My cousin is having me build an AR for him in .204 Ruger and I  am a little confused with the barrels I have seen forsale. Do the .204ruger use m4 feed ramps. If they don't, do they use just a standard upper built for a 223/556? Also does it use the same bolt carrier? I have only built a couple ARs in .556 so any help with the .204 would be great. I  was looking into the Shilen match drop in bolt and barrel. Thanks ahead of time for your information

David

You will have to check with the barrel supplier as to whether the barrel extension has M4 ramps.
If it does, get an upper receiver with M4 cuts to match.
If it doesn't, get an upper with no cuts....there are a few flat tops around with no cuts.
Same bolt and carrier.

Build a .20 Practical


 

1.  You absolutely do not need the M4 feed ramps.
2.  All the upper parts (evcept the barrel of course) are the same when building a .204.  Same upper receiver, bolt and carrier, and magazines.
3.  You don't need the match anything.  Once the bolt is selected that you want to use with the barrel, just check headspace with that combination and you are good to go.

.223 to .204 is about the easiest caliber swap you can do on an AR.  For all you really anal folks, yes there are others that are equally as easy with just a barrel swap.

Here's mine:

I went with a 24" .204 ruger WOA barrel.  My upper had feed ramps.  I asked WOA to add them to the extension.  No problem at all.  It shoots well. Under an inch with most factory and less with reloading for it.  I use my Pmags for it.  I have a beta mag that will get used when its pdog time...

MAHA