Thoughts about HICAR program's proposed requirements: Short barrels, M855A1+ pushing 82,000 PSI, Overbuilding and the limitations of the AR-15 in context.

Posted by StrangerOutrageous68@reddit | ForgottenWeapons | View on Reddit | 17 comments

Crane has put out a solicitation for the HICAR (Hypervelocity Improved Capability Assault Rifle) project. To fulfill USSOCOM's needs for a carbine utilizing the 5.56x45mm cartridge, and existing M4 lowers that provides twice the effective range of an M4.

Achieved by utilizing much higher pressure loads eg. M855A1+ at 82000 PSI and potentially even higher pressure loads in the future. All that while retaining functionality with lower pressure ammunitions such as the M855A1 and Mk262.

(The table from Eric B's article about the HICAR, where many of you, including myself have probably first heard about the proposed requirements.): https://www.thefirearmblog.com/blog/ussocom-s-hicar-program-wants-to-double-the-m4-s-effective-range-44828497 )

Requirement	Threshold	Objective
Barrel Length	11-12 inches	11-12 inches
Weight (unloaded, no suppressor)	8 lbs	6.5 lbs
Overall Length	31 inches	28 inches
Accuracy (avg mean radius)	1 MOA	0.5 MOA
MRBS*	800 rounds	1,600 rounds
MRBF*	5,000 rounds	10,000 rounds
Barrel Life	8,000 rounds	20,000 rounds
Trigger Pull	Under 5 lbs	Under 3 lbs
Chamber Pressure Rating	82kpsi (M855A1+)	Future HV loads
Submersion Resistance	3 ft / 2 hr, fire in 30 sec	Fire in 10 sec

(MRBS* = Mean Rounds Between Stoppage)
(MRBF * = Mean Rounds Between Failure)

My personal thoughts:

I don't think there's a need for this but if this project continues and progresses to a competition, some of the initially proposed requirements would be changed. But right now, as it stands I don't think that the AR-15 platform is the most viable candidate for the task the requirements call for. Not because of it is a bad platform, but it not designed to handle the type of abuse as compared to for example a SCAR.

Even with an enhanced in all respects and reinforced and strengthened BCG built with cutting edge materials, the upper receiver limits how much you can overbuild the BCG.

So we might see submissions that are completely different uppers, since the solicitation calls for M4 lower receiver utilization. Interestingly enough, breaking out the SCAR could be an option, for this use case, as it is overbuilt and already has a gas-key.

All in all I'm very curious to see the submissions and how the project itself turns out! What do you think?

(image sources: Windham Armory, FN America, midwestgunworks. com, Guns&Ammo)

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One-Strategy5717@reddit

If the requirement is to just use a standard AR lower, this is completely achievable. Maybe not with a traditional DI upper, but there's a lot of alternatives that will fit on a AR lower.

I think it would be advisable, however, to use a beefier bolt, such as on the LWRC Six-Five, the CMMG Mutant, or an AK style bolt like the Robinson XCR-L.

Likewise, I think they should switch to an quickish barrel swap system (LMT, Robinson, MGI Hydra) and treat the barrels as a disposable item. High-pressure/small-caliber rounds cut barrel life significantly, but stainless barrels with nitride coating can be as cheap as $50. Pack a new barrel with each case of ammo, and replace them when accuracy starts falling off.

StrangerOutrageous68@reddit (OP)

You'd want the barrel cold hammer forged, chrome lined and heavy profile. That's my take on it.

Why? Spend $300 on a barrel that will last 3000 rounds at optimal accuracy, or $50 on a barrel that will last 1500 rounds at optimal accuracy.

Remember, the accuracy requirement is 1 MOA. Easier to get that with stainless, and cheap enough to burn through them and replace them.

somerandomguy101@reddit

Seems like we've reached the limitations of the AR. Honestly, all of the engineering work going into these would be better spent on a bullpup with a full length barrel. All issues with bullpups are solvable, and fixes a lot of problems you can't just engineer out of an 82k psi round.

It seems like the only reason we are sticking with ar derivatives is because that's all the army has used for the past half century.

HavelsRockJohnson@reddit

Logistics will always be king of military industrial procurement reasoning. The cost of retraining, reissuing, and restocking entirely new materiel is entirely too high. Unless it becomes absolutely necessary to do so, the AR-15 isn't going anywhere.

True, but if you want to adapt to new adversaries, you need to update your logistics. Using a new round means there's going to have to update all of your logistical infrastructure anyways.

I suspect a bigger reason to stick to an AR derivative specifically is that they don't want to update and retrain on a new platform.

_That_Guy_in_AZ_@reddit

This is a question for Modern Tactical Shooting's reddit, a retired 18B who has insight into your questions.

u/stukas87

stukas87@reddit

My next video is on Hicar! In a little over a week!

cryptidhunter101@reddit

This is the absolute limit of "5.56 is the pinnacle". 5.56 was excellent with the tech of the time and used in conjunction with 7.62x51. It is not a modern cartridge, it is not a long range cartridge, it is not a good solution past 400 yards. If we want more in the same size platform pushing a 6mm ARC or 6.5 Grendel to 65,000 PSI makes a lot more sense. This is just a fantasy system imo.

BigBoarBallistics@reddit

Same issue as with the SiG M7 and M8.

If they don't issue good quality ammuniton, the 2x the range of the M4 is worthless. M855 out of an M4 is at best 2 moa, and that's with a skilled shooter.

Once again, I argue that small fpv drones make the need to reach out and touch someone 1000 meters away a non-issue.

I predict some AR - platform submissions with a 12.5" barrel, as it is noticably less flashy/concussive than a 10.3/11.5 while not noticably less handy. And in short barreled ARs, every inch counts drastically in velocity and in turn fragmentation distance

Lu1zBeast@reddit

An AR can already work with high pressure ammo just fine if you use the monolithic steel cased stuff in development. Shellshock and Sigs 2 piece cases increase bolt thrust over traditional brass or Federals HP steel case. This program will certainly only feature AR like uppers because that's all anyone is comfortable with anymore, the SCAR failed because no one likes the ergonomics (in US Forces anyways, Rangers didn't really like them even though they had them).

BillWilberforce@reddit

I can't see many armies buying a rifle that only has an 8,000 round barrel life.

It's for special forces, I can see that being used.

BeenJamminMon@reddit

I would love to see my beloved SCAR be used to its engineering maximum to field such an outrageous cartridge. Not that I'm biased or anything...

This might very well happen. Who knows?

DullMechanic8597@reddit

I think we're starting to approach the limits of both the gas-operated rotating bolt as well as traditional double base propellants. The stuff your average infantryman will breathe in during a long day at the range (let alone in combat) is already well in excess of what OSHA would consider to be "allowable". Overbuilding the chamber allows for other primary engineering considerations in propellant formulations.

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