Magnum primers with Hodgdon H335 in 223/556 cases

PaulS

I took three loads that I had worked up in my AR and substituted magnum primers for the standard primer. One of those loads was the one that gave me the most consistent velocities.----standard deviation
Load #--------SRP---------SRMP
1.--------------40.32--------22.99
2.--------------27.61--------28.21
3.--------------55.99--------29.70

It was just a "let's see what happens" trial but I may have to do some more testing to see if I can get a load in the teens.
As a note load 1. was 25 grains; load 2. was 25.7; and load three was 26 grains.
All using a 55 grain FMJBT and CCI primers.
The magnum primer does seem to be better in most loads. #2 is close enough to be within the tolerance at 0.6 FPS difference.

The values were collected using a LabRadar on the same gun, on the same day with 10 rounds of each load fired.

pete4d

Paul,,,, Gonna mark and study this ,,, I'm not close to my load data ,,,, I normally reload 62-gr FMJ but i do 55-gr sometimes just not as much. Only thing I've found with the 335 powder is there maybe a few grains of UN-burnt powder left in the case ( never been able to figure that one out) the magnum primers may fix that issue .

Good luck on the loads

Bushmaster

As most have AR 15s and I have to be different and have an AR 10 (.308/7.62X51 NATO). My load data would be of no use to most on here, but....

I found that I have best results using 45 grains of H380 and a WLRM primer and a 150 grain Flat base soft point. 2400 fps +/- 25 fps. Not so worried about the other specs. More into accuracy. Found that the standard primers just didn't do the job.

Remember that if you use a magnum primer that you reduce your powder charge by .5 grains if you are at or near maximum charge.

Elvis

Bushy...my bolt action .308 gets fed magnum primers (cause I bought a big box full) Im pushing a 180grn round nose not much slower than that.
as for standard velocity deviation.....yeah nah dont know and dont care LOL.

PaulS

That 26 grain load is not far from the maximum but none of them showed any signs of pressure. I will be concentrating on the loads between 25 and 25.7 for my shooting,

H380 is a good powder for the 308. I have used it in the past when my brother had a 308. Nice groups at around 5/8" with his Remington 788.