Re: Question for Extreme LR 338 hunters
The boys I know using the 300 Whisper are getting 2400 fps pretty comfortably with the 150 gr bullets out of 20" barrels.
I would say the 338 version would get very close to the same velocity with the 180 gr bullet out of the same length barrel but would run a bit less in a 17" pipe. Not alot less though.
I would highly recommend the Lilja barrel. If I were to build myself a rifle like this I would use a Rem short action with a Holland Comp recoil lug and a 20" Lilja 1.250" straight cylinder barrel for shear rigidity and stiffness. I would get a 20" barrel just for a bit better balance and to keep the muzzle blast a little further from my face.
For more of a field rifle instead of a target, I would use a straight taper with a muzzle diameter in the .800" range.
The 1-10 twist would be my choice but I would refer with Mr. Lilja, telling him what velocity and bullet I would be using and go with his recommendation, he has never steered me wrong with a customes rifle or one of my own.
If you wanted to go with a 17" barrel, this would work fine as well, like I said 20" would just be personal preference.
You are correct that this round does not need alot of barrel to work well, you will get slight velocity gains with a 20" barrel bt probably not much over 50-60 fps over the 17" pipe.
Keep in mind one thing, the 300 gr Mk is huge, both in weight and length. When using a case as small as the Whispers case, you really need to be aware of bullet seating depth. If you have a throat designed to use the 300 gr MK seated to the bast of the neck, no conventional 338 bullet will be able to be seated to the lands or anywhere near them.
Design your throat to be able to work with the 180 r Ballistic Tip and the base of the big MK will probably plug your flash hole!!!
If you are going to build this rifle as a dual purpose rifle, you may want to fore go the 300 gr MK and use the 250 gr version.
This will help you make this round work as a dual purpose round easier. Remember, dual purpose rifles are always a compromise and generally on both usages.
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