I removed my old plastic carbine length handguards to install a free float handguard assembly.

Using a DPMS armorer's wrench,  I removed the barrel, and later reinstalled it just guessing how many ft lbs of torque i was applying.

I've come to realize that I may have overtorqued it,  and have noticed that since I've re-installed the barrel,  recoil is significantly heavier.  Another thing, i've had quite a few feed problems since I did this as well.  I'm going to remove the barrel today and THIS time,  use a torque wrench to tighten the barrel nut.

Any ideas on this,  overtightening the barrel nut causing heavier recoil due to tighter headspace??? Maybe tighter bolt/lug lockup also, making the bolt unlocking a lot harder than it should be?

No chance of your barrel nut torque changing your headspace, nor is there any chance of headspace changing the pressure and recoil generated. Headspace is determined by the bolt and the barrel extension and the chamber. None of which should have been altered when you pulled the barrel nut. The barrel extension has the locking lugs in it and it is very solidly torqued to the end of the barrel. In fact, the barrel nut clamps the extension in the upper reciever.

The TM specs out 30 ft-lb of torque, and then keep tightening until you line up the next notch for the gas tube. That gives you quite a bit of latitude on torque...

Some float tubes decrease gun weight, which will increase felt recoil...

After re-reading your note, the TM does specify that you should tighten and loosen the nut to 30 ft-lbs three times to settle the assembly. Is it possible that you free float handguard/float tube did not settle completely, and the barrel is loose now? That might account for some feed errors. Also, the index pin (in the barrel extension might have a sloppy fit to the slot in the upper, and have cocked enough to cause some interference. Some things to check...

Check your gas tube alignment, if its binding in the key it could slow things down a bit, which may cause some feed problems.

Thanks for the response guys,
I'll check on that ASAP.  

One other question,  hard chroming the bolt makes cleaning the carbon deposits off the rear of it much easier???  correct?

Thanks again for the advice.

Hard chroming the bolt makes it... chrome!  Cleaning the carbon off the rear of the bolt is a non-issue.  Excess will blow off.  I just use a ScotchBrite pad and give it a few twists.  I get what I can out of the rear of the carrier bolt cavity with a brush, but I don't get anal about it.