338 Ultra Mag C.O.L.

[Defc0n]

I will preface this with the fact that I'm shooting all of these rounds out of a stock Remington 700 (XCR II).

So I've been reloading some 338 RUM rounds using the recommended overall length as suggested by my reloading manuals and have not been getting the accuracy that I would hope for. I've been using 250gr Hornady match bullets but switched over to some 250gr SMK's.

I started at 3.580" (Hodgdon even recommends this for 300gr SMK's, which to me seems awfully short) as my COL and they weren't that great. I worked up to 3.600" and the groups have started to shrink.

I was wondering if anyone here has any experience reloading for this round and what COL they found to be best. I know even at 3.600" there is still a decent jump to the lands (as far as I can tell loading the 250gr SMK's to right about 3.750" (going off the top of my head here) is when they will touch). I've seen some forums where people are loading them well beyond 3.600", sometimes in the 3.7XX" range.

I've already loaded some up a little longer than 3.600, I just haven't shot them yet. Might make up a few more test rounds with increasing COL to see if that helps even more. Just wanted to see if anyone had any advice as to whats worked for them, just to give me an idea instead of lots of guess (educated of course) and check.

 

[ironworkerwill]

You might want to see where the lands are before you get too carried away.

 

[iShoot17]

I completely agree with ironworkerwill. Finding the lands is one of my first procedures when getting a new bullet to try/use in all of my firearms.

For what it may be worth..

I don't shoot a .338 Ultra, but did shoot a .338 Lapua for a while. Every bullet I put through that rifle liked being in the realm of .015" and .010" off of the lands, including the 250gr and 300gr SMKs. If you opt to try and chase the lands, be smart, and work up. Pressure will build as you approach the lands. You also have to be mindful of the length permitted by your magazine.

If you have found the powder node that works for your rifle, seating depth could be your fine tuning. You may find (as you already insisted) that running that bullet a little further out, may make your groups shrink that much.

However! Shooting a .338 Ultra many many times in a row may not be helping you either!

 

[gamestalker]

This discussion comes up fairly often around here.

When trying to find the most accurate OAL I always find zero" to the lands first, then I work back from there, or maybe from .010" to eliminate issues associated with getting into the lands due inconsistencies with olgives, and they are definitely inconsistent, by as much as .010". And then with consideration to pressures, the first thing you need to do is drop your charge back to start. This is because pressures will grow considerably when you get close to the lands.

I begin my charge work up at the closest distance to the lands I intend to work from. Doing it the other way can get you into some pressure situations, pretty quickly too. Once you've found the charge your going to use, then begin seating the bullet deeper in .005" increments, 5 shot batches at each depth should be enough to determine if things are changing, but that's your call.

Hope this helps.

GS

 

[Defc0n]

I only single shoot the rifle, so magazine length isn't really a concern for me. I went back and actually rechecked max COL and I was a bit off (my memory never has been fantastic). Using a dummy round loaded long and closing the bolt down on it gives me a COL of 3.910" (seems long, but probably some fantastic Remington quality control at work here).

I'll definitely slowly work up (I understand pressure will build after a certain point when working closer to the lands). I still have quite a ways to go to reach .01-.015" off the lands, which I've also heard from other forums as well. Also, yes the 338 ultra definitely beats me up pretty good and I do my best at taking a break and shooting other things to help me not develop a flinch.

Thanks gamestalker... I may end up going about this your way instead. Chasing the lands gives me quite a ways to go. Could drop it back down to starting powder charge and move away like you said.

 

[ironworkerwill]

Gs's method is bassakwards than mine, but I don't see why it wouldn't work. I might try it sometimes. Anyway, make a few .010" off and paint the ojive with a marker to make sure.

3.9xx" seems long to me. It is what it is I suppose.

 

[gamestalker]

Ironworker, how do you do it?.

Ironworker, do you work the powder charge up first at the farthest distance from the lands? That would be opening yourself up to some seriously high pressure spikes, and it would very likely require reworking the powder charge multiple times throughout the process also, IMO. Although, I suppose if the oal you settle on isn't closer than .020" to the lands, you might not experience as much of a pressure difference.

GS

 

[ironworkerwill]

Ironworker, do you work the powder charge up first at the farthest distance from the lands?

Yes.

That would be opening yourself up to some seriously high pressure spikes

Yes, if I seated to the lands.

Although, I suppose if the oal you settle on isn't closer than .020" to the lands, you might not experience as much of a pressure difference.

Yes.

I had some issues a few years ago with wssm's and I wanted to see how well it'd shoot in the lands.

Long story short the pressure was too much with a good moderate load that was previously .030 off(cause that was what fit in the mag).

It never occured to me that it would cause the pressure to spike, as I was mostly self taught.

I have noticed later, after I have become less invincible, that I can't shoot good enough to really notice the difference between in the lands or at some other point before I reach the lands. And by that, meaning, I continue to adjust the col without actually getting into the lands.