Max Load: H322 in 223 AR

[rfwobbly]

Loaded up some 223 plinking rounds last night and consulted the Sierra manual for 55grn with H322 in an AR. Sierra gave 24.3 as max at 2.250" (3000fps). My load of 23.5grn at 2.250" should have put me right under 2900fps for good accuracy.

Afterward I consulted Hodgdon which gave 23.0 as max for H322 at 2.200" (3100fps).

► Can't believe .050" makes that much difference.

► Going to put some over the chrono and see who to believe.


Any guesses on what the findings will be ?

 

[rcmodel]

No.

Two totally different test barrels, seated two different lengths.

And I didn't check, but I doubt the brass and primers were even the same brands??
Were they?

rc

 

[Walkalong]

LC brass (91 to 93 Grs), Honady 55 Gr V Max, OAL 2.230 to 2.235, CCI # 41 primer. 16" AR.

24.0 Grs H322 gave an Avg 2943 FPS @ 88 degrees.

24.2 Grs H322 gave an Avg 2954 FPS @ 96 degrees.

24.4 Grs H322 gave an Avg 2983 FPS @ 96 degrees.

24.7 Grs H322 gave an Avg 3041 @ 104 degrees. (3035 @ 102 degrees)

MAX! Approach with caution.

 

[rfwobbly]

Hodgdon used Win cases/ Win pri

Sierra used Fed cases/ Rem pri

I'm using Lake City cases/ Wolf 223 pri

 

[Walkalong]

Can't believe .050" makes that much difference.

I can. Looking forward to your results though.

 

[steve4102]

► Can't believe .050" makes that much difference.

It doesn't.

Hodgdon tested in a 24 inch barrel. Sierra tested in a 20 inch barrel. 4 inches of barrel length is the difference!

 

[ngnrd]

What does barrel length have to do with peak chamber pressure?

 

[steve4102]

What does barrel length have to do with peak chamber pressure?

Nothing, why do you ask?

 

[Walkalong]

Bullet construction can make 50 FPS difference, but yea, with a 4" barrel difference, which I did not look at, and assumed it was the same since it wasn't mentioned, all that is out the window.