Hey guys i just purchased a Vltor MUR and i tried mating it with my POF lower, but the hole where the rear take down pin is supposed to go through is too big on the MUR and it gets jammed everytime i try to assemble the upper with the lower and it won't budge, do you guys have an ideas?

There are a lot of variances in lowers, unfortunately.  That "shelf" can be high.  I have two MURs, one of which is very tight on my Stags, and loose on an LMT.

I'd talk to POF and see what they say.

Ok so good news bad news.... Good news is i figured out that it was the rear take down pin that was pertruding like 1/16 of an inch out and the shelf couldn't fit into the lower reciever, so i took the stock off and switched the position of the spring and detent so instead of the detent first, it's the spring first followed by the detend which gives the rear take down pin that 1/16 inch to move to the right which in turn allows the upper to be mated to the lower.. Ok so.. Bad News that upper is on there tight, and i mean tight i had to put a lot of effort to close the rear take down pin all the way, so if i have to break the rifle down it's gonna take me about 10-15 seconds longer than it normally would. As a result of this i have a few questions

1. being that the upper is very tight on the lower will that pose an issues later one?

2. being that the spring is first instead of the detend will that pose an issues?

Thank you-

The detent should be against the takedown pin.

If the spring is too long, you can cut it. I know, heresy.

It's supposed to be tight. All my Vltor uppers are tight. Some need lots of persuasion to close.