Gunsmithing Question

[TooTallTom]

Has anyone on the forum had an AR chambered in .223 reamed out to 5.56 NATO? What did it cost, and what was the turnaround time?

Thanks.

[gunmunky]

The chambers are the same dimensions (unless you're talking match chambers). The 5.56 are loaded to higher pressures and are not safe in a barrel marked 223. You can safely shoot 223 in a 5.56 barreled gun. There are barrels marked as a Wilde chamber and are safe for both rounds.

[fishattacker]

I would guess it would not take too long. All they are doing is pushing the rifling back a little bit.

I would think it would be pretty easy for a gunsmith to knock out.

[TooTallTom]

Thanks for the responses. They're telling me two different things, though. What are your backgrounds gunmunky and fishattacker (Pro 'smith, had this done before, etc.)? I'm just trying to figure out what the deal is here, and don't mean any offense by asking.

I had always heard that 5.56 NATO is slightly larger/ different angle up front than .223 rem rather than same cartridge dimensions, but 5.56 is loaded to highter pressures. That's why I asked about reaming a chamber.

[carpshooterdeluxe]

It can be done; ar15.com has a bunch of threads on this. you can do it yourself for the cost of the tool plus shipping.

[fishattacker]

I by no means am a pro gunsmith. I just happen to read an article about it. My dad shoots an AR15 and I have been in the military for 18 years and have shot the M4, M16A1 and M16A2. I also checked out AR15barrels.com and they have a breakdown of dimensions on each cartridge. Your freebore length is longer and throat angle is less in the 5.56 NATO.

If you shoot a 5.56 NATO in a .223 chamber there is a possibility of having a large pressure spike due to the shorter freebore and sharper throat angle. Top that with the higher pressure the 5.56 fires at and you may have a catastophic failure.

Just throwing this out there. The military is willing to sacrifice some accuracy for terminal performance. So if you change your chamber to the 5.56 NATO you may lose some accuracy.

[gunmunky]

I am by no means a gun smith expert but I have been building AR's since the late 80's. I've built AR 15s and AR 10s. I'm not talking about buying parts and assembling them but taking raw material and machining the components. I've had custom .17 cal and 30 cal barrels made to my specs for the ARs. I have actually had a 223 blow up in my hands and that was an eye opener (it was not an AR and I believe that's why I didn't get hurt). I'm old enough now to error on the side of caution.

[SmilinBob]

I am a professional, full time gunsmith. There is a difference in the chamber specs, the 5.56 is slightly larger. I charge $100 to open a chamber and turnaround times are up in the air as I'm currently moving the shop, otherwise the longest part is the waiting for the reamer as its much more economical to rent vs buy them. The odds are that opening that chamber won't affect accuracy as its slight modification to the throat and shoulder area.

[TooTallTom]

Okay, thanks a lot for the responses everyone.