MCX Rattler Upper Conversion Kit - any drawbacks?

[Steve Shannon]

Where have you seen mcx lowers?

The MCX conversion kits fit AR-15 lowers and include an adapter that attaches to the lower to support the recoil spring assembly of the MCX upper.


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[Corse]

I am using an ar lower now, but the MCX upper is wider and doesn’t look right, although it functions fine.

[Flint_Ironstag]

I am using an ar lower now, but the MCX upper is wider and doesn’t look right, although it functions fine.

Picture is worth 1000 words Which lower?

[Steve Shannon]

I am using an ar lower now, but the MCX upper is wider and doesn’t look right, although it functions fine.

Are you using the adapter with it?



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[Corse]

Yes. The MCX upper is just wider than an AR lower. No issue function wise that I can tell

[archad]

Do you have to use the 2 stage trigger with upper?

[Corse]

A standard Ar trigger doesn’t work. The rattler upper ships with the Sig match duo trigger.

[kyjd75]

A standard Ar trigger doesn’t work. The rattler upper ships with the Sig match duo trigger.

The Sig match duo is a nice two stage trigger. I have a couple of mcx virtus rifles, and have found them good enough as to not need replacing with Geissele models (which I have in my AR's). I have an 11.5 mcx virtus SBR which uses the mcx lower, and a 16 mcx virtus running on a Centurion Arms lower. Yes, the mcx virtus upper is slightly wider than the AR lower, but it still runs perfectly.

As to whether a stock trigger will work, there is much debate and opinion about that. The hammer safety that Sig instituted with the mcx virtus supposedly requires a purpose designed trigger. However, I have had Sig CS tell me that a true mil-spec ar trigger will work. I have also read that if one removes the hammer safety a regular trigger works fine. I am using the hammer safeties for now with my Sig triggers without problems.

I really like the mcx virtus system. It is accurate, has light recoil, and the stock mounting system provides options not available to the regular AR rifle. Also, there are now plenty of accessories available for the mcx, and more coming seemingly everyday. Pretty much my favorite rifle for the time being.