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Brian Enos's Forums... Maku mozo!


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About cking

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    Beyond it All

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    gainesville Florida
  • Real Name
    Roy King

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  1. cking

    CMMG Guard tuning (9mm)

    Update of new BCG. CMMG put a new BCG in my Guard, it runs! However the recoil impulse is noticeable harsher even with 223 flatwire and hyd buffer. Which makes me think they changed the angle of the locking lugs to leave more momentum in the BCG. So now I'll move on to testing a 308 spring and probably a 308 flat wire.
  2. Here is the thread and patent link https://www.ar15.com/forums/AR-15/CMMG-GUARD-ROTARY-BOLT-QUESTION/15-731462/
  3. cking

    which comp for 9mm PCC ?

    I like the simple one CMMG sells for less than $50. https://mantisx.com/pages/how-it-works-1 Take look at this product, I've talked with them about using it to compare comps, they say they are working on it. If the collection speed is fast enough this thing could help you tune your gun, bullet weight, charge, springs, buffers, even LOP, COMPS.
  4. cking

    How to Determine Best LOP for an AR9 PCC?

    I think it more about your stance, if you using the squared approach then the trend is shorter LOP. I like short LOP and light/short barrel for fast close work. I like my charge handle close my nose, I feel it helps me move the gun faster. What I haven't worked on is the notion of move the head and gun will follow is faster than drive the gun to next target.
  5. cking

    CMMG Guard tuning (9mm)

    In hopes of saving this project I ordered a new bolt. What I'm thinking is too much play when bolt is locked, will measure the new next to the old. I found using a weaker spring cured the bolt over run jam
  6. Since the angled locking lugs of the rotary delay never really lock and show signs of battering I.e. setback will you end up with excessive headspace. If so would a symptom of excessive headspace be failure of the extractor to fully seat in the rim groove? Which would show as a failure to eject, not extract. As the case is blown out because it is somewhat of a blowback design. I have trouble with and extracted case being shoved forward by the ejector but not rotating out on the extractor. Or is this all hogwash, because on bolt closing the barrel extension and bolt face slam into each other allowing the extractor time to hook the round. So excessive headspace would be function of chamber depth. So case length becomes critical. Also extractor groove size compared to rim thickness are there any recommended standards?
  7. cking

    CMMG Guard tuning (9mm)

    SUCCESS BUT NOT WITH MOD 2! Now runs with Federal 115gr ALUM Actually mod 2 was the worst FTE's every other round, but I learned something … I was wrong on less extractor needed, just the opposite more is needed. So mod 3 is mod2 polished extractor with a brownell CS spring with black insert and CS ejector spring and polished the walls of the bolt. I think the bolt face was hair too small. So take the bolt apart and take fine cratex on your Dremel and polish the bolt recess and edge and smooth the extractor put brownell CS springs in. Now I can go back to the flat wire and hyd buffer too see if things are back to normal and I can run Cheap alum ammo Now I get back to drilling the lower for lefty mag release going right in front of trigger about the size and shape of 1911 mag release. The reason is for the man on man match we shoot you are required to make change before you shoot the dueling popper. Just two slow too use my right hand to release the mag and then put new in. With new left side release the trigger finger will release the mag while right hand is bringing a new one up. Should save a solid half second.
  8. cking

    CMMG Guard tuning (9mm)

    Tthinking about CMMG and it always extracts but some times doesn't eject. I had bolt out and was examining again the bolt and the round interaction. Found there was still spot were the round would hang binding between the extractor hook and the recessed bolt walls. Inspecting ejected cases showed that ends of extractor hook had scored the rim. So the pistols and some PCC bolts use a extractor like on the 1911. So I narrowed the extractor, but still some binding, then I polished the bolt walls. That made the difference there is NO position that case will hang, it always falls. So I waste some more ammo testing.
  9. cking

    CMMG Guard tuning (9mm)

    SUMMARY: I bought a lower, barrel, bolt from CMMG. Used an existing upper and opened up the ejection port. The gun ran fine for about 1200 rounds, then it started loosing ejected case velocity, they just dribble out, then started FTEing. Contacted CMMG and sent picks of bolt and they sent me a new modified extractor. Also reminded me to use 308 carbine spring and standard carbine buffer. In mean time I started using 9mm Federal Alum ammo $$. I found the ejector spring was weak and same extractor, both are now CS springs. When new I was running flat wire 223 spring and hyd buffer. So my hopes that this gun would be FTE free which to me means 1000+ rounds of new factory ammo with no problems.
  10. cking

    CMMG Guard tuning (9mm)

    I give up! Today I went out thinking everything would be fine since my test with three mags loaded with ten rounds, it cleared them all. Today I went out with three full mags didn't run single one, this is federal alum cases dumping rounds as fast as I can pull the trigger. Ejection is very consistent angle and distance till you find a mangled case sitting on top of half loaded round. Guess I try to get video
  11. cking

    CMMG Guard tuning (9mm)

    No I was very careful to not shorten hook depth, the CMMG extractor had not been head blasted and showed the cutter marks. It also had large flat section right above the edge. So mainly changed the radius and got rid of the ridges also radius the ejector.
  12. cking

    CMMG Guard tuning (9mm)

    Here is bolt with modified extractor and ejector
  13. cking

    CMMG Guard tuning (9mm)

    Alum cases made it more pronounced. I'm going to look into more 9mm PCC that uses a AR extractors, also going to compare cases rim groove shapes, also came across a site that said the ejector pin should have slight radius to make it easier to slide across the case face as it rotates out.
  14. cking

    CMMG Guard tuning (9mm)

    So I ran it today, did the port relief solve the problem? NO! This is running Federal Alum 115gr. Glock 33 rounder, a FTE's on two rounds last eight rounds in the mag. So I inspected the spent casings and the extractor had dug some gashes on the inner edge of the case rim right at the point where extractor ends. So I polished sharp edges back and dropped a round in the chamber and pushed the carrier by hand until the extractor snapped over the rim. Then I slowly pull the carrier to the rear watching it pull the round out of the chamber expecting it to pop out when the round cleared the barrel extension. So what happen NOTHING! The round was wedged at about a 15' angle between the arc on extractor face and the far side of recessed bolt face. It was struck there firmly and it was repeatable. So I inspected the extractor face and compared it two four other 223 extractors on hand. About the same. So with my 4x magnifying eye piece I put a round in the groove and rotated it like it supposed to roll out on extractor face. It bound with the edge of the extractor digging into the inside of the rim. So I rounded the ends extractor and polished the extractor face until the round rolled out with no binding. Performed the slow extraction again and the round hopped right out when it cleared the barrel extension. Loaded 3 mags with 10 each and burned right through them. Also noticed that ejection pattern was now consistent right 3 o'clock instead varying between 2 and 5.
  15. cking

    CMMG Guard tuning (9mm)

    .So I was bored and I was looking over my 9mm PCC and I noticed the alum cases had left some marks on the barrel locking lug face. As soon as the case cleared the inner area of the barrel extension you can see the drag marks across the rear face of the barrel extension. The Ejection port was slightly to the rear of the barrel extension forming a sharp edge for case to catch on and knock it loose from extractor. My Theory is the alum cases are lighter and therefore accelerate faster and didn't clear the ridge like brass does. See pics of modified port.