New Loads for New M1

[akinswi]

Im trying to finish off my remaining WLRPs, I have 400 left

For the past two years all my load development has been based on CCIs 250 and IMR4895.

Would you recommend trying both primers thru the load development process?

For example I am using Hornadys 9th edition load data but im substituting H4895 for IMR 4895 (Dont understand why they dont list that powder for 150 grain bullets) Specifically Sierras 150 grain FMJBT ( the one with the cannelur)

44.0
44.5
45.0
45.5
46.0
46.5 - Hornadys Max is 46.4 ( which is pretty conservative)
47.0

COL - 3.250 (Per sierra 6th edition) For #2115 Projectile
Trim - is 2.488 (Lee Hand Held trimmer , mine trims to this length)
Case - Sig Sauer

Should I do a ladder test side by side for exact same load data using the 250s
and go with the best one. I feel like the 250s just ignite the powder better but interesting too see the results

I do not have a chronograph.

 

[GeauxTide]

I've been using 42gr of H4895 under 150 and 165, in 3-308s, for several years. Rem 788, 700, and Browning Mk3 DBM. I have an unfired M1a Safe Queen, but I'd use these loads in a heart beat. These loads come in at 7fs ES and shoot 1/2". I would ditch the mag primers, as they will run your pressure up 5,000psi. I have had great success with the WLRs.

 

[44 AMP]

(Dont understand why they dont list that powder for 150 grain bullets) Specifically Sierras 150 grain FMJBT ( the one with the cannelur)

The most common reason you don't find a specific component listed in the loads is simple, they didn't test it.

Now, WHY they didn't test it, can be a little more complex, but usually its because a) they didn't have any on hand when they did their testing, or b) there is only so much time, money, and room in the manuals so, something is always left out.

Also, its very common for data from a bullet maker to NOT include data using their competitor's bullets.

 

[Unclenick]

If you look at Hodgdon's data for the 150-grain Nosler BT, also seated to 3.25", it shows the starting load of 46 grains of H4895 achieving 2806 fps at 15 feet from the muzzle (SAAMI standard velocity measuring distance) of their tight tolerance SAAMI type pressure and velocity barrel. M2 Ball was measured to produce 2740 fps at 26 yards from the muzzle (78 feet) of a military P&V barrel, which means that at 15 feet, it would have been going 2789 fps, or 17 fps slower than Hodgdon reports for their H4895 starting load. Powder charge vs. velocity has a fairly linear relationship in the published load range, so you can divide the difference in min load and max load velocities (170 fps for Hodgdon's data) by the difference in the min and max charge weights (5 grains for Hodgdon's data) and get 34 fps per grain of powder in the published load range. 17 fps is half that, so figure you can drop the starting load by half a grain from 46.0 grains to 45.5 grains, and you will have a load that would match M2 ball pretty closely when fired in a 24" P&V test gun.

That load will work in the Garand, but you will get lower velocities out of the Garand because the loading density is only about 73% according to GRT. That low loading density may be why Hornady omitted it. I don't know. But where the P&V test barrel loads are carefully manipulated to fire with the powder back over the flash hole, the Garand tends to throw the powder charge forward in the case when the cartridge stops abruptly in the chamber, so you could well see a 100 fps drop from that. It won't be dangerous; just possibly disappointing as to consistency.

Note that the brass-colored Winchester primers are the result of omitting nickel plating. This change was made due to sensitivity complaints about Winchester rifle primers, and this made them more sensitive. If yours fit that description, just be aware they are now about as slamfire-sensitive a primer as you can put in the Garand.

 

[akinswi]

Nick,

They are the brass color primers but they are seated pretty deep , I do seat them using my Dillion 550 press . I had issues seating primers by hand with the lee hand held .

Would you recommend just single loading them? I only loaded 40 of them or just pull them and just not use these primers for the M1. I have 1000 No 34s

Thanks

 

[44 AMP]

While those primers may be more sensitive than mil-spec, that doesn't mean they will slam fire, in YOUR rifle, but it does mean they COULD.

SO, only 40rnds, sounds like range fodder to me, where you don't chamber a round until your muzzle is down range and you're ready to shoot.

I have used CCI 200 in my M1A and while there is a slight "dimple" in the primer of an unfired chambered round, its never been a problem.

Your Garand uses the same firing pin system, but differences in individual guns AND primers could mean what works for me ok will be risky (possibly dangerous) for you.

 

[akinswi]

While those primers may be more sensitive than mil-spec, that doesn't mean they will slam fire, in YOUR rifle, but it does mean they COULD.

SO, only 40rnds, sounds like range fodder to me, where you don't chamber a round until your muzzle is down range and you're ready to shoot.

I have used CCI 200 in my M1A and while there is a slight "dimple" in the primer of an unfired chambered round, its never been a problem.

Your Garand uses the same firing pin system, but differences in individual guns AND primers could mean what works for me ok will be risky (possibly dangerous) for you.

44amp,

I have great success with CCI 250s. Im just trying to save as many as can during this never ending shortage.