6.5 Grendel Armor Piercing ammunition data/info...

[JASmith]

Point taken.

Bill Alexander may well have gone this way, which is why we see what appears to be a confusing set of data.

My earlier comments apply to the civilian side of the business. Most folks will look at the reported velocities and NOT know how to translate to their barrel length. Few of those than know how will bother. Hence my view that AA is seriously underselling their cartridge.

[stanc]

I can't think of a good reason for reporting the 50 yard velocity.

Those loads on the AA site which show 50-yd velocities are because of the related gel tests. The gel blocks were set at 50 yards. In gel testing, it seems to be standard practice to note the impact velocity. I imagine that's why AA lists it so.

[stanc]

IMO muzzle velocities of milspec ammo should be given from 20 inch and 14.5 inch barrels, as these are the two most likely lengths to be used in military weapons.

Concur. But, I don't know if any 6.5 Grendel loads can actually be considered milspec.

The closest are the 123gr SMK (which correlates to 5.56 Mk262 w/77gr SMK) and 120gr TSX (which compares to 5.56 "brown tip" optimized w/70gr TSX).

The 123gr SMK bullet lacks a crimping cannelure, and the 120gr TSX projectile is seated too deep to crimp. Plus, I doubt that either has sealing of primer and case mouth.

[coastguardchas]

stanc: Aha, the curmudgeon returns. I am limited to TSX or similar non-lead bullets, and have been using TSX in 120 and 100 gr exclusively. I load the 120gr to 2.260 and the 100gr to 2.250. I could crimp the 100gr as is, or the 120gr by seating a little deeper. Don't crimp either.. Chas

[Tony Williams]

Concur. But, I don't know if any 6.5 Grendel loads can actually be considered milspec.

Well, if the Grendel is to be taken seriously as a potential military cartridge, it should surely be available in at least one FMJ loading? Preferably two, in fact: one with lead, one without.

[stanc]

Well, if the Grendel is to be taken seriously as a potential military cartridge, it should surely be available in at least one FMJ loading?

I can't disagree with that. FWIW, Alexander did try to get FMJ ammo made. Unfortunately, the low-cost FMJ from Wolf has been subject to ongoing delay (although it is still listed on the Wolf web site), and Hornady reportedly was just not interested in producing FMJ ammo in 6.5 Grendel.

I suppose there is no technical reason preventing AA from making FMJ ammo with the Norma 120gr bullet, but I suspect that pricing would not make it worthwhile. Besides, wound profile of the Norma FMJ is very much like that of non-fragmenting 7.62 M80, and lacking the early yaw that you desire. See attached.

[JASmith]

But it's a start...

Better some offering than none.

I am rather curious to see what kind of bullet the requirements discussions take us to. Performing well without deforming in gel while at the same time being able to defeat a handful of different barriers sounds like a tall order!

[stanc]

But it's a start... Better some offering than none.

Perhaps, but I think that isn't the way Bill works. It seems that he'd rather take all the time needed to get the design as nearly perfect as can be, instead of going with something less perfect, even if readily available off-the-shelf.

And despite occasional comments that he isn't interested in military contracts, he continues to work on development of military-type (Ball and AP) bullets.

I am rather curious to see what kind of bullet the requirements discussions take us to. Performing well without deforming in gel while at the same time being able to defeat a handful of different barriers sounds like a tall order!

Indeed it does. However, I'm not sure if there are any practical options at present other than:

1. Conventional (albeit unleaded) FMJ for UK/Europe.
2. M855A1/M80A1-type projectiles for the US Army.*

* Of course, if the M855A1 proves to be a major failure, then the US Army may become open to other bullet types, such as the Mk318 SOST round currently used by the USMC.

[Tony Williams]

That unsatisfactory gel test of the FMJ bullet has already been used in a British report on future small-arms ammunition to discredit the effectiveness of the 6.5mm calibre, so it is indeed important to get it right.

RUAG are offering an interesting new lead-free 5.56mm loading which is like the M855A1 except that the steel penetrator is still enclosed in the jacket (or like the M855 only with a copper rather than lead plug), thereby meeting European sensibilities. That looks like a promising starting point for scaling up, but I suspect may be problematic for a small firm to develop. Take a look at the LF HC SX (they really must think of a snappier name!) at the bottom of this page: http://www.ruag.com/en/Ammotec/Defen...ket_ammunition

[kamrr4437]

Ive got some of those MK318 SOST rounds. There open tip rounds. They were designed specifically for the SCAR and are barrier rounds. The theory behind the open tip was to be able to penetrate glass windshield so to speak and the bullet stay on track after entrance through the glass rather than deflect off the glass like the M855. The M855 and M193 shoot accurately as heck through my AR, but the 62 grain SOST round im not real impressed with at least for my gun. They are here and there at 50 yards with about a 5 or 6 inch group. Whereas the other 2 or any Hornady ammo will just make a consistent circle. I had to have me some though lol. It would be very nice to have some Grendel rounds that could do what the M855 does. I have shot through a 1/2 inch of plate steel at 50 yards with that stuff. I would love to see the Grendel with a steel core penetrater in it. Like Bwaites said we all have dreams

[stanc]

That unsatisfactory gel test of the FMJ bullet has already been used in a British report on future small-arms ammunition to discredit the effectiveness of the 6.5mm calibre, so it is indeed important to get it right.

Ah...I didn't realize that the Norma FMJ gel test had been used to discredit 6.5mm. That tidbit certainly puts a different light on things. (Although it's still the best FMJ option currently available for testing. A pity that the 113gr 6.5x55 AP bullet can't be had in quantity; that could be interesting to test.)

RUAG are offering an interesting new lead-free 5.56mm loading which is like the M855A1 except that the steel penetrator is still enclosed in the jacket (or like the M855 only with a copper rather than lead plug), thereby meeting European sensibilities.

Other than being eco-friendly, I see nothing new in the design; it's essentially just the same ol' M855. I wonder if barrier performance is any different than M855?

That looks like a promising starting point for scaling up, but I suspect may be problematic for a small firm to develop.

Maybe so, but it has to get done by somebody if an intermediate cartridge is to have a chance of success.

[JASmith]

Ref Posts #52, #55, and #57: Too bad the gel test in the first frame wasn't reduced to a sketch to allow a more direct comparison with the results sketched in the second frame.

We need to establish a consistent set of experimental data -- comparing a stoutly designed FMJ bullet in one caliber with one that breaks up in another caliber is not a consistent check.

The folks that make this kind of comparison are either naive or have an agenda...

[stanc]

Ref Posts #52, #55, and #57: Too bad the gel test in the first frame wasn't reduced to a sketch to allow a more direct comparison with the results sketched in the second frame.

We need to establish a consistent set of experimental data -- comparing a stoutly designed FMJ bullet in one caliber with one that breaks up in another caliber is not a consistent check.

If you're referring to the pics in post #52, neither bullet breaks up. Both are non-fragmenting projectiles.

I got to thinking about the topic this morning. Wound profiles of the majority of FMJ rifle bullets show undesirably late yaw. This is especially true of FMJBT projectiles, regardless of caliber (the notable exception being the 5.45x39 M74 round). So it should not be surprising that the 6.5mm Norma 120gr FMJBT also displayed late yaw; the same would almost certainly be true of the 6.5mm Lapua 144gr FMJBT, as well as the Swedish military 140gr Ball and 113gr AP bullets.

I question if the RUAG design (shown in post #57) -- scaled up to 6.5mm, per Tony's suggestion -- would provide the desired results. Gel tests of M855 show the late yaw typical of FMJs, when the bullet has a very small angle of attack (see right pic at http://www.itstactical.com/wp-conten...09/07/pic4.jpg)

Those FMJs which show relatively early yaw are typically short-for-diameter designs -- 7.92x33 Kurz, 7.62x39 M67, 6.8x43 SPC -- and they are hardly spectacular in this regard, with onset of yaw at ~3 inches.

The only example I've seen of early yaw in a streamlined, long-for-diameter bullet -- which is the configuration needed to give an intermediate caliber the necessary long range capability -- is the Russki 5.45x39 round (see attached). AFAIK, that's the only proven design; either copy it, or spend a lot of time and money trying to reinvent this particular wheel.

[JASmith]

Stan,

Many thanks!

I was just looking at one of M. Fackler's reports, and it looks like the 7.62 bullet was not the M80, but a 150 gr FMJ, and the sketch showed an outline of the bullet in different attitudes.

I think you see the reason for delayed onset of tumble in the boattail designs is the same for why Tony has been suggesting a hollow windscreen. The boattail moves center of gravity forward, which helps stability. We want to move it backward...

The good news is that there may be some clues in the BT/non-BT results to give us a clue on how far it needs to move and whether the void can be filled with something visible to x-ray but otherwise low density.

Thanks!
Joe

[stanc]

I was just looking at one of M. Fackler's reports, and it looks like the 7.62 bullet was not the M80, but a 150 gr FMJ...

It doesn't seem to make a difference if it's a 147gr FMJ. Attached shows "copper" (actually gilding metal) jacket M80, with same wound profile.

I think you see the reason for delayed onset of tumble in the boattail designs is the same for why Tony has been suggesting a hollow windscreen. The boattail moves center of gravity forward, which helps stability. We want to move it backward...

The 5.45x39 M74 bullet also appears to have a rather large-caliber ogive. Perhaps that is another factor effecting early yaw?

The good news is that there may be some clues in the BT/non-BT results to give us a clue on how far it needs to move and whether the void can be filled with something visible to x-ray but otherwise low density.

Why fill the void? Any substance will necessarily have much higher density than air.

Again, why bother trying to reinvent what has been shown to work? Just scale up the 5.45 bullet to 6.5mm and be done...