Ruger AR 556 MPR

Dizzle · Feb 17, 2018

What kind of barrel can I buy to have my gunsmith swap out for the stock barrel to make the Ruger AR 556 MPR legal in Maryland?

https://www.mdshooters.com/showthread.php?t=217434

I see it has been done before but no information was given on a good barrel to use for the swap...

Ifdot · Feb 17, 2018

Any 16in HBAR will work.

Dizzle · Feb 17, 2018

I think the stock barrel is 18" so wouldn't it have to be 18" and the MPR has a full length gas system... Does that require a specific barrel?

Ifdot · Feb 17, 2018

if you want an 18 in barrel get an 18in HBAR, if you want a 16in instead it will cost an extra $10 for a new gas tube.

Dizzle · Feb 17, 2018

For better accuracy do you have any recommendations? 16" 18" or 20"? What twist rate and do you know of any manufacturers that have one in stock?

molonlabe · Feb 18, 2018

Dizzle said:
For better accuracy do you have any recommendations? 16" 18" or 20"? What twist rate and do you know of any manufacturers that have one in stock?

This all depends on what you want to use it for. You have selection of bullets from 55 to 75 gr rule of thumb for all round use 1 in 9 but that will not stabilize a 75 gr bullet but then again that's for matches and longer AR,s. A 1/7 will stabilize it but kind of rough for a 55 gr bullet. I like the 18 inch but just personal preference. Again there is no easy answer for this without knowing your shooting preferences. There are just too many mfg to list I'll leave this for someone else. The search function can help you a lot.

Dizzle · Feb 18, 2018

Using this rifle for hunting and plinking.

outrider58 · Feb 18, 2018

Generally speaking, barrel longer length will add velocity, not necessarily accuracy per se. Barrel quality will determine accuracy.

Magnumite · Feb 18, 2018

FWIW, if you want a quicker handling arm the 16” carbine hbar will have a shorter hbar section. This will keep weight lower and more between the shoulder and the support arm...far less front heavy.

zoostation · Feb 18, 2018

Or just buy a complete HBAR upper and replace the factory one for what it's costing to buy a barrel and have a smith swap it. Then sell the "banned" upper to someone who can legally use it to recoup some costs.

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