[Grumpy]

So, there has been quite a bit of speculation regarding the weight differences between DI guns and piston guns.

Some claim as many as 2 to 3 pounds difference (with the piston gun being heavier of course).

So I decided to grab the good old postal scale and do some non-scientific weight measurements to give a few general weights for folks to go off of.

Here are the two uppers weighed. A 14.5 inch govt. profile M4 style barrel, an AAC blackout pinned and welded, a KAC freefloat RAS, with the full BCG installed. Other then that it is as clean as I can get it as all other accessories are user dependent and obviously add more weight.

The other is an MR556 with the barrel profiled to .72 under the handguard, barrel cut to 14.5, and a Gemtech bi-lock pinned and welded. Once again, a full BCG, and slick.

Here is the MR556 upper with the handguard removed to show barrel profile:

Here is the DI upper on the scale:

And here is the MR upper:

The MR556 upper is 4 lbs, 14.6 oz. The DI upper, with a slightly smaller barrel profile and the M4 stepdown, is 4 lbs, 1.7 oz. A difference of 12.9 oz.

This means that a real HK416 with a govt. profile will be somewhat less then my MR556, and probably around a half a pound heavier then a similar DI gun, if that.

Also, keep in mind that the KAC FF RAS is a damn light rail system as well, which might be skewing the results a little bit.

What does this mean in the greater scheme of things? Not a damned thing as I don't have a "real" 416 upper in my hands. But it's a start.

 

[dwillHK]

Interesting, but I think there are a lot of variables like differences in the rail attachments and receiver height affect comparisons like this. I think the only way to calculate the true weight of a piston vs. DI system is to just weight the specific components related to the types of operation. Weigh just the gas blocks, DI tube and piston, bolt carrier, and possibly the buffer. I think everything else is just a feature that could be varied on both piston or DI guns.

 

[Gunschlinger]

Good info Grumpy! Thanks for the post.

 

[chungdae]

I wouldn't say "useless" but "good to know!"

 

[Grumpy]

Interesting, but I think there are a lot of variables like differences in the rail attachments and receiver height affect comparisons like this. I think the only way to calculate the true weight of a piston vs. DI system is to just weight the specific components related to the types of operation. Weigh just the gas blocks, DI tube and piston, bolt carrier, and possibly the buffer. I think everything else is just a feature that could be varied on both piston or DI guns.

I'm of the mind that each gun absolutly requires certian parts to function. So reducing the assembly to the bare minimum it requires to function and weighing it is all that is necessary. The weight of the individual parts is irrelevent as the gun won't work without them.

In this case, I only had an M4 upper avalible that I could not remove the handguard or the front sight (pinned and welded FH), so I left the MR556 upper similarly equipped. Equal ability for equal weight.

Sure, having the exact weight of individual gas blocks are great and the like, but given the circumstances, is it necessary? Not in this case.

 

[dwillHK]

I'm of the mind that each gun absolutly requires certian parts to function. So reducing the assembly to the bare minimum it requires to function and weighing it is all that is necessary. The weight of the individual parts is irrelevent as the gun won't work without them.

In this case, I only had an M4 upper avalible that I could not remove the handguard or the front sight (pinned and welded FH), so I left the MR556 upper similarly equipped. Equal ability for equal weight.

Sure, having the exact weight of individual gas blocks are great and the like, but given the circumstances, is it necessary? Not in this case.

My impression is that the purpose of your post was to compare the the weight of DI vs piston. In my mind, to answer that question, you need to do what I proposed. I see what you've done as just a comparison of the MR upper to one specific DI upper that you had access too. The barrels are different, and the rails and gas systems are mid length vs carbine length. How much of the weight is due to those and other differences, not related to the operating system? If those variables can't be taken out, then I don't think the question of DI vs piston weight has been answered.

 

[Tater2.0]

My impression is that the purpose of your post was to compare the the weight of DI vs piston. In my mind, to answer that question, you need to do what I proposed. I see what you've done as just a comparison of the MR upper to one specific DI upper that you had access too. The barrels are different, and the rails and gas systems are mid length vs carbine length. How much of the weight is due to those and other differences, not related to the operating system? If those variables can't be taken out, then I don't think the question of DI vs piston weight has been answered.

I was thinking the exact same thing. You would need to weigh the components and then you could say that a piston gun will weigh X ounces more than a DI. After that, it is up to the end user as to how much crap he adds to it.

 

[Grumpy]

To do that properly, I would need a "real" 416 to take apart.

Since I don't have that, this was merely meant to be an example of how close the weights actually are, rather then the exaggerated weight claims that we usually hear.

 

[Gunschlinger]

We appreciate your posts Grumpy! I like this one and I like the one about parts compatability with DI parts- good stuff man! Thanks again.

 

[insin]

Has anyone done this weight reducing re-profile to a AF date coded hbar HK416 upper? I am reluctant to try this and ruin a genuine 416. I guess since actual weights have now been supplied for a comparable re-profile job on a mr556, I can estimwte just how much weight can be lost

 

[manik]

informative as usual grumpy! thanks!

 

[insin]

Has anyone done this weight reducing re-profile to a AF date coded hbar HK416 upper? I am reluctant to try this and ruin a genuine 416. I guess since actual weights have now been supplied for a comparable re-profile job on a mr556, I can estimate just how much weight can be lost

Wow, I just got the scale out and I weight both the 14.5" and the 10" HK416 (AF date coded). They were 5 lbs 8 oz and 5 lbs 0oz respectively (BCG, front and rear sights). That barrel re-profile to .72 under the hand guards really does save a bit of weight. You got your MR under the factory weight of a 10" HK416. I have been contemplating doing this. I even contacted Jayson over at IGF and he said that he could do it. I have just been going back and forth regarding modding a true 416. Its hard to get over that $$$ resale value, and possibly ruining it, despite the fact that I know that I will never sell a 416

 

[Aeroshep]

Thanks I have always wondered and been to ;asy to do the scale work myself. Thanks for the effort!!!