Loading 250 AB in 338 WM?

[Bigwheels]

Hey all. I just bought my 1st box of 250gr. AB's for my .338WM I was supprised at how long they are. I was going to just throw a few on my pet load for my 250 SGK's but they are sooo much longer I don't think that will work.
So here's what I want to use.
H-4350, or H-4831
COAL of 3.390" Magazine length.
Whatdo you .338 guru's thik?

 

[JD338]

The 250 gr AB is an awesome bullet, accuracy is excellent out of my
338 RUM. I would try both powders to see which shoots better in your rifle.
I would load to your magazine length.
Let us know how they shoot.

JD338

 

[Antelope_Sniper]

Yep, JD +1. I'd start with the H4831.

 

[OU812]

H4831 was my goto powder for my 338WM. Like stated earlier load to the max seating depth of your mag box and see how she shoots.

 

[Bigwheels]

Well, I just got back from the weekend shooting, & I was able to chrony 2 loads of 250 AB's. These are Molly'd in a 338 WM M70 BOSS.
1st was 71.0gr H4831. Got 2515fps.
2nd was 71.5gr H4831, & got 2520.
I'm not sure I have the case volume to add enough 4831 to get to 2700+. I'm going to go back to my H4350 & try some of those.

 

[Antelope_Sniper]

Hodgdon's manual shows 74gr as max, and a velocity right at 2700.
Work up slowly, and yes it will fit, just pour slowly, and yes, this will probably be a compressed load.

I shoot 78gr H4831SC, Win brass, WMRP 200gr molly BT. I break 3000fps with this comb, and it shoots nice small groups when the OAL is right.

 

[Bigwheels]

Well, I shot some more, & got some strange results.
1st. 74.0gr H4831SC--2690 fps. Load was so compressed, I was afraid it was going to push my primers out. Thats using a 12" drop tube too.
2nd. My go to 250gr load for my SGK's. 71.0gr H 4350 Would chrony the SGK's @ 2760 fps. 250 AB's were only 2610 fps. I was so supprised by this I shot my 225 AB @ 2900 past it to see if it was correct. 2912 fps, so the chrony wasn't wrong. Weird! :?
Well I do have more room for 4350 in the case, & not crunch powder, so I'm going to buy some more of that, & start to work up.

 

[JD338]

Bigwheels

Try this for compressed loads-

fill the case with powder and vibrate the case to settle the powder charge.
I use a Black & Decker Mouse. I hold the charged case on the sander,(with out any abrasive pad on it) and my index finger over the case mouth for 2-3 seconds. It vibrates the case and really settles the powder charge down.

JD338

 

[Bigwheels]

Well JD. Thanks for the advise, but that sounds like too much work for a hunting load. I'll use the H 4350, & work up some more powder. I'm realy curious why the 100fps difference in bullet speed for the same load.Like I said that load would chrony @ 2760 with the SGK, but only 2610 with the AccuBond. Weird. :?

 

[JD338]

Well JD. Thanks for the advise, but that sounds like too much work for a hunting load. I'll use the H 4350, & work up some more powder. I'm realy curious why the 100fps difference in bullet speed for the same load.Like I said that load would chrony @ 2760 with the SGK, but only 2610 with the AccuBond. Weird. :?

Actually, not that much work, just an additional step is all.

Make a comparison between the 250 gr AB and SMK. I'm thinking it has to do with bearing surface between the two bullets.

JD338

 

[Bigwheels]

I think the AB has a slightly shorter bearing surface than the SGK. Thats the only thing I could think of that would cause a difference. Bummer. I was hoping it would do the same as the SGK, & save me the trouble of working up another load. Oh well, I guess it makes me shoot more.

 

[Bigwheels]

Well I have them @ 2800 fps. with no pressure signs. I had to go up a couple grns of H-4350, now @ 73.0 gr. but there it is. Now I just need to make up a few more batches for accuracy checks, & a larger pool of chrony data. Probably won't have them ready for deer season this year (starts on 10/11) but I'll have them shooting to perfection for next year. :grin: I think I'm going to like these.