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Old June 18th, 2020, 08:51 PM #21
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I got my basic kit from Thunder Tactical....LOVE IT!
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Old June 19th, 2020, 06:00 AM #22
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My 9mm pistol build(pictured):

QC10's QC5 lower(takes MP5 mags) with QC10 sidecharger upper.

SB PDW brace with Tubb AR10 spring

ADCO 5" 9mm barrel with LH threading

Faxon 9mm bolt

Surefire Ryder 9 TI suppressor
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Old June 20th, 2020, 11:00 PM #23
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The main difference among "AR9" builds is the mags you intend to use, Colt, Glock, Pmag/endomag, MP5 or whatever, and most can be had with a dedicated lower, or AR15 with magwell adapter. As others have said, AR9s can be a bit tough to get running right anyway, adding in the possibility of spec issues inherent to 80% build, a dedicated lower may be the better way to go for the first one. There are a lot of bolts you can use, I prefer those with standard AR15 extractors and pinned weights around 14-15oz, ala Faxon, Kaw valley, QC10 etc. they can be hard on firing pins, so keep a pare or two.

For a buffer I've had better luck with moving weights, at least 7oz. I like heavier buffers and lighter springs, seems to control recoil better, and feel more consistent with a wide range of loads. Kak 10oz with a standard carbine spring functions well with less slap as the round is chambered, and less gas in the face supresssed compared to a lighter 5-7oz buffer and 308 spring. Lots of companies make bolts, barrels and uppers, would try to stick to one brand for the upper/lower/bolt/barrel unless using endomags or a magwell adapter, then any decent brand should be OK. Bolt travel length also makes a big difference as 9mm are 1/2 the length of 5.56, you will need an extended buffer or spacer to take about 3/4" of travel out. Last round bolt hold open can be nice, but linkages can be crazy and unreliable. Took a while to get my QC10 LRBHO to run well as it is basically a long lever with little mechanical advantage., my FM products lowers function 100% with the rotating shaft actuated LRBHO

As far as 300 blackout, I've found the caliber easier to run well than 5.56. Get a decent barrel with pistol length gas, and it will probably run fine. Pressure is lower, dwell is longer, so choking off gas with an adjustable block isn't usually needed. Most I've messed with run great with gas wide open and a H2 buffer using primarily supers and supressed subs. Unsupressed subs and short barrels may run better with a standard 3oz buffer
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Old June 30th, 2020, 08:13 AM #24
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Quote:
Originally Posted by alucard0822 View Post
my FM products lowers function 100% with the rotating shaft actuated LRBHO
Your suggestion was one reason I went with FM and my experience with them so far has been very good, esp. with the LRBHO feature. I did not have to adjust anything, it just worked when I took it to the range.
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Old June 30th, 2020, 11:53 AM #25
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Quote:
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Your suggestion was one reason I went with FM and my experience with them so far has been very good, esp. with the LRBHO feature. I did not have to adjust anything, it just worked when I took it to the range.
My first AR9 GLOCK mag build was on a QC10 lower, it's slim, well made, nicely finished, and when paired with a dedicated QC10 or Vltor upper it is goregous. The QC10 barrels feed EVERYTHING, and are really accurate, fit and finish are excellent. Problem is it took a LOT to get it to run right, ejector tuning, and the LRBHO is basically a lever with about a 4:1 ratio working against the mag spring vs bolt catch, very tough to get that to work, although otherwise it has been flawless with all ammo. Running a KAK10oz buffer and standard car spring runs great open or suppressed.

The FM9 was a little rougher, little plainer, and really boring, slapped it together, and it just works. It's the best design IMO, and while it isn't as aesthetically sweet as a nearly $500 receiver set, it's awesome for the money. I got a FM upper years ago for another build, and the early barrels had a massively oversized chamber, any ammo with a decent crimp (reloads and most HP ammo) would occasionally get shoved past the chamber by the ejector and not only wouldn't fire, but would take a screwdriver to pry out. His "gen 2 match" barrels have a normal chamber and run fine, I was a "beta-tester" for them, got one of the first, and after a lot of competitions and several thousand rounds it's still great.
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