I never reloaded for a long jump, not unless it's a Weatherby rifle and cartridge. When I conduct load development, I always start at .030" jump and decrease from there for increased accuracy. If it's a long throated chamber, I seat the bullet as long a I can, so that the COL just fits in the magazine well.
Bullet Jump
- Thread starter BCBRAD
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I never reloaded for a long jump, not unless it's a Weatherby rifle and cartridge. When I conduct load development, I always start at .030" jump and decrease from there for increased accuracy. If it's a long throated chamber, I seat the bullet as long a I can, so that the COL just fits in the magazine well.
I usually start at .03 off and in and out. I have mostly been loading eldm s and found .03 to .025 is where they work for me.
I am sure you have lots of room to play with seating depth with the 185 g.
My tikka was chambered so long I almost ran out of magazine room to chase it.
I am sure you have lots of room to play with seating depth with the 185 g.
My tikka was chambered so long I almost ran out of magazine room to chase it.
I have been testing seating depth over the last 36 rounds, 2 shot group per depth.
First I've started with a known good load that was developed with soft ware ( 7mm-08, 150gn ELD-X, 44.00gn H-4350, 6.25" 3 shot at 1 000 is the best with this load) .
Adjustments were done in 0.005" jumps from base line, which is 0.008" off rifling, 9 sets of two, then another range outing 9 sets of two at 0.003" off. The two tests were done at different but complementary depths to see where this thing goes.
So far I have observed the base line load had two shots very close to touching both trips at base line, as seating went deeper the two shots opened up, then closed up, then opened up again.
Anyone else observe this?
Next trip out I will use the standard set up and COL but will start at 0.1 grains increments lower than 44 gns , probably go with 43.7 thru to 44.5 gns to see if there as anything there.
First I've started with a known good load that was developed with soft ware ( 7mm-08, 150gn ELD-X, 44.00gn H-4350, 6.25" 3 shot at 1 000 is the best with this load) .
Adjustments were done in 0.005" jumps from base line, which is 0.008" off rifling, 9 sets of two, then another range outing 9 sets of two at 0.003" off. The two tests were done at different but complementary depths to see where this thing goes.
So far I have observed the base line load had two shots very close to touching both trips at base line, as seating went deeper the two shots opened up, then closed up, then opened up again.
Anyone else observe this?
Next trip out I will use the standard set up and COL but will start at 0.1 grains increments lower than 44 gns , probably go with 43.7 thru to 44.5 gns to see if there as anything there.
Exactly. Those techniques are used by benchrest, F Class shooters that all have custom barrel and chamber.
Great accuracy is obtained for hunting, factory barrel by sticking the SAMI OAL. Choosing and testing bullets, powder charge and primers should get good accurate load without anything else.
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Awhile back I picked up a bunch of Winchester factory ammo in 300 WSM so cheap that it was a good deal just for the brass. Naturally I had to try it first, but it shot 2 1/2- 3". I wouldn't waste the barrel shooting that for off-hand practice.
When I got home I pulled one bullet and established that on the factory ammo the jump was well over .100" though I can't remember the exact number anymore. Just by tapping the bullets ahead with an inertia puller and seating them at magazine length minus a smidge for function, groups shrunk to under 1". Hmmmm
Ironically it turned out I didn't need the brass anyway.
The seating depth will behave just like a powder node. Pick the middle of the seating node. I go by 0.003” at a time with my 270 and 6.5CM
Erik is FOS sometimes... His advice is not wrong exactly, but it is highly dependent upon the specific set of conditions in his rifle that make the statement temporarily correct for him. He also changes his barrels out long before he gets enough throat erosion to need to chase his lands.
bearhunter above is more true to fact... The correct answer depends entirely upon the length and diametrical clearance of your neck and free bore. Also how many rounds before you plan to change out your barrel.
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I start on the lands because then there's only one way to go. Typically end up staying there too, but not always.
If I can't reach the lands I regard it as poor planning on my end. Standard length cartridges in magnum length actions take of that for the most part. Some thought to the reamer and or throater take care of the rest.
I did quite a bit of testing on jump myself and found there is a general sweet spot.
From too far away, in my testing, there were wide velocity spreads... I assume it was caused by pressure getting around the bullet before it gets into the rifling and seals off the pressure. As a consequence I also found accuracy was not so good.
As I moved closer to the lands, the velocity spreads reduced incrementally as accuracy improved as well... to a point...
Eventually as I jammed more and more everything started to get worse again and I knew I was in the lands too far.
I do believe though that just lightly touching the lands is a safe all around starting point. Keep in mind that this ignores things like magazine length that may prohibit you from positioning the round where it is optimal relative to the lands.
