What an 11.5" BCM upper does to a blank firing adapter

[Voodoo_Man]

I was recently involved in an LE training exercise as OPFOR and I used my 11.5" BCM with a blank firing adapter which shot about 150 rounds. After around 120 or so rounds the birdcage began to loosen and I did not notice until it stopped cycling due to the blank firing muzzle device/adapter deforming. I am assuming it is because the 11.5" has more pressure than a standard 16" upper which caused the issue. Thank fully the threads on the barrel did not get messed up.

Figured I would post up and share my experience for those who may have the opportunity in the future to use a blank firing adapter.


http://i.imgur.com/uSarUV3.jpg

http://i.imgur.com/2Ql6BVr.jpg

http://i.imgur.com/urrjmfi.jpg

http://i.imgur.com/8hP3tJj.jpg

Needs a good cleaning:

http://i.imgur.com/n1VqcCK.jpg

[SilverBullet432]

That's crazy! Sucks about your gun but i must ask: What type of "OPFOR" did you play? Sounds exciting!

[Kain]

I think we can officially say that it was the rifle rejecting the adapter and demanding real ammo. ;)

That said. Damn! Is interesting nonetheless.

[Voodoo_Man]

That's crazy! Sucks about your gun but i must ask: What type of "OPFOR" did you play? Sounds exciting!

From what I understand there was video taken so I'll wait for the clips to be edited before I ruin it, the short answer is it was an active shooter.

[vandal5]

Hmmm, sounds like a redesign is needed for the blank firing adapter to allow it to be used with a short barrel.
Someone could make a lot of money, just remember to send me 5% for thinking up the idea.


Just wondering, were you using an approved ammo/blank for this? I have never used one, do they list recommended blank loads if there is such a thing?
I can't believe you were the first to try this.

[3ACR_Scout]

One observation: If that's a military blank firing adapter (BFA), then it's an M16 version (distinguished by the red color). M4 BFAs are yellow, and I believe they are designed to allow more gas to vent to accommodate the higher pressure of a 14.5" barrel. This might have still occurred, but maybe it was more likely to happen using an M16 BFA? I'm not too smart on the difference between the two BFAs, but that's the only reason I can think of for having two distinct versions.

Glad there wasn't more damage to your rifle.

Dave

[CoryCop25]

One observation: If that's a military blank firing adapter (BFA), then it's an M16 version (distinguished by the red color). M4 BFAs are yellow, and I believe they are designed to allow more gas to vent to accommodate the higher pressure of a 14.5" barrel. This might have still occurred, but maybe it was more likely to happen using an M16 BFA? I'm not too smart on the difference between the two BFAs, but that's the only reason I can think of for having two distinct versions.

Glad there wasn't more damage to your rifle.

Dave

Correct. There is one BFA for rifle and another for M4.

[Dave_M]

Your last picture is a good demonstration of why everyone I know hated using blanks. Phenomenal way to foul the crap out of any weapon. Sure, lube it up and it'll run but if you gotta clear it out before turning it into the armory....

[Iraqgunz]

Glad you mentioned it, I was thinking the same thing.


One observation: If that's a military blank firing adapter (BFA), then it's an M16 version (distinguished by the red color). M4 BFAs are yellow, and I believe they are designed to allow more gas to vent to accommodate the higher pressure of a 14.5" barrel. This might have still occurred, but maybe it was more likely to happen using an M16 BFA? I'm not too smart on the difference between the two BFAs, but that's the only reason I can think of for having two distinct versions.

Glad there wasn't more damage to your rifle.

Dave

[Voodoo_Man]

The last time I did an OPFOR thing using a BFA I used a 16inch upper and had no issues with it.

I was using these - http://www.keepshooting.com/223-5-56-blanks-german-dag.html

Next time I'll have to see if I can find a yellow BFA.

[throwback]

After around 120 or so rounds the birdcage began to loosen and I did not notice until it stopped cycling due to the blank firing muzzle device/adapter deforming. I am assuming it is because the 11.5" has more pressure than a standard 16" upper which caused the issue.


It's not just your 11.5 that does it. Blank firing adapters have failed rather routinely in the Army over the years, on 14.5'' and 20'', though I am sure it happens faster with the shorter barrel lengths. I saw complete or partial failures twice in Ranger school, one in AIT, and have heard of it happening anecdotally with some regularity otherwise. It's why we were always briefed to point the weapons away from OPFOR and call out "safety kill" when within a few meters of anyone for training. Any idea how long your dept. had been using this particular unit?

[Voodoo_Man]

It's not just your 11.5 that does it. Blank firing adapters have failed rather routinely in the Army over the years, on 14.5'' and 20'', though I am sure it happens faster with the shorter barrel lengths. I saw complete or partial failures twice in Ranger school, one in AIT, and have heard of it happening anecdotally with some regularity otherwise. It's why we were always briefed to point the weapons away from OPFOR and call out "safety kill" when within a few meters of anyone for training. Any idea how long your dept. had been using this particular unit?

Not my dept. but, I know they've had them for at least two years.

We didnt point at people either since there is always a chance the thing goes off and then it is bad news.

[Blastem]

Ha nice seeing that. BCG. In AIT I was op for and fired 800 blanks. Had to chamber each round with the forward assist. Took FOREVER to clean! No degreasing station etc. Just brushes and CLP. I'm still traumatized and that was 1985. :-)

Sent from my DROID RAZR using Tapatalk

[markm]

One observation: If that's a military blank firing adapter (BFA), then it's an M16 version (distinguished by the red color). M4 BFAs are yellow, and I believe they are designed to allow more gas to vent to accommodate the higher pressure of a 14.5" barrel.


THIS! For God's sake!!!

And I bet the Yellow one isn't a good idea on an 11.5". Still too much pressure.

[MarkG]

The exhaust hole in the carbine version is MUCH larger.

26689

[3ACR_Scout]

Thanks, MarkG - it's actually been at least 10 years since I last saw an M16 BFA, and I've never actually compared them side by side.

Dave

[Dave_M]

Probably one of the, 'Hollywood style' BFA's would be best for an SBR (not the internal threaded one, obviously). However, they are not immediately visible and are tailor made for high flash blanks; therefore not the best choice for training use.

[K_K]

One observation: If that's a military blank firing adapter (BFA), then it's an M16 version (distinguished by the red color). M4 BFAs are yellow, and I believe they are designed to allow more gas to vent to accommodate the higher pressure of a 14.5" barrel. This might have still occurred, but maybe it was more likely to happen using an M16 BFA? I'm not too smart on the difference between the two BFAs, but that's the only reason I can think of for having two distinct versions.

Glad there wasn't more damage to your rifle.

Dave

I think I am missing something here. Would more pressure be created from the length of a 20" barrel because it would have space to burn all the powder. So if there is more unburnt powder and less pressure in a 14.5" barrel why does it need to be stronger? I guess im comparing the buffer weights too. M16 creates more back force requiring a heavier buffer to dampen the effect. Am I mistaken? And why wouldn't they just use one style than can handle any length?

[Quiet Riot]

Volume. The longer the barrel, the more volume there is inside the bore. By the time the gas reaches the end of a longer barrel, it has a lot more room to fill, and the pressure drops faster than the additional burning powder can increase it.