Ballistic gelatin testing of select 6.5 Grendel loadings was performed this past Monday, May 8, 2006, and I've finally got my hands on the results. I've waited two years for this! CentCom tested one 6.5 Grendel load in August 2004, but, apparently, didn't feel the need to release the results for civilian or commercial use.

Alexander Arms contracted this latest round of gel tests from Speer Law Enforcement representatives in order to have these tests serve as an experimental "control" for ballistics gelatin tests performed by other entities.

Speer performed these tests according to the standard F.B.I. Protocols, as well as their standard in-house procedures. They use 6 x 6 x 16" blocks of ten percent ballistic gelatin, calibrated with a BB. It is interesting to note that Speer uses green dye instead of red to better delineate the temporary and permanent cavities; we conjecture it's for "politically correct" considerations.

Alexander Arms tested four loads: (1) 120 Norma FMJ, (2) 120 Sierra MatchKing (SMK), (3) prototype 123 SMK, and (4) 90 Speer TNT. All tests were performed using production Alexander Arms Tactical 14.5 and Tactical 16 M4-style carbines at ranges of 50 and 100 yards. Here is a summary of the results:


120 Norma FMJ



The 120 Norma FMJ, above, penetrated 16.5" before veering out the side of the block and impacting the support frame. No fragmentation was evident, but the slug is believed to have tumbled at about the 7" mark, with the maximum permanent cavity at the 11" mark. Lesions of more than 6" were created on the top and bottom block surfaces. The Alexander Arms Tactical 14.5 was used in the three 120 Norma FMJ photos shown here. Range: 50 yards. Impact velocity: 2405 fps.



Another shot of the 120 Norma FMJ.



Close-up of 120 Norma FMJ.


120 Sierra MatchKing



The 120 Sierra MatchKing penetrated 3.25" before yawing and fragmenting. The Alexander Arms Tactical 16 carbine was used in the three 120 SMK photos shown here. Range: 100 yards. Impact velocity: 2383 fps. (Velocity from 24" test barrel was 2660 fps @ 49,800 psi.)



Maximum penetration of the 120 SMK was 19.5", maximum permanent cavity diameter was more than 6" with lesions running to block exterior surfaces. Depth to the maximum permanent cavity was 7.5". Bullet fragmented, with seven large pieces visible within the block. Jacket sections came to rest at 11.75" and 16.25", and the bullet core at 19.5".



Close-up of 120 SMK penetration neck before yaw.


123 Sierra MatchKing Prototype



The prototype 123 SMK penetrated 2" before yawing and fragmenting. (The 123 SMK is not currently a Sierra catalog offering.) The Alexander Arms Tactical 14.5 carbine was used in the three 123 SMK photos shown here. Range: 50 yards. Impact velocity: 2385 fps. (Velocity from 24" test barrel was 2650 fps @ 49,500 psi.)



Maximum penetration of the 123 SMK was 16.2", maximum permanent cavity diameter was more than 6" with lesions running to block exterior surfaces. Depth to the maximum permanent cavity was 7". Bullet fragmented into multiple small fragments with jacket pieces visible at 11" and 13". Small core fragment was visible at maximum depth of 16.2"



Close-up of 123 SMK penetration neck before yaw.


90 Speer TNT



The 90 Speer TNT performed as expected for a varmint bullet.


Auto Glass



Entry hole of the 120 SMK through auto glass.



Impact of 120 SMK into ballistic gelatin after passing through auto glass.


Summary

These tests demonstrate the flexibility of the 6.5 Grendel cartridge in tactical scenarios. Each loading is a tool designed to perform a certain job. If you need penetration, use the 120 Norma FMJ. If you need a general-purpose tactical OTM with decent penetration of intermediate barriers yet with very good fragmentation, use the 120 SMK. If you want a long-range bullet that shoots like the 123 Lapua Scenar yet exhibits very early and explosive fragmentation, call for the 123 SMK.

It's interesting that the 123 SMK, a bullet that rivals the 123 Lapua Scenar with its .547 BC, also proved to be the most violently fragmenting round of those tested (well, not counting the TNT). We had been led to believe that bullets that perform extremely well at long range would perform poorly at CQB in MOUT. However, testing now shows that the 123 SMK provides wicked fragmentation at CQB ranges with twice the lead mass of 5.56 NATO, as well as shooting flatter and drifting less than 7.62 NATO out to 1000 yards. This capability in one loading truly makes the 6.5 Grendel a unique tool in the AR15/M16/M4 tactical toolbox.

I will update this report as more data comes in. It's unfortunate that the Wolf 6.5 Grendel ammunition did not arrive in time to test, so that will also have to wait until later.

John

Great start!  I've been waiting to see some gel testing with various 6.5 Grendel loadings.  Can't wait to see more hard data for each projectile like Average neck length, Average MAX TC, Average MAX TC location, total penetration, recovered round diameter, etc. for a minimum 5 gel block test each projectile.  I may have more questions after I have a chance to review this in further detail, but no time right now.  Thank you for sharing!

Neat, keep the info coming!

thank you.

www.65grendel.com/forum/showthread.php?p=9654#post9654

Very impressive.  Been looking for data like this for a long time.

Thanks Grendelizor.  Very interesting and nicely presented.

Any word on when the 123 gr SMK is going to be available?

but....but.....I thought the Grendel didn't perform at close range!

Looking good. I can't wait for the 6.5 piston uppers.

.

My dream upper is a 6.5 Grendel upper, but until they lower the price of the ammo, I'll stick with the .223 or try the 6.8 Rem before I switch to the Grendel.

Man those are NASTY! Maybe I need to go with a 6.5Grendal upper and mags

I've been following the 3 threads (2 ar15.com, 1 65grendel.com) and it is still unclear how many times each test was performed and if it was tested multiple times, if these represent averages or the best performers.  Did the 123gr SMK consistently yaw in the 2-3" range?  Was the 123gr SMK tested against auto glass as well and if so, can you share any details?  Thank you for your help.

These are pretty well average results. Obviously certain loads were selected for repetative testing and also velocity strings were checked to ensure that the velocities seen were representative of the sample.

Until the data set is significant the avarage figures can be squewed by a single aberation and the resulting data will be rubbish. The samples shown as average results also were measured and these figures are the mean for the rounds performance until proven otherwise.

It is not possible to measure the tempory cavity with any great degree of accuracy from the gel block except by means of high speed photography. Also remember that tempory cavitation has no proven effect on a target except within certain tissue types. What you are observing in the gel after the event is the permanent cavity.

Bill Alexander

It is not possible to measure the tempory cavity with any great degree of accuracy from the gel block except by means of high speed photography. Also remember that tempory cavitation has no proven effect on a target except within certain tissue types. What you are observing in the gel after the event is the permanent cavity.

The above is not correct.  

A large scale study was recently completed looking at hundreds of shot lines in calibrated ordnance gelatin and analyzing the temporary cavity measurement using both high speed video as espoused by ARL and via measurements of the radial fissures as developed by Fackler at the LAIR Wound Ballistic Research Lab; no significant differences were noted between the dynamic and static methods--both yield accurate results when correctly done.  

We always measure the temporary cavity, as it can be a significant mechanism of wounding, especially with rifle bullets. However, temporary cavitation effects are extremely variable and erratic. The severity of any injury resulting from temporary cavitation is highly dependent on anatomic and physiologic considerations. The shape of the temporary cavity can help elucidate injury patterns with rifle bullets.  Unlike rifle bullets, the small temporary cavity size from most handgun bullets does not reliably damage tissue and is not usually a significant mechanism of wounding.

Remember, the temporary cavity is merely the empty space very briefly formed by the transient, radial displacement of the tissue surrounding the projectile's path. The tissue that is stretched by the temporary cavity is analogous to an area of blunt trauma surrounding the permanent cavity. Elastic, flexible soft tissues are good energy absorbers and are highly resistant to temporary cavity stretch injuries, ex. Muscle, Bowel Wall, Skin, Blood Vessels, and empty hollow organs. Inelastic tissues are highly susceptible to severe splitting, tearing, or rupture due to temporary cavity stretch insults, ex. Brain, Liver, Kidney, Spleen, Pancreas, and completely full fluid or gas filled hollow organs.

Rifle bullet fragmentation in tissue can greatly increase the tissue disruption, due both to the direct crush from the fragments, as well as the synergistic effects of stretch on tissue newly cut by fragments.

Rifle Bullet Fragmentation Mechanism
1. The rifle bullet fragments in tissue.
2. Multiple fragments spread out radially from the wound tract.
3. Temporary Cavitation stretches tissue.
4. The multiply perforated tissue cannot absorb the stretch which would ordinarily be tolerated by intact tissue.
5. The weakened tissue is torn and disrupted.

Very impressive results considering the testing was done using the 14.5" and 16" barrel versions at 100 yards out.  I wonder what the the result of the added velocity of the 19.2", 20", 24", and 28" models would be in the gel tests - I can only imagine more impressive!