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I think I’m firmly in the laser as my second optic camp... exploited it today on 3 out of 5 stages... One stage the match director set up had 2 targets behind and literally at a 90 degree angle back behind a barrier on the left and right, an offset dot was useless; I just held the gun out there at arms length and got 2 Alpha 2 Alpha, shot 1 righty (my normal) then transitioned and held the other one out there the same way lefty

Awesome info guys, thanks!

I don’t reload (more due to time than anything else), that said, the MPX system is so soft shooting I doubt you’d see any benefit going below like a 140pf power factor... I’ve been running a bunch of rounds through mine alternating between Federal’s Syntech 130gr PCC-specific stuff and crap 115gr Tula and the difference isn’t a whole lot... the Syntech 130gr is way cleaner and is Nerf-gun-soft rated at a supposed 147pf, but the Tula is soft as hell too... I think the MPX is just a different thing from a blow-back AR-9, and the load doesn’t matter as much until you go too soft and it doesn’t like it. IMHO: MPX @ 145pf more or less = BB AR-9 @ 130pf YMMV.

That’s awesome man, thanks for sharing that experience.

Searched and found plenty on guys switching out the stock bulky Keymod OEM handguards on Gen 2 MPX’s for the Isler CF with all thumbs up... Can anyone offer an opinion on the newer 15.5 PCC OEM handguard vs. the Isler..? Any lighter? Pros/Cons? Worth it? I like the 15.5 OEM just fine, but one of the main reasons I’m looking at the Isler is he offers a lower-height piece of pic rail to keep your laser out of the way of the optic when mounted at 12 o’clock... currently on the OEM 15.5 I’ve got my laser at 6 o’clock to keep it out of the way of the optic, and while it works, it’s a little wonky and I know I’m going to bash the laser into something sooner or later (also, at 6 o’clock it snags on anything). Thanks.

It’s just a roll pin, whack it out with a punch in like 2 minutes; if you don’t dig it, putting it back in is just as easy.

If anything isn’t right , Foxtrot Mike are fast and a pleasure to deal with.

I totally get it... building is a lot of the fun. You’ll inevitably play around with the buffer stuff I bet... FYI the FM9 bolt with the weight removed is really nice with their 6.5oz buffer weight as it comes (and is free to try), but bolt-weight-out with FM’s 8oz buffer is even better (using the supplied .308 carbine spring). YMMV

From my experience there’s nothing shoddy at all with the Foxtrot Mike stuff, you might be GTG with just that, it’s well made, great functioning stuff...

I haven’t had to go that deep yet on my MPX, that said, you might want to shoot In Lead We Trust an email, as they offer this: https://inleadwetrust.com/product/mpx-type-gas-valve-detent/ Seems like they’re THE MPX-whisperers...

Yeah, mounted the laser at 6 o’clock near the comp and think it’ll live there until I smash it into something, I definitely prefer the FOV through my optic with it out of the way... I may never use it, but if I didn’t have it and the opportunity presented itself to turn my whole squad into cats for a bit, I’d be bummed Boresighted it in my kitchen @ like 5-7 yards lol.

No problem! Again though, I’d seriously consider spending the extra loot up front and going JP, or risking the same money to go the MPX route like some fools do (me lol)... if you’re like most of us around here, you’ll more than likely spend the difference dialing your build anyways... Besides, PCC’s are so fun you can always sell an AR you won’t use so much anymore hahaha

I don’t reload so I just buy what’s around and has free shipping lol... That said, the Syntech PCC 130gr stuff is just laughs... it’s like toy Nerf gun stuff through the MPX, it might actually be too soft, but super fun, hahaha...

Watching this thread... I’ve had and witnessed a bunch of issues with the older MPX’s, but picked up the latest 3rd Gen 16”, and through its first 1500rds, thus far it’s been flawless without any cleaning and just a little FP-10 on the bolt between range trips at like maybe 500rd intervals... was beginning to think Sig finally has it dialed with the few changes they made... I’ve been feeding it 50/50 with Tula 115gr crap and super-soft shooting Syntech PCC 130gr stuff... We’ll see if any issues pop up as I put more rounds on it..?

Personally, buy once cry once, order a short-stroke JP and you won’t have to second guess or regret it and you’ll have about the best s#!t out there (and it’ll hold more value if you decide to let go of it for some reason down the road)... Plus, JP’s new ultralight barrel option (5-6” barrel + integral shroud for 16” looks pretty Gucci). That said, I’d order it pretty “vanilla” and add stuff once you’ve got it and can dial it in, but they’re supposed to be coming out with a slimmer M-Lok rail soon, so maybe inquire or wait for that if you can... Hopefully one of their team guys on here will share a coupon code via PM that’ll save you some cheddar... Hiperfire definitely. I have a complete Foxtrot Mike, and if talking “for the money”, it’s awesome and probably the best out there bang-for-buck IMHO, but if you end up diving in deep, the JP is worth it. This is coming from a guy who just ponyed up JP-like money to go 3rd Gen MPX (if it doesn’t run, I’m definitely going JP).

Mounted up and zeroed my CT CMR-206 today...IDK if it's staying honestly. It's not a zeroing thing at all. I think I've found a couple issues I've got with it that I didn't foresee having: 1. If I mount it in front of my sight, the laser just projects right into my thumb (I shoot thumb-over-bore), so not only is it useless unless I change my grip, it's also distracting as hell if I use my normal grip. 2. Mounted at 12 o'clock at the end of the rail nearest the muzzle, the laser projects fine and my hand isn't in the way anymore; except then, the laser unit, small as it is, takes up a whole bunch of field-of-view looking through the sight and overall makes things much less "open". I don't dig it. Though I think I'm just not used to it, because my thumb blocks nearly as much if I'm real about it, so this is probably my best option. 3. It looks like it may just be bright enough to be distracting indoors or under overcast/grey outdoor conditions compared to the brightness of my reticle IMHO... I didn't think it would be, and I can definitely turn up the brightness on my sight to match or be brighter than the laser, but the laser is one-brightness-fits-all, and indoors or on a greyish day it is without a doubt brighter than I'd set my sight. I don't think I like any of the compromises I've stumbled upon here. That said, I suppose I could try mounting it out front at 6 o'clock ... but IDK if I'd like that because then it'd only be a matter of time until I smashed it into a barricade or something lol! So, unless I get used to it at 12 o’clock on the end of the rail, AND actually use it here and there, more than likely the laser is coming off. IDK, guess I could try it at 3 or 9 o’clock too... On a side note: looks like the HE507C-GR is shipping, so might try one of those on 45-degree mount...

Ran and zeroed with the riser on my Holosun HE510C-GR today (MPX 3rd Gen PCC)... No contest, WAY better for me with the riser! Seems so much easier and more natural to mount the gun for me. Again, IDK why Holosun just doesn't include the riser with the units..?

Not sure how much the Foxtrot Mike bolt-weight weighs that I removed, I'd guess between 2-3oz, but sounds like your CMMG bolt-weight might be heavier... again, all these proprietary AR-9 parts can make one's ideal recipe an exercise in experimentation lol. 1. Doubt it, 4.5oz for a 9mm blowback buffer weight seems really light. I have no idea what your Endine buffer weighs... but I was using longer 9mm-specific buffer weights without spacers so my experience is based on those. Plus, you'd just be taking weight out of the end of the stroke, you'd still have mostly the same reciprocating mass for most of the stroke, only with less mass to slow it down... 2. There are more then a few ways guys measure this stuff... I don't know if anyone has the perfect equation. I'm talking a less scientific "shoulder/shooting-feel" test. 3. A tunable buffer weight probably isn't a bad idea if you feel like buying one and really want to play around with it. - My thoughts are this: basically, in my experience it's not so much the total weight, but where the weight is in the system: For me, a lighter reciprocating bolt is noticeably better, but in a way I ended up putting most of that weight back in, but at the end of the stroke with a heavier buffer weight... the mass that moves the most (bolt) being lighter felt better. YMMV FWIW, the JP bolt's that lots of guys love don't have added/removable weights and are usually a couple ounces lighter than most other companies' bolts out there with weights installed... that's worth noting because JP is usually out front on a lot of this PCC AR-9 stuff. So IMHO, removing the weight from the bolt and trying it out like that, is in a way, trying that same "lighter bolt" concept with the gear you've already got.

Not to sound snarky, but you probably just have to try removing the weight from your bolt and try it out... There’s just so much variance in the vast array of AR-9 parts out there that IMHO that’s the only way to know for sure... I can say in my Foxtrot Mike AR-9, it ran great with a 6.5oz buffer weight + .308 carbine spring + weight in the bolt, but I wanted both a lighter recoil and less dot bounce... after experimenting with more than a few different things, I ended up with an 8oz buffer weight + .308 carbine spring + weight removed from the bolt (it improved even with the same 6.5oz buffer weight, but ended up liking the heavier one better with the mass out of the bolt): 100% reliability remained, but no contest, the recoil softened and the dot recovered faster, for ME (that’s the important part, it’s gotta feel better to YOU and everyone is different). It’s worth a try, it won’t take many rounds to feel the difference I bet...

The buffer-thing tuning/stroking options bothered me so much chasing recoil characteristics I decided to try an MPX again... hopefully it runs and you guys won’t find one fully kitted out in the Classifieds with me taking a $500 or more loss lol!

Just thinking it’s kind of weird Holosun just doesn’t include the riser for $10-20 more, every other T-1 type Holosun comes with a mount at lower 3rd type height... then there wouldn’t have to be any posts wondering about it lol!

Cool Mine shows up Monday hopefully...

Think I’ll probably end up around there somewhere... Thinking 25 & 7, or maybe even 20 & 7 might work..? Zeroing at 20 seems like a decent compromise to me, around 1” low 7-15ish, 1” or more high at 25+, I like my pistols to print a little high at 25yrds so I can “lollipop” a 6” plate at 25 by putting it on top of the front blade... I’m not married to any particular load yet, so I’ll have to experiment anyways... I just got a Gen 3 MPX and am still learning it’s recoil/dot tracking, I don’t reload so I’ve been going back and forth between 115gr Tula (seems pretty nice actually ) and 130gr PCC-specific Syntech (Nerf-gun recoil, might be too soft), not sure what will end up being my “go-to” ammo yet... I’ve pretty much changed everything (gun/sight,etc) recently, and my work schedule hasn’t been kind as far as hitting matches, so I’ve got some dialing ahead of me...

That’s exactly what I was thinking I’ll try... if the laser dot is “buried” in the halo it shouldn’t annoy me and be a better POI for the closer targets I’ll be using it for... that’s the plan anyway hahaha