338-378 Weatherby Questions

[Magnum_Willys]

Shot some more today with 300gr  SMK's.  Same story, 113 gr RL33 was good @ 2850.   n570 was good at 107 @ 2855 fps @ .75 moa.

Ran numbers for Optimum Barrel Time (OBT) and checked with Quickload.  Optimum speed prediction was 2848 for RL33 and 2855 for n570 which is exactly what I found shooting.

That said - I'm not beating factory 225's in accuracy yet. 

Neck sized, 3.795 Coal, CCI Primers.

[bearpaw]

Have you tried federal match grade magnum primers, not much more cost, I think they are hotter, you might pick up some speed or accuracy? If I ever get a chance that's what I plan to try.

[JimmyHoffa]

Have you tried federal match grade magnum primers, not much more cost, I think they are hotter, you might pick up some speed or accuracy? If I ever get a chance that's what I plan to try.

I've been using the 215 GMs.  They've been working fine.  Real consistent, though, the only others I have compared to are Rem 9 1/2 M and CCI Mag.  All of those worked fine too.

[high country]

Most of the guys over here that build big 338's see the least sd with h1000 and 300 gr pills. I'd never worry about chasing the lands on a wby because of the massive freebore. If you want to set up the best dies I'd consider a lee collet, or any bushing sizer that does not use an expander. Forster has the superior seater die....read up on their seater and it will make sense.

[Magnum_Willys]

Have you tried federal match grade magnum primers, not much more cost, I think they are hotter, you might pick up some speed or accuracy? If I ever get a chance that's what I plan to try.

That was my goto plan but can't get em. Saw a guy had 1000 on gun broker but wanted $250 for them 

[high country]

I've not been able to tell any difference between them and 250s other than 250s seat in loose pockets much better. I've got at least a thousand here if you want to try, but I'd just jump to 250s myself.

[Magnum_Willys]

Update: Pretty much settled in on these three for use with the 300 gr SMK's.  Hope to try the 285 ELD-x and the Nosler LRAB this summer when available.  The 225 Barnes TTSX may be the the winner out to 700 yards but haven't tested it yet.   

Speed in the 2850-2870 range seems to shoot best.  The RL33 can push it over 2900 but doesn't seem to help accuracy and kicks more.   

Running about 3/4 moa at 300 yards.  Not sure this factory barrel can do much better with the 3/8" jump to the lands with these.

Next to test for speed consistency among these 3 loads. 

Note: These loads are in fired brass, neck-sized only, 3.800 coal.  Full-sized brass takes somewhat less powder and Virgin new brass is much smaller and takes as much as 3 grains less for the same pressure.

[Magnum_Willys]

Well finally got a brick of 215M match primers. Wow much hotter than the Cci 250s in this gun. All my above loads are too hot with them but showing much less velocity spread. Gotta work some new loads up with these primers.

[bearpaw]

That's good to hear, I found them to be hotter too, I think there is more efficient powder burn because of that in the big cases! Anxious to hear your results! 

[Magnum_Willys]

I tried the new Match primers out today - was windy so I only shot at 100 yards.  My first ladder test with RL33 started at 110 gr and worked up 1/2 grain at a time.  First 4 shots were in the same hole - .25 moa so I'm sold on these primers!  Gotta stretch out to 300 yards now to dial it in.  Much more predictable results with these in this big case. 

Had to drop 2 whole grains with Retumbo with these primers. 

[Magnum_Willys]

Update:  Same story today.  110.5 gr RL33 is a tack driver.  215M Primers, 300smk are < .5 moa at 100, and < 2 inch groups at 300.   The 215M primer is very accurate with the RL33 at lower loads.  I think the CCI primers probably work better for Retumbo and N570 allowing more velocity with the 300 gr. bullet. 

Was hoping for 2900+ speed but will take 2800 and accurate for the moment.

[bearpaw]

most excellent 

[Magnum_Willys]

That plate on the lower left was 4 shots with 110, 110.5, 111, and 112 grains through basically one hole. Crazy. 

Overall two days, 6 different loads, new brass, necksized brass, full sized brass they all went into that same hole.   I guess they like that node. 

[Biggerhammer]

Exellent results. I have exclusively used Federal 210M & 215M primers for many years.

[Magnum_Willys]

Tried the Hornady 285 ELD's today at 525 Yards - scattered all over the place with both RL-33 and Retumbo in the loads I used with the 300 SMK's.  Velocity was 40 fps higher.   

I then shot a group with 300 SMK's and 112.3 gr RL-33 that was .7 moa at 525 Yards and would have been .4 moa if I hadn't pulled that one shot to the right that I knew immediately.  I'm sticking with the SMK's.

RL33 - 112.3 and Retumbo - 104.8 around 2820-2840 are my current loads for this rifle at 500+ yards.