Hi, i bought an earlier mnp15 sport 5.56 when they first came out.
Mines doesn’t have the forward assist or dust cover.

Fast forward…i heard about the ability to swap out the upper for a .300 upper.

Have any of you done this?
Can you recommend where to get the hardward that will be compatible please.

If you would like a inexpensive upper, check out joe bob outdoors or delta team tactical for a variety of upgrades.

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viking

Click on the link, buy one and attach it to your existing lower. *Keep it legal.

Just a moment...

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SIC SEMPER TYRANNIS

+1 👆 Just make sure the upper is a rifle upper aka has a 16" barrel @Badmatrix.

FYI: you may also have to purchase another charging handle and bolt carrier group (if it's not included in whichever upper you purchase), or you can steal them from your M&P Sport upper.

I'd go AR pistol upper myself, still totally legal.

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Dave Ramsey Cultist

Then he'd have to also buy a brace and then pull the stock on and off his lower.

The pistol braces are under universal injunction now, but that may flip-flop on and off for the next few years before the case is settled once and for all. Being that his rifle started out asca rifle and not a pistol, if the injunction is lifted, the OP can't use the upper. Period. He wouldn't even be able to remove the stock and brace, and shoot with the buffer tube only.

That whole thing is just too much to worry about being on the legal fence about. A complete upper research is in progress since I have no idea what this involves. I am attracted to the prospect of shooting subsonic rounds with my alaskan360. We enjoy hunting paper. The AR platform is good for one thing, not sure if SBR or AR pistol would be a good fit. I was shopping for the Ruger Ranch G2 300BO, then I remember seeing stuff about AR 300BO uppers.

Attached Images

IMG_7915.jpg (84.1 KB, 11 views)

I'd yank the stock off and attach a brace and stay pistol length, but if it's a rifle already not sure you're allowed to go that direction.

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Dave Ramsey Cultist

Once a Rifle alwasy a Rifle. The same goes for shotguns

Even if you pull the stock and replace it with a brace, in the eyes of the National Firearms Act of 1929 as amended in 1934 the firearm would still be a Short Barreled Rifle

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"Acta non verba"

Compete 300BLK uppers are for sale just about anywhere. I have a PSA shorty that serves me well.

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Sure you did

Cool. So for these complete uppers, one can pay a little or pay a lot. Does this correspond to how accurate the uppers will shoot?

Price points depend on several factors. There are inexpensive uppers made by some manufacturers that that will be plenty accurate and there will be some that aren't.... Personally, I'd just purchase a PSA 300blk upper, and be done with it.

Part of the equation is how accurate of a rifle are you expecting, and what constitutes acceptable accuracy to you? Whether it is worth spending more for an upper usually depends on your expectations and end goals.

The differences in cost are a reflection of a number of things. Higher dollar uppers usually are made of "better" materials when it comes to things like metals. They may also more rigorously test their components with things like magnetic particle inspection (MPI), and HP testing.

Some of the higher dollar manufacturers also use processes during the build that can improve accuracy. The different rifling processes have their pros and cons. They also may do things like thermal fit the barrel to the upper. There also may be differences when it comes to QC checks.