6.5 Grendel & Mags In The Ar

[Mick]

C Products LLC has a 25 round mag for the AR-15 in 6.5 Grendel. Is the Grendel making major in the ARS?

[MasterLefty]

I think Henning is running the Grendel cartridge.

Kenny

[itento]

According to the performance tables in the latest Special Weapons magazine, this round makes 2670 fps out of a 20" barrel with a 110 gr bullet. That a pf of 294.

[Patrick Sweeney]

So a 123 could make major if you were careful. But, are the extra points worth the shoving around you'll get?

Guess I'll find out, as I'll have a 20" Grendel to play with for this 3-gun season.

[Mick]

I went and checked some more and found the 144 FMJs will do 2450 which would have a PF of 352. If you slowed them down to get a 330 PF @ 2300 fps or so you start to lose the trajectory. That kinda negates that great BC of .587....

[sinnsyk]

I shot the 6.5 Grendel last year. With a 19.5" barrel I was just breaking into major shooting 120MKs and 123MKs. With the F4 comp the shot recovery is acceptable. Alexander just built a beautiful 20" SS w/ a quasi F2 comp (F2 made for 6.5). It's got a billet receiver and a Satin barrel. 20" barrel and a minimum of 120gr bullets is necessary for major. You can push this cartridge, but I wouldn't go with 18" barrels. I've got some pics and report:

http://henningshootsguns.com/pages/65gren_main.html

As soon as I get my 20" I'll do an article on it. I will probably be selling these uppers on my site.

[uscbigdawg]

Henning,

Great stuff! I'll be building a 6.5 Grendel rifle when I get back and this info is definitely great for helping with parts selection. Keep up the info.

Rich

[itento]

Rich,

Here's a good site I ran across.

http://www.65grendel.com/

[Mick]

I would think if you get a decent major load that works a brake well it would be the way to go....

[uscbigdawg]

I'm not too worried about recoil. The reason is simple enough in that I primarily shoot Open. If the muzzle rise/recoil is that much more harsh than a .223 w/ a tactical brake, then there's always bumping up the comp to the JP Recoil Eliminator.

My only concern is consistently and with a good margin for "error" to make major in it. This is part of the reason I was talking with the guys from Sabre Defence so much at the A6-3G. I had been doing some numbers crunching/comparison with the 6.8 vs. 6.5. There just seems to be a HUGE gain in being able to go with a 6.5, if only as a cooler long range option (ITRC type matches where the carbine guy has some long shots).

The upside is that one random caliber shouldn't really de-rail the market as a whole on calibers for 3-Gun (like 9mm in Limited I feel would). There are enough matches (probably a majority) where the advantage of major scoring on the rifle, is not worth that much more as the ranges (less than 250 yards) at most matches don't really necessitate a big advantage to scoring major since A-hits and steel hits are easily completed rapidly with the smaller caliber.

Rich

ETA: So now, comes some serious testing. Can I make major in 6.5 Grendel in a 16" barrel. If you can make it at 20, if there's enough margin of velocity drop (say about 150 fps) then there's room.

Edited February 1, 2007 by uscbigdawg

[ar15performance]

I'm not too worried about recoil. The reason is simple enough in that I primarily shoot Open. If the muzzle rise/recoil is that much more harsh than a .223 w/ a tactical brake, then there's always bumping up the comp to the JP Recoil Eliminator.

My only concern is consistently and with a good margin for "error" to make major in it. This is part of the reason I was talking with the guys from Sabre Defence so much at the A6-3G. I had been doing some numbers crunching/comparison with the 6.8 vs. 6.5. There just seems to be a HUGE gain in being able to go with a 6.5, if only as a cooler long range option (ITRC type matches where the carbine guy has some long shots).

The upside is that one random caliber shouldn't really de-rail the market as a whole on calibers for 3-Gun (like 9mm in Limited I feel would). There are enough matches (probably a majority) where the advantage of major scoring on the rifle, is not worth that much more as the ranges (less than 250 yards) at most matches don't really necessitate a big advantage to scoring major since A-hits and steel hits are easily completed rapidly with the smaller caliber.

Rich

ETA: So now, comes some serious testing. Can I make major in 6.5 Grendel in a 16" barrel. If you can make it at 20, if there's enough margin of velocity drop (say about 150 fps) then there's room.

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR.

the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.

[caspian guy]

I'm not too worried about recoil. The reason is simple enough in that I primarily shoot Open. If the muzzle rise/recoil is that much more harsh than a .223 w/ a tactical brake, then there's always bumping up the comp to the JP Recoil Eliminator.

My only concern is consistently and with a good margin for "error" to make major in it. This is part of the reason I was talking with the guys from Sabre Defence so much at the A6-3G. I had been doing some numbers crunching/comparison with the 6.8 vs. 6.5. There just seems to be a HUGE gain in being able to go with a 6.5, if only as a cooler long range option (ITRC type matches where the carbine guy has some long shots).

The upside is that one random caliber shouldn't really de-rail the market as a whole on calibers for 3-Gun (like 9mm in Limited I feel would). There are enough matches (probably a majority) where the advantage of major scoring on the rifle, is not worth that much more as the ranges (less than 250 yards) at most matches don't really necessitate a big advantage to scoring major since A-hits and steel hits are easily completed rapidly with the smaller caliber.

Rich

ETA: So now, comes some serious testing. Can I make major in 6.5 Grendel in a 16" barrel. If you can make it at 20, if there's enough margin of velocity drop (say about 150 fps) then there's room.

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR.

the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.

Doesn't look like any of those go major?

[ar15performance]

I'm not too worried about recoil. The reason is simple enough in that I primarily shoot Open. If the muzzle rise/recoil is that much more harsh than a .223 w/ a tactical brake, then there's always bumping up the comp to the JP Recoil Eliminator.

My only concern is consistently and with a good margin for "error" to make major in it. This is part of the reason I was talking with the guys from Sabre Defence so much at the A6-3G. I had been doing some numbers crunching/comparison with the 6.8 vs. 6.5. There just seems to be a HUGE gain in being able to go with a 6.5, if only as a cooler long range option (ITRC type matches where the carbine guy has some long shots).

The upside is that one random caliber shouldn't really de-rail the market as a whole on calibers for 3-Gun (like 9mm in Limited I feel would). There are enough matches (probably a majority) where the advantage of major scoring on the rifle, is not worth that much more as the ranges (less than 250 yards) at most matches don't really necessitate a big advantage to scoring major since A-hits and steel hits are easily completed rapidly with the smaller caliber.

Rich

ETA: So now, comes some serious testing. Can I make major in 6.5 Grendel in a 16" barrel. If you can make it at 20, if there's enough margin of velocity drop (say about 150 fps) then there's room.

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR.

the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.

Doesn't look like any of those go major?

The 6.5 Banshee has about 200fps on the Grendel so if the grendel does it then the banshee will easier. Big debate here, no one wants to shoot major anyway but if you do the 6.8 will do it with 130s and the 30HRT will with 125s or the cheap 147 FMJ. On top of all that the PRI mags are much better than the CPs. you can load to 2.31"

[Religious Shooter]

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR.

the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.

What do you mean by "badly"?

Can you give examples?

[ar15performance]

There are several cartridges that will badly beat the Grendels ballistics now. 6mmAR, 6mm Turbo, 6mmBanshee, 6.5Banshee, 6mmHagar, 5.56x42DMR.

the .243 95gr Sierra MK with a BC of .480-.510 makes it easy to smoke the Grendel. 2965fps from a 22" Banshee. and a .224 75gr Amax at 3150fps from the 5.56x42.

What do you mean by "badly"?

Can you give examples?

ballistic comparison

[Chills1994]

@ AR15Performance:

Obviously, you have something to sell. Have you thought about joining the rest of the dealers here:

http://www.brianenos.com/forums/index.php?showforum=58

??

[ar15performance]

@ AR15Performance:

Obviously, you have something to sell. Have you thought about joining the rest of the dealers here:

http://www.brianenos.com/forums/index.php?showforum=58

??

I don't sell much to 3 gunners because there are too many others selling .223s, I mainly deal in wildcats for varminters and AR10s for big bore guys.

Besides I don't want anymore business I can't keep up now.

I'll throw a plug for PRI mags and LWRCs "Advanced Combat bolt" whenever I get a chance, they've made everything I do alot easier. Nope I don't sell them so you'll have to go direct.

presentation of the "ACB" to the DOD

Development and Testing of a Replacement Bolt for the M4/M16 Service Rifle

Abstract

Field failures of the M4 and M16 bolt have been widely reported and are

considered a substantial problem that impacts weapon reliability and warfighter

safety. While there has been significant work by others in the field, no

heretofore proposed solution has proven entirely successful. This paper outlines

the origination, design, development and testing of a possible direct

replacement for the existing bolt providing a potential ten-fold extension of

component life.

Introduction

The M16 rifle was fielded into the U.S. Army in 1968 during the Vietnam War. The

rifle has since been the primary assault rifle used by U.S. forces. The M16 has

been through several modifications in its more than 30 years of service in the

military and the most recent modification has been given the designation M4. In

July of 2003, an increasing trend in the frequency of M16A2 bolt failures was

observed by the U.S. Army amongst a sample of rifles that had been used for nine

years during summer military training. The results prompted numerous other

studies that collectively provide a valuable source of data from which to build

a comprehensive understanding of the dynamic interactions of the rifle and

design of the standard bolt. The most recent data suggests that the M4 appears

to suffer from a higher degree of failures than the M16A2.

From the results of the published studies, XXXXXXXXXXXXXXXX concluded it was

possible to design a bolt that overcame the flaws of the original design.

Extensive live-fire testing was carried out in field conditions to demonstrate

that the final design met the reliability objectives and provided a minimum bolt

life of 35,000 rounds, an improvement of at least 1,000% over the standard M16A2

and M4 bolts.

Failure experienced with the Original Bolt

Finite analysis of the original bolt design had shown high von-Mises stress

distribution around the fillet, or root, of the locking lugs and even higher

stress concentrations were present in the two locking lugs immediately adjacent

to the cartridge extractor. All of the failed bolts had fractured at these

specific locking lugs. The design of the original bolt is such that the

extractor cut-out in the bolt body creates an asymmetry, or imbalance, in the

bolt. When the rifle is fired the pressure of the cartridge forces the bolt

rearward and the lugs transfer this energy to the matching locking lugs of the

barrel extension. The bolt flexes at the rear inside corner of the lug during

this process. Because of the extractor cutout and resultant lack of symmetry,

the stresses are unevenly distributed and the deformation is greatest in the

area of the two lugs immediately adjacent to the cutout. A series of engineering

analyses suggested that the two lugs on either side of the extractor, of seven

total lugs, each receive a disproportionate amount of the total recoil load:

approximately 20% of the total load each while the remaining 5 lugs each carry

approximately 12% of the total load. The integrity of the bolt is further

compromised by the fact that these overloaded lugs are undercut in order to

accommodate the extractor claw, lowering their yield strength relative to the

under-loaded lugs by 48%. Most bolts will start to exhibit small cracks before

they reach 3,000 rounds fired with terminal failures occurring between 6,000 and

8,000 rounds.

See Figure 1, below.

Figure 1. Fractured bolt specimen.

The original bolt design also experiences fracture failures at the cam-pin hole

located midway along the bolt body causing the bolt body to fracture at this

point. Another major reliability problem is poor extractor spring life, which

leads to failures to extract fired cartridge cases from the chamber.

Approach

To resolve all of the problems and achieve acceptable bolt life required a

fundamental redesign of the bolt. The only parameters constricting creative

development were that the proposed design should be a “drop-in” replacement and

work with as many component parts in the existing rifle as possible, i.e., bolt

carrier, firing pin, barrel extension etc. Other than these, the design elements

were open. Computer modeling was carried out using Solid Edge from UGS and

finalized designs were prototyped and sent for proof testing.

Material Choice

Because the standard bolt material, Carpenter Steel 158, has proved to be

susceptible to corrosion, a new bolt material was selected. Chemical analysis of

the composition of the failed bolts revealed no significant differences between

the failed bolts and Carpenter Steel 158 specifications; failures were not

ascribed to flawed material batches, but a suboptimal material choice. After

extensive evaluation and prototyping of potential material choices including the

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The final design embodied a number of improvements over the original bolt

design. Working within the constraints outlined above, the first approach was to

reduce the amount of stress transferred to the fillet or root of each locking

lug during the firing phase of operation. This was accomplished in by adding a

radius to every 90° angle of the locking lug. The effect of this is to

dramatically reducing the amount of stress transmitted down the lug to the root

fillet.

The improved design also incorporates a fully supported bolt face. The original

bolt has a substantial area of the bolt face removed to accommodate the

extractor claw and therefore a combination of the bolt itself and the extractor

claw support the cartridge head. This arrangement leads to further flexing of

the bolt assembly during firing and increases stress on the bolt lugs adjacent

to the extractor claw. By fully supporting the bolt face, a significant

reduction in bolt flex was achieved in this area. Additionally, the undercuts in

the lugs adjacent to the extractor accommodating recess were removed, and

instead a radius transitions from the side of the lug adjacent to the extractor

accommodating recess into the fully supported bolt face. The omission of the 48%

undercut beneath each of these locking lugs has increased the strength of these

lugs from around 24% of the strength of the uncompromised lugs to approximately

85% of their strength. Finally, the locking lugs were held to the maximum

tolerance indicated in the Technical Data Package for the original bolt design

so as to provide as great a surface area as possible without altering the barrel

extension.

Due to the modifications incorporated into the bolt head to strengthen the

locking lugs, it became necessary to redesign some elements of the extractor

claw to allow it to fit into the new design. Although the extractor claw appears

radically different than the original design, there was no requirement to change

the material choice. The extractor spring itself is an area of weakness in the

original bolt, in particular the placement of the pivot point. Noting that

others had already looked at a twin extractor spring arrangement and met with

varying degrees of success, the placement of the pivot point was changed. The

final design allowed for the use of the original spring design and added an O

ring developed by the Naval Surface Warfare Center at Crane, Indiana which

extends the bounce resistance to 230,000 cycles per minute and extends life

expectancy to 10 million cycles. Finally, as with the standard bolt the spring

is integrally dampened with a synthetic insert that is designed to increase

spring life and reduce the chances of extractor claw bounce during fully

automatic fire. Even with the above modifications to the body of the bolt, the

original firing pin is compatible.

The new bolt is manufactured in the same fashion as the original, including the

heat treat method and shot peening of the bolt body although an additional shot

peening is carried out after final grind to further enhance the outer molecular

structure of the bolt. Suppliers of the original bolt have all the expertise and

equipment necessary to manufacture the new design, although the new bolt is more

complex and takes more time to machine as a result of the attention to detail

needed to ensure a reliable product.

Testing and Qualification

Once the first prototypes had been produced, they were subjected to proof

testing with a 30% over-pressure load (approximately 70,000 psi) followed by a

crack inspection. One bolt has been subjected to 18 proof loads to date with no

deformation or cracking. The bolts were subjected to live-fire testing over a

period of several months to ensure that the bolt and its component parts were

not susceptible to fatigue or accelerated wear from heavy use. Round counts on

individual bolts varied from 9,000 to over 40,000 in full auto, semi-auto, and

mixed fire modes with no failures, cracks, or signs of wear or fatigue.

The original claw of the extractor was redesigned to create 25% greater surface

area to grip the case rim. The use of this second-generation extractor claw

eliminated extraction failures, even from barrels with roughly finished or

otherwise sub-standard chambers. Generation II extractor claws are identified by

the ????? engraving on their surface. The extractor claws are shown in Figure 2,

below together with the original bolt design.

Figure 2. From left to right, the original bolt, the new bolt with Generation I

extractor and with Generation II extractor. The fully supported bolt face is

clearly seen in this photograph.

Once internal testing was completed and had demonstrated that there were no

safety or reliability issues inherent in the design or the material choice, the

bolt is now being offered for initial commercial sale.

Conclusion

The test results and commercial use of the “Enhanced Performance Bolt” (EPB)

demonstrated a drop-in replacement for the original bolt that eliminates

premature wear and failure and alleviates continual inspection and frequent

replacement of the original bolts. The use of a bolt design that allows lifetime

use of the host weapon without the need for extraction enhancing devices means

that in a hostile situation the warfighter can be confident in the abilities and

reliability of his primary defensive weapon platform. The EPB’s material choice

with its resistance to corrosion, combined with its ability to handle repeated

high pressure loadings, the stress relieving design, and the strengthening if

the weak areas of the original bolt have resulted in a component that exceeds

all current government requirements in terms of component life. Although

primarily designed for military use, these benefits are passed on to commercial

and competitive users resulting in consistent headspacing upon lock-up and

improved extraction and ejection together with the lifetime durability detailed

above.

Acknowledgements

Figure 1 photograph:

Edited February 7, 2008 by ar15performance

[Sandro]

Interesting ballistics...

grendelballistics.pdf

[ar15performance]

Interesting ballistics...

The key to that chart is at the bottom where it says velocities for all but the Grendel from loading manuals but the Grendel is from actual velocities.

The 6.8 will push the 115 to 2800fps from an 18" barrel. act.

308 -2540 from a 18" act.

Charts are only fair if you hot rod every one of the entries or shoot everyone to the same pressure. Then if you compare the best bullets available with every case which the 175SMK is not. Drop a 155 Scenar in there if you want to compare the best to the best.

grendel velocities from grendel.com

How many people shoot ARs at 1000yds? 300-500 is a much more usable range for 90% of us.

I can't think of 1 1000yd competitor that uses a AR. Highpower sure.

Edited February 7, 2008 by ar15performance

[320pf]

If you push the 6.5 Grendel to max pressures to make major PF you are likely to experience premature bolt failures. This problem has been debated to death on AR15.com. The 7.62x39mm in an AR15 platform will also has the same problem if you push the pressures high enough to make major PF.

The problem is two fold. First, the bolt face has to be opened up up to accommodate the much larger case head of both of these cartridges. This removes some of the support material from the lugs. Second, the interior area of the case head is larger with the 6.5 Gren. and 7.62x39mm therefore there is more thrust on the bolt for any give pressure.

The standard 5.56 NATO generates between 6000 and 7000 lbs of thrust on the bolt at 55000 to 60000 psi chamber pressure. The 7.62x39mm and the 6.5 Grendel will generate about 7000 to 8000 lbs of thrust on the bolt at 50000 to 52000 psi chamber pressure. If you push the pressures up to ~60000 psi chamber pressure the bolt thrust jumps to about 9000 lbs.

Besides much more recoil, the other major disadvantage with these rounds is that the magazines only hold 25 rounds instead of 30.

The way USPSA 3-gun is scored and the use of steel at distances of 100 yrds or greater, there is not much advantage to be gained shooting major rifle.

I have been down this road... unless they change how 3-gun is scored, shooting major is not worth it.

"The 6.8 will push the 115 to 2800fps from an 18" barrel. act."

I have seen this claimed on several blogs...I think that this load is way off the "reservation"! The max 115gr load listed in the most recent Hodgdon database (listed for a 24-inch barrel) is 28.2 gr of H322 (compressed) generating 53300 psi and pushes the 115 gr bullet to 2608 fps. The claim that an 18-inch barrel is 200 fps faster is... well dubious. I believe that people might be getting these velocities but they are way over max pressure!

Yea yea, I have also heard all about the three groove barrel and 1:10, 1:11 twist and the "improved" chamber etc... But it all sounds too special to me!

320pf

Edited February 8, 2008 by 320pf

[Religious Shooter]

....

Edited February 8, 2008 by Religious Shooter

[Chills1994]

@ ar15performance

Dude!

DUDE!!!

Where'd you dig this thread up?

NECROPOSTER!!

LOL!

My "Is shooting .308 for Major PF vs. 223 Minor PF worth it? thread from April 2007

The "Is .243 competitive?" thread also from April 2007

I think those two threads ^^^^^ pretty much sum up what everybody's thoughts are on shooting major vs. minor, at least here in the US, where anything past 100 yards is gonna be steel anyway.

So I just have to ask a couple of questions (not to be a Debbie Downer):

1. Will 6.5 Grendel (or 6.8 SPC) rounds fit in and work reliably with a Beta Mag (C?) ?

2. How hard or easy or EXPENSIVE is it to find Grendel/SPC/ other wildcat brass (or to make it)? Said another way, are we gonna see 3 gun competitors out sweeping the bays with metal detectors looking for their Grendel/SPC/High Fallutin' Wildcat brass after the match?

(slight thread drift on)

The Grendels and SPC's sound cool and all. Maybe if you had an AR-15 already and wanted to thumb your nose at the Zumbo's and Fudd's of the world and take it whitetail deer or antelope hunting, then a Grendel or SPC upper might be just the ticket.

The DNR (game wardens) folks might freak out if they saw you out in the woods in your militia outfit Mossy Oak or Real Tree with an Evil Black Rifle .... err... assault weapon ... err semi-automatic sporterized version of our military's current issue long gun in your hands though.

LOL!

(drift off)

Edited February 8, 2008 by Chills1994

[Religious Shooter]

(ooopse...)

Edited February 8, 2008 by Religious Shooter

[ar15performance]

There are a lot of people out there who read magazine articles and believe every word, afterall you couldn't print it if it wasn't true right? Someone once said RE7 was way to fast for the 6.8 and 10x was way to fast for the grendel in print. RE7 will push a 90gr TNT 2950fps from a 18" 6.8 and I've been doing it for almost a year and I'm not talking 20 shots a week either. Same with the Grendel and 10x.

Most people don't get in and dig for the real info and test loads, slow twist VS fast twist and different chamber specs and try powders that aren' t listed in the latest reloading manual. Some of us do so if someone is way off base I throw out a little shadow so they'll think about it or check into it before making the decision. How many here knew about PRI mags and being able to load them to 2.31" The LWRC super bolt? I think that whole article zipped right over everyones head at the speed of light.

320pf, I'm sure you're the same one that posts on arfcom and I don't mind a bit if people shoot slow loads but, I like flat shooting cartridges.

Why should I care if someone buys a mag that you have to work on before it will function or buys a hyped up caliber just to find out in a month it was all hype, it's not my money so why should I care? Who cares if the guy next to you is shooting at half the velocity you are?

Why do people answer post on forums when someone else asks a question? some people just post to be a jackass and some post to help.

Chills, did I say I try to shoot major? did I say you should? my short range 3gun is a 223, my long range 3gun is a 5.56x42 and yes there is a reason.

Very first post, simple "don't make the mistake of buying a Grendel blindly" read up to see if the bolts break or if they have mags that work and does it really ballistically beat the other cartridges as everyone says.

[dak]

Now, keep in mind that Hennings nic "sinnsyk" means "insane" in Norwegian, and that pretty much summarizes Bill Alexanders comments on Hennings reloading data for the Grendel;-) I've been running it major in a 20" custom made upper from Alexander Arms, and it's possible to get consistent major PF without excessive pressures, but it's not easy. I will not publish the loads, if anyone wants them send me a PM.

/D