how to get consistent neck tension??

[6BRinNZ]

If I understand correctly you have ~.002" spread in loaded OD? Would the one that seated in further have been #5?

Edit - just answered my question by looking at your chart. Putting it all together - the one round that went out of the norm was #5 2.0715 base to ogive (it seated deeper than the others) and coincidental that also has the smallest OD loaded. To me this makes sense.

With respect to neck thickness consistency there are two measurements that are important. The wall thickness variation within the same case and wall thickness variation between cases, in your case this is ~.002" which is too much.

Assuming that I have understood everything, I think that neck thickness consistency between cases will provide your greatest consistency gain at this point, as you clearly don't have .002" variation in bullet diameter.

okay thank you i think you may have nailed it on the head and solved my riddle for me.

the two cases that stand out are #5 and #10.

# 5 was the shortest from base to ogive. it required the least amount of force to seat, and also had the smallest Outside diameter after the bullet seating (thus indicating that it likely had a thinner neck wall than the rest assuming my other measurements are accurate.

#10 was the longest from base to ogive. it also (not coincidentally?) required the most amount of force to seat and had the largest OD on the neck after seating. logic would dictate it had a thicker neck.

this is what seems to make sense....

okay so new questions. what tool would you recommend to measure neck thickness??? is a caliper sufficient or do i need something else??

also, about neck turning...obviously i must not be using my neck turner (it is a km with cutter pilot) correctly or precisely enough. any quick thoughts on why i would have neck thickness inconsistencies after turning? it seemed as though i turned the entire neck, i.e.- the cut was deep enough to take material off the entire neck. although there is some wobble in the case while it sits on the mandrel, which at the time did give me pause for thought but i assume this is normal??

Check this link out, a caliper definitely won't suffice. http://www.accurateshooter.com/technical-articles/case-neck-mics/

The case should be snug on the turning mandrel. Snug enough that if you didn't lube the mandrel and or case, the neck would over heat and jam. At this point I don't think neck turning technique accounts for the differences you have listed so I suspect as Wayne has suggested that the major error is coming from the sizing and expanding process.

I know what you are saying with respect to having run the turner over the necks already but in reality .002" is such a small amount that it could be accounted for with a tighter or more loose fit on the mandrel.

Good luck - the journey is well underway

PS check this site out - there is a lot of useful info there as well - http://riflemansjournal.blogspot.co.nz/

 

[nra-for-life]

Good luck - the journey is well underway

Very very true...Thanks!!