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Topic: seating depth adjustments (Read 417 times) previous topic - next topic

Re: seating depth adjustments

Reply #15
As far as the bullet seating goes, I think i may try to reduce my overall neck tension.  I think I may go the route of the expander mandrel.  Looks like the sinclair expander mandrel is the way to go.  At least that way, I can still make use of my FL sizing die. 

Would I even need to remove the expander ball?  Since I'd be expanding it beyond what the ball does, seems like the expander ball would just expand it most of the way, with the mandrel finishing the job.  Might benefit from getting the die honed, though, to reduce work hardening of the brass?

PowerMetal,
I have done exactly as you have described, but removed the expander from my die.  The neck tension i got from the sinclair mandrel was very consistent across my brass.  I just screwed up and tried to use the same load, and lost some MV because of the lower neck tension.  The hornady dies were giving me anywhere from .003-.004 neck tension, and the Mandrel was about .0015 consistently, whether on 3x fired brass or fresh annealed.  One more step in the process, but very consistent.

Re: seating depth adjustments

Reply #16
Ran some tests today, got my new expander mandrel.  I had some brass ready to go from previous work, so I took my case mouth brush, gave it a quick spray of 1 shot and proceeded to "re expand" my already prepped brass.  Initial thoughts, I did notice that i had alot more success  making incremental seating depth adjustments.  Was able to do .001" decent;y, and .002" fairly reliably.  Not perfect, but based upon the feedback ive seen, I don't think I can complain.

I haven't had a chance to really review my labradar data, but I "think" (based on some glances over) that I may have made some improvements to my ES/SD.  Regardless of what it says though, my sample set wasn't big enough to make a definitive claim either way.

As a side note, during my testing today, I started running a new lot of H4350, and this jug (8 lb this time) seems quite a bit faster.  Again, I have to process the data, but based on quick looks, my previous 41.3's were 2730ish.  I think they are 2750 ish now.  I think that may have bumped me between nodes (my low node was the 2730, higher node about 2770).  Might need to go down a few tenths to stay in the sweet spot.

I may need to reconcile ALL the data tho....compare my old lot velocities, as I had both.  My gun was just cleaned prior to this test, and it had about 500 through it since its last bath. (shout out to the folks at Bore tech for the C4 carbon, and Eliminator!)

I'll post back with data, once I process it, assuming I can isolate the variables into something meaningful.  Ill be the first to admit, I had way too many variables this time.  One thing i did not do, was run duplicates of my 42.2 grain loads with the new lot.  Being a fair amount above published max, I took the safer route of only duplicating my 41.3 loads, not the 42.2 (wanted to see what the 41.3's did)

Until next time...May the winds be ever in your favor!

 

Re: seating depth adjustments

Reply #17
so here's the gist of data:
All data is from twice fired hornady brass, unannealled, ELD 140 bullets, cci200 primers

Based on the info below, there was no "obvious" change, but the sample sets were small, so its hard to really read much into it.  EX spread seems to be around 10 for 5 shot groups (not sure what the normal distribution should be, prefer STD dev much more).  The only thing that i think was fairly obvious, is that the new powder is 30FPS faster, roughly...seems significant.  With the old powder lot, the 41.3 put up two 1/2" 5 hot groups.  I think the new, faster powder pushed me off a node, 2 five shot groups around an inch.  The 42.2 (faster node) put me back down to 2 five shot groups, 1/2".  (oddly, my 1st fouler, 2699 FPS (not included in numbers) placed in my first .5" group just fine)

Anyhow, here's the data.  feel free to offer thoughts...

#1- 41.3, mandrel expanded, old H4350 lot
Average   2725
Highest   2732
Lowest   2706
 Ext. Spread   26
Stats - Std. Dev   7.7
N= 9

#2- 41.3, mandrel expanded, NEW H4350 lot
Average   2755
Highest   2762
Lowest   2748
Ext. Spread   14
Std. Dev   4.8
N=10

#3- 42.2, mandrel expanded, old H4350 lot
Average   2778
Highest   2782
Lowest   2772
Ext. Spread   9.91
Std. Dev   4.81
N=5

#4- 42.2, Ball expanded, old H4350 lot
Average   2772
Highest   2779
Lowest   2768
Ext. Spread   10.31
Std. Dev   4.13
N= 5

#5- 42.2, Mandrel expanded, old H4350 lot
Average   2773
Highest   2787- outlier, next closest was 2778
Lowest   2764
Ext. Spread   23
Std. Dev   6.3
N=12