be purchased rather than needing to be manufactured and tested in house.

I think we as Canadians are sol for actual manufacturers who will build and guarantee their own parts.
 
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Brian46 said:
I ran a 223 bolt opened up to work on the 450 bushmaster and that was fine given its low pressure. There will always bee people on the bolt thinking they can get away with it, and those that don't use an adequate alloy on a custom bolt.

I recently had a discussion about bolts when I was shopping around for a new NR semi and after some discussion it was a no go from the manufacturer unless a bolt could be purchased rather than needing to be manufactured and tested in house.

I think we as Canadians are sol for actual manufacturers who will build and guarantee their own parts.
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This is where I think a rifle like the CMMG Mutant would be prefect, a mid sized AR with a beefier bolt. Unfortunately the RCMP said that it is a variant somehow so restricted only
 
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cr5 said:
This is where I think a rifle like the CMMG Mutant would be prefect, a mid sized AR with a beefier bolt. Unfortunately they RCMP said that it is a variant somehow so restricted only
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Remington actually did a hybrid first with the R15 in rem 30 AR. There is also the POF revolution. All restricted.

The whole point of keeping everything ar15 sized is to keep weight down. With the right alloys, there is no need for the extra size.
 
Brian46 said:
I also have a 7.62x39 conversion and I bought a bolt built for the round rather than modify a factory 223 one to work.
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Regardless of whether it was built for x39 or 6.5G it still has the same outside dimensions of the 5.56 bolt with the larger opening for the case head. This leaves it thin and weaker. You're right though, with the right materials it could be compensated for and still provide a good service life.

I wonder if they could use a custom barrel extension and bolt rather than just a custom bolt in the original AR-15 extension. As long as the outside dimensions of the extension were the same it would still fit the AR-15 receiver. It would give it the strength is needs without adding a bunch of weight to the rifle.
 
cr5 said:
I wonder if they could use a custom barrel extension and bolt rather than just a custom bolt in the original AR-15 extension. But the barrel extension still had the same exterior dimensions and still fit the AR-15 receiver. It would give it the strength is needs without adding a bunch of weight to the rifle.
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Did NEA not do this with their 7.62x39 barrel extensions and bolts. IIRC the bolt was beefier and had larger lugs and would not fit into a regular Ar15 barrel extension. But the exterior dimensions of the NEA barrel extension were still the same so it fit in a standard upper. I'm not saying the quality was any better, they still had failures. I'm just saying that they tried to accomplish exactly what you're talking about.

The only other option you have with your 6.5 Grendel (if you're concerned about bolt failure) is to buy a JP enterprises 6.5G bolt. I haven't been able to find any reports of failure with them.

ht tps://www.brownells.com/rifle-parts/bolt-parts/bolts/ar-15-m16-6-5-grendel-enhanced-bolt-assembly-prod77850.aspx?avs%7cManufacturer_1=J%2bP%2bENTERPRISES

They're not cheap but it's better than blowing up your gun.
 
cr5 said:
Regardless of whether it was built for x39 or 6.5G it still has the same outside dimensions of the 5.56 bolt with the larger opening for the case head. This leaves it thin and weaker. You're right though, with the right materials it could be compensated for and still provide a good service life.

I wonder if they could use a custom barrel extension and bolt rather than just a custom bolt in the original AR-15 extension. As long as the outside dimensions of the extension were the same it would still fit the AR-15 receiver. It would give it the strength is needs without adding a bunch of weight to the rifle.
Click to expand...

Ar15 performance does exactly that with their bolts and proprietary extension.
 
jiffx2781 said:
Did NEA not do this with their 7.62x39 barrel extensions and bolts. IIRC the bolt was beefier and had larger lugs and would not fit into a regular Ar15 barrel extension. But the exterior dimensions of the NEA barrel extension were still the same so it fit in a standard upper. I'm not saying the quality was any better, they still had failures. I'm just saying that they tried to accomplish exactly what you're talking about.

The only other option you have with your 6.5 Grendel (if you're concerned about bolt failure) is to buy a JP enterprises 6.5G bolt. I haven't been able to find any reports of failure with them.

ht tps://www.brownells.com/rifle-parts/bolt-parts/bolts/ar-15-m16-6-5-grendel-enhanced-bolt-assembly-prod77850.aspx?avs%7cManufacturer_1=J%2bP%2bENTERPRISES

They're not cheap but it's better than blowing up your gun.
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The NEA ones probably failed more because they were made by NEA than because it wasn't a good idea. Lol.
It's too bad they've ruined their reputation with so much garbage in the past. I'm done with thinking they'll ever get it right consistently enough for me to ever give them a chance again.


Brian46 said:
Ar15 performance does exactly that with their bolts and proprietary extension.
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Their prices don't seem that bad, too bad they don't export.
I really like their descriptions and info provided about their products. It's about time a manufacturer actually tells the customer exactly which bolt to buy with the barrel they're buying and warns not to buy a nitrided bolt and why.

They have some really great calibers available for the AR platform. I wonder if we shouldn't try to get a group buy going to save on import costs.
Have you imported any of their stuff before?
 
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cr5 said:
The NEA ones probably failed more because they were made by NEA than because it wasn't a good idea. Lol.
It's too bad they've ruined their reputation with so much garbage in the past. I'm done with thinking they'll ever get it right consistently enough for me to ever give them a chance again.




Their prices don't seem that bad, too bad they don't export.
I really like their descriptions and info provided about their products. It's about time a manufacturer actually tells the customer exactly which bolt to buy with the barrel they're buying and warns not to buy a nitrided bolt and why.

They have some really great calibers available for the AR platform. I wonder if we shouldn't try to get a group buy going to save on import costs.
Have you imported any of their stuff before?
Click to expand...
I have not, but I was considering it back when I was contemplating my first 30ar conversion. I would buy a bolt and extension just to have though for when I build my lightweight 30ar
 
cr5 said:
Anyone seen this before?
I've read warnings about loading a little lighter than book max for the AR-15 as well but can't remember where I saw that. I'll link it later when I find it. Might explain the broken bolts some people have experience in the Grendel.


https://www.jprifles.com/safety.php?document_id=55
Click to expand...

If you google "6.5 Grendel chambers" it is crazy how many variations of variations of chambers there are ( 264 LBC , 6.5CSS , 6.5 Grendel Type 1 and Type 2 ). Even after AA released rights in 2011 and it became a SAMMI cartridge , there are enough differences that you need to make sure you know what you have

As far as bolt breakage, AA designed the system to utilize a .136 bolt face depth ( to ensure extractor had enough meat on it etc ) . Lots of Grendels were and continue to be built with the .125 bolt face depth, which is what a 7.62X39 bolt is . More readily and available bolts . To jump on the 6.5 G craze, manufacturers where taking off the shelf 7.62x39 bolts , which vary in quality. Much of the reported bolt issues are from this style chamber
All the .136 bolts are of high quality such JP , AA ( which is what I have ), Young Mfg

I have broken a DPMS 7.62X39 bolt and just replaced it with a much better LMT bolt which has chugged out at least 3K rounds .

IMO If you do a 6.5G then stick with the original design of the .136 bolt face . This is known as 6.5 Grendel Type II chamber

This post on ARFCOM has good picture showing why the Type II is better option

h ps://www.ar15.com/forums/ar-15/Grendel-type-1-and-type-2-bolts/121-727986/

Lastly, what does not help is the 6.5 Grendel may look cute, but it really has limited case capacity. If you have a Grendel , you are probably shooting relatively long VLD style match bullets such as the Lapua Scenar 123gr

Freaky how far the bullet is in the case to meet the 2.260 COL of AR magazine which takes up lots of case volume. Doesn't take much to get excessive pressure

The bulletin is correct regarding Lapua brass . Completely waste of time and effort forming 7.62X39 cases into Grendel . I also have used Norma and have some Hornady which I haven't used yet
 
TRG-42 said:
If you google "6.5 Grendel chambers" it is crazy how many variations of variations of chambers there are ( 264 LBC , 6.5CSS , 6.5 Grendel Type 1 and Type 2 ). Even after AA released rights in 2011 and it became a SAMMI cartridge , there are enough differences that you need to make sure you know what you have

As far as bolt breakage, AA designed the system to utilize a .136 bolt face depth ( to ensure extractor had enough meat on it etc ) . Lots of Grendels were and continue to be built with the .125 bolt face depth, which is what a 7.62X39 bolt is . More readily and available bolts . To jump on the 6.5 G craze, manufacturers where taking off the shelf 7.62x39 bolts , which vary in quality. Much of the reported bolt issues are from this style chamber
All the .136 bolts are of high quality such JP , AA ( which is what I have ), Young Mfg

I have broken a DPMS 7.62X39 bolt and just replaced it with a much better LMT bolt which has chugged out at least 3K rounds .

IMO If you do a 6.5G then stick with the original design of the .136 bolt face . This is known as 6.5 Grendel Type II chamber

This post on ARFCOM has good picture showing why the Type II is better option

h ps://www.ar15.com/forums/ar-15/Grendel-type-1-and-type-2-bolts/121-727986/

Lastly, what does not help is the 6.5 Grendel may look cute, but it really has limited case capacity. If you have a Grendel , you are probably shooting relatively long VLD style match bullets such as the Lapua Scenar 123gr

Freaky how far the bullet is in the case to meet the 2.260 COL of AR magazine which takes up lots of case volume. Doesn't take much to get excessive pressure

The bulletin is correct regarding Lapua brass . Completely waste of time and effort forming 7.62X39 cases into Grendel . I also have used Norma and have some Hornady which I haven't used yet
Click to expand...

I have an Odin 20 inch 6.5 type 2 barrel, came with matching BCG. I'm not overly worried about it breaking as I don't run factory ammo and don't have plans to load to max trying to get more out of the cartridge than it's capable of. I have a NR 6.5CM semi for when more is needed.

I've got some 120 and 123gr projectiles but would really like to get down into the 100-110gr range. Unfortunately no local shops have any in stock.

The limited case capacity has always had me wondering why guys jumped on this so quickly as the new top dog in an AR-15 size action. On paper it seems really limited as a hunting round even though it has fantastic long range target potential. I'm still not convinced it's better than a 6.8SPC when it comes to hunting. But then again I don't have a lot of experience with the 6.8 and have never shot a 6.5G (waiting for my second MS upper to arrive).
It's a neat little cartridge that I'm looking forward to experimenting with. Definitely an improvement on it's parent :p
 
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