338-375 Weatherby free bore

N

nnewbern

Guest
Free bore can it be removed?

I have a 3ea 338-375 KT, I was considering re-reaming it to 338-375 Weatherby. I have lost all of my old brass and do not want to go to all of that trouble anymore. Just want an accurate gun that I can buy off the self brass for.

I assume the term free bore is concerning excess clearance in the chamber that most guns do not have.

Question:
1. If I have a new reamer made and have the free bore removed, is this reasonable and or safe?
2. Will it have a positive effect on overall accuracy?
3. As I understand the Weatherby free bore is not good for accuracy?

Nathan
nnewbern@hotmail.com
 
nnewbern said:
I assume the term free bore is concerning excess clearance in the chamber that most guns do not have.
Click to expand...

"Freebore" refers to chambering a barrel such that a bullet must travel a long distance after it leaves the case before it engages the rifling. There is a distance ahead of the bullet in front of the chamber that is free of rifling and the bullet moves over this distance and hence is "free." Weatherby and others adopted this to avoid excessively high pressure that would result with hot loads if the bullet immediately was forced into the rifling after firing. The freebore briefly delays and reduces the pressure spike.

You can "get rid" of the freebore by setting the barrel back and rechambering, or rechambering to a longer cartridge. I don't think the rechambering you are suggesting will eliminate freebore.

Despite the freebore, some of the Weatherby rifles are very accurate. Bullet "jump" appears less detrimental to accuracy in hunting rifles (maybe not target rifles) in the bigger cartridges compared to the smaller ones. Or, at least rifles with freebore can still perform accurately for huning purposes.
 
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nnewbern: Depending on the bullet you intend to shoot you will probably end up with a little free bore anyway. I had mine set up to shoot 300 gr. SMK's and the freebore needed so the bullet is not seated deep in the case ended up being so long, I don't know how long. I can seat the bullets reasonably in the neck and touch the lands as necessary. But the key (or to minimize any accuracy concerns) to the freebore is that it is only .001" over bullet diameter. Your gunsmith can do this. This reduces the amount of possible bullet wobble in the freebore area. Keep in mind that this close clearance needs cleaned well when you do clean. It don't take much crude to make it hard to chamber a round. Not a real problem but something to be aware of if you don't clean often. Also, published max loading data could be a little hot when your bullets are set at the lands. I hope this helps. Sam.
 
First

Buy all the brass of the same lot you will ever need.

Buy several different boxes of bullets you might like, assuming some will shoot and some will not; however I would bet on Nosler Accubonds and Barnes TXS.

Next seat the different bullets without powder or primers. What you want to do is to seat all the bullets to where the ogive is the same distance from the base of the cartridge case. The overall length will be different. When doing this insure all finished cartridges will fit and function out of the magazine. Send the carefully assembled brass and bullets to who ever is going to grind the reamer. This person will know what to do and make you a reamer. It would be best to work through a good gunsmith.

When going through all this work I hope you are starting with a new barrel.
 
Thanks for all the help; can anyone advise the best price & place for re barreling of my rifles. It would be nice if the all ready had a 338-378 W dies.
Can the gun smith set the free bore or is it all ready in the reamer?
I am in Ft Worth Tex
Thanks
Nathan
817 994 4864
 
338-375 or 338-378 ?

these are 2 different cases. The 375 based case is from the 375H&H family .532 head size, the 378 case has a .582 head size. Weatherby made a 375 but I don't believe it's in production anymore.I have seen 375 Weatherby brass/loaded ammo for sale but not very often.
 
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show me the brass

Buy the brass first. If you can't find the brass....end of story.

Find any buy the reloading dies.

Buy several makes and weights of .338 bullets.

Find a good gunsmith to help design the reamer and barrel the rifle.

The project will not be inexpensive.
 
Be Warned

Ever read what is written on a Weatherby Box. It says to fire the Factory ammo ONLY in Weatherby Rifles.

The reason is that they have that generous freebore which allows the Factory Ammo to be loaded at the velocities that Weatherby is known for.

About seven years ago, a fellow shooter at the old Lake Houston Gun Club had a custom Rifle built in 300 Weatherby. The gunsmith used reamer which did not have the generous freebore. The shooter stopped at the local store and bought some Factory Weatherby Ammo.

The third shot, he blew a primer, and could not get the bolt open without the aid of a dead blow hammer.

That Factoy Ammo was WAY too hot for that chamber without that freebore. Just be careful.........jackie
 
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