Well I had fun trying to zero today.  I got a f*cked up match.  My FSP was almost all the way up and I still was a bit high at 50 yards.

I ordered the .040 FSP from Bushmaster, even though it will stick up higher than the protective "ears".  It will look goofy as hell.  Oh well, this is a back-up after all, my aimpoint is my regular sight.  

Still, this pisses me off!!!

While I'm ranting, my Buffer spring(brand new RRA 6-position) is too weak to strip a round from a fresh mag when I do mag changes.  What's up w/ that?  I ordered a new one from BM....

It's discussed at length in the FAQ under "Excess Elevation". You can buy a Colt barrel and your problems will be solved and your rifle will be more reliable to boot.

You sure your hammer isn't catching the bolt  carrier on the battery stroke? That'll cause a failure to go into battery or FtF.

It's not that a brand new spring can't be bad, the hammer/bolt carrier interference is just one more thing to check. That's in the FAQs too.

I installed the higher post on my #40/Bushmaster combo to zero at 50 yards and it doesn't extend past the top of the front sight assembly.


Chris

MP906,

Are you using a 16" or 20" barrel?

What kind of magazine - new Thermolds?

14.5" barrel.  Several new LEO/military mags.

Each time, the bolt had locked open, I put in a fresh mag loaded w/ 28 rounds, hit the bolt release and the bolt stopped when it hit the case.  It seemed very weak and sluggish, that's why I was thinking spring...?

I had to recharge w/ the charging handle or use the forward assist each time.


With the front sight:  I have my standard front sight post all the way up(to the point where it is wobbly) and I'm just about on target.  The post is flush w/ the ears, so with the higher FSP it will stick up past the ears a little bit.  I don't think it will screw up the sight picture to bad though.

Screw COLT!  How exactly is a Colt barrel more reliable than a Bushmaster?

Were those rounds feeding low MP906?

Colt barrels are more reliable in every way possible. If you want to get into a brand bashing thread pull up the designated one here and post in it. It's linked from The Rules.