Howdy all, I won a Geissele MK4 rail in their God Bless Texas raffle. The super gas block is included. It is the 7 in rail, and I am wondering if anyone has experience with a rail this length and what the best application for it would be. Is a rail this size best suited for an AR pistol build? Will it also work for a SBR build? I am on the fence about whether to sell it or keep it for a future project. Thanks.

Op, I'm about to post a big for sale thread in the next day or two. If you see anything in it you'd like to trade the mk 4 towards, please let me know.

I'm not entirely sold on the .300 blk as a round. Is 5.56 not a viable option in an AR pistol? What about builds using pistol calibers like .45 acp or 9 mm?

Thanks Bender. Will do.

Caveman Ag said:

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I'm not entirely sold on the .300 blk as a round. Is 5.56 not a viable option in an AR pistol? What about builds using pistol calibers like .45 acp or 9 mm?

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Under 10.5" a 5.56 round isn't going to perform that well, so 10.5" is the shortest useable length in barrel. 300blk is pretty popular and fine for anything up to 150, maybe 200, yards and is perfect for suppressing.

You can do a 9mm pistol build, but last I checked a 45acp build is going to be expensive. I can only think of one bolt manufacturer off the top of my head for a 45acp ar build: Angstadt.

DO IT.

Log said:

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DO IT.

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Very nice! What are the specs on it Log?

There are a couple more .45 ACP parts makers now. Prices have dropped a lot. Even PSA is in the AR 45 business now.

Pistol caliber builds are a blast. My 4.5" Barrel suppressed AR-9 is probably my favorite rifle. Great gun out to 100 yards, and very maneuverable even with the suppressor. Only thing I would change on it would be to add the Dead Foot Arms MCS, which has a folding stick that allows firing while folded.

8" Ballistic Advantage .300 BLK barrel, Geissele SSA trigger & ACH, Surefire can.

I have a .45ACP SBR that I built from parts, and can confirm it is expensive (not even counting the tax stamp), BUT it is a full DI gas operated AR like the great Eugene Stoner intended. 30 rounds of .45acp with the recoil of paintball gun is pretty fun.

BenderRodriguez said:

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Op, I'm about to post a big for sale thread in the next day or two. If you see anything in it you'd like to trade the mk 4 towards, please let me know.

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Will you cross link the classifieds in the OB or do I need to be checking classifieds?

Thanks for all of the input everyone. Y'all have convinced me to look seriously at an AR pistol or SBR build, depending on what cool stuff Bender posts for sale of course.

reddog90 said:

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BenderRodriguez said:

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Op, I'm about to post a big for sale thread in the next day or two. If you see anything in it you'd like to trade the mk 4 towards, please let me know.

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Will you cross link the classifieds in the OB or do I need to be checking classifieds?

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I'll cross link here.

Thought I'd have time this week, other stuff came up. It'll be up late Tuesday or early Wednesday.