Home Forums Hunting & Shooting Gunsmithing Rechamber what's the optimal way to set up the throat?

Having a new barrel put on a Model 70 classic in 25-06 and not sure how to set up the throat. Will be using mostly Berger, Hornaday and Nosler Bullets. Should I set it up for the Berger as they can be the most temperamental or will it be too short for the others? I will probably use Hornadays the most in the 100 - 120 gr. range with 117 the mainstay if they work out.

I believe the mag length is 3.36" how much room should I leave for functioning and "chasing the lands" as it wears? Is seating for 3.34" a good OAL to start with for throating puurposes?

If you're going to "chase the lands" as it were, you better be setting up for a much shorter OAL in the mag box. The SAAMI 25-06 reamer will give you most likely much more throat than you need to begin with - therefore it would be wise to obtain a "no-throat" reamer and do the chamber to minimum headspace..

Then use a throater to get you where you wanna go - OAL-wise.. The Hornady OAL gauge coupled with their modified case and some loose bullets will give you the measurements you need to set the throat..

With a mag box IL of 3.36, I'd be thinking of starting out at 3.15. That'll allow you to chase lands for nearly .020 over time..

Throaters are the logical solution for this conundrum. I use one in my .30 cal rifles dedicated to cast bullet shooting.* The downside to using a separate throating reamer is the (slim) chance of going in crooked and spoiling everything. A solid one piece reamer that cuts the desired "non-standard" throat at the same time as the chamber is ideal, but not always practical. Extra cost being an issue, and then probably never using it again.


* I use a throating reamer with interchangeable pilots to perfectly match existing bore diameters to within a couple ten thousandths to give the best chance at straightness/concentricity. It also cuts a shallow leade at 1½º included angle, for eaaaaasing the lead bullet straight into the rifling, with a standard .309 ball seat.

Said reamer might also be beneficial for someone using a jacketed bullet with a long ogive such as a Berger VLD- the long tapered leade would be receptive to the long tapered bullet and allow for maintaining a throat of "normal" dimensions instead of a longish throat with "normal" leade taper. It would also allow for increased COAL length with any other shaped bullet. Not to mention every bullet, not just cast lead bullets, deserves a chance to be gently funneled into the rifling. Then of course, magazine length is always the bugabear.

Dunno for a fact, thinking out loud here.

Or.....run a quality barrel and shoot hybrids without the fuss.

Some good advice, thanks. Combining the answers I think I will load the 117gr Hornaday to 3.15 OAL and use a 1.5 degree taper if my smith has one but I won't sweat it if it is 1 or 2 degrees. He makes his own pilots so have that covered. Berger doesn't make a 25 cal. hybrid but if the VLD doesn't shoot I won't loose any sleep over it. The Berger will be a specialty load so no problem if it is a single load proposition as long as the mainstay loads work out of the magazine.

Barrel is a Bartlein 5R 1-9" twist so that should shoot about anything well up to 125 grains or so.