AR Sponsor
Posted: 3/12/2025 7:44:11 PM EDT
|
need a little advice. below is what i have been using: CMMG MK9 (colt style ) intregal magwell 9 lower CMMG upper w/ 5in bbl with a Bowers CAC9 can. CMMG 9MM bolt (13OZ i think ) KAK 10oz buffer (23oz of mass i thought should be plenty) std. carbine spring & buffer tube. with all this...i still get 1 rd fired with 2nd rd chambered with a light pin strike and hammer up after opening the gun. ammo i`m using are my own hand loads ( subsonic 147 gr. appx. 950 fps & 115 gr around 1150 fps.) funny thing is, with this same upper and a friends reg. lower with a Spikes Tac. 9mm adapter in the well, it runs perfectly w/ both types of ammo. was thinking about switching to an longer Vltor A5 tube and a Foxtrot M.`s 12oz buffer made for the A5 tube length. as an aside...i was using a WOT & GMR and it made no difference. any suggestions? |
|
https://c3junkie.com/?page_id=164 https://blowback9.wordpress.com/ And FWIW... to heavy a buffer weight caused noticeable muzzle dip on my 9MM PCC. |
*Hold on to your AR-15s. Their magic must be very powerful, or they wouldn’t want them.*
JAFOM.... Just another fat old man.
________________________________
TOGC,IADC
JAFOM.... Just another fat old man.
________________________________
TOGC,IADC
|
Finally got mine working after both using a proper heavy buffer, (StonerAR, iirc) and getting rid of the AR10 buffer spring that Foxtrot Mike uses. I then proceeded to cut a few coils off of that spring. I adjusted the weights in the buffer to get it just right. Filing the bolt carrier to trip the frt only when the bolt is in battery helped, too. It still worked after adding a silencer to the mix. |
And then, he arrives at the last item on his bucket list...
Joined:
Jan 2025
Posts:
26
EE: 0% (0)
TX, USA
|
Originally Posted By SARonin: Powdered tungsten is available at any on-line gulf supply, and at most gulf shops. Golf, not gulf. In any case, I've put together powdered tungsten AR buffers for more than ten years. In the last several years, the cost of tungsten powder has increased a lot, and the purity of tungsten powder has gone down (seems to be diluted with iron) for the money. In the carbine length case, it's getting more difficult to find a level of purity that will get to a 4 oz. load that still has free moving powder, which is needed to counteract bolt bounce as well as provide a smoother recoil and bolt to barrel impact. MHO, YMMV, etc. |
|
So with a blowback 9mm gun, if the bolt is closing, but it's not quite closed when the hammer begins moving, how close must the bolt be to fully closed in order to get closed before the hammer hits the firing pin? Seems like this is a critical timing issue where the hammer starts to fall before the bolt is closed. And then the bolt and hammer are racing each other. Hopefully the bolt closes fully just as, or just before the hammer hits the firing pin. In gas operated 5.56 guns it looks like the bolt lugs are already rotated into a locked position before the carrier reaches its forwardmost position, and the last few mm of bolt carrier travel doesn't affect the bolt lockup at all, so the hammer dropping a little early probably isn't as big of a deal. But in the case of a blowback, the bolt is either in battery, or out of battery. The only way to correct an early hammer drop would be to remove material from the front of the trip ledge on the bolt. But, remove too much and you can't add it back easily. So since by design, the trip has to initiate before the bolt is fully closed, the question then becomes, how much before the bolt is closed is safe to prevent an OOB discharge? |
|
I don't have a technical or informed answer to that, but I adjusted mine so very close to the fully-in-battery position that it is liable not to work with any appreciable wear, lul. The distance between when it trips to when it is fully in battery is barely even perceptible. Got a little too carried away with that file.... |
And then, he arrives at the last item on his bucket list...
|
Originally Posted By GySgt_D: I don't have a technical or informed answer to that, but I adjusted mine so very close to the fully-in-battery position that it is liable not to work with any appreciable wear, lul. The distance between when it trips to when it is fully in battery is barely even perceptible. Got a little too carried away with that file.... I was going to say you might need a skilled welder to put a little spot welder on it. But then it occurs to me it's an opportunity to install an ajustable trip. |
Member
Joined:
Feb 2024
Posts:
85
EE: 0% (0)
AZ, USA
AR Sponsor