fishingstockwell
Active Member
- Joined
- Jun 12, 2016
- Messages
- 32
Hey guys I have a question about how a long throated custom chamber effects velocity with factory ammo. I have two 30 Noslers. The first is a semi custom built on a model 70 action, brux barrel and has a sammi spec chamber. The second is a brand new Carbon Hunter from Rbros, which I picked up 3 days ago, with a lot more freebore to load the 215 and 230 bergers out as far as possible. I have a once in a lifetime antelope tag in CA that starts next week, and rarely shoot copper bullets anyway, so no time to reload. I had a couple of boxes of copper factory loads from a Tule elk hunt a couple years ago, so I figured I'd try those. The loads that I had left from the tule elk hunt, had shot at 3000 fps out of the semi custom rifle, but only 2825 out of the new rifle with the long throat. I know the barrel will speed up after it is shot it, but I doubt it will speed up 175 fps. I'm guessing that I am loosing velocity shooting factory bullets, at 3.34", in a chamber throated for a 3.6-3.7" coal. Pressure usually rises with the bullet seated closer to the lands, and pressure equals velocity, so I imagine the opposite happens as you move farther away from the lands. Do you believe that the excessive jump is the reason for the low velocities?
BTW, the new rifle from Travis at RBros is a fantastic rifle, with some of the best components available. He keeps built rifles in the "white", so he can get them out fast. I called travis, told him the colors that I wanted, and sent him payment. That week he put the gun together exactly the way we discussed. The following week he shot it to confirm that it was grouping well, and I had it by the end of the second week. What an outstanding way to order a new rifle, and not have to wait 6-12 months. First trip out to the range it shot two different brands of bullets into multiple 3/4" groups, with factory loads. Can't wait to start load development and see what it can really do.
Any opinions about the excessive freebore with factory ammo effecting velocity would be appreciated.
Thanks,
Matt
BTW, the new rifle from Travis at RBros is a fantastic rifle, with some of the best components available. He keeps built rifles in the "white", so he can get them out fast. I called travis, told him the colors that I wanted, and sent him payment. That week he put the gun together exactly the way we discussed. The following week he shot it to confirm that it was grouping well, and I had it by the end of the second week. What an outstanding way to order a new rifle, and not have to wait 6-12 months. First trip out to the range it shot two different brands of bullets into multiple 3/4" groups, with factory loads. Can't wait to start load development and see what it can really do.
Any opinions about the excessive freebore with factory ammo effecting velocity would be appreciated.
Thanks,
Matt
