338 win mag load devolpment.

[Mtstalker]

My wife suprised me with a new new winchester m70 alaskan in 338 win a while back. I fired 10 rounds of factory to make sure it functioned/shot ok before doing load devolpment. Today it was a nice 21 degrees out so i went to the range with new remington brass loaded with 225 grain hornady interlocks, cci 250 primers and loaded with Imr 4350, 3 rounds of each charge. I seated the bullets -.010" off the lands to start. Here is the average velocity for each charge.
68=2675
68.5=2720
69=2740
69.5=2765
70=2787
70.5=2794
71=2801
71.5=2865
The best groups were 70 to 71, they averaged .75 inches. 71.5 is where i called it quits due to primers and slight bolt lift. The rest were in the 1.5" range. I do belive this to be a node. Should i stick with 70.5 grains and mess with seating depth next? I did leave the ammo on the truck consol with the heater going and only pulled them out right before i shot them to make sure they were a constant temp.

 

[JLT]

That's where I'd look. Very flat spot for velocity and if the loads grouped well across the range, I'll bet you're on to something.

Do you have the distance available (300 yds. or more) to shoot a ladder to confirm?

 

[Mtstalker]

Unfortunately i only have access to a 100yard range. This is strictly a hunting rifle but i am a bit ocd when it comes to finding a load.

 

[JLT]

Unfortunately i only have access to a 100yard range. This is strictly a hunting rifle but i am a bit ocd when it comes to finding a load.

For hunting purposes, I'd be willing to bet you're knocking on the right door between 70 and 71 grains. 3/4" is plenty for anything you'd point that rifle at.

 

[Mtstalker]

My previous 338 win. Shot this same bullet and powder at 72grains at 2920fps and it was a hammer. With only 40 rounds through this gun im sure it will pick up a bit of velocity. Im worried about the now fire formed brass not shooting as good due yo the .019" growth from shoulder to base.

 

[Ledd Slinger]

Which powders and primers do you have available for testing?

 

[Mtstalker]

I have h4350,imr4350 and h4831sc. And winchester, rem and cci primers. This is what i have that should work for this gun.

 

[Ledd Slinger]

Try just swapping the primer to a Rem 9 1/2 Mag and re-shoot 70, 70.5, and 71. Then try H4350 at appropriate charge weights with both primers. Swapping primers can often have a HUGE effect on load accuracy and consistency.

The last 338 Win Mag we dealt with wouldn't really shoot any great groups at first. Maybe 1" at best. We were using IMR 4350 and Fed 215 Mag primers. My father in law swapped to a CCI 250 while leaving everything else the same, and wham! it was shooting sub-1/2" bugholes with the 210gr Partition.

I know you are using CCI 250, but your rifle may not like it with IMR 4350. Point being that a swap to a different primer manufacturer is all it takes sometimes.

I didn't mention trying Winchester primers because I have NEVER found "consistent" accuracy with them. But that's just my peraonal experience. You can try them if you want. Maybe they'll work for you.

 

[Mtstalker]

Lol funny you should say that my winchester primers are from 2006 and only have 50 missing from 2 1000 count boxes. I mostly use cci or federal but im out of the fed 215's

 

[Ledd Slinger]

Lol funny you should say that my winchester primers are from 2006 and only have 50 missing from 2 1000 count boxes. I mostly use cci or federal but im out of the fed 215's

Yeah I can't even remember how long I've had the Winchester primers sitting on my shelf. They've been collecting dust for a looooong time now

 

[Mtstalker]

The snow finally melted and the weather is in the 60 degree range so I was able to finish load devolpment. I did run the 70 to 71 grain charge again with the 225gr hornady's seated .010" and .030" off. At .030 the group's were averaging 1.5" across the charges except at 70grs it was about .75". At. 010" off all the group's were hovering around a inch and at 70.5grs of IMR 4350 i shot 3 groups of 3 that all were .5 to .6 inches. The velocity remained in the same ballpark and the 70.5 was in the middle of a node. I then put on the magnetospeed to double check against my Caldwell chronograph and it showed slightly higher velocity. The average for 5 rounds was 2820 FPS with a ES of 22 and SD of 10. For a factory hunting rifle I think this is acceptable. The load ended up being a 225 hornady interlock loaded -.010" or 3.320" rem brass 70.5grs of IMR 4350 with a CCI250 primer.

 

[wboggs]

What game are you using the .338 for? For very large game requiring deep penetration the Hornady 225 will be lacking.

 

[Mtstalker]

Deer and elk and bear.

 

[jetboat]

338 was made for 250 gnrs My pre 64 loves 250 gn nosler Part.
my 338-06 is loaded with 225 Hornady's as the 250 is are too long.
225 @ 2700fps is a great 200 +- elk round.

 

[wboggs]

Deer and elk and bear.

Assume you mean black bear. 225 is ok.
For browns/grizzly you need 250 for penetration at all angles. The old guides on Kodiac used 300 gr win loads. They penetrated better than a .375 which many of them used.
250 nosler and Barnes x are also good. A 210 Barnes TTSX is a good all around load for the lower 48.

 

[Mtstalker]

So I finally finished firing all the new brass. I sized and loaded the now once fired brass and shot some of it. I shot 5 foulers on a clean barrel and then shot a group and chronographed it to see if the once fired brass had changed and sure enough the average of 5 with the once fired was 30 fps slower than the virgin brass. I thought it should have been a touch faster since it wasn't expanding the cases as much. What could have caused this.

 

[Zero333]

So I finally finished firing all the new brass. I sized and loaded the now once fired brass and shot some of it. I shot 5 foulers on a clean barrel and then shot a group and chronographed it to see if the once fired brass had changed and sure enough the average of 5 with the once fired was 30 fps slower than the virgin brass. I thought it should have been a touch faster since it wasn't expanding the cases as much. What could have caused this.

You said the shoulder moved forward quite a bit on the first firing. So the internal volume of the cases increased accordingly. So I theorize this is the reason.

Did you use the Same primers as when developing the load ???
Primers will affect velocity and pressure. A 300winmag load I developed with cci250 and 208eldm yielded me 3,005 fps avg. and no pressure signs.
Then I switched to fed215m and lost about 30 fps, and felt the odd (I think) barely noticeable harder bolt lift. But groups got much much smaller with the 215m's primers.

 

[Mtstalker]

Yes the same powder and primers were used. All the same lot. I bumped the charge to 71grs and accuracy was good and velocity was 2825FPS with a es of 12FPS.

 

[rwk]

Any of u folks do 160 gr. barnes, i'd like to try for deer under 200 yards. Thanks Rich

 

[Mtstalker]

I used the 180gr Barnes x bullets in my 338 win about 10 years ago. At the time I did not own a chronograph but they were loaded fairly hot. I shot a very large bodied mule deer buck a touch over 400 yards with it. It was very effective.