OPTIMUM military caliber report

[malern28us]

I would smoke the hell out of any of mine that underloaded their Mags to 28...

That is leaving half a Mag out of your Combat Load!

If that idea actually worked as suggested, all our troops could carry 7.62 and just put 15 rounds in each magazine....

 

[ssblair]

Maybe the BEST answer is to develop a whole new round and new platform???

My vote is for sharks with laaasers...

 

[Meister]

Having a mix of weapons on the field shooting the same or similar rounds would seem to be the better approach IMO. DMR rifles with LR 5.56 loads would be a substantial leap forward in the distance department. 75g thin jacketed ball rounds would be capable of one shot stops with decent placement. Keeps the door kickers with the current platform to save cash and allows the versatility of shared ammo between both groups. The occupying force must also consider over-penetration in villages and cities with regard to the provisional government's will to protect it's citizens.

Another issue is throat wear on many of the higher powered rounds. Why field a weapon that will eat barrels in less than 3000 rounds. Add in higher weight per round and added cost, it's just not feasible.

The 7.62x51 round fits the bill for the next step up from 5.56, IMO. 118LR will reach out and touch someone, so why develop a new round, mags and platform when the current tech still does the job fine. Maybe cross train on a 7.62 AR style weapon instead of reinventing the wheel.

7.62x51 and 5.56 rounds aren't very hard on barrels unless utilized with sustained auto fire- That's what the 240 is for anyway!

 

[melensdad]

Another issue is throat wear on many of the higher powered rounds. Why field a weapon that will eat barrels in less than 3000 rounds. Add in higher weight per round and added cost, it's just not feasible.

None of the rounds discussed in this thread, which are capable of cycling through an AR15, would be considered as throat burning rounds. In fact all are pretty tame. You need higher case capacities, combined with higher pressures, combined with small caliber bullets to begin to erode the throat and none of these rounds qualify.

 

[Meister]

None of the rounds discussed in this thread, which are capable of cycling through an AR15, would be considered as throat burning rounds. In fact all are pretty tame. You need higher case capacities, combined with higher pressures, combined with small caliber bullets to begin to erode the throat and none of these rounds qualify.

I was under the impression that the 6.5 grendel would half the barrel life. Scuttlebutt, but came from a qualified source.

 

[melensdad]

I was under the impression that the 6.5 grendel would half the barrel life. Scuttlebutt, but came from a qualified source.

Impression wrong. Qualified source is not qualified. The 6.5 Grendel is NOT a barrel burner by any measurement. To erode the throat you need a combination of high case capacity, small relative bore diameter, and reasonably high pressures. Something like the 6.5x284 Lapua would qualify as a barrel burner, as does the 220 Swift; both are large capacity, high pressure cartridges with a small bore diameter relative to the case capacity but neither fit the AR15 sized action. Typical rounds that fit the AR15 action simply don't have the case capacity to erode the barrel, with the possible exception of the 223 WSSM, but that round is really not very common in the AR15, has not been discussed in this thread nor was it mentioned in the attached PDF.

Just for reference the A.A. factory loaded 6.5 Grendel ammo operates at roughly 49,000psi while factory loaded 5.56 is pushing 62,000psi. ​

 

[SSGSAD]

I am "old school", I like the 7.62, for long range "work"... AFAIK, "we" still have M-14 in "mothballs" some troops are using now... Maybe, keep BOTH, and use what is needed, when it is "needed" ..... JMHO

 

[downzero]

Impression wrong. Qualified source is not qualified. The 6.5 Grendel is NOT a barrel burner by any measurement. To erode the throat you need a combination of high case capacity, small relative bore diameter, and reasonably high pressures. Something like the 6.5x284 Lapua would qualify as a barrel burner, as does the 220 Swift; both are large capacity, high pressure cartridges with a small bore diameter relative to the case capacity but neither fit the AR15 sized action. Typical rounds that fit the AR15 action simply don't have the case capacity to erode the barrel, with the possible exception of the 223 WSSM, but that round is really not very common in the AR15, has not been discussed in this thread nor was it mentioned in the attached PDF.

Just for reference the A.A. factory loaded 6.5 Grendel ammo operates at roughly 49,000psi while factory loaded 5.56 is pushing 62,000psi. ​

"Barrel burning" is almost completely a function of powder amount burned. As you're pointing out, friction does play a part.

The question is not whether the barrel throats will erode, but how fast. And I'm sorry to inform you that there is no free lunch; all that extended range and performance does come at a cost of decreased barrel life.

The examples you point out are the extreme fringes of barrel burners--calibers that have very large powder capacities for their bore sizes combine the worst of both worlds.

Pressure = force / area. So you're onto something with considering pressure and area. But you're leaving out perhaps the most important variable--force, which is probably almost completely dependent on powder capacity.

 

[melensdad]

"Barrel burning" is almost completely a function of powder amount burned. As you're pointing out, friction does play a part.

The question is not whether the barrel throats will erode, but how fast. And I'm sorry to inform you that there is no free lunch; all that extended range and performance does come at a cost of decreased barrel life.

The examples you point out are the extreme fringes of barrel burners--calibers that have very large powder capacities for their bore sizes combine the worst of both worlds.

Pressure = force / area. So you're onto something with considering pressure and area. But you're leaving out perhaps the most important variable--force, which is probably almost completely dependent on powder capacity.

Again, all of the cartridges discussed in the PDF in the onset of this thread have very modest capacities. The capacity of the Grendel case is roughly equal to the capacity of the 6.8SPC case. Both are only very slightly larger than the 5.56 case and substantially lower than the 7.62NATO case.

Case capacity of the 5.56 is roughly 31 grains. Both the 6.5 Grendel and 6.8SPC are roughly 35 grains. 7.62NATO case capacity is roughly 56 grains.

All cartridges will ultimately wear out a barrel.

As stated previously, NONE of these rounds is particularly harsh on a barrel, none have a reputation as being barrel burners. None will prematurely erode the chamber throat.