Shhh! Be quiet. (Suppressed MP5s)

[programmatore]

After 5 long months of waiting my Gemtech Multimount suppressor finally arrived! It went pending on July 21 and the stamp arrived on Friday. I picked it up Saturday morning along with a couple of boxes of Sellier & Bellot subsonic ammo from Loudon Guns in Leesburg.



I also got a notice in the mail on Friday that I had a registered package on hold at the post office -- my MKE MP5-K was back! I had sent it to S&H Arms in Oklahoma to have a 3-lug barrel extension added so I can mount the suppressor.



Finally, here is the MP5-K and the full-size MP5 with the Gemtech Multimount with the 3-lug adapter.



Next on the wish list: Sig Sauer P229 threaded barrel and the Gemtech LID adapter so I can mount it on the pistol.

[gunderwood]

Nice!

[Jakeiscrazy]

Awesome!

[bryanrheem]

once I get my CA89k threaded, we should do a side by side comparison with my Osprey. It'd be interesting to see the difference!

Congrats and welcome to the silencer addiction. Soon you'll be shopping for a can for your Sig556.

[programmatore]

Hey Bryan. Did you get your MP5K barrel threaded yet? I still need to order the #28 locking piece for the MP5K from hkparts.net. Once you get the barrel threaded and I get the locking piece it would be nice to do a side by side comparison of the Gemtech Multimount and the Osprey.

I shot the full-size MP5 suppressed today. It ran great using Sellier & Bellot 140 gr subsonic ammo but had FTEs with the WallyWorld Winchester White Box 147 gr. The Winchester was pretty dirty too -- I will not be buying those again! I ordered 2 cases of the Sellier & Bellot 140 gr from Cheaper Than Dirt so that should arrive in time for shooting next weekend.

[bryanrheem]

I just sent my upper so it'll be a couple weeks until I get it back. My Osprey is a .45 so it won't perform as well as the Gemtech, but I also shoot it on my p239 in 9mm and it does a surprising good job so I figure it will do the same on my mp5k clone.

I'm really confused about the #28 locking piece buzz. Why is a change in locking piece required?

[programmatore]

This is what I read from G3Kurz (on HKPRO.com) who used to work as an engineer for H&K:

Based on tests by HK when the first Choate folding stocks and Mickey Finn/Qual-a-Tec suppressors were placed on the MP5K-N's in the 1980's to create the “MP5K-PDW” and the 147 grain OSM round was developed and first used in it your guidance is as follows:

Use the # 16 Locking Piece
(gun runs @ or above 800-1000 rpm cycle - STANDARD FOR A K)
-When firing the K w/o a stock
-When firing the K with standard 115-124 grain ammo
-or both

Use either the # 16 or # 28 (80 degree) Locking Piece
(> 1000 rpm - high but still acceptable in some K’s)
-When firing the K with the stock and suppressor

Use the # 28 Locking Piece
(> 1200 rpm – cyclic rate is too high)
-When firing the K with the stock and suppressor
-When firing the K with stock, suppressor and 147 grain ammo

There is some overlap here. Some guns will run okay with the # 16 LP with the stock and suppressor, some will not. Ammo and suppressor variances make a difference as does the wear and condition of the weapon.

The common stoppage is failures to feed caused by excessive bolt velocity which is increased above normal as you add both resistance to the weapon (a stock) and recoil impulse to the bolt (suppressor back pressure, heavy ammo). The cartridge column in the magazine simply cannot keep up with the advanced speed of the bolt group and thus the top round in the mag is not in optimum feeding position. You may also see failures to eject but often these are caused by damage to the extractor spring from repeated faiulres to feed or chamber causing the extractor to get pushed out by the obstruction permanently damaging the extractor spring.

G3Kurz

I guess it wouldn't hurt to try shooting with the standard 110 or 100 degree locking piece, stock, suppressor and subsonic ammo. If it feeds reliably then you're good to go. In fact, I may try that this weekend.

[programmatore]

Okay, I just got back from the range. I test fired 50 rounds of Sellier & Bellot 140gr ammo through the MP5K with the suppressor on and using the standard K (110 degree) locking piece.

The weapon cycled fine and I did not feel any more recoil than when shooting without the suppressor. I guess the 85 degree locking piece is really only needed to slow down the cyclic rate on F/A -- not an issue with the S/A MKE. I might try it on heavier 147 gr. ammo next time to see how it handles but so far so good.

[bryanrheem]

great news! btw, is the yellow tape to let you know which ammo is subsonic?

[programmatore]

great news! btw, is the yellow tape to let you know which ammo is subsonic?

I color-coded my mags to tell them apart. Green for the brand new German HK mags that I know run 100%, yellow for the used LEO German HK mags that I take to the range, and red for the Korean ATI mags that run perfectly on my MP5K but would FTF on my full-size MP5.