Neck tension

[OFtrash]

I tried a search with no results. Im currently working up a load for a M70 SG in 300WM. Im using H1000 and 180 Accubonds. What Im seeing is inconsistent BTOG that I believe is due to a compressed load of 79.5 grains.Im seeing between .004 and .006 difference in BTOG. Im currently running about .002 of neck tension. For those that are more knowledgeable Im wondering if thats a concern or if I need to increase neck tension to hold things in check. Ive have not tried these for accuracy to see if there is actually a concern due to the current supply shortages.

 

[nksmfamjp]

BTOG?

 

[Varmint Hunter]

Compressed lods almost always result in varied seating depth, IME. Increasing neck tension will not fix that. Try a lower volume powder and watch things improve.
FWIW - I'd prefer a bit more nect tension for a hunting cartridge.

 

[OFtrash]

BTOG?

Base to ogive

 

[Coyote Shadow Tracker]

Base to ogive

CBTO
Cartridge Base To Ogive
Are you running your cartridge length to the max in you magazine? Why running a compressed load? How much off of the lands?

 

[OFtrash]

79 grains of H1000 is 102% of case capacity and yes I'm running max mag length

 

[Mike D Texas]

It may help to go to .003-.004 but you run the risk of deforming the ogive with your seating stem.

 

[slikmrc]

Check a few unloaded bullets to see how much of the variance is bullet induced. Case mouth chamfer and inside case neck prep can cause some of this to.

 

[Ol' Red]

I have some compressed loads in my .300 win mag and they would seat, but the bullet would back out when sat for a while. 200 grain ELD-X and 76 grains of H1000. I seated them again and crimped five o them. They shot good. But I backed the load to 74 grains, tapped the powder down a bit and they shot just as well in my rifle without a crimp. A drop tube might help.

 

[slikmrc]

Using a drop tube and pouring powder slow when dropping the charge helps greatly on compressed loads.

 

[Koda_]

I tried a search with no results. Im currently working up a load for a M70 SG in 300WM. Im using H1000 and 180 Accubonds. What Im seeing is inconsistent BTOG that I believe is due to a compressed load of 79.5 grains.Im seeing between .004 and .006 difference in BTOG. Im currently running about .002 of neck tension. For those that are more knowledgeable Im wondering if thats a concern or if I need to increase neck tension to hold things in check. Ive have not tried these for accuracy to see if there is actually a concern due to the current supply shortages.

79 grains of H1000 is 102% of case capacity and yes I'm running max mag length

Its a concern because seating depth nodes can be around .006" affecting accuracy. Increasing neck tension wont work because after .003 brass elasticity doesnt change, but a crimp might solve the CBTO growing.
If your compressing (102%) you might try putting the case on a vibrator before seating the bullet, this will help settle the powder. A drop tube on a powder funnel might work as well to settle the powder before seating the bullet, these can also solve the problem.

If your seating to mag length and compressing the load it could be you need a shorter bullet. If the heel of the bullet is seating past the upper neck junction you might get higher ES/SDs, accuracy loss or case donuting. You might not. If your bullet heel is not past the shoulder junction and your compressing the load... Id use caution and double check your starting charge weights.

 

[FireFlyFishing]

Lee factory crimp die may help.

 

[338 dude]

.

 

[Barrelnut]

If your compressing (102%) you might try putting the case on a vibrator before seating the bullet, this will help settle the powder. A drop tube on a powder funnel might work as well to settle the powder before seating the bullet, these can also solve the problem.

^^^ This ^^^

I use and electric toothbrush (hard side) on the side of the case while holding my finger over the neck to stop powder from jumping out. Works great but it's a bit time consuming. I back off on the load whenever possible.