Any problems with using these? Someone posted that you couldn't use them because:
Differential heating and expansion of alminum and steel will casue gas leaks and malfunctions. You must use a steel gas block for reliability.

But they do sell aluminuim gas blocks:

www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=7592&title=AR-15+ADJUSTABLE+GAS+BLOCK

......do you only get problems after the barrels heat up? Or are they just making the aluminuim gas blocks for people that don't know any better?

Thanks
AoD

Quoted: Any problems with using these? Someone posted that you couldn't use them because: Differential heating and expansion of alminum and steel will casue gas leaks and malfunctions. You must use a steel gas block for reliability. But they do sell aluminuim gas blocks: www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=7592&title=AR-15+ADJUSTABLE+GAS+BLOCK ......do you only get problems after the barrels heat up? Or are they just making the aluminuim gas blocks for people that don't know any better? Thanks AoD

I may have posted that.  In my ITRC report from this year, I wrote that several carbine shooters using aluminum gas blocks held in place with set screws at 6'o'clock had problems on the stage that required 500-600 shots in 15-25 minutes.   The aluminum would expand at a higher rate than the steel barrel, the set screws would lose purchase, and the gas block would migrate forward slightly under recoil until the gas holes no longer lined up and the rifle was rendered single-shot.

Of course you can use an aluminum gas block, and people sell them.  JP Enterprises even uses them on their 3Gun rifle (the CTR-02).   The shooter must understand that under extreme heat, such a problem might reveal itself.  

If you are planning to shoot that kind of a sustained rate, it's a good idea to heed lessons already learned and go with a gas block of similar material as the barrel.

-z