I just picked up my MP Sport II and so far not a happy camper. The stock handguards were not seated all the way inside the delta ring and now after installing Magpul ACS, it is stuck all the way in the collapsed position. No matter what I do I cannot get it to budge or move to the rear.

Every shooter that owns an AR-15 needs a handguard tool. They are less than $20 shipped.

Let me understand, it appears that you are blaming your Sport because the Magpul stock is jammed?

Did you check whether it's commercial or Mil-spec ? Different rifles use one or the other, for the buffer tube.

I installed a Magpul CTR a week ago, it needed a little more force than I realized to get it to slide on. I agree with MichiganScott though; it's not a problem with the rifle, it is probably the stock or user error. Magpul stuff has a rep for great quality.

Or just a strong grip and determination, that $20 can be another box of ammo!

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Isaiah 43:1-3

I finally got the stuck off by just tugging and wiggling it. The first time I installed the ACS, it was darn tight but now it is smooth as a baby bum.

I am not sure about Magpul Quality. The MOE front hand guard I used on another rifle, I have never got the barrel hot but where the mounting threads are that locks into the barrel nut was melted slightly.

I have 3 entry level AR-15's and one of them has a commercial buffer tube and two have Mil-Spec buffer tubes. The S&W M&P Sport II was a Mil-Spec buffer tube by the way.

This is one, among many, reasons I buy it the way I want it, and do not try to do "add-ons."

After four and a half decades of shooting, the first couple of decades ruining some good Colt 1911s and some great S&Ws by letting nationally known gunsmiths mess them up (in one case, the hammer followed on my 1911 after the work, but not before), I learned my lesson long ago that either I or even a well known gunsmith, can screw it up more often than not, and even when I do not, I often end up switching it back to the original configuration.

I bought a Mil Spec ACS and I can tell you the front barrel end cap is not mil spec as it does not fit another drop in that I used on my Windham's. The barrel end cap is way too big.

As I said, you need to know which buffer tube the S&W uses. The commercial tube, has a slight bit more diameter. As I remember, the Windhams use a commercial tube. But I'm not positive about that. I did have a Windham, but didn't make that change.

Having bought one AR complete, and built three more, going onto the fourth, I'd rather build a complete rifle any day. But it does require the proper tools, research, and the will to do it. In my case, there have been no screw ups. We even went to the trouble of hydro-dipping my wife's AR-15 which turned out great. That, itself, takes some trial & error the first time around.

It's plastic... it is going to melt slightly. Mil-spec hand guards do the same. As do polymer hand guards made by BCM or others.

OMG@ i TOTALLY INSTALLED THE UTG PRO SLIM INCORRECTLY! i DIDN'T REALIZE THERE IS A RECESSED AREA WHERE THE GUARD HAS TO SLIDE INTO OR IT WILL NOT FIT OVER THE DIAMETER OF THE END CAP. MY BAD. FITS PERFECTION NOW.