338-300 Norma Improved 35 degree

[Alex Wheeler]

Now that I have used the last of my Broughtons I am on the hunt for the next best .338 barrel. Have some different ones on order for testing. The volume on the Broughtons was perfect for the 300s.

 

[Ledd Slinger]

judging by those numbers, getting to 3100 fps with the Berger 250gr should be no problem. For 2K competition shooting, the 300gr Berger @ 2950 fps is still the best choice for drop and wind deflection. But the 250gr @ 3100 fps would be one heck of a hunting round option.

Not sure about volume on my 26” Brux 338 barrel but its fast and very accurate in my 338-375R. Im sure it would perform great with the 338 NMI as well, especially if stretched out to 28-30”

 

[Alex Wheeler]

Brux's geometry usually produces a fast barrel. The tighter barrels will shoot very well, they just pressure out sooner.

 

[tom]

Second trip out with the broughton today. Shot above and below the 94.0 area with two different bushings. The .363(repeat of trip 1), and a .364.

It repeated almost identical to day one with the 363, and didn't like 364.....except the 94.0 charge.

Surprised I didn't see anything to indicate an obvious speed up yet today.

V570/cci 250s/300 otm, seat die on #12 same as day 1. I guess tomorrow I'll shoot some different seating settings on 94.0.

I formed 10 sticks from 300 norma adg brand today, and they're within a tenth of h2o capacity of my lapua sticks. Gonna stick with lapua for now, was hoping they might have more capacity such as their version of 338 lapua does.

Tom

 

[tom]

Out again now this morning shooting seating adjustments at 94.0. I did take my foulers and step up incrementally all the way to 97.0, that one went 3,012 and I can't feel or see pressure signs, will measure later once I'm done. Hopefully today I'm smart enough to adjust up off my aim point so I can see what's going on down there!

Tom

 

[DHuffman]

Out again now this morning shooting seating adjustments at 94.0. I did take my foulers and step up incrementally all the way to 97.0, that one went 3,012 and I can't feel or see pressure signs, will measure later once I'm done. Hopefully today I'm smart enough to adjust up off my aim point so I can see what's going on down there!

Tom

How's the weather? I'd planned to shoot but 4* and 15-20 mph winds, think I'll turn some necks instead.

 

[rhovee]

The 338 Norma Lapua brass does weight 3 grains less than 300 Norma Lapua. I’ll form a piece snd see if that equates to more volume or not.

 

[rogina]

Out again now this morning shooting seating adjustments at 94.0. I did take my foulers and step up incrementally all the way to 97.0, that one went 3,012 and I can't feel or see pressure signs, will measure later once I'm done. Hopefully today I'm smart enough to adjust up off my aim point so I can see what's going on down there!

Tom

What was the temperature?

 

[tom]

18 degrees (above) and here's what it did today. I finally noticed a 20 fps increase today on rounds 50 through 70 since new. I can't say that I made poorly executed shots while shooting the -5 group so I don't know what to think. The -3 is where I've had it set until today's outing, which did repeat again. And after measuring rim expansion, I WOULD NOT pursue the upper node, and will continue to tune around the low 2900s. These damn BATS will let you hurt stuff if you just go by feel.


Tom

 

[tom]

Notice I was smart enough to give it extra clicks today though!

 

[rhovee]

I need to form it to be sure. The shoulder on 338 brass is .007 wider than 300. So couldn’t do a volume test on virgin brass. The 338 and 300 are very similar, except the shoulder measurements. 300 Norma is .559 on shoulder and 338 is .567. So need to fire form a piece then I can measure volume of each.

 

[tom]

I need to form it to be sure. The shoulder on 338 brass is .007 wider than 300. So couldn’t do a volume test on virgin brass. The 338 and 300 are very similar, except the shoulder measurements. 300 Norma is .559 on shoulder and 338 is .567. So need to fire form a piece then I can measure volume of each.

Formed cases, sized are right on .566 on my setup.

Tom

 

[rhovee]

Seems like the 338 already has the body taper to .010 per inch. Should help with fire forming because of the body being able to catch on the walls of the chamber. I am headed to range now to FF some 338 head stamp brass.

 

[tom]

Seems like the 338 already has the body taper to .010 per inch. Should help with fire forming because of the body being able to catch on the walls of the chamber. I am headed to range now to FF some 338 head stamp brass.

I would think we should have comparative h2o weights by dinner then! Hurry up, I'm getting hungry lol.

Tom

 

[rhovee]

Well the 3 grains difference didn’t equate to more volume. Volume was within .1 grains of each other. 109.2-109.1

 

[tom]

Sorry I don't have an update for this weekend guys. It was just to windy for the 338 this weekend, so I tuned on one of my 6's instead.

 

[Alex Wheeler]

I unlocked the steel gate at the range this morning and when the wind blew it open I just locked it back up and went home.

 

[tom]

Well at least the winds have settled down on this Christmas Eve morning.

 

[tom]

Gave it a go with a .362 bushing today since it liked .363 vs .364. The seating force required was a bit extreme, so I tried it with and without graphite in the necks. All in all, I'll probably just finish tuning it around the original .363 bushing. This was rounds 70 through 90 through the barrel, and it is hinting at possibly speeding up, but is subtle.



Tom

 

[Alex Wheeler]

This is good info Tom. It really gives a good visual for how a bushing effects poi stability. I dont think guys realize how much a bushing can widen a window of tune. Even though this is a .338, it plays out similar in every other case. Great stuff.