AR15 101 Question: Convert Bushmaster XM15 to 6 ARC?

[General RE LEE]

Sorry folks for an embarrassing simple question but here it goes.

I have this Bushmaster XM15-E2S in 5.56 but I want to convert it to either 6.5 Grendel or 6.5 ARC.

I’ve never done a conversion before but is it as simple as buying an upper assembly with a bolt carrier group and just getting 6 ARC mags? I know nothing about the guts of an AR except removing the BCG to clean. Don’t know anything about gas blocks etc.

I’m a reloader, bolt action guy but considering turning this Bushmaster into a box blind, tree stand deer rifle.

 

[Downtown]

Yes, it's that simple.

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[Steel+Killer]

I’m a reloader, bolt action guy but considering turning this Bushmaster into a box blind, tree stand deer rifle.

Saying you are turning the Bushmaster into something else is probably a bit of an exaggeration. You are simply using the lower from the Bushmaster with a different upper and yes for the most part all AR15 uppers and lowers are compatible with one another.

 

[General RE LEE]

Another 101 question.

To save money, can I just use the bolt carrier that came with my rifle and swap out the 5.56 bolt with a 6.5 Grendel/6mm ARC bolt? This is less expensive than having to purchase a whole new BCG.

 

[DDGKunia]

You can reuse the carrier but will need a new bolt

 

[General RE LEE]

Will I need an adjustable gas block since I’m shooting suppressed? Or should I see how the gun operates first before spending the extra money.

 

[JMC]

adjustable gas block is up to you but I’d recommend it. You can turn the gas down and tune it to just enough to cycle.

Are you looking at keeping the iron sights or going to an optic? If optic you probably want to get a different upper receiver.

 

[General RE LEE]

adjustable gas block is up to you but I’d recommend it. You can turn the gas down and tune it to just enough to cycle.

Are you looking at keeping the iron sights or going to an optic? If optic you probably want to get a different upper receiver.

Optic

I’m getting a Grendel Hunter 6mm ARC receiver.