208gr Amax in .300WM

[Black-X]

I've been trying to come up with some load developement on a Remington Sendero that I picked up recently but I'm struggling to get the 208gr AMAX to group worth a darn. I tried out 20rds yesterday loaded to 3.560 (IIRC) COAL, new Winchester cases, Federal LRM primer, over 72gr of R22. Width wise the groups were under 1 inch at 100yds but vertically all of the groups were 2-3 inches tall. I shot some 190SMKs the other day and these groups were sub-moa.

Is there something that would cause vertical stringing like this due to my loading? Maybe my rifle just doesn't like the 208's? I guess I can load up from 72gr up and down in .2 increments and try some more but so far it's not looking good and I'm a bit confused.

Help. Please!

-X

 

[bohem]

Re: 208gr Amax in .300WM

Have you tried a ladder test to find the best shooting charge weight at a specific seating depth?

Amax's, especially those 208's tend to shoot very well from a number of different people's rifles around a 5-15 thousandths jump to the lands.

I'd suggest setting them at 10 thou, and then shooting a ladder test to see what goes down.

Since your groups are vertically stringing and you're getting reasonable results from the horizontal dimension, then keep the seating depth where you have it and load the different powder charges. I'm pretty confident that you'll see those groups come down.

Another thing to check before shooting anymore is that your action screws are tightened properly, the crown isn't damaged, the scope is tight, etc. etc.

 

[Black-X]

Re: 208gr Amax in .300WM

Thanks bohem! Everything is tightened down so I should be good there. I'm about 10-20 thou off the lands right now so I feel better about the depth with the info you provided. I started off at 3.340

. I was concerned with the vertical stringing because of how tall it is. I don't think the horizontal spread actually broke 3/4 moa but the vertical was N A S T Y.

I'll try a ladder test and see what happens. The only other load that seemed to group decent was 70gr of R22 but that's too slow (2700-ish FPS).

-X

 

[desertHK]

Re: 208gr Amax in .300WM

My recipe is 71.6 grains of RL22, fed 215M, win case, 3.600". It's pushing around 3000 fps. sub MOA all the way out to 1K.

 

[ChadTRG42]

Re: 208gr Amax in .300WM

Go back through the "Beyond 1000 yards" section. There are several good threads about loads for the 208.

 

[jrob300]

Re: 208gr Amax in .300WM

Since this is a stock Sendero, it has a SAAMI chamber. The virgin brass may be rattling around in there pretty good. You'd actually have to jam the lands to ensure good alignment. My OEM Tikka barrel had this problem and feeding it once fired helped a lot.

When you do your further load development, make sure to use once fired, neck sized (or FL sized to just touch the shoulder) brass to eliminate this as a possible cause.

John

 

[bohem]

Re: 208gr Amax in .300WM

jrob brings up a good point about spec chambers, but considering how poor the Amax's have shot in 22, 6mm, 6.5mm, 7mm. and 30cal of various weights in each caliber, jamming them sucks.

The other thing that you can do for virgin brass is neck it UP to 8mm, then back down to 30 cal but leave a false shoulder in the neck for a slight jam into the neck of the chamber, seat the bullets at the sweet spot you're already working with.

 

[jrob300]

Re: 208gr Amax in .300WM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"> jamming them sucks.</div></div>

Sorry for confusion... wasn't actually advocating jamming them (fraught with all kinds of issues) just pointing out that, with virgin brass, it was the only way I could think of to assure a good square launch into the rifling, and that some of his problems may go away once he has properly prepped once-fired brass to work with.

Forgot about the false shoulder trick. Good call.

John