The Ultimax reportedly fared badly in the original USMC IAR test (continuous failure to acquire target correctly due to ergonomics issues IIRC),

The LWRC is unique among the three in that it offers a semi-auto mode from closed bolt, which gives you a nice DMR capability in the same package.

If LSAT produces workable plastic cased or caseless ammo, it would be reasonably straightforward to implement it on existing weapons.

But the Corps is FIELDING the M32 revolver GL with the mid-range/hi-cap ammo that weighs the same, shoots a bigger grenade as far and doesn't require a metric shitload of batteries to work without the decade long debacle and ever changing X -nomenclature.

Sustained fire? Define that. Marine Gunners studied this issue over an extended period and conducted trials over a matter of years to specifically define what they wanted out of the IAR. They ditched the QCB requirement specifically because it was found that it was neither necessary nor beneficial if the autorifleman was employing his weapon properly.
Autoriflemen are not MG teams, nor should they be doing that mission.

Nothing illustrates more graphically the differences between the IAR and the SAW as when you watch a SAW gunner run the IAR for the first time. They are trained to aim low and right to allow the burst to walk onto the target when shooting from bipod. With IAR, they just keep missing because the weapon doesn't string in a burst.

I am surprised nobody has tried a smart 40mm grenade launcher yet, I thought the Swedes were going to but I have not heard anything.

Is the IAR supposed to replace the SAW, complement it in some way, or what?

(...)

During Test 2 minor issues developed with each of the weapons systems. Shooters repeatedly had negligent discharges with the Colt, attributable to the Marines forgetting the difference between the closed-bolt M16A2 and the open-bolt AR. The young Marines kept riding the bolt home on a live round, thereby firing the round. With the Ultimax, the shooters realized that the sights were set too low in the rear. Once they achieved stock weld the sights proved to be lower than the eye could see, forcing stock weld to be broken and causing the shooter to search for the sights. With the HK the 3.5 power magnification proved too much at 25 and 50 yards but beneficial at 100 yards. Overmagnification at shorter ranges slowed down the presentation of the weapon onto the target. For the M249 SAW, the weight and length in general made this an extremely cumbersome weapon in field firing positions. Another problem resulted from the commonality of the Colt AR and the M16A2. The familiarity led to initial accuracy, as the young Marines had not yet become familiar with the other weapons.

(...)

On average, during Tests 1 through 4 the 48 shooters preferred the weapons in the following order: Ultimax 100, HK, Colt, and M249 SAW. The questions on the questionnaire focused on nine areas: (1) overall performance, (2) using system sights, (3) detecting and identifying targets, (4) adjusting windage, (5) adjusting elevation, (6) adjusting weapons zero, (7) maintaining zero, (8) malfunctions, and (9) stoppages. Even though the Colt fired the most accurately in most stages, it was next to last in shooter preference.

Recommendations for modifications were requested for each of the weapons systems. The M249 and Colt were viewed as too heavy. The HK failed to stay on target in burst fire while the Ultimax sight system did not present to the eye at all. When the shooter laid his cheek on the stock of the weapon and achieved a proper stock weld he found the sights of the weapon lay below the line of sight capability of his eye. Accuracy—although according to raw data better than the current M249 SAW in every test—was of such a limited amount as to be statistically insignificant. Only on Test 3 did any weapon outperform the SAW by more than 10 percent accuracy.

(...)

Yep, the USMC has always had a long term institutional fetish for the BAR. Probably because so damned few have actually used one USMC is going to optics on everything, which is a great step, if long overdue. The suppressor is much slower in coming, probably due to (mis)perception but also due to heat/fouling issues. S/F....Ken M

Both, sorta kinda. It's supposed to take over the SAW's spot in the fireteams, while the SAWs might be moved to a dedicated team in the squad, or a squad in the platton. It's explained in the Marine Corps Gazette article that also described the tests. It seems the original piece is no longer online, but googling brought it up here among other sites. Here's the part I recalled:

What's the advantage of the SAW over the IAR candidates? How significant is the ability to feed from a belt (200 rounds?) versus 60-100 round box or drum mags?

The Britsh decided that they didnt have enough fire power in their fire teams and have now added a para* Minimi to each fire team while keeping the LSW for its longer range accuracy.

The IAR sounds a lot like the British SA80 LSW. Longer barrel bipod mag feed assult rifle based. The Britsh decided that they didnt have enough fire power in their fire teams and have now added a para* Minimi to each fire team while keeping the LSW for its longer range accuracy.

Acording to the linked article there was only a need for a SAW when the Marines trasitioned from M16A1 to M16A2 and got 3 round burst instead of full auto, does that mean if they went back to full auto M16s they wouldnt need IAR or SAW?

The SA80 LSW, even though it is a bulllpup, is still a big gun due to its very long barrel - hence the accuracy. For a weapon that has only 30rd capacity, its size and weight is not worth the effort as a LSW.

The IAR sounds a lot like the British SA80 LSW. Longer barrel bipod mag feed assult rifle based. The Britsh decided that they didnt have enough fire power in their fire teams and have now added a para* Minimi to each fire team while keeping the LSW for its longer range accuracy.

* Short barrel, retractable stock, effective range 300m.

Acording to the linked article there was only a need for a SAW when the Marines trasitioned from M16A1 to M16A2 and got 3 round burst instead of full auto, does that mean if they went back to full auto M16s they wouldnt need IAR or SAW?

It seems that most western countries seem to be adopting the 4 man fire team

Errm - I suggest you check some stats. The L86 LSW is appreciably shorter than an M16 rifle, despite having a barrel which is 138mm (5.4 inches) longer: it measure 900mm (35.4 inches) overall, compared with 1,006mm (39.6 inches) for the M16.

In fact the L86 is only 60mm (2.4 inches) longer than an M4 with its butt extended, although its barrel is 278mm (nearly 11 inches) longer.

It is a bullpup, after all!

i thought they had full minims for the army except the Para's and i think the RM. which had the Para's. It seems that most western countries seem to be adopting the 4 man fire team

No. AFAIK everyone has the Para. The SAS had the longer barrelled version back in '91 but probably have Paras too now.

I used the word " big ". It's hard to quantify " big " but here's an analogy:

If I cut short the barrel of a BAR so that its overall length is the same as the M16, the sawed-off BAR is still the " bigger " gun.

Furthermore, it weighs the same as the Minimi.

But stats aside, I was critical of the SA80 LSW. So do you have an opinion?

You did say that the L86 is "a big gun due to its very long barrel", which indicated that it was its length that you had in mind...

Just an observation: after avoiding using any of the SA80 family for decades, the SAS recently added the L86A2 to their inventory.

I don't know what's the best way to describe a weapon that looks very chunky and is also very heavy.

And is this because HK finally fixed all the bugs?

The L86 as a sniper rifle/LSW, does sound more and more like a useful weapon now. I rejected it offhand at first as it sounded unfamiliar as a concept.

I had 2 die at a class in 06 and this seems to be a recurring problem that Enidine has been unable to cure. The plastic they use just fails and breaks where the piston arm connects to the end plate. So, good idea but not robust.

The AR is an industry in itself in the US. The real genius is the ability to swap uppers. Unlike QCBs, you don't rezero when changing uppers since barrel, action and sights are all kept in alignment. GENIUS!

It has always been extremely accurate, and is regarded as a 600m gun whereas the Minimi is thought of as a 300m gun.

I have used the Enidine AR-Restor hydraulic buffer on both a DI and a piston AR. It almost completely eliminates buffer slap even with a standard buffer spring and makes a huge difference in perceived recoil and controllability. On FA, it cuts the cyclic to about 700rpm. Sounds too good to be true? It is. I had 2 die at a class in 06 and this seems to be a recurring problem that Enidine has been unable to cure. The plastic they use just fails and breaks where the piston arm connects to the end plate. So, good idea but not robust.

Essentially you put a hydraulic buffer to cushion any slap to the back end of the buffer tube. Using correct srpings, you can acheive this also.

I have never shot beyond 300m.

We were taught that the iron-sight M16S1 (or A1) has an effective combat range of only 300m. We're taught that at 300m the 5.56 bullet is travelling more or less a t level with muzzle.

Does it drop significantly beyond this range?

At 600m, how much lower would the 5.56 have dropped?

Would it have lost its so-called " effectiveness "?

IINM, SAR-21 issued to SAF is 1:7 twist.

I have never shot beyond 300m.

We were taught that the iron-sight M16S1 (or A1) has an effective combat range of only 300m. We're taught that at 300m the 5.56 bullet is travelling more or less a t level with muzzle.

Does it drop significantly beyond this range?

At 600m, how much lower would the 5.56 have dropped?

Would it have lost its so-called " effectiveness "?

But regarding QCB, I didn't know you have to re-zero? So on stuff like GPMG and SAWs when you switch barrels, you have to re-zero? Don't sound quite right...

Is there some reason why the USMC wouldn't just make the IAR standard isue? Most of those designs don't look like they'd be any heavier or longer than an -A3, and they plan to give everyone optics anyway.