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Firearms of note and ridicule


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#4281 bojan

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Posted 03 October 2019 - 1138 AM

.300 fits in the AR-15 form factor, 7.62x39 requires AR-10 based bolt for a long term endurance, AR-15 sized 7.62x39mm bolts are notorious for cracking.


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#4282 Ivanhoe

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Posted 03 October 2019 - 2219 PM

In the US, .300 Blackout offers a lot more to the reloader, due to the massive variety of bullets available in .308 diameter.

 

The downside, AIUI, is that vigorous use of the forward assist can result in a .300 cartridge getting fully chambered in a 5.56, resulting on kaboom.


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#4283 Simon Tan

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Posted 04 October 2019 - 0322 AM

Do not fucking use that forward assist. If it wont go into battery, there is a good reason.
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#4284 Simon Tan

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Posted 04 October 2019 - 0323 AM

AKMB.
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#4285 bojan

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Posted 04 October 2019 - 0830 AM

9x39 AMB-17 :)


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#4286 GregShaw

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Posted 04 October 2019 - 0954 AM

Do not fucking use that forward assist. If it wont go into battery, there is a good reason.

Bingo, if you have to use that button you need to stop and figure out the real problem.


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#4287 Panzermann

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Posted 04 October 2019 - 1518 PM

 

Do not fucking use that forward assist. If it wont go into battery, there is a good reason.

Bingo, if you have to use that button you need to stop and figure out the real problem.

 

 

So far I have recognized only one situation that the forward assist makes sense, when the attached grenade launcher kocks the bolt out of battery wiht its recoil. Happened to me with a G36 with AG36 and I guess is the same for an M4. Otherwoise I agree, when it does not chamber properly there is something in the way and it willm ake problems worse.


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#4288 sunday

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Posted 05 October 2019 - 1604 PM

Sturmgewehr 57 - history, quirks, and features. Or how the Swiss armed all their soldiers with a LMG instead of an assault rifle. Note also the size of those rifle grenades.


Edited by sunday, 05 October 2019 - 1607 PM.

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#4289 GregShaw

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Posted 05 October 2019 - 1844 PM

Makes my K31 look like very hi quality toy.


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#4290 bojan

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Posted 06 October 2019 - 0315 AM

Yugoslavia tested SIG 510 as a LMG* in about 1958. for a paratroopers, but idea was dropped when para brigade was disbanded in 1959.

 

* It is not clear if those tested were in the 7.5x55 Swiss, 7.9x57mm, 7.92x33 or even 7.62x39mm.


Edited by bojan, 06 October 2019 - 0319 AM.

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#4291 Panzermann

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Posted 17 October 2019 - 0111 AM

Yugoslavia tested SIG 510 as a LMG* in about 1958. for a paratroopers, but idea was dropped when para brigade was disbanded in 1959.

 

* It is not clear if those tested were in the 7.5x55 Swiss, 7.9x57mm, 7.92x33 or even 7.62x39mm.

 

The SIG510 was manufactured in several calibres in at least small numbers, so any of the above could be, though I bet on the regular swiss army 7,5 mm cartridge until proven optherwise. Simply because avaiability. Though 8x33 would be kinda hilarious, but make some sense considering that the yugo paras used the StG44.

 

 

 

 

 

T2qFR8Xl.jpg

 

top MG4

bottom MG5


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#4292 bojan

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Posted 17 October 2019 - 0507 AM

Why is it still heavier than 50 years old PKM?


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#4293 Panzermann

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Posted 17 October 2019 - 0650 AM

Why is it still heavier than 50 years old PKM?

 

from the top of my head:

  • push through feeding makes the receiver longer and thus heavier
  • more bells and whistles like the rails and barrel cover -> heavier
  • thicker barrel makes heavy
  • expected lifetime higher also makes it heavier
  • folding and adjustable stock is heavier

 

the list probably even longer.

 

edited to add two more points:

 

  • longer receiver so that the bolt carrier does no crash into the rear of the receiver
  • a very heavy (rumour has it too heavy) bolt carrier to reduce rate of fire to the desired rate (or rates as it is adjustable)

 

But tha tis what procurement wanted.

 

 

At the moment the fitting of the MG5 to FLW100 (remote controlled weapons mount) and other legacy MG3 mountings comes costlier than expected, because there are more adjustments to be made to fit the new guns. e.g. the MG5 has a flip switch safety, whereas the MG3 has a push button. 


Edited by Panzermann, 18 October 2019 - 0155 AM.

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#4294 Chris Werb

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Posted 17 October 2019 - 1508 PM

Why is it still heavier than 50 years old PKM?

 

It's German :)


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#4295 shep854

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Posted 17 October 2019 - 1711 PM

"push through feeding makes the receiver longer and thus heavier"--Panzermann

Are you sure?  I would think pull-push feed would be longer, since the round has to be pulled back from the link/belt.


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#4296 bojan

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Posted 17 October 2019 - 1814 PM

In the PKM belt is positioned over the chamber. That makes a receiver shorter than with push-through where belt has to be behind chamber. Also, due the operating mechanism and a fact that receiver is closed in the rear there is no need for super-heavy receiver walls.

Tank version, but enough to illustrate a point:

PKT_7_62mm_rez_a_cinnost.gif

Also, due the fact that bolt dumps energy by pulling a cartridge out of belt so return spring can be weaker and bolt lighter, which can also removes mass. In push-through bolt has to be heavier and spring stronger so bolt has enough energy to strip a cartridge out of the belt pocket in less than ideal circumstances. Also push-through in general has longer bolt travel, which again lengthens receiver. Browning tried both pull-push and push through for his MGs and decided on the pull-push method as more efficient.


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#4297 shep854

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Posted 17 October 2019 - 2026 PM

I see, thanks!


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#4298 Ivanhoe

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Posted 17 October 2019 - 2149 PM

Reading that diagram is a pain in the kotva.


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#4299 Panzermann

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Posted 18 October 2019 - 0200 AM

I see, thanks!

 

Also the bolt carrier is relatively lighter, because the weight of the bullet being pulled out adds to the reciprocating mass and also the friction from pulling out of the belt is calculated into it. ironic that the legacy tsar's cartridge forced this lightweight design.

 

 

fun trivia: the 6P41 PKP Pecheneg can use PK barrels and most of the other parts interchange as well. Loses the ribbed barrel and its cooling mechanism, but is lighter for recce squads and such. Maing spotting a Pecheneg in a photo a bit diffcult as a PKM wiht plastic furniture looks very similar then.


Edited by Panzermann, 18 October 2019 - 0202 AM.

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#4300 shep854

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Posted 20 October 2019 - 1930 PM


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