how bad would it be?

[steelholder]

Hey all, i'm in the process of load dev for a nice little cz527 I just got my hands on. I am using cfe 223 with 40 gr Hornady projectiles. I am loading CBTO and the powder limits for this projectile are between 27.5 and 29c at 2.280 COAL. When I am loading CBTO it means my overall length ends up being around 2.240 with 28 gr the loading manual says i shouldnt exceed 2.280. Will this cause excessive pressures? Kinda worried about sending those down range.

[ar15barrels]

Maximum length is more limited by magazine length and throat length than anything else.
As you start jamming, the pressure certainly goes up but if you stay 0.020" short of touching, you should be fine with any book data.
As long as you are not jamming, your pressure drops as you extend the OAL because there becomes more effective case capacity.

I load my 223 rounds at 2.480" for my bolt rifle because the throat and my magazines/bullets will support it.