What's the most amount of jump you have ever used? .100? .200? More?
Todd
Todd
Bullet jump. Most amount ever used.
- Thread starter Todd Earhart
- Start date
I had a long range 1000 Yard rile with an Obermeyer barrel that would shoot two separate groups at 1000 yards. I tried everything I could think of, but nothing helped until I started to move the seating depth back. I tested at 300 yards and started with my normal seating depth at .015" off of the lands and moved back in .015" increments at first the groups kept increasing in size until I got .125" off the lands and I had a 5 shot group measure .625" I thought that had to be a fluke, so I loaded 5 more at that depth and shot another group and it measured .500". The next day I shot a 1000-yard match and shot a 10-shot group 4.500" and it's been shooting 8" or under ever since.
Straightshooter1
Gold $$ Contributor
The most I've had was .130 jump for a 175 TMK out of a .308.
If you're exploring and trying to understand the value of "jump" and haven't read this series of articles, you should have a read here:
More Bullet Jump Research!
This is the 4th article in a series on some new research on bullet jumps. Here is a recap of the pr...
Bronsin
Silver $$ Contributor
At magazine length, 50gr Nosler BT's are .115 off in my .223, and they will shoot 3/8ths 3 shot groups. They would probably shoot better at another depth, but for their intended purpose it works. 40gr tipped bullets of any brand jump so far that they're not even in the case when they reach the rifling. Doesn't matter. They still shoot tight. Not that I'm advocating it as the last word, but some rifles/bullets are very tolerant of it when they need to be.
Murray Brook
Silver $$ Contributor
My 257, 270 and 7mm Weatherby mag has .378 and my 30/378 has .361
Just finished working up 140 TTSX for my Tikka 7mm Rem Mag. I was shocked at the grouping. From the land 0.145". Two groups of three to test - two bullets almost one hole with third just low and almost touching the other two.
I think this may be one of those "facts" that everyone knows but only few have adequately tested. If you only have the stated opinions of most reports you will conclude that somewhere around 0.010 is optimum. So the myth feeds on itself. What self-respecting person will report that they have done a statically significant test and found the optimum jump to be 0.150?
In God we trust, everyone else bring data, statistically significant data.
In God we trust, everyone else bring data, statistically significant data.
Dusty Stevens
Shiner
I have found if they dont shoot a bit jammed or a bit off like .015, they will start shooting at .100+. You just lose so much capacity unless you throat them out.
Thanks everyone. I had wondered about a large amount of jump and any adverse effects of a jump of say .250. Sounds like there is no problem.
Todd
Todd
As a thought experiment ... if the bullet hasn't hit the lands until after the projectile max dimension has left the case mouth , that seems unsafe. Expanding gases around the bullet might do just about anything with a totally "freebore" bullet.
No personal experience....just guessing "out loud."
No personal experience....just guessing "out loud."
This was my thought.
Todd
I had 87gr VLDs fly "without barrel/chamber or brass contact", think it was something like 0.18" jump and they SHOT. Was also a quick lets not adjust my DIE load for my son to plink that turned out to work
My example is 77gr loaded to mag length 2.260 in a Wylde chamber where touching lands is 2.550". Lots of jump, the rifle liked one bullet more than others, and seated bullet concentricity became a very important measure.
If you're jumping that far, stay with tangential ogive designs, secants / VLDs almost guaranteed like less jump.
-Mac
If you're jumping that far, stay with tangential ogive designs, secants / VLDs almost guaranteed like less jump.
-Mac
Berger 184hybrid .105 jump
Bigguy1951
Silver $$ Contributor
A 1950's Winchester Model 43, 22 Hornet, just over .250 because there is that much free bore. Not too uncommon in that model and time period.
NorCalMikie
Gold $$ Contributor
Had a friend with an H S Precision in .308 with factory chamber cut to a .050 jump to the lands.
Larger calibers not uncommon to have long freebore. Still shot bug holes.
Larger calibers not uncommon to have long freebore. Still shot bug holes.
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