Alternative to 6.5 Grendel?

[stanc]

It's well documented that 5.56 NATO has inconsistent behavior in soft tissue, which sometimes results in failure to rapidly incapacitate an opponent.

There is also the issue of long range engagements, for which many individuals on this forum consider 5.56 NATO to be inadequate.

Some forum members would like to address these matters by replacing 5.56 NATO with 6.5 Grendel.

While I think that 6.5 Grendel would be a viable solution to the perceived problems, I am inclined to agree with LRRPF52 that it has drawbacks which make it not the best option.

First, as someone in Tony's MG&A forum noted, the 5.56 NATO cartridge is so light that "the warfighter can carry absurdly high numbers of rounds."

Second, the small case diameter of the 5.56 NATO permits rifle magazines of minimum height and weight.

In contrast, size and weight of the Grendel cartridge and its magazines are necessarily much greater than for 5.56 NATO, which would cause a significant increase in the rifleman's carry load and/or a reduction in number of rounds carried.

All of the foregoing leads me to wonder if there might be a better idea. Here's what I've come up with:

I've long admired the superbly streamlined bullet of the 5.45x39 Russian round. I suggest that this bullet be scaled up to 0.224" diameter, and loaded in the 5.56x45 case. That should address the inconsistent terminal performance seen with M855 Ball, and also extend the effective range.

If even greater range should be deemed necessary, the 5.45 bullet could be scaled up to 6mm (or possibly even 6.35mm).

Also, keeping the 5.56x45 cartridge case has manufacturing and logistical advantages, in addition to the end user benefits noted.

Your thoughts?

[cory]

...Also, keeping the 5.56x45 cartridge case has manufacturing and logistical advantages, in addition to the end user benefits noted.

Your thoughts?

I disagree. If the 5.56 is ever replaced, there will need to be senators behind the push, so we have to think politics. In order to get a senator behind this and/or their vote you'll need to convince them that it'll bring jobs to their district. Therefore, a change in the LC machinery, brass and magazines would have more of a chance of getting funded.

[mongoosesnipe]

The 5.45 bullet works because it has a brittle steal jacket and the bullet is a closed tip hollow point

http://www.flickr.com/photos/58269763@N04/7811819704/

[LRRPF52]

All my experiences with M855 on human tissue have been very consistent:

Avulsive tissue destruction, larger-than-normal wounds with grotesque characteristics, life-changing or life-ending terminal performance.

The constant mantra that 5.56 doesn't cut it seems to come from people who have yet to see what it actually does, but won't let this argument alone for whatever reasons. I think we would have been fine with .222 Remington case length, shoulder blown forward with a 30 degree angle, and left it at 1.700", giving us another .060" of OAL. The SCHV proponents really wanted 3400fps mv, but "settled" for 3200-3275fps with 55gr FMJBT from a 20" gun.

If they really wanted the frag threshold performance to be extended out farther, they would have heeded one of the Army Ordnance Board Engineers who suggested using a .25 Remington (necked down .30 Remington) pushing a 68gr FMJBT fast, without having to push the pressures as much. That would have required a redesign in the bolt, extension, magazines, and receiver set, which would have delayed AR15 RDT&E, and production, in an already time-sensitive crunch where the AR15 was basically being looked at as a stop-gap between OICW and the M14 production, which was way behind on schedule, with units in Europe and the States suffering from worn-out Garands, many of which had been through 2 wars, and were totally obsolete in terms of design, capabilities, and being able to support Army doctrine.

The Black Rifle, Volume I is a must read in order to gain a detailed historical perspective of the development of the SCHV rifle concept. In the end, we got an amazing little rifle that blows chunks of flesh from people within most engagement distances, unlike other common military service rifle calibers.

If there is one cartridge we should be looking at that needs replacement, it is the 7.62 NATO.

[stanc]

All my experiences with M855 on human tissue have been very consistent: Avulsive tissue destruction, larger-than-normal wounds with grotesque characteristics, life-changing or life-ending terminal performance.

If there is one cartridge we should be looking at that needs replacement, it is the 7.62 NATO.

I do not doubt that your experiences with M855 are other than what you claim. However, I'm sure that you can have seen only a very small percentage of wounds inflicted by 5.56mm weapons. Plus, tests done by Fackler and the US Army do show variations in onset of yaw with M855, as shown below.

I can't agree that 7.62 NATO needs to be replaced. It works well enough as vehicle armament and in a number of other applications. But, I can see where it might be a good idea to field a SAW/DMR cartridge that is smaller and lighter than 7.62 NATO.

[320pf]

All my experiences with M855 on human tissue have been very consistent:

Avulsive tissue destruction, larger-than-normal wounds with grotesque characteristics, life-changing or life-ending terminal performance.

The constant mantra that 5.56 doesn't cut it seems to come from people who have yet to see what it actually does, but won't let this argument alone for whatever reasons.I think we would have been fine with .222 Remington case length, shoulder blown forward with a 30 degree angle, and left it at 1.700", giving us another .060" of OAL.

Do you mean something like this?

http://www.ar15.com/forums/t_3_121/499109_25_223.html

From a 16.5 inch barrel, here are the typical velocities that you get with the 25-223Ar cartridge.

Horn 75g VMAX (BC= 0.290) 2900-3000 fps (1400-1498 ft-lbs)
Barnes 80g TTSX (BC= 0.316) 2800-2850 fps (1392-1442 ft-lbs)
Nos. 85g Bal. Tip (BC= 0.329) 2750-2800 fps (1427-1479 ft-lbs)
Speer 87g TNT (BC= 0.310) 2750-2800 fps (1461-1514 ft-lbs)
Sierra 90 BK (BC= 0.37*) 2650-2700 fps (1403-1457 ft-lbs)
Speer/Sierra 100 g SBT (BC= 0.393** 2550-2600 fps (1444-1501 ft-lbs)

*Sierra Bullets lists variable BC's
**Speer lists 0.393 as the BC for their SBT bullets. The form/shape for the Speer and Sierra bullets are nearly indistinguishable.

The 25-223Ar can run the Grendel out at distance. Here is a link to several ground squirrel kill out a 721 yrds

http://www.ar15.com/forums/t_3_121/499109_25_223.html&page=50

[Michael]

Stick with the 5.56. Ditch the M855 for the Mk262 or the MK318 MOD 0.

[LRRPF52]

Do you mean something like this?

http://www.ar15.com/forums/t_3_121/499109_25_223.html

From a 16.5 inch barrel, here are the typical velocities that you get with the 25-223Ar cartridge.

Horn 75g VMAX (BC= 0.290) 2900-3000 fps (1400-1498 ft-lbs)
Barnes 80g TTSX (BC= 0.316) 2800-2850 fps (1392-1442 ft-lbs)
Nos. 85g Bal. Tip (BC= 0.329) 2750-2800 fps (1427-1479 ft-lbs)
Speer 87g TNT (BC= 0.310) 2750-2800 fps (1461-1514 ft-lbs)
Sierra 90 BK (BC= 0.37*) 2650-2700 fps (1403-1457 ft-lbs)
Speer/Sierra 100 g SBT (BC= 0.393** 2550-2600 fps (1444-1501 ft-lbs)

*Sierra Bullets lists variable BC's
**Speer lists 0.393 as the BC for their SBT bullets. The form/shape for the Speer and Sierra bullets are nearly indistinguishable.

The 25-223Ar can run the Grendel out at distance. Here is a link to several ground squirrel kill out a 721 yrds

http://www.ar15.com/forums/t_3_121/4...3.html&page=50

That was a .25-223 Bolt gun with a massive bull barrel.



Grendel has taken antelope at 752yd from a 22" AR15, DRT.

Sierra lists the .257" 100gr SBT G1 BC's as:

.355 @ 2800 fps and above
.333 between 2800 and 1600 fps
.310 @ 1600 fps and below

6.5mm 100gr NBT is .350
6.5mm 100gr Barnes TSX is .359
100gr Hornady A-MAX is .390
100gr Hornady V-MAX is .365
100gr Nosler Partition is .326

16" Grendel with preliminary load development for me pushed the 100gr NBT to 2700fps, and I haven't even tried more than 2 powders with that bullet.
I was talking about the .222 Remington with the shoulder blown forward, and a 30 degree shoulder angle, but staying at .222 Remington case length of 1.700".

That .25-223 sure is a nice little quarter bore, and I have always wanted a .257" since my grandpa loved it so much. I think the .30 Remington case necked down to .257" would be ideal for the AR15 for those that are wanting a .257". There is nowhere near the bullet selection for the .257" compared to 6.5mm, especially when talking target bullets and big game bullets, but it is a beautiful little medium game caliber.

That 110 Nosler Accubond would be awesome in the AR15, with a .418 BC. I think there is a void in the market right now that .257" is waiting to fill in the hunting AR15, and a .247x43 or 25 DTI would be awesome. A 16" hunting carbine should be able to spit the 110 out at ~2600fps with the right powder.

The .25-223 is certainly no slouch. You've done a lot of work with it, right? What powders are you finding to work the best with the 100gr? I think it's pretty efficient in the .223 Rem case, as it allows more pressure relief with the bore size, while facilitating nice speeds with the charge weights, powder types, and bullet weights.

[KentuckyBuddha]

It was also interesting skimming those linked threads about the 6x45 wildcat folk chiming in as well. That would probably have some appealing BC and terminal performace options as well.

[LRRPF52]

6x45 is limited by COL, so no high BC pills in the AR15 unless you single load. To get the kinds of speeds the SCHV proponents were wanting, you need a shorter, fatter case that will fit in the AR15, or design a new rifle.

[KentuckyBuddha]

...ergo the Grendel case for the 6.5. Makes sense.


I suppose that would be the same problem with a really long aluminum core high BC shape 85gr...there just would not be enough there there before you ran out of OAL.

[320pf]

That was a .25-223 Bolt gun with a massive bull barrel.



Grendel has taken antelope at 752yd from a 22" AR15, DRT.

Sierra lists the .257" 100gr SBT G1 BC's as:

.355 @ 2800 fps and above
.333 between 2800 and 1600 fps
.310 @ 1600 fps and below

6.5mm 100gr NBT is .350
6.5mm 100gr Barnes TSX is .359
100gr Hornady A-MAX is .390
100gr Hornady V-MAX is .365
100gr Nosler Partition is .326

16" Grendel with preliminary load development for me pushed the 100gr NBT to 2700fps, and I haven't even tried more than 2 powders with that bullet.
I was talking about the .222 Remington with the shoulder blown forward, and a 30 degree shoulder angle, but staying at .222 Remington case length of 1.700".

That .25-223 sure is a nice little quarter bore, and I have always wanted a .257" since my grandpa loved it so much. I think the .30 Remington case necked down to .257" would be ideal for the AR15 for those that are wanting a .257". There is nowhere near the bullet selection for the .257" compared to 6.5mm, especially when talking target bullets and big game bullets, but it is a beautiful little medium game caliber.

That 110 Nosler Accubond would be awesome in the AR15, with a .418 BC. I think there is a void in the market right now that .257" is waiting to fill in the hunting AR15, and a .247x43 or 25 DTI would be awesome. A 16" hunting carbine should be able to spit the 110 out at ~2600fps with the right powder.

The .25-223 is certainly no slouch. You've done a lot of work with it, right? What powders are you finding to work the best with the 100gr? I think it's pretty efficient in the .223 Rem case, as it allows more pressure relief with the bore size, while facilitating nice speeds with the charge weights, powder types, and bullet weights.

[LRRPF52]

I start out my nephews and children at 400yds on the 16" Grendel just for their first shots, then start pushing out. To date, first-time shooters have always made 1st-round hits at the "short" ranges.

I even surprised myself when challenged to shoot out to 1200yds with it. I'll be doing a lot more long-range work with the Grendel this spring and summer, as I have 3 new blaster to play with, but CFE223 is performing amazingly well for me right now. I'll also be testing N530, which should be very temp stable, with ideal performance in the Grendel. It's at the same level as RL12 on a burn rate chart...

I agree on the bolts, where metallurgy really has to be paid attention to, and that is already true with the .223 Rem and especially 5.56 NATO. Neither of those cartridges existed when the AR15 bolt was designed, rather they are an evolution of the .222 Remington, which has a 50,000psi MAP.

I'm looking for lower and lower pressures, with optimally burning medium powders that don't spike, but extend the curve down the barrel a bit, without hitting the gas port too hard.

A .420 BC at 2750fps vs. a .510 BC at 2550fps actually does well for trajectory, but not as well for wind. We could also compare custom bullets to each other with the 95gr GS Customs, but the 123gr A-MAX, Noslers, SMK's, and Scenars are more affordable than GS Customs, and do really well as is, staying supersonic longer, hitting 1 Mil of wind drift at 450yds, etc. with lower pressures on the bolt and operating system.

I personally have found Grendel mags to be priced about the same as other AR15 mags, definitely under $20, and I think I've paid $15 per for all of mine.

Stanc's topic seems to explore what else there could be to deliver good performance from the system, and we certainly have looked at .257" bore before. I actually think .257" would make an excellent military bore for assault rifles and LMG's, especially with high SD projectiles for the LMG's and DM/SASS weapons, but you would have to go to a different case if conforming to trends in COL, and the magazines that are common for assault rifles. Basically, don't exceed that 2.260"-2.350" COL. The reason is how the mags stack on the soldier's load bearing equipment, and the varying body types of soldiers.

Does the 1.700" COL of the .25-223 open up some particular projectile options off the top of your head, that a simple .223 1.760" case would swallow the ogive on?

Have you done any development with the 110gr Nosler Accubond?

[stanc]

Stanc's topic seems to explore what else there could be to deliver good performance from the system, and we certainly have looked at .257" bore before. I actually think .257" would make an excellent military bore for assault rifles and LMG's, especially with high SD projectiles for the LMG's and DM/SASS weapons, but you would have to go to a different case if conforming to trends in COL, and the magazines that are common for assault rifles. Basically, don't exceed that 2.260"-2.350" COL. The reason is how the mags stack on the soldier's load bearing equipment, and the varying body types of soldiers.

I may be mistaken, but I don't see why increasing COL to 2.45-2.55" would have a significant adverse effect on this issue.

[LRRPF52]

2.45"-2.55" gives you mags like the G36, which suck to carry unless you're a large-stock Tutonic brute, and even then, that body type can carry as many STANAG 5.56 mags in less space, with the center of gravity of the mags closer to the soldier's C of G, which has become an even more important consideration due to the rampant usage of body armor.

2.5" COL is doable, but pushing the limits, especially for a small-statured soldier who is part of an army that has doctrine based around a significant basic load for individual infantrymen.

A smaller magazine footprint allows placement of other critical tools like commo, the new integrated electronics devices that combine GPS/radio/computer, IFAK, H2O, NVD's, frags, smoke grenades, and special items of equipment.