quote:

Originally posted by Ferrari Steve:
Had to heat up the flash hider with a blow torch until it glowed red, then whack the bejeezus out of the wrench with the hammer (yes, I know it's left-hand threaded) to finally get the flash hider off.

The SilencerCo Osprey 9 with the XL piston (slightly longer) and the fixed barrel extension are a perfect fit on the MPX.

Yes it is brutal! Wasn't sure if i was going to get mine off at first!

How does it sound with the Osprey? I've been less than impressed so far with the Octane 9. I mean it's a GREAT silencer on a pistol but the MPX has a ton of blowback and loud. Plan on trying mine with a .45 can, might help that out.

I took the MPX carbine to the indoor range today. I brought the 1 supplied Gen 2 mag and 3-Gen 1 mags, all loaded with 30 rounds of Freedom Munitions 124gr new ammo. I started with the Gen 2 mag and had trouble getting a round to chamber. The round wasn't being fully pushed out of the mag. I tried a Gen 1 mag and had the same problem with not being able to chamber a round. After messing with the mags and the gun for awhile, it started working. I attributed the problem with the strong new springs in the mags. I ended up running 220 rounds through the gun using both the Gen 2 mag and the Gen 1 mags. So, bottom line: the Gen 1 mags work fine in the Gen 2 gun. And, the MPX is a lot of fun.

quote:

Originally posted by immawake:
I took the MPX carbine to the indoor range today. I brought the 1 supplied Gen 2 mag and 3-Gen 1 mags, all loaded with 30 rounds of Freedom Munitions 124gr new ammo. I started with the Gen 2 mag and had trouble getting a round to chamber. The round wasn't being fully pushed out of the mag. I tried a Gen 1 mag and had the same problem with not being able to chamber a round. After messing with the mags and the gun for awhile, it started working. I attributed the problem with the strong new springs in the mags. I ended up running 220 rounds through the gun using both the Gen 2 mag and the Gen 1 mags. So, bottom line: the Gen 1 mags work fine in the Gen 2 gun. And, the MPX is a lot of fun.

so the bigger question is, do gen2 mags work in a gen 1 gun?

quote:

Originally posted by CRASH_PRO:

quote:

Originally posted by Ferrari Steve:
Had to heat up the flash hider with a blow torch until it glowed red, then whack the bejeezus out of the wrench with the hammer (yes, I know it's left-hand threaded) to finally get the flash hider off.

The SilencerCo Osprey 9 with the XL piston (slightly longer) and the fixed barrel extension are a perfect fit on the MPX.

Yes it is brutal! Wasn't sure if i was going to get mine off at first!

How does it sound with the Osprey? I've been less than impressed so far with the Octane 9. I mean it's a GREAT silencer on a pistol but the MPX has a ton of blowback and loud. Plan on trying mine with a .45 can, might help that out.

You're the second person I've heard in two days saying the MPX doesn't sound great suppressed and has tons of blow back. It isn't the Octane, that is for sure. This is almost getting laughable at this point.

This is a picture of MPX-K (with a can) on Instagram so I hope it will ship soon.

"You're the second person I've heard in two days saying the MPX doesn't sound great suppressed and has tons of blow back. It isn't the Octane, that is for sure. This is almost getting laughable at this point."

All ARs have this same issue. They blow gas and noise back through the open back of the receiver where the charging handle rides.

I'm stoked. I resubmitted the Form 1 yesterday and it was approved today! Now I can look forward to getting the stock I ordered 06/24/2015.

quote:

Originally posted by AZFoxes:
Fwiw, I heard from someone else that said they put the same thing and theirs was approved. I'm not sure what to tell you other than I don't think I was being treated any different than anyone else in the same situation. When I reapply I will forward the same agent my new ID and Permit numbers with a note referencing the original submission and reason for disapproval with a request for expedited handling. Good luck...I guess for me and you.

quote:

Originally posted by Palehorse0311:
Dang what a bummer to hear about you form 1 getting kicked back for MPX-P. The funny thing is I put that on my eform 1 I submitted back in early September . So heres the question...do I contact the ATF and have them cancel the form so I can re-do and lose my 2 months of waiting or wait until they catch it themselves and hope they show mercy and let me fix and resubmit it with expedited status like yours???


Oh why do our hobbies have to be so frustrating.

Regarding cans and sound, has anyone run a Gemtech MK-9K on a MPX? I am wondering what the heavier, larger volume can sounds like.

I ran both my Tirant 9 and 45 and I think the 45 is quieter I guess due to the larger volume.

On a side note the 9 just won't stay tight, not on the barrel but the end cap holding the fixed barrel spacer.

This message has been edited. Last edited by: pedro66,

quote:

Originally posted by glocke12:

quote:

Originally posted by immawake:
I took the MPX carbine to the indoor range today. I brought the 1 supplied Gen 2 mag and 3-Gen 1 mags, all loaded with 30 rounds of Freedom Munitions 124gr new ammo. I started with the Gen 2 mag and had trouble getting a round to chamber. The round wasn't being fully pushed out of the mag. I tried a Gen 1 mag and had the same problem with not being able to chamber a round. After messing with the mags and the gun for awhile, it started working. I attributed the problem with the strong new springs in the mags. I ended up running 220 rounds through the gun using both the Gen 2 mag and the Gen 1 mags. So, bottom line: the Gen 1 mags work fine in the Gen 2 gun. And, the MPX is a lot of fun.

so the bigger question is, do gen2 mags work in a gen 1 gun?

Anecdotal testimony from a customer of mine says "yes gen2 mags work in gen1 guns."

I ordered a Thompson Machine SG2. I'll provide a review once I get everything in place. I saw someone somewhere that bought one awhile back and said he would review it but never saw the review. I have to assume that the bigger can that was designed for a subgun will make a difference.

quote:

Originally posted by pedro66:
I ran both my Tirant 9 and 45 and I think the 45 is quieter I guess due to the larger volume.

On a side note the 9 just won't stay tight, not on the barrel but the end cap holding the fixed barrel spacer.

Pedro, that's why I asked about the MK9K, it is old school, large (2"x7.5") and heavy (20oz) designed for full auto on SMGs. At that diameter, it will never fit inside any handguard.

A Class 3 nut I know swears by it having run it on MP5s, Uzis and other short-barreled 9mms. He also says the heavier weight makes for a lower sound as well.

quote:

Originally posted by Ferrari Steve:
Had to heat up the flash hider with a blow torch until it glowed red, then whack the bejeezus out of the wrench with the hammer (yes, I know it's left-hand threaded) to finally get the flash hider off.

Do you think they used Rockset to secure the hider? I had a similar experience getting an ACC hider off of a Noveske upper, and they used Rockset.

quote:

Originally posted by gearedforacure:
I ordered a Thompson Machine SG2. I'll provide a review once I get everything in place. I saw someone somewhere that bought one awhile back and said he would review it but never saw the review. I have to assume that the bigger can that was designed for a subgun will make a difference.

That was me, same guy complaining about the blowback up a few post which is why i bought the SG-2 in the first page because i airway tried the octane and wasn't impressed.

My Form 4 is currently at 3.5 months, current average is a little over 4 months so hopefully it'll be here soon!

quote:

Originally posted by cmlasley:
"You're the second person I've heard in two days saying the MPX doesn't sound great suppressed and has tons of blow back. It isn't the Octane, that is for sure. This is almost getting laughable at this point."

All ARs have this same issue. They blow gas and noise back through the open back of the receiver where the charging handle rides.

I would agree with but in the case of the MPX, you can literally see gas escaping between the upper and lower receiver and your in a plume of gas during rapid fire. I don't notice this with the silencer off. That's why i decided to buy a large volume can, the SG-2 says it was designed for open bolt guns and thefore made to have low back pressure to quiet down action noise and gas through the action, I'm hoping it has the same result for the MPX.

quote:

Originally posted by CRASH_PRO:

That was me

Nice, looking forward to hearing how it works for you!

quote:

Thompson Machine SG2

Crash_Pro - Also looking forward to hearing more.

Quick and dirty volume calculations suggests internal volume of SG2 is about 15-16 cubic inches.

Gemtech MK9 is about 21 cu in.

Osprey 9 is about 12 cu in (not round so real guesstimate)

TiRant 9 is about 10-11 cu in.

Thinking is the larger volume allows more gas accumulation so that bullet can leave barrel and let more gas out muzzle rather than blowing back through chamber.

Any suppressor experts want to opine on interior volume versus blowback? Yes, baffles will have an impact as well but this is a layperson's "analysis".

quote:

Originally posted by ctsheepdog:
Any suppressor experts want to opine on interior volume versus blowback? Yes, baffles will have an impact as well but this is a layperson's "analysis".

I won't claim to be an expert, but I've seen a few cans in action.

What I've found is that the internal volume has more to do with the quality of suppression and less to do with alleviating blowback (all other things being equal, bigger, longer cans do seem to be quieter).

The "tightness" of the bore is what generally contributes to blowback. So a 5.56 round shot out of a 7.62 can has less retrograding gas than a 5.56 shot out of a 5.56 can.

If the bullet "seals" really well against the baffles, the excess gas that doesn't enter the expansion chambers between the baffles can't go anywhere except back down the barrel. Theoretically having huge expansion chambers would reduce the blowback but IME, the difference between most cans on the market isn't noticeable.

If you don't want blowback, the easiest way to alleviate the gas trapping effect is to use an overbored can. While theoretically not as efficient sound-wise, this definitely allows gas to keep moving forward. It doesn't take that much overbore to get better results, blowback wise, and most people can't tell the difference sound-wise.

I wondered about that...

My line of thinking was that a bigger volume suppressor would be better, but the longer the suppressor, the longer the chamber stays pressurized, thereby increasing the gas out the ejection port.

I wonder what the difference in suppression is between the 9mm and a 9mm through the .45 is?

LDD, thanks and expert enough.

geared, do some searching and you will find the data out there, either from the manufacturers or folks who use sound meters on Youtube. IIRC, there may be a several (2-5dba) difference when running 9mm through 45. As LDD points out, that is not going to make much of a difference to the shooter, especially if there is environmental background noise. Either way, levels should be below 140 even with larger bore.

FWIW, this past weekend, we ran my Surefire 5.56 and 6.8 cans off of two 14.5" barrel ARs with the same ammo. While we were using standard velocity ammo, no one could discern a difference to the ear (I have tinnitus so kept ear pro in so I was relying on several others). One guy positioned himself a couple feet behind the shooters with a dB meter an noted a couple of dB difference with the 6.8 being higher shooting 556. Candidly, I don't think we can hear the difference over the sound of the mechanicals right next to our ears.