I'm contemplating having another custom barrel made in a hunting caliber (not decided just what yet). I know on bench guns and such, touching or jamming the lands is the norm. But not sure for a hunting rifle, I don't want the bullet to stick on extraction and dump powder in the mag. Whatever caliber I decide, I want the barrel throated for my load of choice, just not sure how much (if any) jump I should request. Let's assume it's a 6.5/06 with a 120 gr bullet, loaded to fit the mag. Should I order the barrel with the ogive just touching the lands or a little more jump? All of my hunting rifles are factory, so this has not been an option so far.

Hey jb

I recently had a rebarrel job from a 300 win mag to a 6.5 rem mag and I would recommend setting the lands where you are .025" from magazine length when you seat a bullet to kiss the lands. That way you can seat out to the lands if you want to, seat them deeper with no problems and will not run into problems with throat erosion any time soon. That is the way I had Hart set the barrel on a 280AI and they hit it perfect.

I'm with Woods!

First off, it is impractical to use an "in the lands" seating arrangement for a hunting gun. You risk having a receiver and magazine full of powder once you extract a round. Totally impractical in the field! Most (custom) rifles shoot way more precisely than what you need for hunting anyway.

Secondly, as Woods mentioned, your throat will recede over time (assuming the gun gets shot a fair bit), and it is nice to be able to chase it by loading out your bullets a bit further.

A number of things determine how to have your throat cut, two stand out: magazine length and bullet seating. As far as magazine length is concerned, you need a bit of space in your mag for the rounds to be able to exit (feed) properly. Call that perhaps .01". Secondly, if you want to be able to chase receding lands, Woods number of .025" below mag length sounds pretty sensible.

If your magazine length is not a concern, take the longest and the shortest bullet you'd like to load, and see if you can find a compromise that will allow you to seat both of these bullets securely into your case neck. I like seating the base of the bullet about to the neck-shoulder junction (or a bit deeper for boat tails), so that is the seating I often specify for my heaviest bullet. I might go a bit deeper than that, if that allows my light bullet to be seated safely into the case as well (compare OAL with a bullet comparator to be sure you measure off the ogive of the bullet). Again, it makes sense to have just a bit of leeway to chase receding lands.

Once you have your max cartridge length, I would specify the freebore to be around .005-0.01" above that. Bullets vary (even when measured over the ogive). I have found .005" to be about the smallest amount of variance to ensure you are always off the lands - and that is with smaller caliber, match type bullets (Sierra). If you want to load Barnes TSX, look on Barnes' website, I believe they recommend a longer bullet jump for those bullets, and their recommendation has worked well for me in the past (I forget the actual number).

- mike

quote:

Originally posted by mho:
If you want to load Barnes TSX, look on Barnes' website, I believe they recommend a longer bullet jump for those bullets, and their recommendation has worked well for me in the past (I forget the actual number).

- mike

I think it's about 20 thou.

Heck, jump would be the last thing I'd worry about on a hunting rifle. With my very light .223 for instance, last Saturday the last 3 shot group with Horn 55g SP was around 3/16. Last night I measured the "jump" to be .165 (to easily fit into the magazine.)

Cheap Win USA brand of 46gr proj would be much more and they consistantly group 5/8".

My benchrest technique (or lack of) will make a much bigger difference, so I'd hate to think of the possible error with a field shot.

Anyway, to touch the lands, my bullet would just about touch my max length brass.
Now that would be an interesting load problem.
Superglue perhaps?

If you're going to actually specify freebore, I would do it with due consideration of the heaviest (longest) bullet I would ever want (be able) to use in that rifle. Otherwise you're restricting your rifle to a certain (maximum) bullet length. As someone before me mentioned, you'll likely never notice the difference (in hunting terms) between the accuracy of a bullet seated to what your rifle really likes, and 10 thou more or less.

Function is key with a hunting rifle. Accuracy is great and important but, as long as it's decently accurate, takes a backseat to function. Especially for dangerous game. Those guys typically full length resize and check every round by cycling it through the gun. I would look for the bullet and powder combination that gave best accuracy before messing with seating depth.

LWD

All good advice, but I'd do one other thing too. I'd have the throat/lead/magazine set up so as to seat bullets in the case neck, not shoved down in the powder space like so many of the new wonder cartridges. I think the Mauser brothers had it right from the get go.

I have a similiar experience as JAL with my .223 CZ527. Nosler 50gr BT jump .150 and still shoot into tight clusters. I also have 2 rifles of different make with crooked chambers that wont shoot unless the bullet is jammed .005. With a custom you should be able to expect a straight chamber and a gun that will shoot whether there is alot of jump or not. I would have it set up to be able to handle 160gr bullets so as not to limit yourself and then figure out which bullets and powders it likes best.