9mm Tech

9mm Tech:

 

 

For General Tech details see 5.56 Tech

 

9mm Configuration specifics are covered below.

 

 

This is how we did it with what we had on hand.  Every 9mm blow back setup is different.

 

Upper brand should not make any difference as long as its machined to Colt upper specs which the majority of AR uppers are to Colt specs.

 

Another brand bolt or buffer/spring should not matter as long as the bolt has the same or very similar bottom profile as a normal 5.56/.223 FA BCG and the buffer is heavy enough to eliminate bolt bounce.

 

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ARIZONA REGULATOR Setup in video running 9mm:

We used the same standard 5.56 A2 rifle lower that we had been using for the 5.56 development.

 

Pulled the 5.56 Colt upper, buffer, and buffer spring.

 

Pinned on a 16" Colt 9mm upper with a Foxtrot Mike Colt style mag BCG part # FMC-9BCG.

 

Dropped in a Kaw Valley Precision 10 oz tungsten carbine buffer part # KVP-10oz and Kaw Valley Precision XP carbine buffer spring part # KVP-PCC-XP-Spring.

 

Installed the proper length spacer configuration to take up the extra space in the rifle buffer tube to accommodate the shorter carbine buffer and get the bolt catch to work properly without having excess rearward travel when the bolt locks to the rear when the mag is empty.

 

Ran a Mean Arms Endomag 9mm mag conversion kit with built in ejector in a PMAG 30 marked AR/M4 GEN M3 part # MAG557-MCT.

 

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Short barrel 9mm Pistol Upper Note:

 

When running a short barrel 7.5 inches with a suppressor we had to go to a standard weight carbine buffer spring.

 

7.5" Yankee Hill Machine 9mm Upper

 

Foxtrot Mike Colt Mags 9mm BCG

 

Kaw Valley Precision 10 oz tungsten carbine buffer

 

Standard carbine buffer tube

 

Standard carbine buffer spring

 

Bowers CAC9 Suppressor

 

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9mm BCG Note:

 

Ensure whichever std FA compatible BCG you use does not have an additional pinned in weight in the tail of it that extends forward past the trip release surface.  Notably the Colt pinned in weight does exceed forward of the trip surface.  When the pinned in weight exceeds forward it interferes with the upper cam and the receiver will not close. 

 

You can either mark the weight, unpin it, and relive a bit of material so it clears the upper cam.  Or do like we did and use the Foxtrot Mike BCG that has a pinned weight that does not exceed forward of the trip surface.

 

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