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Posted: 6/29/2006 7:25:23 PM EDT
| Looking to get one of the MRP Uppers In the rifle version with 16" and 18" barrels, the question here is... would it be recommended to have a different bolt for each barrel? Thanks- Chris. |
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it is recommended to have a separate bolt per upper, but with the MRP, the head space is so rigid and it is pretty prec isely fitted, you can get away with using one bolt for both barrel. If you are getting the match grade 16inch barrel, I would recommend just forgo the 18inch, you will get superb accuracy from the 16inch that you will be pretty happy with the result. I have shot the 16inch SS match barrel in my CQB MRP to under 1MOA with 77gr MK262, and easily MOA to 1 1/2 MOA with factory USA ammo. I can hit out to 500 yard with ease and accuracy. |
 EACH BARREL SHOULD HAVE ITS OWN BOLT FOR BEST LONG TERM RESULTS. I TYPICALLY OPT FOR 16" WHEN GIVEN A CHOICE, BUT THIS 18" S/S MRP I BROKE IN / SIGHTED IN WITH NIGHTFORCE SCOPE FOR A CUSTOMER REALLY MADE ME WANT TO HAVE AN 18" BARREL IN MY PERSONAL INVENTORY. ACTUALLY, I WANTED THIS PARTICULAR BARREL, AS IT SHOT UNDER HALF MOA WITH MK 262. THE GOOD ACCURACY RESULTS WE SEE FROM THE MRP'S IS HOWEVER MORE A FUNCTION OF THE MRP CHASSIS RIGIDITY THAN ANYTHING UNUSUALLY WONDERFUL ABOUT THE BARRELS. WES GRANT M.S.T.N. |
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My 1/8 SS 18" is pretty much MOA with the heavier bullets, but gets down to near 1/2 MOA with the lighter (55gr) loads such as 55gr Silvertips. However, this 16" SS barrel from WES at MSTN is one of the most accurate AR barrels I have, way under MOA with most any quality factory match rounds from 55 to 77 grain, and about MOA with Q3131A. With the NSX scope a better shooter than me did 3 consistent .65 MOA 10 shot groups at 350 yards (it was a full mag) with BH 75gr blue box. In it's current config with the M3 2MOA dot/3xMag, it's more accurate than the sighting system. With a 200 yard zero (about 1/4" high at 50yd) you can place all shots within the 2MOA dot at 200 yards semi-rapid fire. Thanks, WES!  |
I just ordered and received an MRP upper with a 10.5 and 14.5 inch barrel. I ordered their Standard S/A bolt carrier group to go along with it. After I saw this thread, I called and spoke with LMT's tech department yesterday and asked them if I needed a different bolt for each barrel assembly. Their response was ABSOLUTELY NOT and not to believe everything that you see on the internet. That came from LMT's tech department so take it for what it is worth, I'm just going to use the one bolt. 
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I WISH I HAD YOUR JOB ! Sighting in those AR`s |
Make sure that you also own a headspace gauge and use it every few months. When you notice that the headspace is long, buy a new bolt. If the headspace is still long with the new bolt, buy 2 new barrels. When you call the LMT tech department about this, they will happily transfer you to the sales department. |
IF YOU GOT A NAME, PLEASE SEND IT TO ME OFFLINE. THANKS, WES |
I didn't get a name, I just called and asked for the tech department at LMT and they gave me to that gentleman. I wanted to know an answer to this question also since I recently purchased a new LMT MRP upper with both a 10.5 inch barrel and a 14.5 inch. I bought a complete Standard S/A bolt carrier group from them and I was interested in knowing if I needed to purchase another complete bolt carrier group before I fired it (the entire upper and both barrels are un-fired). I'm still undecided on what to do, I nkow that LMT builds the guns, but I also know that you guys (MSTN and AR15 Barrels) have a lot of experience with these also. |
You don't need a complete bolt carrier group. Just a bolt. Should run you around $50 for a good quality bolt. Then, when you take the 2 minutes to swap barrels, you can take another 30 seconds to swap bolts. Ideally, you would engrave 10" on the bolt you dedicate to that barrel and 14" on the other one so you keep them straight. |
Right, I was thinking of just the bolt also, but I thought that it would be easier to just pull out a complete bolt carrier group and slide the other in. But you are right, and as little as I will be shooting the 10.5", it only makes sense to save some money and only buy the bolt. I could always add the carrier later if I wanted. Thanks. |
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