Colt Pencilneck 5.56 1/7 barrel history questions.

[DR. GLOCK]

I almost replaced this barrel with a bull barrel of unknown origin because a friend of mine told me my 20 year old Colt Car had a 1/12 twist barrel. He said they did not make this twist back then.

What is the advantage of 1/7 twist rate.

Also, what is the difference between .223 & 5.56 and what stock AR's come with a stock 5.56.

Thanks.

[Lycanthrope]

The advantage to the 1:7 is that it will stabilize heavy bullets that the 1:12-1:9 will not...say above 70gr. It will, however, spin the jacket right off the very light varmint bullets (sub 40gr).

5.56 and .223 ammo are identical save for the pressure. 5.56 is loaded hotter.

5.56 and .223 chambers in the guns are different. Due to the higher pressure, you shouldn't shoot 5.56 ammo in a .223 chambered gun. You can shoot both .223 and 5.56 in a 5.56 or .223 Wylde chambered gun. Almost all shelf AR's are chambered in 5.56.

For more......

http://www.ammo-oracle.com/

[TonyF]

Originally Posted by DR. GLOCK

I almost replaced this barrel with a bull barrel of unknown origin because a friend of mine told me my 20 year old Colt Car had a 1/12 twist barrel.

You would have broken my heart if you had.

1:7 became the std. twist rate after the PIP in the 1980's which also included a change in ammo to the 62 gr M855 cartridge.

20 years is pushing the envelope regarding the possibility of a 1:7 in commercial production but if you bought it stock, NIB from a dealer then it came that way from the factory.

He said they did not make this twist back then.

IIRC, 1:7's did hit the market in the late 80's.

BTW, the correct terminology for that barrel profile is "A1". It's the same barrel used on the M16A1 except 20 inches long as opposed to the 16 inch length of your CAR.