tapered throat on .375

[wmitty]

Recently received a .375 H&H barrel for Rem 700 action I'd hoped to use to shoot cast. Just checked the throat and found it's a straight taper of .390" immediately ahead of the case mouth tapering over a length of .225" to .377" at beginning of leade (beginning of lands). This isn't exactly what I was hoping for as far as a throat for launching boolets... could I hear any opinions as to how I should proceed in trying to obtain some accuracy? Barrel slugged .3771" and is stainless and appears to be unfired. I'm using the RCBS .375 250 gr. f.n. which shoots really well in the M 70.

[leftiye]

I can only think of two options. First, use it as it is with its problem with aligning bullets, and boolits. Second, set the shoulder forward 1/4", rechamber with finish die with no freebore, or straight freebore (plus .0005" groove diameter) of your desired length. Maybe go to .375 Ackley improved while you're at it.

[Johnw...ski]

I am presently working with three custom barrels and they all have a tapered throat, although about half the length, and seem to work quite well.

As far as the throat ending .0001" smaller than the bore size, consider this the bore and rifling were finished before the chamber was cut so the metal just isn't there for it to be smaller. If in fact it is smaller it has to be a slight burr that was thrown up during the chamber reaming. In any case at .0001" I think it will be gone after you fire a few shots and have at it cleaning.

Good Luck,

John


Recently received a .375 H&H barrel for Rem 700 action I'd hoped to use to shoot cast. Just checked the throat and found it's a straight taper of .390" immediately ahead of the case mouth tapering over a length of .225" to .377" at beginning of leade (beginning of lands). This isn't exactly what I was hoping for as far as a throat for launching boolets... could I hear any opinions as to how I should proceed in trying to obtain some accuracy? Barrel slugged .3771" and is stainless and appears to be unfired. I'm using the RCBS .375 250 gr. f.n. which shoots really well in the M 70.

[Bass Ackward]

Recently received a .375 H&H barrel for Rem 700 action I'd hoped to use to shoot cast. Just checked the throat and found it's a straight taper of .390" immediately ahead of the case mouth tapering over a length of .225" to .377" at beginning of leade (beginning of lands). This isn't exactly what I was hoping for as far as a throat for launching boolets... could I hear any opinions as to how I should proceed in trying to obtain some accuracy? Barrel slugged .3771" and is stainless and appears to be unfired. I'm using the RCBS .375 250 gr. f.n. which shoots really well in the M 70.


I'd say that it's not ideal by any matter or means, but I don't see it as a show stopper. What you are describing is a throat very similar to what is found in levers. And many of these military guys probably are a lot worse off.

So the procedure is the same really. You may need a little harder bullet. Or you may need a slower powder to allow entry fully into the rifle before pressure peaks to maintain integrity, but only the gun will tell you that. You will have a little slower velocity ceiling if your bore ride doesn't fit as well since this is the support for alignment of the slug upon firing. Right now, you are expecting the worst. So the only way to go is up.

Leftiye told you the mechanical correction of the gun. You can also order a custom mold to fit better if this actually exists. Or rent a throater reamer and lengthen the throat so that it has a ball seat portion to support the bearing area of the slug. You can rent one of these for $25 and use a T- handle wrench yourself using the trial and error method of chambering a loaded dummy lead slug.

But unless you wanted to break some world speed records, I would try it first.

[wmitty]

Thanks for the input; I'm going to try it as is with heat treated WW and go from there if results are unacceptable.