Hey fellas.

Although much has been said about bullet tension almost nothing I can find has said much about bullet seating force.

Well I just happen to have a spring compression tester used for testing hydro springs on air craft in cylinders and such items.

Test subject was a 338 Edge.

I was doing up some loads using the Barnes MRX 225 grain bullets and after loading them up decided to test what the seating force was to seat the bullets.

I measured the case neck dimensions and are as follows
OD of the case neck is .3623, wall thickness was .015, OD is .3323.

The three bullets I tested were Nosler's 225 accubond, Barnes MRX 225 grain and finally Sierras 300 SMK. The dia for the nos was .3375, the MRX was .3378 and the Sierra was .3382.

I initially used my RCBS and the Hornady seating die to seat the bullet so that it was straight in the case but seated just past the boattail.

The rest of the seating was done on the spring rate testing machine.

The results were as follows including neck tension
Nos 225 gr 158 lbs of force NT .0052
MRX 225 145 lbs of force NT .0055
Sierra 128 lbs of force NT .0059

It is interesting to note that the largest dia was Sierras 300 but was the least amount of force to seat.

My extreme spreads with the SMK at 2800 fps were around 28 fps. They dropped significantly when pushed at 2850 and up to 2900 but pressure signs showed up after 2800 fps and accuracy went to shit.

Would turning my necks so that .001~.0015 neck tension lower my extreme spreads?

Accuracy was 2.5 inches at 500 yards using the 225 accubonds and around 5 inches for the 300 SMK. Havent yet made it to the range to test the MRX bullets.

I loaded them up to 98 grains of H1000 and seated them at .050 as suggested and have four seating depths that start at .050 and receed in .010 increments to with in .010 of the lands but are all the same powder weight and type.

Quickload agrees with Hodgdons load data at 101 grains of H1000 it is still a safe load. That is of course Hodgdons listing for the 338 RUM but quickload has the 338 Edge listed.

I started out with 98 grains and know thatll be a good starting point as the SMK's best performed at a lower velocity, the noslers at a 3100 fps velocity this should put it around 3200 fps which would be a good speed.

I wonder how or if anyone as tested the force required to pull the bullets and if this is the same amount of force required to release the bullet from the neck tension? I know the base of the bullet sees the brunt of the pressure but Quickload has like 3400 psi to move the bullet or around there.

Your thoughts?

Dave

interesting?
If you anneil the necks that will also reduce the case neck grip.
I tried using a force guage and a pull guage then realized I was over thinking this.
I turn neck on new brass just enough to make the neck the same thickness because the brass is always thicker on one side. I found early on that if I didnt turn a little into the shoulder I would create a donut and that changes bullet grip. also moly bullets seat diffrently, I even tried using moly for a lube inside the case necks and for a while I was convinced that I was on to something.
in the end it turned out to be one more un=necessarry step to gain a few thousands in accuracy.
take all those steps a find which ones make the ammo the most consistent and go for it.
Dave