The Next Infantry Assault rifle for the United States

[Raven22]

There is more to felt recoil than just the Newtonian physics of the bullet and propellant gas leaving the weapon. This is the first impulse contributing to recoil and movement in the weapon. The second impulse is caused by the bolt group moving back and forth in the receiver. The third is if the weapon has the bolt group strike a buffer in the rear of the receiver and the fourth when the bolt group comes to a halt against the chamber while loading a new round. While the bolt group doesn’t move at the same velocities as the bullet) and gas leaving the barrel (about 10-20 feet per second) it is much heavier (500 g rather than 4 g) and its impulses take place over a lot longer time. Typically a bullet and gas has left the barrel in under 2 milliseconds and the action of the bolt group takes about 10-20 milliseconds. Anyway opening up the gas port has the down side of increasing the velocity of the rearward movement of the bolt causing stronger impulses.

How is the movement of the bolt and bolt carrier not Newtonian physics? Masses are moving - that is the very centre of what Newton was on about.

Anyway, the original post was talking about the kick of a weapon, which is caused by the bullet leaving the barrel and the fact that the axis of the bore is above where the weapon is being held. If you want to reduce this just do what Kriss did with their submachine gun.

 

[an94stalker]

Given the u.s progress with the Lightweight Small Arms Technologiesprogram, it's hard to believe the next rifle won't come from this program.
But i wonder what are the access limitations to this technology. How can australia develop their next rifle without access to caseless ammo?

Whatever the case Australia will need to replace their rifle by 2020. The Ef88 is only an interim upgrade, 6000 for frontline troops. No doubt u.s will start to feel pressure from her allies for access to caseless tech so they can develop their next rifle.

ps
Apparently the an-94 patents may be as old as 1980, so very likely they already have expired. Which tells us why the u.s military now wants hyperburst, it's public domain tech.

 

[Raven22]

Whatever the case Australia will need to replace their rifle by 2020. The Ef88 is only an interim upgrade, 6000 for frontline troops. No doubt u.s will start to feel pressure from her allies for access to caseless tech so they can develop their next rifle.

The EF88 is not an interim upgrade - the F88SA2 is the interim upgrade. As stated though, the EF88 will only be issued to combat troops. There's not much point giving gucci integrated sights and NADs etc to pogues that will never fire their weapon anyway. The F88 fleet will eventually consist of a mix of the F88SA2 and the EF88 before the small arms replacement program delivers a new weapon.

 

[Abraham Gubler]

How is the movement of the bolt and bolt carrier not Newtonian physics? Masses are moving - that is the very centre of what Newton was on about.

I didn’t say they weren’t. I referred to ‘more than just the Newtonian physics of the bullet and propellant gas leaving the barrel’.

Anyway, the original post was talking about the kick of a weapon, which is caused by the bullet leaving the barrel and the fact that the axis of the bore is above where the weapon is being held. If you want to reduce this just do what Kriss did with their submachine gun.

The movement of the action also contributes to the kick of the weapon. Which is why I brought it up in relation to the point about the gas settings. If you open up the gas setting without a fouled weapon or ammo and temperature effects requiring it you will get a greater kick from the weapon.

 

[Abraham Gubler]

Given the u.s progress with the Lightweight Small Arms Technologiesprogram, it's hard to believe the next rifle won't come from this program.
But i wonder what are the access limitations to this technology. How can australia develop their next rifle without access to caseless ammo?

LSAT was a demonstration program and is now over. The project definitely focused on cased telescope ammunition (CTA) as the preferred and most viable option. If the USA decides to purpose LSAT and CTA small arms technology further then Australia, the UK and Canada will have no problems accessing the technology. These nations actually have a small arms and weapons access standardisation treaty (ABCA) with the USA.

But it’s a big IF that the USA will pursue LSAT. The demonstrator program was clearly a great success and meet its objectives. They demonstrated a 37% reduction in ammunition weight and a 48% reduction in LMG weight with CTA ammo. However the USA is cash strapped and launching another big project is very unlikely. I think they will want their new IFV (GCV), helicopter (JHX) and tank upgrade (M1A3) before they want to adopt a new type of small arms ammunition.

 

[Raven22]

The movement of the action also contributes to the kick of the weapon. Which is why I brought it up in relation to the point about the gas settings. If you open up the gas setting without a fouled weapon or ammo and temperature effects requiring it you will get a greater kick from the weapon.

Compared to the impulse of the bullet leaving the barrel, the movement of the working parts doesn't significantly add to the recoil. I mean, it will make the weapon move around and make follow up shots more difficult (which is why you need to balance a machine gun by adjusting the gas setting), but its hardly going to contribute to you having a sore shoulder at the end of a range session (ie, the kick being discussed).

To test it, take a Steyr and fire it normally, then turn the gas plug to the grenade setting and take out the gas piston and fire it again. The working parts won't move, but I bet you won't notice a difference with recoil.

Or, go to the WTSS and fire a weapon there. The weapons in the WTSS is gas operated with all the working parts moving as they do with a real weapon - the only thing missing is the bullet. Yet you won't feel any recoil at all, the weapon will just shake in your hand.

 

[Abraham Gubler]

To test it, take a Steyr and fire it normally, then turn the gas plug to the grenade setting and take out the gas piston and fire it again. The working parts won't move, but I bet you won't notice a difference with recoil.

Well it depends on the weapon. It made a big difference with the SLR but obviously not the much lighter powered F88. When we used to operate both calibres concurrently with the M16 it was always a shock just how insignificant the recoil was firing the M16 after the SLR.

 

[old faithful]

Rubbish,it made FA difference with SLR.
IA was to drop the gas setting by 2. Starting at 5.
When working in places like Tully, I started on 2 not 5.
Live firing, the difference in recoil with the SLR was not noticable wet her the gas setting was 5 or 0.
Ballastite round was a different story. kicked like a mule when launching rifle grenade, something I only got the oppertunity to do at Infantry IET 1985.

 

[My2Cents]

But it’s a big IF that the USA will pursue LSAT. The demonstrator program was clearly a great success and meet its objectives. They demonstrated a 37% reduction in ammunition weight and a 48% reduction in LMG weight with CTA ammo. However the USA is cash strapped and launching another big project is very unlikely. I think they will want their new IFV (GCV), helicopter (JHX) and tank upgrade (M1A3) before they want to adopt a new type of small arms ammunition.

While I agree totally with the above, if the Pentagon, or more likely Congress under influence or advocates/pundits, do decide it is necessary to adopt a new cartridge because of the real or perceived shortcomings of the 5.56mm round, then the incremental cost for switching to a CTA design for ammunition is substantially reduced. Factor in the health benefits of reducing the average infantryman’s load and they may even be able to argue that the costs appear negative in an analysis.

 

[Abraham Gubler]

Rubbish,it made FA difference with SLR.
IA was to drop the gas setting by 2. Starting at 5.
When working in places like Tully, I started on 2 not 5.
Live firing, the difference in recoil with the SLR was not noticable wet her the gas setting was 5 or 0.

I can remember it being a difference on a clean weapon and I owned a SLR for a few years before the gun buy back and noticed a difference in target shooting.

Ballastite round was a different story. kicked like a mule when launching rifle grenade, something I only got the oppertunity to do at Infantry IET 1985.

I never got to fire rifle grenades but from memory the procedure was to turn the plug around so no gas could escape down the gas piston as all of it was needed to propel the grenade.

The rifle grenade (Energa) produced a bit less potential energy for recoil as a 7.62x51mm bullet but the potential energy from the ballistite propellant was far more powerful.

 

[Marc 1]

I can remember it being a difference on a clean weapon and I owned a SLR for a few years before the gun buy back and noticed a difference in target shooting.



I never got to fire rifle grenades but from memory the procedure was to turn the plug around so no gas could escape down the gas piston as all of it was needed to propel the grenade.

The rifle grenade (Energa) produced a bit less potential energy for recoil as a 7.62x51mm bullet but the potential energy from the ballistite propellant was far more powerful.

Never got a chance to fire a rifle grenade either - probably best that they got rid of that cumbersome system - bad news if you used ball ammo, bad luck if you had no blank rounds. Was at the small arms wing at Singo when they were trialling the bullet through grenades.... yet another project that died a premature death along with the German paratrooper boots being trialled, the flash all cotton DPCU's that eventually went to the SAS.

Sad times the late 80's early 90's - 6 and 5/7 RAR yet never fired a HEAT round from an 84 (one prac one illum) - never saw more than a subcal for the 66mm SRAAW in the battalions (saw one HEAT at a firepower demo). Only threw probably 4 x M26 grenades in the entire 6 years in the army.

 

[Abraham Gubler]

Never got a chance to fire a rifle grenade either - probably best that they got rid of that cumbersome system - bad news if you used ball ammo, bad luck if you had no blank rounds.

The VietNam AAR for RAInf praised the rifle grenade. Said it was the best infantry support weapon compared to the 40mm GL and 66mm LAW. It was the most accurate at range and had the best terminal effect. While unloading your weapon with ball ammo to use it was a bit clumsy the advantage was everyone in the section bar the gunner could use them. Obviously the bullet through or bullet trap grenades solves that problem.

 

[ngatimozart]

Never got a chance to fire a rifle grenade either - probably best that they got rid of that cumbersome system - bad news if you used ball ammo, bad luck if you had no blank rounds. Was at the small arms wing at Singo when they were trialling the bullet through grenades.... yet another project that died a premature death along with the German paratrooper boots being trialled, the flash all cotton DPCU's that eventually went to the SAS.

Sad times the late 80's early 90's - 6 and 5/7 RAR yet never fired a HEAT round from an 84 (one prac one illum) - never saw more than a subcal for the 66mm SRAAW in the battalions (saw one HEAT at a firepower demo). Only threw probably 4 x M26 grenades in the entire 6 years in the army.

We used the SLR & grenade launcher when I was in the navy, to fire a gun line across to another ship, and it kicked like a mule to. Regulator was set to 0

 

[old faithful]

Balastite is not a blank round, no projectile,but produced a huge amount of gas.
End of year yippie shoot about 89, was one to remember,have no idea how many 84 HEAT rounds we fired, but it was state of origin night, and we went sick on an old CENT, had to wait until dark to get rid of the illum,made it back just after kick off, we fired dozens each.
Navy still use that system to pass re fuel lines etc I think. same round, same recoil.
3RAR must have had it a bit better than most, threw heaps of M26, fired heaps of 84, 40mm not many M72, but a few.
There was a period when Keating took over, that was crook, no blanks, OC, got sick of us pull in the piss on ex, gunners yelling out "BUCKETS of BULLETS" to simulate MG fire, we ended up doing a lot of live fires that year.
I owned an SLR to Abe, got $800 for it in the buy back.

 

[Abraham Gubler]

Balastite is not a blank round, no projectile,but produced a huge amount of gas.

Ballistite is basically a double base explosive (nitrocellouse and nitrogyclerine) with 10% camphor. As in the camphor laurel. The camphor was originally added for stability back before cordite and other smokeless powder mixes were developed. But I guess the camphor is turned into a good dose of high speed gas which is why ballistite is still used for rifle grenade propelling.

I owned an SLR to Abe, got $800 for it in the buy back.

I thought I got screwed...

 

[Abraham Gubler]

Here is the excerpt on weapons from the VietNam AAR I mentioned above. Many comments still relevant today (not much has been learnt).



Infantry Battalion - Lessons learned from Vietnam
Directorate of Infantry (1973)

M16 5.56mm. A versatile weapon, without the stopping power of the SLR, and one which requires careful maintenance to avoid stoppages.
(1) Needed for scouts and in ambushes because of its automatic capability.
(2) It has reasonable incapacitating effect up to 100m, but lacks penetrating power in undergrowth.
(3) Easier to handle than the SLR but, because of the large foresight bracket, still catches on undergrowth in very close country.
(4) Needs camouflage painting or taping to stop shine from the fiberglass components.
(5) The lower receiver assembly must be kept well lubricated, but soldiers must not be allowed to strip or tamper with this mechanism.
(6) Much more effective than the F1 submachine gun.
(7) Present scaling (265) for a battalion is adequate.

SMG 9mm F1. A light, reliable, and easily handled weapon which should be most useful because of its automatic capability. In practice it lacks incapacitating power, and does not now appear to deserve a place in an infantry battalion equipment table. A small pool has been suggested for use in village searches and inner cordons.

GPMG M60. A reliable (when well maintained) machine gun, which has proved its worth in action.
(1) It is heavy and cumbersome to handle, too much so for general patrol and section work.
(2) There is a tendency to regard the M60 as a personal rather than a crew weapon in which every soldier must be thoroughly trained, particularly in advanced handling by day and night.
(3) Particular components have in the past broken too easily. These have largely been, or are being rectified.
(4) The biggest disadvantage is the carriage of belt ammunition. It is awkward, the links splay easily, and it readily collects dirt and mud. Various methods have been tried for carrying the belts, from Claymore bags, pouches utility, to specially manufactured waterproof covers.
(5) The biggest advantage is its dependable sustained fire. The new scaling of 28 per battalion in a pool is considered adequate for the sustained fire role.

90mm RCL. Is mainly used in defensive locations or ambushes close to the base (flechette round thought valuable), as too heavy to patrol with.

Grenades. Rifle grenades performed better than the M79 grenade-launcher or M72 LAW (although it looks like a training deficiency caused problems early on). [US] M26 hand grenades projected from the rifle [with an issue add-on tailboom and fin assembly] are extremely accurate and successful against bunker systems. Projected grenades are far superior to the M79 and M72 in secondary jungle, and must be carried in quantity.

 

[aussienscale]

I can remember it being a difference on a clean weapon and I owned a SLR for a few years before the gun buy back and noticed a difference in target shooting.



I never got to fire rifle grenades but from memory the procedure was to turn the plug around so no gas could escape down the gas piston as all of it was needed to propel the grenade.

The rifle grenade (Energa) produced a bit less potential energy for recoil as a 7.62x51mm bullet but the potential energy from the ballistite propellant was far more powerful.

Agree, I used to do Interservice Taget Shooting and found gas settings on the SLR did make a difference, but also on different rifles as well, most of us usually stuck with the same one, and from memory most in the team had their own preference on gas settings as well in their preffered setup along with different ways of setting up the sling, my favourite was a wrap around the carry handle then looped around the back of the arm and adjusted to make a nice snug fit into the shoulder

Cheers

 

[Volkodav]

I thought I got screwed...

A mate had a semi auto Franchi SPAS 12 and decided to take it out for one more shoot before surrendering it. Murphies law, the chamber cracked, making it pretty much worthless. The gunsmith said it wasn’t possible to repair it during the buy back and suggested smothering it in oil on the off chance the guy doing the inspection at the surrender wouldn’t want to get his hands dirty.

He got away with it and got full price for a stuffed gun.

I was looking at an M1A or a HK 770 for myself and was actually shopping for a 12 gauge pump action for my brothers 21st when Port Arthur happened. Being a leftie I gave up on long arms and have only ever owned pistols.

I did get more than I paid for my last one new (a .40” semi auto) a couple of years before the government decided to ban larger than .38”/9mm. Good timing but not by choice, I was unable to shoot for several months following a MVA and the oxygen thief in charge of the fire arms branch refused to renew my licence as I had failed (by one) to complete the minimum number of club shoots that year.

 

[Marc 1]

Balastite is not a blank round, no projectile,but produced a huge amount of gas.
End of year yippie shoot about 89, was one to remember,have no idea how many 84 HEAT rounds we fired, but it was state of origin night, and we went sick on an old CENT, had to wait until dark to get rid of the illum,made it back just after kick off, we fired dozens each.
Navy still use that system to pass re fuel lines etc I think. same round, same recoil.
3RAR must have had it a bit better than most, threw heaps of M26, fired heaps of 84, 40mm not many M72, but a few.
There was a period when Keating took over, that was crook, no blanks, OC, got sick of us pull in the piss on ex, gunners yelling out "BUCKETS of BULLETS" to simulate MG fire, we ended up doing a lot of live fires that year.
I owned an SLR to Abe, got $800 for it in the buy back.

3 RAR (Para) = ODF back then. Unlimited bucket of money/allocation of IET's/Ammo whatever compared to rest of army. You guys, 1 and 2/4 RAR.

 

[Marc 1]

Here is the excerpt on weapons from the VietNam AAR I mentioned above. Many comments still relevant today (not much has been learnt).

...snip...

(4) The biggest disadvantage is the carriage of belt ammunition. It is awkward, the links splay easily, and it readily collects dirt and mud. Various methods have been tried for carrying the belts, from Claymore bags, pouches utility, to specially manufactured waterproof covers.

And only now being solved by the yanks with their containerised feed linked 750 round backpack units. Hmmm, only 40 years to fix.... If others haven't seen one (I know you have Abe!) think of the feed system in Terminator linked to the 7.62mm minigun - except its got the same sort of flexible feed chute clipped to the Minimi Feed cover. Nice way to keep your link clean, not twisted, devoid of leaf litter/twigs etc with a full 750 rounds available.... A gunners wet dream.

(5) Grenades. Rifle grenades performed better than the M79 grenade-launcher or M72 LAW (although it looks like a training deficiency caused problems early on). [US] M26 hand grenades projected from the rifle [with an issue add-on tailboom and fin assembly] are extremely accurate and successful against bunker systems. Projected grenades are far superior to the M79 and M72 in secondary jungle, and must be carried in quantity.

Didn't know that - Thanks. Very interesting.