300BlkTalk

civilian75 wrote: I am still having trouble visualizing where would the glue be applied. I don't even want to speculate

Loosen the Gas Key Screws and remove the Gas Key from the Carrier.



Make sure the mating surfaces of the Gas Key and the Carrier are perfectly flat, then use brake cleaner (from any auto-parts store) to rinse out the Carrier and Key.

When both are clean and dry, apply a bit of Loc-Tite 401 to both surfaces (where part #2 attaches to Part #3. Don't use so much as to cause it to squeeze out into the gas passages), and re-assemble the Gas Key to the Carrier, and torque the screws to 80 INCH-POUNDS and re-stake.

Let the Loc-Tite cure before firing the weapon.

This drawing certainly explains A LOT! Very much appreciated.

I wished I had taken the gas key out before I re-staked the screws. I feel very compelled to take it apart and perform this procedure, that is, unless by doing so I mess the gas key up and then it won't re-stake correctly the next time.

I wouldn't. As you stated, the weapon functions now, after simply torquing and re-staking the screws. The Loc-Tite article came from an armorer doing complete rebuilds on old worn Australian Army M16's, some Gas Keys of which would simply not seal up onto the BCG's.

Yours is fine. If the screws are tight and staked, don't butcher it.

Quiet Riot wrote:

civilian75 wrote:

SpaceWrangler wrote:I would return the Upper to CMMG for evaluation before I started drilling bigger holes or anything else that would void the warranty.

Warranty is already voided. here is what CMMG said:

...as for the warranty, since you have used re-loaded ammunition (Hornady 225gr Match, 10.5gr A1680, OAL:2.160", clocking 1020fps
average) , it has already been voided: http://www.cmmginc.com/pages/ammunition.html

They just screwed the pooch. I will be sure to mention this every time I answer a "which upper/barrel should I buy?" post.

They just took a barrel back that was out of spec, it was the 6.5" 22LR, the threading was not concentric (and it must have been the whole batch of them because they sent me an email telling me to send it back). Initually they said it would come back 6" (meaning they were gonna hack off the front and rethread, which I didn't much like the idea of) but recently they said they would send back a 6.5" barrel that was threaded proper. I also had a SS 22LR adapter kit with a damaged chamber adapter (cracked) and they sent me a new one no questions asked and let me keep the old one (which is useless, but still the could have made me cough up 6-8 bucks to send it back to them).

Now, this isn't the first time I've seen threading issues from CMMG (a friend had issues with a 5.56 upper) but that said, I've had pretty good luck with their CS. My guess is the reason they said no on the return for service was because he opened up the gas port (which I probably would *not* have done before I sent it back to them for a look over).

bp_968 wrote: My guess is the reason they said no on the return for service was because he opened up the gas port (which I probably would *not* have done before I sent it back to them for a look over).

Um, no. From post number two:

I took out the gas block. Port is 0.110". Don't feel comfortable drilling a larger hole. So, it is now either weaker spring or somehow a hotter load (?)

And from post number 9, CMMG said why the warranty was voided.

...as for the warranty, since you have used re-loaded ammunition (Hornady 225gr Match, 10.5gr A1680, OAL:2.160", clocking 1020fps
average) , it has already been voided: http://www.cmmginc.com/pages/ammunition.html

civilian75 wrote:

HotHolster wrote:Since then I have ordered and received a shipment of UMC ammo from Bullseye Range and Guns out of Georgia, and when I decide what optic to put on, I'll head back out to sight the gun in for hog hunting.

If anyone wants this info:

125gr. chrono'd-----130gr chrono'd
1895fps----------- 1974fps
1885--------------1909
1923--------------1933
1861--------------1941
1904--------------1945
1918--------------1921
1977--------------1961
1960--------------1934
1904--------------1953
1935-------------- 1925

Wow! That is slow muzzle velocity. That's not very close to 7.62x39 ballistics! This is one area 300 AAC Blackout I think failed to deliver, in my book.

123gr, 762x39 out of various length barrelled AKs
715 m/s - 123 gr - 415 mm barrel (16.3in)

650 m/s - 123 gr - 320 mm barrel (12.5 in)

600 m/s - 123 gr - 215 mm barrel (8.46 in)

The 125gr factory 300 BLK ammo is allmost always doing 2230(ish) out of a *quality* 16" barrel. The numbers get even better when you go down to a 8-9" barrel in 300BLK VS a 8-9" barrel in 762x39.

Remember, this round works in a 16" barrel but its *designed* for a short barrel. Its why its 620m/s out of a 9" barrel and 675m/s out of 16" barrel. A barely 10% energy loss after hacking off 7" of barrel length. 5.56 is taking over a 500fps(ish) loss going from a 16" to a 9" (in fact, most people would avoid anything under 10.3" in 5.56 unless as a toy).

Honestly I'm impressed it does as well as it does at HV against the 762x39 simply because of the case volume advantage 762x39 has over 762x35/300BLK.

300BLK is neat, and I'm excited about building one, but it, like everything else, has a specific purpose and can't do everything equally well.

L1A1Rocker wrote:

bp_968 wrote: My guess is the reason they said no on the return for service was because he opened up the gas port (which I probably would *not* have done before I sent it back to them for a look over).

Um, no. From post number two:

I took out the gas block. Port is 0.110". Don't feel comfortable drilling a larger hole. So, it is now either weaker spring or somehow a hotter load (?)

And from post number 9, CMMG said why the warranty was voided.

...as for the warranty, since you have used re-loaded ammunition (Hornady 225gr Match, 10.5gr A1680, OAL:2.160", clocking 1020fps
average) , it has already been voided: http://www.cmmginc.com/pages/ammunition.html

Your right, post two wasn't 100% clear in my first read through. I thought I saw him say he actually drilled it bigger.

He should try them again on the warranty thing. Denying warranty because of reloads on a weapon like a 300BLK is pretty foolish IMHO. I suspect a large percentage of the people buying them plan to reload. Its pretty expensive if you don't. I know *i* wouldn't buy one from them if they intend to continue to enforce a policy like that.

Honestly the only rifles/uppers that have been 100% trouble free for me are my Noveske and the one's I've built myself (a Daniel Defense rifle, and a RRA rifle). It's why I'm spending the extra bucks on the Noveske 8" 300BLK barrel.

bp_968 wrote:He should try them again on the warranty thing. Denying warranty because of reloads on a weapon like a 300BLK is pretty foolish IMHO. I suspect a large percentage of the people buying them plan to reload. Its pretty expensive if you don't. I know *i* wouldn't buy one from them if they intend to continue to enforce a policy like that.

I was very close to ordering an 8" upper from them tomorrow but think I'm going to explore other options having read this.

Thanks for the heads up...

I'm not an "upper-tier" koolaid drinker and have been seriously considering a CMMG upper while waiting on my Delta Company upper but this and another thread about non-concentric barrel threads remove me from their buyers list. Bad QC is a serious problem, and using the old "re-loaded ammo taboo" without even examining the upper is a major black mark for me. CMMG just joined Oly on my will not buy/own list.

firefuzz wrote:I'm not an "upper-tier" koolaid drinker and have been seriously considering a CMMG upper while waiting on my Delta Company upper but this and another thread about non-concentric barrel threads remove me from their buyers list. Bad QC is a serious problem, and using the old "re-loaded ammo taboo" without even examining the upper is a major black mark for me. CMMG just joined Oly on my will not buy/own list.

I looked at few other manufactuters (Core15 being one) and they won't touch a rifle that used hand loads too and they say they have a 'no bs lifetime warranty'

I'm not sure who would touch an upper that shot handloads through it.

I think best bet is to just not tell them. Screw them in their own game