DI or Piston?

[themonk]

I heard it was the SCAR but could be just hearsay

[Leuthas]

Are we referring to this, in which "C" is indeed the FNH.

http://www.lightfighter.net/topic/ma...16848815108623

[Arctic1]

No, that is the USMC M27 Trial.

Rifle C is from the now-cancelled US Army Individual Carbine competition.

[MistWolf]

No, there will not be.

I don't have pictures now, but I will continue shooting my gun without cleaning it and break it down at about 3000 rounds and see how it looks.
I don't shoot very much rifle these days, preparing for the handgun World Shoot in France, so I'm only at approx 800 rounds since my last clean and lube.

As to your point on the gas tube heating up and slightly cooling the gas, sure. From the gas block to the carrier key you lose about 200 or so degrees on the DI gun, compared to 370 on the piston gun. The DI bolt body is 100 degrees hotter than that of the SCAR or the piston AR. The carrier key is 160 degrees hotter. The firing pin and cam pin are 120 and 90 degrees hotter, respectively. That is a significant difference.

As I said above, the lack of fouling in the upper/lower and the cooler temps of the BCG components is why people say piston guns run cooler and cleaner. You can argue semantics all day long, but you could see for yourself if you would just try to shoot one.

Did you want me to be Keith or O'Connor?

[Arctic1]

Did you want me to be Keith or Connors?

I don't get the reference.

[Leuthas]

No, that is the USMC M27 Trial.

Rifle C is from the now-cancelled US Army Individual Carbine competition.

Gotcha

[tom12.7]

You guys need to put more of a proper prospective on things.
I would tend to question some of the items posted here on this thread.
I'm not against external pistons for use, many non AR systems do well with that. The issue arises though about retrofitting an originally DI AR type of system. Without the ability to support the deflection properly with a DI to external piston makes the system a less desirable base for that external piston.
There's pro's and con's from each. The HK has gone through many evolutions from it's inception.
There's been more of an acceptance of DI systems properly done as well.

[Arctic1]

I don't have anything against DI guns, and have said repeatedly in threads here that the M16 FOW is a very reliable and proven weapon system. It has also gone through changes since it was first put to market.

What I do take issue with is people making assertions about a system they admittedly have no experience with, just based off of experience with a completely different weapon - the FN FAL that was made in 1954.

I get that this is the internet, and everyone has an opinion, but this individual's opinion apparently carries weight - in spite of him saying that he has ZERO experience with the system. None.

I have, and he argues that I am mistaken because he understands "the science".

And it's not even clear what his point is, seeing as all that is presented are vague comments about heat, particulates and exposure to these factors.

[tom12.7]

I do have (did have?) experience with the HK 416 system variations. They do things differently than DI. Some are more pro's than con's and vice versa, but for most, I see no real advantage overall with HK's external piston for most, especially when cans are involved.

[Arctic1]

I do have (did have?) experience with the HK 416 system variations. They do things differently than DI. Some are more pro's than con's and vice versa, but for most, I see no real advantage overall with HK's external piston for most, especially when cans are involved.

It was developed specifically for use with suppressors for increased reliability with short barrel weapons.

Per HK, their design is so that 90-95% of all the carbon/particulate matter is ejected from the front of the weapon - out of the muzzle or gas block.