Shoot 0.005" Jam Loads or seat Bullet Deeper?

[MMH]

A while back I loaded up for my Remington 700 300 WinMag. I loaded 212 ELD-X bullets with various H1000 charges. Trying to break in the rifle while doing a ladder. Yes I know this is a compromise, but want to play around with my LabRadar as well.

Anyway, I seated the bullets by feel meaning, I would seat the bullet & try to close the bolt. If the bolt would not close or was 'tight', I would bump the bullet back. Yesterday I checked the length from the back to the ogive using the Hormady O.A.L. gauge & bullet comparitor. I was surprised that I was jamming the bullets into the rifling by about 0.005" With this bullet & the the Hornady modified case the length was 2.928". My seated bullets are at 2.933" Just surprised that the bolt closes VERY easily even with this bullet jam. BTW, the COAL with the bullets seated this way is at 3.646".

Should I re-seat the bullets deeper? Or just start firing the loaded cartridges starting with lower charges first & look at primers. I have 3 cartridges per load starting at 72.0 gr. going up to 78.5 gr. in 0.5 gr. increments (total of 51).

 

[Supersubes]

.0005 jam isn’t much, may not even mark the bullets.


No need to back off charges, pressures will drop when you start setting deeper and jumping bullets.

 

[Cascade Hemi]

Brass is elastic which is why it's hard to feel .005" of jam. I think most people will tell you to do load development off of the lands and then do your seating test after. However, I think so long as you just stay consistent with the depth across all of the charge weights it shouldn't matter. 51 rounds is a goodly amount of shooting and you may find the barrel broken in when you're done. You may also find you need to redo the ladders because pressure and velocity will likely change.

 

[MMH]

Good to hear. That's kind of what I figured, but wanted a reality check. So, w/ these loads if I increase bullet jump, the pressure should drop. Does the velocity decrease as well w/ bullet jump?

 

[Supersubes]

Good to hear. That's kind of what I figured, but wanted a reality check. So, w/ these loads if I increase bullet jump, the pressure should drop. Does the velocity decrease as well w/ bullet jump?

Yes and yes. There may be a point where pressures start to go back up, but it’s way way back from the lands, like .150-.200 range.

 

[Barelstroker]

It is worthwhile being cautious with bullet jam. Remember, the angle of the ogive or tangent is very small.
When pushing this very slight angle into the rifling, you basically have a roughly 10:1 wedge ratio.
For example, if you set a digital scale at 45 degrees angle, you will measure approx 1/2 the mass on the weigh plate. This is also the case with a bullet ogive or tangent but, in reverse.
If you're using the Hornady gage, & you are very gentle, you should be fine b/c the bullet is free floating with almost no stickshen involved however, if you're using something like a neck sizing mandrel, I believe some care should be taken.
There will be much less force needed to drive the bullet ogive into the rifling than most realize.
Without something like the pressure trace setup, you are basically in the dark &, measuring case head expansion has been proven to be a complete waste of time.

Regards..........Barelstroker