COL determination

[TheDecliner]

Hi, I'm working on reloading 450 bushmaster for the first time and I'm doing drop tests to determine case overall length. At the max COL according to my die set of 2.26 I'm still not touching the lands and groves. I can drop the round in and spin it so it is definitely not engaging them at that length.

I'm using Hornady 230gr FMJs with Hornady brass in a Bear Creak AR 15 Upper.

I'm assuming I should not go over the max length but wanted to see what length others may be using with this combination. Also, what is the minimum length I should have the bullet into the case? Currently at this COL of 2.26 the bullet is only about 1/8 of an inch into the case and I'm concerned it needs to be further in to build up the correct amount of pressure. On the flip side I'm concerned if the bullet is too far from the Lands and Groves I'm going to have serious accuracy issues. Thanks!

[s4s4u]

In an AR you will not likely get close to the lands as the maximum OAL (2.26) that will fit in the magazine will set that limit. You just have to live with it if you want a repeater. Neither of my 5.56 guns allow me to get near the lands and they both shoot sub-MOA with my handloads. I doubt my 450 will either once I get it finished up, and I will lose zero sleep over it. Also, you don't want to be pushed into the lands with a max or near max load as pressure may spike more than the gun can handle.

[Hoot]

I use 2.05 COL for 230 FMJ's. Its a good compromise that leaves about .296 of bullet down in the case. I try to stay at 1/2 caliber insertion depth of more in the caliber so that the case has enough bullet to hang onto to give reasonable neck tension. Neck tension is important in this caliber.

Hoot

[Al in Mi]

here is the chamber spec for the 450B. As you can see there is .200 of freebore and as S4 mentioned you won't get close to the lands if your running a AR. The 275gr Barnes for reference, has a 2.460ish OAL to the lands in my guns, I have a few dummy rounds seated to the lands, and if I get a chance this weekend I'll post the OAL's.