Tony Williams Wrote:While I laud the motivation for carrying out such testing, I must draw attention to the recent ARDEC calibre study which may make it unnecessary.
The Army is keeping very quiet about this, but according to the info I am picking up, they did a thorough job. 5.6, 6.2, 6.5, 7.0 and 7.8mm projectiles were tested, each in two bullet styles (Barnes TSX and a "GP" bullet similar in design to M855A1 EPR) ranging in weights from 61 for the 5.6mm to 165 for the 7.8mm. MV and ME varied by calibre. Shooting tests included Angle of Attack (yaw) at 50m and 300m and barrier and post barrier penetration in 20% ordnance gel using many of the FBI test targets (Level IIIA vest, glass, concrete, steel plate) and the 2005 JWB-IPT protocol. An analysis was then done with the raw data of EKE (Kinetic Energy), Pi/Pi/h versus weight, cost, felt recoil, etc. High speed photos were captured of all shots as were images of the bullet fragments. Finite Element Simulations were then developed for expected performance out to 600m (the expected maximum range for future rifle fire).
The 6.5 and 7.0 performance was superior across the board with the exception of Stowed Kills, which is always slanted towards the smaller, lighter calibres.
So it seems that the technical argument has been won. The problem will be to get the Army to act on its own findings. The message seems to have been acknowledged at least to some extent, since future LSAT development will be aimed at delivering improved long-range performance over any 5.56mm loading. Intermediate calibres are now to be examined by the LSAT team, but it would obviously be much quicker and cheaper to resolve the optimum calibre/ballistics/bullet type using conventional ammo and gun techology before redesigning LSAT (and preferably with Geneva-compliant bullets as a part of the development).
It is also important to bear in mind that there are three separate reasons for adopting an intermediate calibre:
1. To improve on the terminal effectiveness, barrier penetration and long-range ballistics of the 5.56mm.
2. To match the long-range ballistics of the 7.62mm with significantly less ammo weight and recoil.
3. To save on procurement, training and support costs by fielding only one calibre and weapon range in portable small arms rather than two.
Our focus tends to be on the first two of these, but I suspect that it's the third one which will prove to be the strongest argument (although of course, it only applies if the first two can be achieved).
Tony / Guys:
You said you found this out which means you have a copy of the ARDEC report or can send a link or means of obtaining the report.
Not that the findings you state are earth shattering. We stopped using the .308 competitively many years ago when the bullet industry started making a bigger variety of 6.5mm match grade bullets than .308. Lighter recoil, equal or significantly better ballistics to 1000 yards, and for .308 based 6.5mm cartridges -- equal barrel life. Lighter recoil probably played as much a role as a decent selection of match grade bullets. Although the improvement in accuracy was probably not significant, the reduction in recoil most certainly was and this meant higher scores.
The 7mm never caught on as it really wasn't that much different in recoil from a .308 and only had one or two types of match grade bullets available.
I can already predict the outcome for Stan though.
His CQM controlled pair test would show the 5.56 to hold a significant advantage.
The mythical DMR test (there is no issued 5.56 DMR for the conventional side), 550 meters is the effective range. Why 550 meters? Maybe the KD range the AMU owns probably doesn't have a 500 yard line? Or they figured that in order for their DMR idea to get traction it needed to show a improvement over the 500 yard (460 meter) max effective range of the issued carbine / M-16A2. Most likely because their KD range is made in yards and not meters and they had to show a improvement. Either way, given a rifle made with the same features as the non existent DMR, the results would not show significance.
Comparing a 20 inch barrel Grendel firing one of the match grade bullets to a 110 firing M-118 Long Range -- both would be statistically equal in terms of hit on a E-Sil at 800 meters (again the max effective range on a point target for a US SWS). I predict that 118 would out shoot the Grendel past 800 and at 1000 the difference would be enough to determine significance.
As for the cinder block test -- it will take less rounds of M-80 to destroy that cinder block than Grendel simply due to kinetic energy differences. Not sure if the advantage would be significant as I am not sure what the test was intended to prove or disprove.
LR1955