????Figuring free bore????

[bigngreen]

I'm tossing around getting a reamer for a 270 WSM and I have found a couple that might work but I don't quite know how to figure out what kinda free bore I want.
I have room in my magazine to push the bullets out farther and I want to have that for a new barrel. Any help would be great!!

 

[Loner]

I'm tossing around getting a reamer for a 270 WSM and I have found a couple that might work but I don't quite know how to figure out what kinda free bore I want.
I have room in my magazine to push the bullets out farther and I want to have that for a new barrel. Any help would be great!!

I am going through the same process with a 22-250. I want to have a reamer made
with the freebore at .224 instead of the .2244 that leaves the throat long due to
starting at larger than bullet dia. Of coarse the idea comes from the Wylde .223 chamber
design. After loading and shooting the Wylde chamber I no longer believe the theory that
a round won't chamber if the case neck is a little off center. I haven't decided on twist
or land count either. I want to shoot up to the 69 smk's and down to 50's. I haven't
seen anyone try a 22-250 with an 80 grain pill for really long range but it should do
well.
Not trying to hi-jack your thread, just drum up some interest on the subject.

 

[Kevin Cram]

What bullet are you planning on using?

 

[bigngreen]

Kevin, I don't know if you meant to ask me or Loner. I'm wanting so set up for a 150 Berger and the 169.5 Wildcat if we see it.
I found a good deal on a reamer but it lists the freebore as .187 but I don't really know how to figure or measure what it take to get a freebore measurement for the reamer.

I was thinking of measuring from the neck of the case to the ogive but I have no idea what is right.

Thanks for responding, guys hijacks welcome!

 

[Loner]

You have to combine the freebore with the throat width and figure how far
down that angle the bullet will actually have to travel before touching. Sin,
cosine and tangent. Remember your high school trig.?

 

[BountyHunter]

Go to Pacific Tool and Guage and ask Dave Kiff for suggestions and to send you a suggested reamer print for the bullets you are thinking shooting.

He can have you a reamer to your specs within 30 days normally also.

BH

 

[Kevin Cram]

bigngreen,

I was asking which bullet you were going to shoot. The 270 WSM according to Dave Kiffs book of reamer prints has no throat and only.0185 of lead. I have some reamers with the throat (aka free bore) built right into the reamer which is nice, sometimes. But for alot of the type of rifles I build, my customers are shooting the longer heavier bullets and each one wants their throat set a little different. I like to have a little shorter throat then have a customer supplied dummy round with the bullet seated to where they would like it. I then can go back in after the head space is set and set a custom throat length to match the dummy round. But also as Bounty Hunter stated Dave Kiff is a very knowledgeable man about this stuff and he could grind the throat right into the reamer for whatever length of throat you want.

 

[bigngreen]

Thanks guys for some replies, I think I'll call Dave Kiff and see. The reamer I was looking at is his any way so that's probably the right way to go.

Kevin, if you would humor me, my brain is not grabbing this very well. I roughly measured from the front of my case to the ogive and it is in the .180-.190 range, what am I measuring? Is it free bore that Savage has determined ?
So if I wanted to move my ogive out another .200 would I be looking for .385 of free bore needed in the reamer, this would put 150 gr Bergers just right, the bullet would fully engage the neck but only the boat tail would be bellow the neck.

 

[Kevin Cram]

You better talk with Dave on this one. Something doesn't sound right with your measurements. On my 338-408 Chey-Tac I only have throat length of .256" for a 300g SMK and it's seated with the boat tail junction just below the neck shoulder junction. If I had to guess a ballpark for amount of throat length for your bullet I'd think somewhere around .150" ish. But Dave would know better than me.

 

[bigngreen]

Your right! I'm just not getting it I think and I'll give him a ring today.

Thanks