XM8 (yes I know it's dead)
HK416
Bushmaster ACR
FN SCAR
Robinson Arms XCR
LWRC M6A4
Rate of fire is designed in with a number of variables. Gas port opening size = amount of gas to push a certain mass such as bolt, bolt carrier (there are lighter and heavier bolt carriers through the life-span of the M-16, M-4 family of weapons)and gas piston. Heavier the mass, slower the rate of fire. Spring rates can also effect rate a fire to certain degree.
I see. That makes sense. So is a faster rate of fire generally considered better, or is there some sweet spot where your firing a lot of bullets but the recoil is controllable enough to make it accurate while in fully-auto?Originally Posted by surfgun
In the past a slower rate of fire is considered desirable. The first clear example is when the M-3 Grease-Guns came out (a much slower rate of fire than the Thompsons), Through the history of the M-16 they have gone to heavier bolt carriers (actually w/ heavier buffers) to slow the rate of fire. The reasons include higher hit probability (easier to control point of impact) and perhaps a stronger reason is to save ammo.
Last edited by surfgun; 25 Nov 09, at 01:48.
Honestly, I think the ACR in a 6.5 Grendel would be king. But neither the platform nor the caliber are gonna be adopted in the next 5 years. Let's face it, another few years and we will have some kind of product from the LSAT program. Polymer cased ammo with significant weight reduction is already operationally ready, they're just hoping to not even stop short and go straight to caseless.
So here is what I suggest for the current remedy, which is fairly doable:
1. Gas piston retrofits, if its found to be absolutely necesarry.
2. Fail Zero EXO-coated bolt kits.
3. Spreading around the heavier grain ammunition much more.
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Another great AR,comes in 4 different calibers.Robinson Armament XCR
Robinson Armament XCR - Wikipedia, the free encyclopedia
That would be the most economical and best first thing IMO. It would solve the main problem with the AR.
To be clear, I have minimal understanding of engineering. But I have heard that you actually can't just put gas piston upper on a M-4 lower and expect the same service life, because the receiver Eugine Stone designed was not made to take the recoil force of the bolt and would wear out faster than a GI M-4.
All those who are merciful with the cruel will come to be cruel to the merciful.
-Talmud Kohelet Rabbah, 7:16.
Not what I have seen so far. The jury is still out on longevity, but function is unrivaled at this point.
I believe it has something to do with the fact that the rear buffer gets in the way a lot and the bolt grinds into the walls of the buffer tube as the gun recoils. This is due to the fact the recoiling forces on a piston system are slightly above the bolt of a gun and causes it to tilt a bit. Compared to a DI gun which the recoiling force is directly inline.
Interesting point! I will have to check into that. I was actually thinking of doing one on my AR in leiu of getting an XCR or Masada.
Of course I dont need something that will last to 10,000 rounds or so..........or do I?
All excellent weapons, but the HK416 would have by far the easiest transition.
F/A-18E/F Super Hornet: The Honda Accord of fighters.
I'm going to assume that reliability is probably comparable for these rifles. Does anyone have any info on cost and accuracy among the contenders? I think those would be the debatable factors since they are all pretty much clones of each other.
IMO, HK has never been a giant in the accuracy dept and I know the XCR had issues as well.
I'm betting they all retain the same amount of accuracy about 2 moa. I believe that because almost all these guns use short-stroke piston systems which degrade accuracy by about 0.5 MOA compared to a DI gun. But hey you gain a lot in reliability and it's not so much of a big deal in normal combat conditions. All of these use free floated rails as well. The only thing is I think the XCR would have the worst accuracy but not by much. Maybe a 2.5 to 3 moa gun because of it's AK style piston system.
Why that makes any sort of sense at all is because piston guns are naturally heavy in the front and are connected to the barrel of gun. So the DI being the lightest will give the least amount of uneaven oscilation as the barrel likes to flex as the bullet travels down. So the uneaven weight displacement with the vibration of the barrel causes slight differences in where the barrel is pointing as opposed to where your sight picture is as the bullet travels down. This is also why bolt action guns are ALWAYS more accurate than equivelent Semi-autos.
I was just wondering if anyone had any actual tests. I have found lots of articles but no real tests.
As for the gas piston though, a well regulated gun or a propperly set adj gas piston can affect that accuracy greatly. My M1A is a piston, though not AK type, and it is a sub-moa gun. I was just looking for an apples to apples on the the listed pieces.
why not a 6.8? its has better damage then the 5.56 and a bettter range then the 7.62x39mm. and if you add the gas piston to it you have a investment in technology that puts you ahead of the world. while the russians make they overly comlicated and over priced an-94 we can make a weapons that we can use for many years to come
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