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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons, particularly in larger calibres (12.7+mm).

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Incremental improvement and the M4   Small Arms <20mm

Started 12/2/18 by gatnerd; 17045 views.
In reply toRe: msg 240
gatnerd

From: gatnerd

12/5/18

Some interesting info on the US Air Force, which is adopting the "IMR Blue" improved M4 for their base security troops.

http://soldiersystems.net/2018/05/11/us-air-force-small-arms-update

"Although the final configuration of IMR – Blue has not been disclosed, it will include a [Free Float handgurd,] 1-8 Variable Power Optic and improved trigger group."

 What's especially interesting is what spurned the adoption - the average shooting performance from multiple shooting positions for a group of soldiers averaged 20 MOA for the M4A1 w/ Red Dot, which shrunk down to 3.7 MOA with the addition of the free float handguard + improved trigger.

"People are misunderstanding the 20 MOA thing. It is not a 20 MOA shooter group. It is-

M4 with RAS and 2.5-10x magnified optic using MK262 MOD 1. Zeroed neutrally without any outside influence on the handguard. 1×10 round groups fired at 100m and 200m for baseline. Then the same repeated from 9 different positions=

Prone Mag monopod
Prone Sandbagged
Prone with sling
Prone with bipod
Prone with handguard resting on wood
Prone with guard resting on metal
Prone using VFG
Kneeling using barricad (rifle supported in rear)
Prone with light and laser attached

Each position was measured and plotted on every target. Target was an NRA B-8 bull overlaid on a standard E-Type. When complete the targets from an unfloated M4 averaged over 20moa for all shots. For an optimized M4 (FF stiff handguard, Geissele SSF, etc) the average was 3.7moa.

The testing was done with 20 shooters from multiple branches. Shooters ranged from “average” infantry skill to high master Service Rifle competitors and top level 3-gunners.

People can think what they want about USAF “shooting”, however this test was done correctly and has been verified twice since. It will be verified again shortly."

 

When we look at the improvements seen through the IMR-Blue / SOCOM URG-I, and then the latest insanity of the .270 Weatherby equivalent NGSAR, the case for the M4A2 looks better and better.

 

Mustrakrakis

From: Mustrakrakis

12/5/18

gatnerd said...

 What's especially interesting is what spurned the adoption - the average shooting performance from multiple shooting positions for a group of soldiers averaged 20 MOA for the M4A1 w/ Red Dot, which shrunk down to 3.7 MOA with the addition of the free float handguard + improved trigger.

There were other changes besides that.  There must have been.

I'd argue that if they were using "rack grade" shooters that weren't coached and practiced above and beyond the norm, the shooters likely wouldn't have been holding for 3.7 MOA, let alone actually achieving it.  They certainly didn't achieve those gains, with the same shooters and the same ammunition, simply by changing the triggers and hand guards.

gatnerd

From: gatnerd

12/5/18

From the comments, with someone involved in the testing, the biggest change is the POI shift cause by the original non-free float handguard when fired in different field positions:

"But this is very easy to demonstrate. Use the VFG. Measure the force put into it from “trained” shooters under both physical and mental stress. Have those shooters get a prone sandbagged zero. A true zero with good ammo (MK262) at 100m with 3×10 round groups to center. Take that exact same gun and shooter and have them shoot 10 round groups at 100m with the exact same force they put into the VFG. Measure the center point of impact shift between base zero and VFG. The average user had a shift between 11-19moa.

That’s what’s being discussed, not can a person make a hit at 300m doing everything correct. Take ANY infantry unit with standard non-FF M4’s and make them shoot a stress test from multiple conventional and unconventional positions under time constraints off of common barricades at bullseye targets placed at 100m. Pull the target- you will see good shooters have a 20” or so vertical deviation. Take the exact same shooters and give them a FF rail and do it again. Pull the targets- you will see less than half of the vertical deviation as you had with the non FF rail. Yes the Marines shoot to 500 yards. Ok, they also have different zeros based on position, and they have to hold for it or they miss a massive target. Do you think that’s because the gun can tell it’s being shot from sitting versus prone? Or because the sling is pulling the barrel out of alignment with the optic as it was initially zeroed?

Proper training is extremely important but it will only take someone so far if their barrel isn’t pointed where their sights are because the gun is gripped or rested different.

In reply toRe: msg 243
gatnerd

From: gatnerd

14/5/18

Now definitive testing from CRANE on the improvements offered by the Midlength gas system + the use of Cold Hammer Forged Barrels:

http://soldiersystems.net/2018/05/14/nswc-crane-carbine-mid-length-gas-system-testing-shows-increased-performance/

Some highlights:

"SOF M4A1s normally start to see accuracy degradation at around 6,000 rounds. But during testing of the mid-gas system, they’d hit 12,600 and still hadn’t seen any changes."

"Mid-length cyclic rate of automatic fire was 62.7 rounds per minute (rpm), or 7%, lower than carbine-length for suppressed fire and 127.2 rpm, or 16%, lower for unsuppressed fire."

"For high temperature testing, carbine-length weapons had 576.0 mean rounds between failures (MRBF) compared to 836.1 MRBF for ambient temperature testing and mid-length weapons had 2800 MRBF compared to 1993.8 MRBF for ambient temperature testing."

"For low temperature testing, carbine-length weapons had 333.3 mean rounds between failures (MRBF) compared to 836.1 MRBF for ambient temperature testing and mid-length weapons had 562.5 MRBF compared to 1993.8 MRBF for ambient temperature testing." 

 

Also of general interesting, the lot of M855A1 they tested average 2906fps from a 14.5" barrel, so less hot then the original loading. 

roguetechie

From: roguetechie

30/5/18

Honestly it squares with the difference I see between me with a rack grade non free float gun with carbine gas system and red dot and how I shoot with my middy night force nx8 topped gun with a decent trigger (not great, just decent) a different stock and a free float handguard.

And I'm not anything close to a "great" shooter!

Still, it's actually pretty close to disturbing how much better I shoot with that setup.

stancrist

From: stancrist

30/5/18

gatnerd said...

Some interesting info on the US Air Force, which is adopting the "IMR Blue" improved M4 for their base security troops.

Seems like a needless extravagance.

   - Do USAF base security forces really require the improved accuracy?  And how much of the group size reduction was due to the switch from a red dot sight to variable power optic?

   - At the engagement distances that seem likely on air bases -- assuming they've ever even had armed engagements on air bases -- is there truly a need for a variable power optic?

I have to wonder if this is a case of somebody in the Air Force just wanting to "keep up with the Joneses" (i.e., SOCOM), rather than filling a genuine need...

stancrist

From: stancrist

30/5/18

roguetechie said...

Honestly it squares with the difference I see between me with a rack grade non free float gun with carbine gas system and red dot and how I shoot with my middy night force nx8 topped gun with a decent trigger (not great, just decent) a different stock and a free float handguard.

What difference do you get just with your middy, using red dot sight versus Night Force scope?  Or have you tried this comparison?

Refleks

From: Refleks

30/5/18

There have been a few armed engagements on airbases in the past (active shooter).  

Keep in mind these are also the patrol rifle in cruisers for base policing, not just force protection.   So you may be shooting across a whole flightline in one scenario, or clearing houses in another, so variable optics may not be so outlandish.    Then you have overseas work (ravens, airbase security at places like Baghram, in an environment where green on blue is a risk) as well as your other combat arms airmen (TACP, FAC, Para, etc)  The air force already sends some of its security forces to sniper school (shooting portion not stalker portion), and they evidently see the utility. 

 

The 20 MOA seems to be a cone of possible POI shift due to the non FF barrel, with the extent of the shift varying depending on how the weapon is rested / supported (groups should theoretically still be reasonably tight as long as it's done consistently in each position -- simply not where they were aimed).  So evidently there is a significant relative improvement going for a FF system with better trigger pack and optics.

  • Edited 30 May 2018 20:33  by  Refleks
NathanielF

From: NathanielF

30/5/18

stancrist said...

 

roguetechie said...

Honestly it squares with the difference I see between me with a rack grade non free float gun with carbine gas system and red dot and how I shoot with my middy night force nx8 topped gun with a decent trigger (not great, just decent) a different stock and a free float handguard.

What difference do you get just with your middy, using red dot sight versus Night Force scope?  Or have you tried this comparison?

 

I can speak to this. Went from a stock 6920 to a midlength 14.5" upper and SSA-E trigger, and SF WC556CTN. The difference in felt recoil is greater than when going from my 6920 upper to my 20" rifle upper. HUGE improvement in shooting characteristics, and the trigger allows maximum exploitation of that.

Mustrakrakis

From: Mustrakrakis

30/5/18

roguetechie said...

Honestly it squares with the difference I see between me with a rack grade non free float gun with carbine gas system and red dot and how I shoot with my middy night force nx8 topped gun with a decent trigger (not great, just decent) a different stock and a free float handguard.

How objective was your evaluation?  What courses of fire did you use for this test?  How different were the times?

Someone else already mentioned it, but I'm curious about it myself: were any of the upgrades evaluated on their own, or was it just the complete package?

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