Bullet jump

Sabertooth · Posted: Sat Jun 11, 2011 10:17 am Post subject: Bullet jump

4 different 30-06 rifles. 2 factory rifles and 2 customs. Bullet jump difference.
The case OL in the custom rifles are so long that the case overall is longer then the magazine. The 2 factroy rifles the case OL barley fits in the magazine. Using 168gr boat tail bullets.
So the question is what is the correct bullet jump distance for a 30-06?
Case over all length?
Just because you've been reloading for 40 years does not mean you asked all the questions. Confused

shrpshtrjoe · Posted: Sat Jun 11, 2011 10:55 am Post subject: Re: Bullet jump

Welcome to the HuntingNut Howdy

Accuracy will be effected by seating depth. You may find one oal that functions well and gives acceptable accuracy in your four rifles but if you experiment and vary it in each rifle you will probably find each rifle has a depth it likes best..

Joe

Ominivision1 · Posted: Sat Jun 11, 2011 11:23 am Post subject: Re: Bullet jump

Welcome Sabertooth, I owned at one time 3 different /06 rifles from different manufactures and in each case, the rifles had their own identity. No rifle whether factory or custom made is the same, I think its like human dna. When I reload for any of my rifles, I always make a dummy round and check chamber specs.

I take an empty /06 and loosely put a bullet in the case and chamber it, when pulling the case out, I can then measure chamber specs for that particular gun. What I do is once chamber specs are known and written down for that rifle, I will then back off 0.050 for starting loads and gradually work closer towards the lands as accuracy improves.

Each rifle from then on had their own load specs.

gelandangan · Posted: Sat Jun 11, 2011 3:30 pm Post subject: Re: Bullet jump

Gday Sabertooth!

Welcome!

I have been shooting wildcat for a few years, where almost all the aspect of reloading are trial and error.

I have not figured it all out yet, and I might be wrong,
but I feel that the bullet jump factor is a function of the burning speed of the powder and the hardness of the projectile (jacket),
and the size and depth of barrel lands and grooves..

With the faster burning powder, you would have to reduce the chamber pressure early at the detonation of the charge.
This is achieved by increasing the detonation chamber (by moving the projectile out) as soon as possible.
Having the bullet jammed to the groove will significantly increase the drag of the projectile,
thus leaving a "jump" space would let to better distribution of pressure curve, and ultimately lends to a better accuracy.

The other end of the theory, which is in contradiction from the above Razz

Is that the energy required to engrave the projectile onto the rifling is very high.
On slower burning powder, this energy pressure came slow,
thus for projectile that sit away from the groves have enough acceleration to carry over the engraving smoothly.
And again, ultimately lends to a better accuracy.

Pardon me to ramble. But thats what I thought.

English Mike · Posted: Sat Jun 11, 2011 4:52 pm Post subject: Re: Bullet jump

Bullet jump is one of the lesser factors viz firearms accuracy, so unless you're punching paper off a bench rest, it often has little effect on the end result - except with Barnes copper bullets, which in general like to be seated away from the lands.
Remember you need to seat the bullet into the case by at least one caliber for reliability.

Elvis · Posted: Sat Jun 11, 2011 5:53 pm Post subject: Re: Bullet jump

I dont measure my bullet jump at all. if it fits in the magazine and will chamber with no dramas its good enough for me. I use a factory load or a reload that I know works fine for setting the dies try the first in rifle then load the rest. as English Mike says if you arent punching paper and trying for that last mm of group size dont sweat it too much.

slimjim · Posted: Sat Jun 11, 2011 6:22 pm Post subject: Re: Bullet jump

I have found that consistent bullet jump is important to accuracy, but the amount of bullet jump that provides the best accuracy and smallest groups is unique for each rifle. I've read recent accounts that the optimum distance off the lands can be much further than expected. Barnes bullets like being further off the lands than other bullets. I've loaded as far as 0.200" off the land with good results. All my current loads are between 0.010 and 0.100. You just have to try different distances. If you can't find a common overall length that works in all your .30-06s, you might load all your bullets to the longest length you need then reseat the bullets further when you need them based on the rifle that you will use them in. Here is another post that talks about bullet jump.

www.huntingnut.com/ind...73&start=0

Sabertooth · Posted: Sun Jun 12, 2011 12:07 am Post subject: Re: Bullet jump

Thanks for the reply's and jogging my brain cells loose. One 06 is target only. We call it The Beast, just under 20 pounds. 28 inch barrel. The others are hunting rifles with 24 inch barrels.

Elvis · Posted: Sun Jun 12, 2011 12:40 am Post subject: Re: Bullet jump

I guess when you go hunting then its eany meany mino mo .
my big bro has 2 .308s and the ammo thats great for 1 will do the job in the other. bullets seated out to be close to the rifling for 1 will not go in the magazine of the other. so they get seated out to magazine length and used in both. I have two loads for my rifle a old model 70 .270 one is a great accurate 130grn load and the other a 170grn bush load. I guess you could sort out your favourite rifles pet seating depth and the other rifles would just have to lump it. or have a super duper load for those longer shots and a near enough load for anything else. with your 30/06 and a deer sized beasty near enough would be good enough at normal ranges anywaythats a fine deer cartridge.

Vince · Posted: Sun Jun 12, 2011 5:04 am Post subject: Re: Bullet jump

Welcome aboard Sabertooth...grab a beer and pull up a stump mate.

Seeing as how your '06 is solely for paper punching, the first step should be consideration of what sort of "paper punching" you intends doing. If it is everyday "fun" target shooting, then pretty much any of the standard die manufacturers products will be suitable.

From the description of your rifle, I get the impression that it is most likely a Bench Rest rifle, so you need to look at what sort of reloading dies that are most suited to that style of shooting.

There are specialised dies that are available for Bench Rest reloading that allow you to finely tune the reloading process. When you start handloading for Bench Rest you have a long road in front of you as far as load development is concerned. I would recommend you also look at a Forum targeted specifically at Bench Rest shooting if this is the discipline you intend shooting.

Whichever way you choose to go mate, there is a wealth of information and knowledge available from the guys here. Let us know how it all goes ,ate.

Cheers, Vince

bracer · Posted: Mon Jun 13, 2011 5:23 am Post subject: Re: Bullet jump

Most all of my shooting is at prairie dogs. I wont the the most accurate loads for shooting the little critters. The Stoney Point-Hornady O.A.L. w/modified cases guage to measure bullet free bore, The Bullet Comparator Comparator w/caliber inserts to seat the bullets, and the Headspace Guage Tool w/ bushing when full size resizing case are some of my reloading tools. The amount of bullet jump from the case to the rifleing is an key measurement in finding an accurate reload. When I miss a shot I wont to know that it was my shooting, not the ammo, rifle, or scope.