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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.

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FN SCAR Mk 2 and Evolys   Small Arms <20mm

Started 14-Apr by Guardsman26; 7541 views.
DavidPawley

From: DavidPawley

18-Apr

Redefining zero as positive doesn’t make it a valid claim.

Relying on the shear strength of the rear of the receiver to stop bolt travel also seems like bad design.

If your feed design requires the residual energy of the bolt after collision with the receiver to chamber a round, how will it ever fire the first shot to get some residual energy?

Your rationalisation of an incorrect claim is spurious and is decreasing the s/n ratio in this thread.

stancrist

From: stancrist

18-Apr

gatnerd said:

Id define what Max is talking about as "Spring +" power.

I dunno.  He very clearly talked about "velocity" in post #12.

mpopenker said:

...initial velocity of 3-4 m/s...

gatnerd

From: gatnerd

18-Apr

Regardless of what word he used, he's describing the bolt bouncing off the rear of the receiver, adding a bit more power to the bolts forward stroke then spring power alone. 

smg762

From: smg762

18-Apr

Does the PKM pull mechanism shorten the total length by several inches?

mpopenker

From: mpopenker

18-Apr

yes, as it allows placing the belt feed unit above the barrel breech

Just look atthe Polish UKM-2000 machine gun which is, basically, the PKM mated to MG-42 belt feed

nincomp

From: nincomp

18-Apr

gatnerd said:

Regardless of what word he used, he's describing the bolt bouncing off the rear of the receiver, adding a bit more power to the bolts forward stroke then spring power alone. 

Some buffers can also add power to the forward stroke.  A spring type can prevent solid impact with the rear of the receiver,  if it is not fully compacted at the end of the bolt's travel, then use the stored energy to accelerate the bolt forward.  The amount of energy returned to the bolt would likely be higher than if it had impacted the rear receiver.   A hydraulic buffer can also return energy for forward bolt motion, although by design, a certain fraction of the energy has been absorbed.  Nevertheless, since a hydraulic buffer, like an automotive shock absorber system, can be combined with springs and valved for relatively high damping in compression and low damping in "rebound",  it can return a significant amount of energy to accelerate the bolt back to its original position.

roguetechie

From: roguetechie

19-Apr

Yeah that one, I'm not an engineer I just play one on tv lol.

I'd love to be better educated than I currently am, working on it but there's so mucg to work on so little time.

roguetechie

From: roguetechie

19-Apr

What baffles me about that is both the Chinese and arsenal Inc can and do make rimless pull feed 308 pkm's. 

There's even ways to do that with a disintegrating link, and the impetus to do so since NATO/American standard push through links aren't all that light efficient or otherwise favorable.

It makes much more sense to me to just keep the pull feed and design a better cheaper and lighter disintegrating link

smg762

From: smg762

20-Apr

Are you an actor IRL?

roguetechie

From: roguetechie

20-Apr

Lol no, I did some PA work on tv shows long ago but I'm definitely not an actor.

I'm just an eccentric gun nerd who likes to tinker in his basement ...

I used to want to be something more but recently I've decided there are worse things to be than me.

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