I'm talking about the amount of a bullet that the brass case will
be "gripping" versus the distance the bullet will travel (jump)
before it contacts the rifling of the bore.

The problem at hand involves a 30-06, WW brass, and Nosler 150 grain
Ballistic Tip bullet. Rifle is off-the-shelf Rem. 700 ADL with good
3x-12X Burris scope.

Tech support at Nosler says that "grip" area is more important than
accuracy concerns over "jump". They recommend at least .308 grip
area for my 06 load.

If I seat this Nosler so it's being gripped over .308 inch of its
surface, that will give me a bullet "jump" of about .223 inch.

THat seems like a lot, and it seems that it would really be
detrimental to accuracy. However, I feel a certain "need" to respect
Nosler's advice and opinion.

I neck size the WW brass, and don't use an expander ball. That
results in this lot of brass after neck sizing.........having an
inside diameter of .304-.305. This lot of bullets mikes out at .3076 inch.
inch. I also do NOT lube the ID of the neck at any time during the
reloading process. I put a small but distinct chamfer on the mouth
of the case, and the bullets are boat-tail....and they will seat with
no "shaving" of bullet material at all.

I'd like some opinions and observations from others who may have
agonized over this dilemma.

Can I get away with a little less grip area, thereby reducing bullet
jump? I wonder what would happen if I used .250 inch grip area, and
therefore had jump of about .164 inch. Would I be likely to see
difference on paper target with my 9 pound hunting rifle? Would
bullet still be secure in the case with grip of .250? Would ignition
still be consistent?

Since this is hunting rifle and hunting ammo, am I being to nit-picky?

Thank you....... Lee Carkenord

I'm talking about the amount of a bullet that the brass case will
be "gripping" versus the distance the bullet will travel (jump)
before it contacts the rifling of the bore.

The problem at hand involves a 30-06, WW brass, and Nosler 150 grain
Ballistic Tip bullet. Rifle is off-the-shelf Rem. 700 ADL with good
3x-12X Burris scope.

Tech support at Nosler says that "grip" area is more important than
accuracy concerns over "jump". They recommend at least .308 grip
area for my 06 load.

If I seat this Nosler so it's being gripped over .308 inch of its
surface, that will give me a bullet "jump" of about .223 inch.

THat seems like a lot, and it seems that it would really be
detrimental to accuracy. However, I feel a certain "need" to respect
Nosler's advice and opinion.

I neck size the WW brass, and don't use an expander ball. That
results in this lot of brass after neck sizing.........having an
inside diameter of .304-.305. This lot of bullets mikes out at .3076 inch.
inch. I also do NOT lube the ID of the neck at any time during the
reloading process. I put a small but distinct chamfer on the mouth
of the case, and the bullets are boat-tail....and they will seat with
no "shaving" of bullet material at all.

I'd like some opinions and observations from others who may have
agonized over this dilemma.

Can I get away with a little less grip area, thereby reducing bullet
jump? I wonder what would happen if I used .250 inch grip area, and
therefore had jump of about .164 inch. Would I be likely to see
difference on paper target with my 9 pound hunting rifle? Would
bullet still be secure in the case with grip of .250? Would ignition
still be consistent?

Since this is hunting rifle and hunting ammo, am I being to nit-picky?

Thank you....... Lee Carkenord

Think you can get away with less bullet seating (less distance seating inside the case)..would re-work any loads developed with the deeper seating, but do not belive that you need a bullet-diameter of seating.

Neither does the US military (but I'll conceed they arrange the case/bullet fit to be very tight). Standard NATO ball ammo (with it's 150-ish FMJ bullet) has all of .250" of bullet contacting the case neck. Depedning on lot, that's about what you'll find between crimping groove and the start of the boat tail. these rounds get slammed arround in full auto weapons, and yet rely on less than a full bullet diameter of case/bullet grip.

Personally, I'd run a test...seat some for .223" of jump[, next batch for .200", next batch for .150", etc. Would use a "moderate" load and keep track of both vel. and accuracy. If you find accuracy improvoing as you get closer to the rifing, would certainly use that seating depth (in loads worked up from below) so long as rounds fed into and ejected from teh rifle showed no ill effects.


Is excessive jump the "kiss of death" to accuracy? Sometimes...if the throat (lead/freebore/whatever you want to call the section between the leading edge of bullet bearing area and the start of rifling) is large in diameter, it can be. In a tightly chambered/throated rifle, it makes less difference...in most sproting rifles it makes a good deal of differnce...and in some old rifles with larger than normal diameters, it can be the kiss of death.

Generally, if faced with a rifle with a large throat, I'll "cheat" and use (1) a larger dieamter bullet (if using cast bullets) and (2) select a bullet that has enough bearing area that at some point, the bullet has both the front of the bearing area in the rifling AND the bullet base still in the case. this last bit of advice has gotten acceptable accuracy from rifles that other's had given up on.

Bullet jump is WAY more important for accuracy. It would be rare indeed for a rifle to not respond to small changes in bullet seating depth. Now sure, you want consistent neck tension, but 'consistent' is different than 'maximum.'

My reloads for the 6.5x55 have barely any of the base of a 120gr. Ballistic Tip in the case..... and are very accurate. Maybe 0.1" of the base.

Now - you do have to deal with the possibility of rough handling knocking a bullet loose. With a 0.305" or so inside diameter of the case neck, that should be a fair amount of grip on a .308" bullet, not max, but should be a good start.

Personally, I start reloads for hunting rifles 0.020" from the lands, and work back, unless that just makes them too long to feed from the magazine (in which case I just start at the max length for the mag). If it shoots well seated as deep as Nosler recommends, great. If not, you'll have to weigh the accuracy tradeoff for ammo reliability.

Or shoot heaver BTs. That's an easy option in your case, you can go to 165s, 180s, or the 200gr. Accubond.

My Ruger 77 / 338 Win shoots very well, with the bullets a LONG way from the lands (would really like to know what that gun is throated for, 300gr. bullets?). So in that case I have no choice..... am lucky I suppose. Everything else I gets rounds loaded as close to the rifling as I can get.

Good luck.

If you're going to shoot single-shot, you can seat the bullets where you have whatever standoff of the lands you care to have. And, if a magazine rifle and they will still feed, its that much better.

Personally, I seat all bullets so that there's enough clearance in the magazine well to feed properly. Sometimes, with large magazines for cartridge size, this means I can experiment and derive the best standoff distance. Usually, it means a pretty fair jump before engaging the rifling.

That in itself has an advantage. It allows for the bullet to travel a bit before peak pressure is attained, therefore lessening chamber pressure. This is the way Weatherby gets the velocities they do without substantial greater chamber pressues. They have what is called "free-bore" to allow the bullet "jump".

The more bullet body the neck can grip, the better the alignment between case/bullet centerlines. Some cartridges have such short necks you have to go with what is available (i.e., 7mm Rem Mag, .35 Rem, etc). The distance of the bevel on the boattail doesn't count for neck grip (tension) - just takes up space in the case.

As said before, you can juggle these problems somewhat by bullet style choice.

Before this turns into a free-for-all, will state what I've found to be true and be done with it. IF the throat is TIGHT (which is NOT the case with most commercial throats) then small changes in bullet "jump" does not offer that drastic an accuracy change.....015" off the lands or .005" off, the difference in grouping is going to be small. The larger the diameter of the throat, the more drastic the difference in accuracy from a seating change.

The deadly combination is a large diameter throat combined with a long throat.

Or shoot heaver BTs. That's an easy option in your case, you can go to 165s, 180s, or the 200gr. Accubond.
.

Yup, that's what I'd do. Use a heavier (longer) bullet, and my humble opinion is that the 165-180 grain bullets are supreme in 30-06! :)