frnkeore
posted this
21 December 2012
Chargar wrote: frnkeore...Why would one want to limit himself to cast bullets of .309?
The aforementioned 1960 Marlin 336 has a Microgroove barrel with a groove diamter of .309 and a bore of .304, both specs on the large size. I would choose to shoot at least .310 bullets with .311 being a stronger preference.
You seem quite strong about a throat being no bigger than .3095 and I don't understand your reasoning.
Bear in mind here, I am not talking about building target rifles here, or high grade bolt actions of any kind. I am talking about older lever and pumpguns that currently are not cast bullet friendly, due to short throats. In both cases, there really is not any freebore, just a bevel on the end of the chamber.
I think you guys sometimes are more concerned about the ideal, that you lose sight of the issue on the table.
As an aside about ten years ago, I had Mountain Molds make me a custom mold for the Marlin. It has no full diamter outside of the case neck and a taper nose that will allow the bullet to be chambered with light engraving and still have good nose support. It shoots very well when sized .310 which is the as cast diamter. I would just like to load ammo for it that will shoot in my other 30-30s of which I have a 5 more.
charger,
I don't size bullets anymore than I have to, i'm a target shooter and always go for the best of everything.
Are both your rifles .309 grooves? I believe that you'll find that the Rem is closer to .306. I have 3 of them and they are all .306. If you shoot .311 in it, you'll be sizing them .005 in the barrel. Like Tom, I make my freebores a little over groove dia but, in my case my reamer is .309, .001 over a .308 groove.
If you wanted to digest .311 bullets then by all means do your freebore at .311/.3115. It will shoot better than a none freebore chamber but, remember that your limited on OAL. Make up a dummy round at the max length that you can feed it, then measure the full diameter bullet and freebore that much in front of the case or sent it to PT&G and let them do it for you.
Always remember, the more you size your cast bullet, the more distorted it will be.
Frank