.375/.338 Lapua Magnum Improved - Load Data

[RockyMtnMT]

Dave,

Where did you ultimately finish up with this project. I am in the process of getting a new barrel for my hunting rifle and this cartridge is my short list. Have pretty much decided to go this route after this thread was brought to the top this morning.

I'll be going with a 30" in 10" twist and my Lapua imp will be a 40* shoulder.

Thanks for your info.

Steve

 

[Rockfish Dave]

Interview with David Tubb using the .375-.338 Lapua Magnum Improved for the 'King of the 2Mile' competition.

[ame]https://youtu.be/6C7ZXS7MrKc[/ame]

 

[RockyMtnMT]

Did a quick load work up with our 375 BigDog (375 Lapua imp) last week for the Wingspan show last week with our 394g Hammer Hunter. Used RL-26 with a vel of 2865fps. Only got to shoot it out to 780y but the .444 G7 bc ran very close. It was hitting high but the incline was pretty steep and I did not run drops with that factored in. Just made the change in elevation and then let people at the show shoot the rifle if they were interested. Everybody that tried the rifle was able to ring the steel plate that measured 15" dia.

This rifle is wearing a 31" Rock Creek medium palma barrel with a medium Pain Killer muzzle brake. Defiance Deviant action and a Nightforce . Weighs in at 14lbs ready to go. Fairly pleasant to shoot but has enough recoil that you can't free recoil it. Gotta be a bit more firm with it or it will bite you.

Hopefully will get out and shoot it a bit further soon.

Steve

 

[Rockfish Dave]

Impressive my next barrel will likely be a 40 degree shoulder as well..

 

[AfricaBob]

My gunsmith is about to cut the grooves in the barrel of my new .375/.338 LM Imp. Please would you recommend a twist suitable for this rifle using the bullets listed below:
- For thick skinned dangerous game I'll be shooting a 300gr FN bullet 1.34" long
- For general purpose hunting I'll be shooting a 300gr expanding bullet 1.62" long
- For long range I'll be shooting a 355gr spitzer bullet 2.04" long

Initially I felt 1:10" twist would work well, however, now I'm leaning toward a 1:9" twist for better stability in my 355gr bullet at lower velocities. I'm not certain how this will effect the shorter bullets I've chosen.

 

[Rockfish Dave]

Berger has a twist rate calculator. If you know the velocity you can punch it in. For me, I went with a 1:9.7 twist as it will stabilize any of the bullets that I care to shoot.

I created a spread sheet that calculates stability at sea level knowing that if it is good at sea level it should be good in all conditions.

 

[AfricaBob]

Is there such a thing as too much spin on a bullet? If so how much is too much?

What is the shortest bullet you put through your .375/.338 LM Imp?

 

[Rockfish Dave]

The risk is with high velocity and a fast twist rate the bullet will come apart from the centrifugal force. I don't think you will get much over 3000 fps with the 300 gen bullets. You would likely be fine with 1:9 twist.

I tend to like how fast twist barrels shoot everything. Personally I have not had issues.

Best to play with the Berger bullets twist rate calculator your self to make sure that you are making the right choice for your conditions. There is a lot more information on their website.

http://www.bergerbullets.com/twist-rate-calculator/

 

[RockyMtnMT]

We did an 8" twist with ours. With our bullets or other monos there is not the worry about bullets coming apart in flight. In my opinion for hunting the better you can spin a bullet the better the terminal performance will be. We are currently re-barreling a 375 Allen Mag for a customer and used an 8" twist for that one as well.

Steve

 

[Hatting]

Hi
who makes chamber Reamer and Die's for .375 / .338 Lapua Magnum Improved ??
i want to build one

Best Regards
Anders Hatting

 

[RockyMtnMT]

Hi
who makes chamber Reamer and Die's for .375 / .338 Lapua Magnum Improved ??
i want to build one

Best Regards
Anders Hatting

We have a reamer. If you are wanting to purchase a reamer any of the manufactures can make one for you. There are a ton of different slightly varying designs.

Steve

 

[Hatting]

We have a reamer. If you are wanting to purchase a reamer any of the manufactures can make one for you. There are a ton of different slightly varying designs.

Steve

have already written to PTG (14 days ago) but have not heard anything from them yet
do you have a drawing of your reamer ??
if yes do you want to share the drawing ??

 

[RockyMtnMT]

have already written to PTG (14 days ago) but have not heard anything from them yet
do you have a drawing of your reamer ??
if yes do you want to share the drawing ??

We have a whole series of lapua ai reamers from 6.5 thru .375. All of them are the same except the 338. The 338 came from ptg and the others are from jgs.

Steve

 

[Hatting]

We have a reamer. If you are wanting to purchase a reamer any of the manufactures can make one for you. There are a ton of different slightly varying designs.

Steve

Hi Steve
have spoken to Becky Humbert, CFO from jgstools.com
and they want a drawing
do you have the drawing ???
if yes will you share it with me ??

Best regards
Anders Hatting