Working on a load with IMR 4350 and 130 accubonds. Started with 68g at 3.25" and got the following group. Was thinking of playing with seating depth to see if it would tighten up. Is 0.02" too much at a time? For reference the circle is a quarter outline.
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270 wby seating
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std7mag
Well-Known Member
What rifle is it?
Vangard?
Mark V?
Other?
You may be able to load it longer, to fit the magazine on a Mark V.
But the ejection port is short on them.
The longest I can load my 7mm & 257 Weatherby's is 3.360" COAL.
Realistically, your group is about 1 MOA.
Take it out and hunt with it!
Vangard?
Mark V?
Other?
You may be able to load it longer, to fit the magazine on a Mark V.
But the ejection port is short on them.
The longest I can load my 7mm & 257 Weatherby's is 3.360" COAL.
Realistically, your group is about 1 MOA.
Take it out and hunt with it!
MagnumManiac
Well-Known Member
I built mine on a Model 70 switch barrel, it has a 3.4" mag box and I load them to 3.38-3.39" and get excellent accuracy.
I haven't loaded to 3.25", you may get better results longer loading.
Cheers.
I haven't loaded to 3.25", you may get better results longer loading.
Cheers.
Agree with longer, make 3 at 3.30 and
3 at 3.35. What is your max mag. length.
See what they do.
3 at 3.35. What is your max mag. length.
See what they do.
You said you started with a 68 gr load. This is the max load that Nosler lists. Did you try lower powder charges first? If not, you could have passed up a load with a tighter group.
Lots of variables to consider, seating depth is one. Different powder or even a different bullet.
With a freebore of .378" not sure how a tiny bit of seating depth will change things. Suppose you could go in both directions in .005" increments and see if there is a trend.
Lots of variables to consider, seating depth is one. Different powder or even a different bullet.
With a freebore of .378" not sure how a tiny bit of seating depth will change things. Suppose you could go in both directions in .005" increments and see if there is a trend.
Laelkhunter
Well-Known Member
I agree with AZShooter. Weatherby has lots of freebore in their barrel/chamber by design. Messing with the seating depth might not do anything. Adjusting your powder charge could reveal the desired results of shrinking that group.
Seating depth made a big difference in my 257. I m at 3.415" oal which runs fine in my Rem 700 action. It too has same .378 freebore as the 270 WB does.
I ve heard lots of guys claim a flat base bullet is sometimes the trick on a long throat WB; don't know I was able to get BT, AB and TMK (Gamechanger) to all shoot good in mine at same 3.415-3.425 range.
I ve heard lots of guys claim a flat base bullet is sometimes the trick on a long throat WB; don't know I was able to get BT, AB and TMK (Gamechanger) to all shoot good in mine at same 3.415-3.425 range.
Bullwhacker
Well-Known Member
140 Accubonds and 7828sc are a combo in my MkV that has been deadly for over a decade for me. Seat them long as you can.
How close are you to the lands now? For instance, if you are .010-.020" from the lands with the group, I would start seating depth in .005 " increments and see what yields, then adjust accordingly.
I've never tried chasing the lands with factory freebore on wby chamberings. Bullet would barely be in case.
I am in no way implying that you should chase the lands. I prefer to measure CBTO over COAL because it is more accurate and provides a better reference point. I do not have a .270 WBY, but I have a .257 WBY, and yes, I can touch the lands. But I use heavier and longer bullets.
(L-R: 110 SGK, 145 Black Hole, and 163 Chinchaga).
These loaded with Retumbo/163 Chinchagas .015" off the lands, which is 2.790" CBTO or 3.415" COAL, similar to @MagnumManiac.
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std7mag
Well-Known Member
Not as bad as you would think.
The Weatherby Magnums have a long neck, especially when compared to cartridges like the 7mm Rem Mag.
If it were me, I'd try the 7828 powder that you have.
Fastest burn rate I'd use would be in the RL19/4831 range.
Weatherbys whole premise is speed.
The slower burn rate will also affect the recoil impulse. Giving more of a push, instead of a slam.
7828 I ran into a lot of pressure towards max load and no where near the grouping pictured above.
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