LRAB , how much jump?

I tend to run them on the lands or jammed 10 thou. Worked in three barrels.

However; and just to show that barrels have a mind of their own I do have a factory Vanguard in .300 that I had to jump .080" to use the magazine. They shot well enough that I never bothered looking for anything else.

Nosler swears that they like to jump; though it hasn't been my findings. I suppose if I marketed factory ammo I'd have to claim that too.
 
seating depth doesn't matter for accuracy. Seat them .030" off the lands, or as close as the magazine length will allow
 
Loaded some up for my brother's 7x57...150gr LRAB to the book max OAL with a compressed load of IMR4831, shot excellent and performed better then anticipated on a deer this year. Blew through a 1/4ing shot...shoulder, heart, lungs, and out the ribs. Fell right there, not even a step, and the pile of blood that flew out of it's nose and mouth on impact left us both impressed.
 
KT, I don't shoot the 300WM for the simple reason I'm recoil shy.

That certainly doesn't mean there's anything wrong with the cartridge or the bullet you're going to use.

I find that as a rule of thumb, when reloading for hunting rifles, that as long as the base of the bullet is still being held by the case neck, when the ogive makes contact with the leade, accuracy will usually be acceptable.

Seeing as you have a new tube on this rifle, if the chamber dimensions are on the tight side, especially in the throat, all should be well as long as your loaded cartridge fits and feeds consistently from your magazine.
 
Craige cut the chamber to 3.540”

My magazine will fit 3.550”

My previous and last tests were at 3.400”

So , I’m thinking I may go with 3.500” , it will open my case capacity , fit the internal magazine as well give me a bit of play to go longer or shorter if I decide to fine tune my seating depth.Not as deep as most are recommending but I can always work out longer.

bearhunter said:
KT, I don't shoot the 300WM for the simple reason I'm recoil shy.

That certainly doesn't mean there's anything wrong with the cartridge or the bullet you're going to use.

I find that as a rule of thumb, when reloading for hunting rifles, that as long as the base of the bullet is still being held by the case neck, when the ogive makes contact with the leade, accuracy will usually be acceptable.

Seeing as you have a new tube on this rifle, if the chamber dimensions are on the tight side, especially in the throat, all should be well as long as your loaded cartridge fits and feeds consistently from your magazine.
Click to expand...
 
Well if there's a magic sweet spot for accuracy, I've yet to see a trend. Here's a couple recent examples that come to mind with rifles that had long freebore.

Model 70 Extreme Weather 300 Win Mag, 190gr Barnes LRX, 0.255" jump to lands. 0.48moa group
Tikka T3x SS 7mm Rem Mag, 160gr Nosler Accubond, 0.122" jump to lands. 0.62 & 0.47moa group back to back at 400y

Set your loaded length, then tune accuracy with the powder charge in 1% increments, fine tune in less than 1%.
 
todbartell said:
Well if there's a magic sweet spot for accuracy, I've yet to see a trend. Here's a couple recent examples that come to mind with rifles that had long freebore.

Model 70 Extreme Weather 300 Win Mag, 190gr Barnes LRX, 0.255" jump to lands. 0.48moa group
Tikka T3x SS 7mm Rem Mag, 160gr Nosler Accubond, 0.122" jump to lands. 0.62 & 0.47moa group back to back at 400y

Set your loaded length, then tune accuracy with the powder charge in 1% increments, fine tune in less than 1%.
Click to expand...

Take your favourite rifle and load, whatever it's length is, and seat 3 bullets 0.003" longer or shorter if you need to go that way. Do it 6 times and shoot groups at 300.( seating change adjustments 0.003, 0.006, 0.009 etc.) Seating depth is infinitely adjustably, unlike a large RL22 or H4350 kernel.
 
todbartell said:
So how much does changing the seating depth .003" effect group size/velocity?[/QUOT
Its just like an OCW powder test. You will find a flat spot where you can select your depth. So to answer that, if you seat to 0.155 and you happen to be on the edge of your seating depth node, it may only take one 0.003" adjustment to see the difference, or it may take two or three attempts to see the change. Put up a target at 300 and try it. You might be surprised. Lots try 0.20 then 0.40. etc., but thats way too far in my opinion.
I did a small test @ 300 a year or so ago, my good load 2.155" BTOG, 2 shot group, shot twice. One measured 0.669" center to center, the other measured 0.712" c to c.
2.139" BTOG 3 shot measured 2.6" horrible vertical
2.140" BTOG 3 shot measured 2.6" horrible vertical.
2.141" BTOG 3 shot measured 2.47", better fertile but still not great.
The two separate 2.155" BTOG groups, you can add the 4 shots and still they smoked the other ones, badly. The vertical was less that the bullet diameter.
Click to expand...
 
Sorry did not crono the seating depth tests.
I do know with my one load, when I seated a whole bunch deeper, I started seeing ejector marks, so I knew I was on the hot side.
If you work up your load with OCW, and you have a flat node, you should be able to mess around with depth and not screw it up too bad. I think a person needs to be close in powder charge to use seating depth to fine tune.
 
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