Dumb question; having a lower on double duty for carbine and SPR

[TheGerman]

I think I know the answer in that there is zero problem with it but before spending money I just wanted to ask.

Right now I have a HCS Mk12Mod1 upper on a complete from factory KAC lower with the SOPMOD stock, KAC trigger, everything.

I am considering getting a SR15E3 Mod1 complete upper as I feel I do not need to spend money on another lower (plus I already have another complete carbine on hand).

Will running the lower as a carbine lower have ANY EFFECT WHATSOEVER on the ridiculous accuracy of the Mk12Mod1 upper when I switch the uppers back and forth? I am 99.9% sure the answer is that I am retarded and go buy the SR15, but wanted to be sure first and have someone tell me I'm just over-thinking this.

 

[DWood]

The only real question I have is about the trigger in the lower. Is it a two stage trigger that is set light for your MK 12, and if so, is it suitable for what you are doing with the carbine?

You won't hurt the lower by moving it around between uppers. I did the same thing recently, but in the opposite direction. I have two LMT lowers, one with a 16" BCM mid-length upper and one with an LMT carbine length upper. I just built an SPRish upper and dedicated a lower to it, installing a Geissele DMR trigger in it.

The other lower, with an LMT single stage trigger, will be the base for the two carbines and the one with the DMR is for the SPRish upper.

 

[bp7178]

The only consideration is having a lower which is ideal for both uppers. Stocks, triggers, grip and buffer / spring combo.

One of the things I didn't like about my SR15 lower was the KAC trigger, it was one of the types with the two-piece disconnector. Total pain in the ass to install. I like the Geissele SDC MUCH better, and feel it would make a good trigger on a carbine as well.

 

[TheGerman]

It has the KAC 2 stage which I don't mind for either carbine or SPR as I've used it on the SPR with no issue and have a similar in pull RRA national Match 2 stage in my other carbine. I may eventually mess around with Geissele triggers as they've gotten hugely popular as of late, but as far as the trigger I don't think its an issue. If it is, its an issue that can be solved rather easily.

Other than that, I love the SOPMOD stock and the only real adjustment that would be needed when switching is the stock position which takes all of 2 seconds as well as the slings are different (VTac on carbine, TAB RAS on SPR).

 

[HOGTOOTH5R]

Should Not have any problems as long as you're ok with using the Trigger Group for Both Applications. Some of the MK12 Mod 1s were setup with Carbine Lower with the SopMod Stock for the Adjustability. They were just as accurate but more handier platform than the Fixed Stocked Versions.

 

[tickled pink]

Last fall I bought a Colt LE6920 M4 and installed a Geissele SSA-E trigger myself. I used to shoot High Power so I am used to a two stage trigger. I am an accuracy nut so I ordered a White Oak Armament complete 18" upper with 1 in 7" twist and having it fluted to save some weight. I'm not expecting any issues with it except it being much more accurate. I am also putting this scope on it. The big sale is off. I paid $174 with free shipping.

BUSHNELL 4.5-18X40 BDC RETICLE TARGET AR-SCOPE | Sportsman's Outdoor Superstore

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