Got a chance to talk with the RO at my local range Saturday and got some interesting trivia from him.

He was irate with a city ordinance eliminating the use of full auto fire at the range. The range has a contract with contractor (he wouldn't give me any details; but from an article in the local paper I believe it is Raytheon) to test some AR15-related equipment.

The testing is for recoil endurance purposes and each item is being tested to several thousand rounds. Earlier, they had used machine guns to do this but they now have to do it semi-auto. Here are a few details he shared:

1) The cycle of firing is 210 rounds semi-auto, swap uppers (5 different uppers) and repeat. Barrels are shot as long as they are safe to shoot, regardless of accuracy issues. 15 barrels replaced so far - was unable to estimate a round count per barrel though it must be pretty high as program has been going on for at least 7 months according to article.

2) From an unspecified ambient temperature (70-90F), 210 rounds fired as fast as you can pull the trigger semi-auto will heat the barrel to 620 degrees (didn't think to ask barrel type, sorry; but given the program I am guessing M4)

3) No cooks offs yet; but twice now the single-heatshield round carbine handguards have caught fire and interrupted the test before they finished their 210 round cycle.

Interesting... you should offer to show em how to bump fire. [:D]

City of McKinney SCREWED Collin County Gun Range!!!!!

Yes, it was Raytheon.  I happened to be there one day when they were testing - full auto.  M4 uppers - correct.

They went through about ten cases of 55 gr PMC.

Pretty cool when you have to wheel your ammo in on a dolly! [:D]