Freebore selection for a 338 Lapua

[Never Forget]

Looking for some advice on which freebore to go with. I’m putting a new barrel on my Savage 338 Lapua, it just doesn’t meet my expectations. I’m planning on running 300 grain bullets by both Sierra and Berger, leaning toward the Sierra’s as they have been less picking on seating length for me in the past with other calibers and on the factory Savage barrel.

I don’t mind single feeding but also want to run mag length. Its hard to get the best of both worlds in a 338 with those heavy bullets as they are seated pretty deep in the case. To get a 300 Berger above the donut I need a .233 freebore at a minimum, over .300 for a Sierra. If I get a CIP reamer with a .129 freeebore I can get Sierra’s to the lands from a mag length but the bullet will be buried all the way to the shoulder body junction, that’s pretty deep and will cause pressure earlier than I want and cut down on speed.

What I’m leaning toward is splitting the difference and getting a PTG 338 Tactical reamer with a .187 freebore. Yes both Bergers and Sierra’s will still be a little past the donut zone but mag length wont be buried quite as deep. And I can chase the lands longer as it wears.

So am I asking for trouble trying to get the best of both worlds? If I don’t have donut issues am I really loosing that much in accuracy seating it a little deep? I know going with the .233 is the right way to do it but I’ll be jumping a huge gap from mag length then.

For what its worth my Savage was a CIP reamer, a McMillian TAC338 is a CIP, and other quality tactical style 338’s are made with CIP reamers. From what I’ve heard these all shoot pretty darn good from mag length with 300 grain bullets. I was able to achieve 2720 fps with Sierra’s in my factory barrel before I hit pressure.

Thanks in advance, John

 

[B23]

A few years ago Kirby Allen did a test on throat length, in his 338AX aka Lapua Imp., to see if there was much velocity gain by having a bullet seated way out versus one with a shorter FB length. Long story short, he found it to be very minimal at best so I'd make up a dummy round seated out to where you can still run them through the mag, with a little extra room to spare so as the throat wears you can chase the lands and still get them to feed through the mag.

 

[dkhunt14]

A few years ago Kirby Allen did a test on throat length, in his 338AX aka Lapua Imp., to see if there was much velocity gain by having a bullet seated way out versus one with a shorter FB length. Long story short, he found it to be very minimal at best so I'd make up a dummy round seated out to where you can still run them through the mag, with a little extra room to spare so as the throat wears you can chase the lands and still get them to feed through the mag.

I called Kirby Allen on thread. After long posts of how it didn't change and a few arguments back and forth. I finally asked him what is the difference if you improved the case 3 grains like Allen Magnums or throated it out 3 grains. He didn't respond after that. 3 grains capacity is 3 grains. Matt

 

[B23]

When you say 3 grains do you mean 3 grains more case capacity in water or actual powder? I ask because 3 grains more powder, especially considering the types of powders used in 338 Lapua's & 300gr bullets, seems like it would be a lot of volume to try and gain and I'm not sure you could gain that much volume by just seating the bullet out a little further, but maybe you can.

 

[Never Forget]

I called Kirby Allen on thread. After long posts of how it didn't change and a few arguments back and forth. I finally asked him what is the difference if you improved the case 3 grains like Allen Magnums or throated it out 3 grains. He didn't respond after that. 3 grains capacity is 3 grains. Matt

Can you be more specific on what adding 3 grains equaled? Does that mean it was worth it?

 

[Drop Port]

If you want to shoot mag length 338 Norma is the way to go. A Lapua at 3.6" leaves an extra 1/4" of bullet in the case. If you are accuracy minded the Lapua set up correctly is a single shot and that dog will run with some R33. Your 2720 fps is just getting warmed up in an optimal setup.

From my experience there are two 338 Lapua's, one set up short with the bullet stuffed in the case that often reaches pressure early and is often inconsistent day to day. The second being long throated that can run faster and is less finicky.

 

[dkhunt14]

Can you be more specific on what adding 3 grains equaled? Does that mean it was worth it?

3 grains is just an example. 3 grains in my Lapua IMP is worth 150 FPS. The point was 3 or whatever number gain is the same whether you do it with improving the case or throating. It is all a gain of capacity which relates to more powder and more speed. Matt

 

[dkhunt14]

When you say 3 grains do you mean 3 grains more case capacity in water or actual powder? I ask because 3 grains more powder, especially considering the types of powders used in 338 Lapua's & 300gr bullets, seems like it would be a lot of volume to try and gain and I'm not sure you could gain that much volume by just seating the bullet out a little further, but maybe you can.

We have gained 2 grains in a WSM CASE. Which is alot smaller then a 338. My 338 was. Already throated out and IMP. I just used 3 grains as an example. But if you have the bullet stuffed way down in the case and you out to the middle if the neck I bet it is 3 grains or more. Those 300 grain bullets are long and can be moved a lot. Matt

 

[germanlongbow]

I improved mine and throated for 277 gr Cutting edge. The improved will allow for more capacity. I throated only due to bullet dimension. Im pushing 3080 out of my 32 inch Krueger with no issues of pressure. I can push it harder but accuracy suffers. I use 96.6 gr Retumbo. Shoots same accuracy with RL 33 but at 104.2 grains.