A pretty sweet "G"

[RattleAkAk]

Grendel Recce tip to butt;

Surefire SF3P
BA Hanson 16" Midlength
Modlite Dual Fuel light goodies with Unity switch
Geissele Mk14 13.5" DDC w/ Magpul covers
Geissele ODG upper w/ Toolcraft bolt carrier and Brownell's bolt with JP extractor and ejector (soon to be all JP when stuff comes back in stock)
Geissele 40mm green lower (Blemula)
Geissele lower parts kit w/ Geissele G2S trigger
Geissele DDC trigger guard
VZ G10 grip
Geissele SCH DDC
Geissele receiver extension DDC with Geissele 42 spring and H1
Contract Coyote SOPMOD stock
Vortex Viper PST Gen2 1-6 with ADM mount and Switchview
Sig Romeo 5 backup on a Arisaka 35 degree mount

[shooter545]

Good looking rifle. In for the range report.

[myrifle]

Congrats on the new grendel sir. Looks good.

Stick with the bolt you have are get one of the sixfivearms bolts when they come back instock. The JP is no diffrent then the bolt you have now.

The strongest grendel bolt on the market is the sixfivearms bolt do to its design.

[RattleAkAk]

Good looking rifle. In for the range report.

After some gas issues, I opened up the undersized gas port to .076 with a HSS reamer and now she's running like a Singer. This group was shot off bags at 100y with Hornady Black 123, not too shabby!

[RattleAkAk]

Congrats on the new grendel sir. Looks good.

Stick with the bolt you have are get one of the sixfivearms bolts when they come back instock. The JP is no diffrent then the bolt you have now.

The strongest grendel bolt on the market is the sixfivearms bolt do to its design.

Hmmmm really? No different than the Brownells bolt? Can you elaborate a little.

[myrifle]

Hmmmm really? No different than the Brownells bolt? Can you elaborate a little.

I have grendel bolts made from every company that makes them, even the older JP bolts with the surface treatment they use to use and some of the old AA hard use bolts.

Everyone of them are made from the same material and made to the same dimensions, even the extractors are the same.

The surface coatings/treatments may be a diffrent color or a diffrent process but psychically and materials wise they are the same bolts.

The sixfive arms bolts is the only true grendel bolt that is built too be stronger as it has a thicker side wall.

[RattleAkAk]

I have grendel bolts made from every company that makes them, even the older JP bolts with the surface treatment they use to use and some of the old AA hard use bolts.

Everyone of them are made from the same material and made to the same dimensions, even the extractors are the same.

The surface coatings/treatments may be a diffrent color or a diffrent process but psychically and materials wise they are the same bolts.

The sixfive arms bolts is the only true grendel bolt that is built too be stronger as it has a thicker side wall.

Thanks for the info.

[VASCAR2]

I seem to always mention this but Brownell’s is one of the few companies to have a different overall length with their 6.5 Grendel bolt. Bill Alexander used the deeper .136” bolt face compared to the 5.56/223 .125” bolt face depth. AA lengthened the 6.5 Grendel bolt .01 to a overall length of 2.810”. The Brownell’s bolt measure 2.800” with a usual tolerance of + or - .002-.003”.

I would not switch firing pins between different AR-15 bolts without first measuring the firing pins. The specification for firing pin protrusion is minimum .028” maximum .036”. The maximum AR-15 firing pin length is 3.279” with a tolerance of -.009”. Excessive firing pin protrusion can contribute to pierced primers or failure to fire with a short firing pin. Forum members have measured Brownell’s firing pins and most measure 3.269” + or - .002”.

This problem became evident when Odin Works released their 6.5 Grendel and people were getting pierced primers. The problem was 2.800” length bolt with standard AR-15 length firing pins and out of spec firing pin protrusion. Toolcraft released 2.800” length bolts for a short time but switched to 2.810” bolts. Brownell’s list a shorter AR-15 firing pin on their web site but I’ve never seen them in stock. I called Brownell’s technical a couple years ago and they were unaware of the issue. I have never read where Brownell’s has started using the longer 2.8100” bolt.

As a safety concern I try not to get my AR-15 firing pins mixed up. Excessive firing pin protrusion can contribute to a slam fire with an AR-15 when chambering a cartridge.

As long as you use the correct length firing pin the Brownell’s bolt/BCG in 6.5 Grendel seem fine. I just wish all the 6.5 Grendel bolts were 2.810” length so their would be less confusion. Any time you use a different caliber in the AR-15 than 5.56/223 there isn’t as much standardization.

[biodsl]

Congratulations on your build. Quality parts. Difficult to think of a task this rifle couldn't be pressed into. And the rainbow of colors is fun! It gives new meaning to the term Rainbow Coalition.

[myrifle]

I seem to always mention this but Brownell’s is one of the few companies to have a different overall length with their 6.5 Grendel bolt. Bill Alexander used the deeper .136” bolt face compared to the 5.56/223 .125” bolt face depth. AA lengthened the 6.5 Grendel bolt .01 to a overall length of 2.810”. The Brownell’s bolt measure 2.800” with a usual tolerance of + or - .002-.003”.

I would not switch firing pins between different AR-15 bolts without first measuring the firing pins. The specification for firing pin protrusion is minimum .028” maximum .036”. The maximum AR-15 firing pin length is 3.279” with a tolerance of -.009”. Excessive firing pin protrusion can contribute to pierced primers or failure to fire with a short firing pin. Forum members have measured Brownell’s firing pins and most measure 3.269” + or - .002”.

This problem became evident when Odin Works released their 6.5 Grendel and people were getting pierced primers. The problem was 2.800” length bolt with standard AR-15 length firing pins and out of spec firing pin protrusion. Toolcraft released 2.800” length bolts for a short time but switched to 2.810” bolts. Brownell’s list a shorter AR-15 firing pin on their web site but I’ve never seen them in stock. I called Brownell’s technical a couple years ago and they were unaware of the issue. I have never read where Brownell’s has started using the longer 2.8100” bolt.

As a safety concern I try not to get my AR-15 firing pins mixed up. Excessive firing pin protrusion can contribute to a slam fire with an AR-15 when chambering a cartridge.

As long as you use the correct length firing pin the Brownell’s bolt/BCG in 6.5 Grendel seem fine. I just wish all the 6.5 Grendel bolts were 2.810” length so their would be less confusion. Any time you use a different caliber in the AR-15 than 5.56/223 there isn’t as much standardization.

Thanks for reminding us. I had totally forgot about that.

[BluntForceTrauma]

After some gas issues, I opened up the undersized gas port to .076 with a HSS reamer and now she's running like a Singer.

Do you remember what the factory original gas port size was?

[RattleAkAk]

I seem to always mention this but Brownell’s is one of the few companies to have a different overall length with their 6.5 Grendel bolt. Bill Alexander used the deeper .136” bolt face compared to the 5.56/223 .125” bolt face depth. AA lengthened the 6.5 Grendel bolt .01 to a overall length of 2.810”. The Brownell’s bolt measure 2.800” with a usual tolerance of + or - .002-.003”.

I would not switch firing pins between different AR-15 bolts without first measuring the firing pins. The specification for firing pin protrusion is minimum .028” maximum .036”. The maximum AR-15 firing pin length is 3.279” with a tolerance of -.009”. Excessive firing pin protrusion can contribute to pierced primers or failure to fire with a short firing pin. Forum members have measured Brownell’s firing pins and most measure 3.269” + or - .002”.

This problem became evident when Odin Works released their 6.5 Grendel and people were getting pierced primers. The problem was 2.800” length bolt with standard AR-15 length firing pins and out of spec firing pin protrusion. Toolcraft released 2.800” length bolts for a short time but switched to 2.810” bolts. Brownell’s list a shorter AR-15 firing pin on their web site but I’ve never seen them in stock. I called Brownell’s technical a couple years ago and they were unaware of the issue. I have never read where Brownell’s has started using the longer 2.8100” bolt.

As a safety concern I try not to get my AR-15 firing pins mixed up. Excessive firing pin protrusion can contribute to a slam fire with an AR-15 when chambering a cartridge.

As long as you use the correct length firing pin the Brownell’s bolt/BCG in 6.5 Grendel seem fine. I just wish all the 6.5 Grendel bolts were 2.810” length so their would be less confusion. Any time you use a different caliber in the AR-15 than 5.56/223 there isn’t as much standardization.

Thanks for bringing that up, I read the thread on that. I dont mix and match firing pins. The pins follow the bolts they come with.

[RattleAkAk]

Do you remember what the factory original gas port size was?

I dont have a set of pin gauges but I did find a rollpin punch that fit and measured .062, however there was some slop in the fit so I attempted to get my calipers in there and between the rollpin and my calipers I landed on ~.068 +/- .002.

[RattleAkAk]

One thing I am noticing is that after a couple hundred rounds on the Geissele G2S, the trigger is picking up a considerable amount of creep I didn't expect. I haven't ran Geissele triggers in any of my rifles prior and was pretty surprised by this. One of the reasons I went G2S was to try one out without spending $240 right out of the gate. I love my LaRue MBTs and as of this writing, I may swap out the G2S, my only complaint about the MBT is the trigger bow profile, its a little on the blocky/chunky side. We'll see.

[LRRPF52]

Congrats on the new grendel sir. Looks good.

Stick with the bolt you have are get one of the sixfivearms bolts when they come back instock. The JP is no diffrent then the bolt you have now.

The strongest grendel bolt on the market is the sixfivearms bolt do to its design.

After market was all over the map for at least 10 years with dimensional variances on “Grendel” bolts.

Differences on the original and improved AA bolts relative to a standard 5.56 bolt are:

.136” recessed bolt face
2.810” OAL to set the firing pin back so you don’t have excess firing pin protrusion with Mil-Std firing pins
Extractor pocket depth is different
Extractor pin location is different to mitigate extractor binding inside the barrel extension
Extractor engineered specifically to work with 6.5 Grendel case head and rim dimensions with a strong lip
Tiny radiuses were optimized to increase bolt lug root strength.
Materials and processes were tightly controlled to ensure tough bolts.

In the after-market, we saw:
Cheap 8620 heat-treated improperly for some of the original low-costs parts companies (Model 1 Sales as an example)
.125” face depth
Thin-lipped extractors that failed quickly, lips ripped off
5.56-based extractor shelf dimensions
5.6-based extractor pin locations

Then we saw:
Correct .136” face depth
2.800” COL requiring specific shorter firing pin
Varying types of extractor shelf locations
Varying extractor pin locations
Varying materials and processes

Bill tried his best to get ahead of this by licensing actual Grendel bolts out to companies so that everything would stay standardized based on his years of testing and experience with the .50 Beowulf and initial 6.5 Grendel work, but too many in the industry assumed they could do it better, totally overlooking all the RDT&E he had done.

Same with chambers. He spent $11,500 on different reamer configurations trying to find a set-up that would shoot both 123gr Scenar and 90gr TNT accurately and almost gave up until testing the compound throat.

Aftermarket: “That guy doesn’t know what he’s doing. We can figger it out more better.”

It’s been interesting to watch.

The whole “Grendel II” chamber and bolts is a funny moniker to see all the time. No such animal exists, and yet “that’s the standard now”.

[RattleAkAk]

After market was all over the map for at least 10 years with dimensional variances on “Grendel” bolts.

Differences on the original and improved AA bolts relative to a standard 5.56 bolt are:

.136” recessed bolt face
2.810” OAL to set the firing pin back so you don’t have excess firing pin protrusion with Mil-Std firing pins
Extractor pocket depth is different
Extractor pin location is different to mitigate extractor binding inside the barrel extension
Extractor engineered specifically to work with 6.5 Grendel case head and rim dimensions with a strong lip
Tiny radiuses were optimized to increase bolt lug root strength.
Materials and processes were tightly controlled to ensure tough bolts.

In the after-market, we saw:
Cheap 8620 heat-treated improperly for some of the original low-costs parts companies (Model 1 Sales as an example)
.125” face depth
Thin-lipped extractors that failed quickly, lips ripped off
5.56-based extractor shelf dimensions
5.6-based extractor pin locations

Then we saw:
Correct .136” face depth
2.800” COL requiring specific shorter firing pin
Varying types of extractor shelf locations
Varying extractor pin locations
Varying materials and processes

Bill tried his best to get ahead of this by licensing actual Grendel bolts out to companies so that everything would stay standardized based on his years of testing and experience with the .50 Beowulf and initial 6.5 Grendel work, but too many in the industry assumed they could do it better, totally overlooking all the RDT&E he had done.

Same with chambers. He spent $11,500 on different reamer configurations trying to find a set-up that would shoot both 123gr Scenar and 90gr TNT accurately and almost gave up until testing the compound throat.

Aftermarket: “That guy doesn’t know what he’s doing. We can figger it out more better.”

It’s been interesting to watch.

The whole “Grendel II” chamber and bolts is a funny moniker to see all the time. No such animal exists, and yet “that’s the standard now”.

Thank you for sharing your knowledge!! With that said, and in the spirit of info sharing, not to ruffle feathers, do you agree with myrifle regarding Monster bolts being the very best out there currently?

[LRRPF52]

I don’t have any experience with the new Monster bolts, unless that’s what I have in my 12”.

I’m trying to remember what I put in there now. I seem to recall ordering some Monster bolts but it might have been before the newer ones.

The thing with me and bolts is, since 2009 across all the Grendels I have built or owned....I just haven’t had any issues with bolts.

My first one was an AA 16” barrel/bolt combo I ordered from Midway USA.

If I could go back in time, I would have ordered one of the highest-tier rifles Bill had built personally, but I didn’t trust anyone at the time except for a precious few number of companies, and at that, I only wanted their parts so I could build with them and make sure things were right to the best of my knowledge. Those models are no longer offered, unfortunately.

I never had any issues with my 16” original Grendel build. I’ve also Cerakoted some upper-end original/early AA rifles and was pretty impressed with what I saw.

2nd Grendel was through the first Group Buy with Lilja barrels, and I used Precision Firearms bolts in several of those builds.

I helped a lot of people along the way build with AA, PF, Maxim, and AA Hard Use bolts. Don’t recall any issues.

I now have 22” Lilja, 3x 18” AA/Lilja/LaRue, 16” Lilja, 12” Faxon Group Buy, and 10.5” PF Criterion Grendels.

I did 2x 12” Grendels with Group Buy Monster logo barrels. I just checked and I did use Monster logo bolts in them.

So far, zero issues with them.

I’ve shot almost entirely suppressed with my 12”, and the other one has been shot suppressed the whole time too.

I used Bootleg adjustable gas carriers in them so we could choke the gas for suppressed use.

I’ll get some of the new ones to use.

[RattleAkAk]

I don’t have any experience with the new Monster bolts, unless that’s what I have in my 12”.

I’m trying to remember what I put in there now. I seem to recall ordering some Monster bolts but it might have been before the newer ones.

The thing with me and bolts is, since 2009 across all the Grendels I have built or owned....I just haven’t had any issues with bolts.

My first one was an AA 16” barrel/bolt combo I ordered from Midway USA.

If I could go back in time, I would have ordered one of the highest-tier rifles Bill had built personally, but I didn’t trust anyone at the time except for a precious few number of companies, and at that, I only wanted their parts so I could build with them and make sure things were right to the best of my knowledge. Those models are no longer offered, unfortunately.

I never had any issues with my 16” original Grendel build. I’ve also Cerakoted some upper-end original/early AA rifles and was pretty impressed with what I saw.

2nd Grendel was through the first Group Buy with Lilja barrels, and I used Precision Firearms bolts in several of those builds.

I helped a lot of people along the way build with AA, PF, Maxim, and AA Hard Use bolts. Don’t recall any issues.

I now have 22” Lilja, 3x 18” AA/Lilja/LaRue, 16” Lilja, 12” Faxon Group Buy, and 10.5” PF Criterion Grendels.

I did 2x 12” Grendels with Group Buy Monster logo barrels. I just checked and I did use Monster logo bolts in them.

So far, zero issues with them.

I’ve shot almost entirely suppressed with my 12”, and the other one has been shot suppressed the whole time too.

I used Bootleg adjustable gas carriers in them so we could choke the gas for suppressed use.

I’ll get some of the new ones to use.

Taking advantage of the opportunity to pick your brain. I currently have a JP Enhanced bolt in my 20" Grendel however it hasn't been to the range yet as I've been focused on shaking down the 16" pictured. The 16" is a "fighting carbine" Recce type build and reliability and longevity is very important to me. I have another JP bolt coming for it. Do you see any reason to abandon the JPs in exchange for a Monster? What is your thoughts on JP Grendel offerings? In all my 5.56 rigs, I haven't ventured into expensive bolts as I've never had a need to, pretty much Colt and Toolcraft so I have no real frame of reference. The Grendel being a horse of a different color anyhow.

[VASCAR2]

There are things that show up with 6.5 Grendel bolt failures. Having a receiver that is not square can contribute to shorter bolt life. A short chamber where the bullet is crammed into the lands. Another potential problem is over gassed where the bolt starts to unlock before pressures have dropped to a safe level. Using a suppressor without an adjustable gas system and over sized gas ports are generally associated with over gassed 6.5 Grendel. Running hand loads that are to hot and over 52,000 psi. Each of these situations are bad but put two or more together you’ll likely ruin the bolt.

One powder in particular (IMR8208XBR) has shown to spike pressures and you should approach max charges cautiously. It is also recommended to increase powder charge no more than .3 grains in load development with the 6.5 Grendel and if approaching max loads a chronograph is very useful.

[RattleAkAk]

There are things that show up with 6.5 Grendel bolt failures. Having a receiver that is not square can contribute to shorter bolt life. A short chamber where the bullet is crammed into the lands. Another potential problem is over gassed where the bolt starts to unlock before pressures have dropped to a safe level. Using a suppressor without an adjustable gas system and over sized gas ports are generally associated with over gassed 6.5 Grendel. Running hand loads that are to hot and over 52,000 psi. Each of these situations are bad but put two or more together you’ll likely ruin the bolt.

One powder in particular (IMR8208XBR) has shown to spike pressures and you should approach max charges cautiously. It is also recommended to increase powder charge no more than .3 grains in load development with the 6.5 Grendel and if approaching max loads a chronograph is very useful.

I have mostly used CFE223 and will be trying some LeverRevolution when I get back to the bench here this summer. I run a MagnetoSpeed and really like it.