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BAC · June 24th, 2009, 01:56 PM

Most rifles with 1:9 twist barrels are actually chambered in .223, not 5.56 NATO. Some companies, like Rock River Arms, use a Wylde chamber, which is a hybrid falling somewhere between .223 Remington specs and 5.56 NATO specs; I don't know exactly what differences there are, just that it's supposedly safe to fire 5.56 NATO through them. Others, like Noveske, have slightly modified 5.56 chambers designed for shooting match-quality ammo like the Mk262. So far as I know, Noveske rifles have always been designed to shoot 5.56, so they're good to go. Consider having someone run a 5.56 reamer through it if you expect to shoot 5.56 ammo.

NATO specs call for the 5.56x45 chamber to have a longer leade than SAAMI spec'd .223 Remington chambers. A shorter leade means greater pressures. Additionally, while .223 Rem and 5.56 NATO have identical external dimensions, the case walls of the 5.56 are slightly thicker than that of the .223 Rem. Reloaders and gun rag writers like Glen Zediker estimate a combined 15,000 psi (or more) jump when using 5.56 NATO ammo in .223 Remington rifles.

-B

June 24th, 2009, 01:56 PM	#7
BAC VIP Member Join Date: May 2007 Location: Tampa, Florida Posts: 2,154	Most rifles with 1:9 twist barrels are actually chambered in .223, not 5.56 NATO. Some companies, like Rock River Arms, use a Wylde chamber, which is a hybrid falling somewhere between .223 Remington specs and 5.56 NATO specs; I don't know exactly what differences there are, just that it's supposedly safe to fire 5.56 NATO through them. Others, like Noveske, have slightly modified 5.56 chambers designed for shooting match-quality ammo like the Mk262. So far as I know, Noveske rifles have always been designed to shoot 5.56, so they're good to go. Consider having someone run a 5.56 reamer through it if you expect to shoot 5.56 ammo. NATO specs call for the 5.56x45 chamber to have a longer leade than SAAMI spec'd .223 Remington chambers. A shorter leade means greater pressures. Additionally, while .223 Rem and 5.56 NATO have identical external dimensions, the case walls of the 5.56 are slightly thicker than that of the .223 Rem. Reloaders and gun rag writers like Glen Zediker estimate a combined 15,000 psi (or more) jump when using 5.56 NATO ammo in .223 Remington rifles. -B __________________ RIP, Jeff Dorr: 1964 - July 17, 2009. You will be missed. Defensive Carry Search Tips Step 1 - Choose a subforum on right side under "Search in Forum(s)" Step 2 - Type general topic of interest in "Search by Keyword" textbox. Step 3 - Read results and refine/repeat as necessary.