How to figure out freebore? How much is too Much??

[dxlbaile]

Just toying around with a ole Ruger m77 270 win ... I have been shooting the 170 berger at 2900 from a sami chamber but the bullets seem to shoot better longer than my mag box.. If I am going to make this thing a single shot why not give it some freebore, to free up some case capacity..?

How do you know when too much is too much? I would like to move the bullet up to where the neck shoulder junction meets.. I just don't know if this is doable or not?
I don't have the availability of a good gunsmith unless I drive 3 hours so I was hoping someone might help me out.. I really think I might gain at least 50-75 fps with the extra room in the case if I do this.. Maybe I won't..

Anyone got some great advice..??

Thanks..

 

[L.Sherm]

Are you just wanting to know the freebore number if you did that.
You can pull up Bergers bullet deminsion page and it will give you all the measurements of there bullets .
Look at a 270 win reamer print JGS's are great at showing what freebore is on there prints so between the 2 you can figure it out.

 

[L.Sherm]

If I'm doing the math correct its around .100. A call to JGS or Manson could tell you also.

 

[dxlbaile]

Thank you ... I will explore these options.. Just thinking this might put this baby in the 3000 fps range if i get lucky.

 

[pig ranch deadeye]

Older Weatherby rifles used .75 inch on freebore.

 

[dxlbaile]

I think L Sherm answered my question.. I am trying to figure out how much freebore i would need to get the bullet at the junction and if it would work..
I have seen some bullets people shoot and the bullet is quite aways up in the neck.. .. How far is too far for safe shooting.??

 

[pig ranch deadeye]

Try .75 inch. That should let you load out to the full magazine length and still have a bit of bullet below the neck. This dramatically reduces pressure.

 

[MagnumManiac]

General rule of thumb is to throat for the bullet to have the shank in the neck and the heal of the bullet below the neck/shoulder juncture, .010"-.020" extra from that measurement is what most folks do. The heal is the boat tail, only it should be below the neck.
With my new custom 264WM, I am at 3.54" COL plus .020" for the 142gr ABLR. This will also suit the 156gr Berger...if I ever get my hands on some.
Most 'smiths will ask for a few dummy rounds to work off, I ask for 3, use new brass, just don't do what I did, I used fired/sized brass and I couldn't get them to fit the newly cut chamber. I had no other brass, so had to size down 7RM brass.
If this makes no sense, search for bullet seating to the heal on here, I can't post pics to help, sorry.

Cheers.

 

[Russell123523]

I think L Sherm answered my question.. I am trying to figure out how much freebore i would need to get the bullet at the junction and if it would work..
I have seen some bullets people shoot and the bullet is quite aways up in the neck.. .. How far is too far for safe

Try .75 inch. That should let you load out to the full magazine length and still have a bit of bullet below the neck. This dramatically reduces pressure.

Take bullet length 1.49 - boat tail .254 - caliber -277 add to case 3.449 is the longest I would go have a gun Smith throat it off a dummy round at 3.48 or maybe 3.46 for chasing the rifling

 

[pig ranch deadeye]

Take bullet length 1.49 - boat tail .254 - caliber -277 add to case 3.449 is the longest I would go have a gun Smith throat it off a dummy round at 3.48 or maybe 3.46 for chasing the rifling

.75 inch of freebore helps with the Nosler Partition. They tend to be long. .75 inch gives plenty of freebore let's you load more powder for more velocity, and seating them out long leaves more case capacity open.

 

[L.Sherm]

You will never even get within a mile of the lands with .750 freebore.
Bergers and the likes require way more than partions

 

[pig ranch deadeye]

One point of view is to seat close to the lands. That is not the only point of view. As in all things, there is a tradeoff.

If you don't approach the lands that can be a plus. If the bullet jumps a bit first, pressure is reduced. You can always find a load that gives a good group even if your bullet is far behind the lands. You might have to try a few loads before you find the right one. This is how I loaded the Weatherby 300 back in the sixties, using 4831. You could always find a group by experimenting with different charges. The extra free-bore is good for an additional 150 fps in velocity when loading to the same pressure limit.

 

[L.Sherm]

This is my opinion and you can take it for what its worth, I would much prefer my rifle to be able to shoot close to the lands IF that's were it shot the best than seating it out untill it will literally fall out of the neck.

 

[pig ranch deadeye]

I agree on your comment about "falling out of the neck."' The base of the bullet (excluding the boat-tail) should always be a smidgen below the bottom of the neck. Never any higher.