Chronic issues with high SD and ES with N320

[Clint007]

I load for IDPA and commonly use plated round nose (Berrys, Xtreme) or jacketed HPs (Precision delta, RMR, etc)

Right now I’m using up some XT 124 RN and Berrys 124 gr TPHBRN.

I’ve always struggled with N320 at these target power factors (124g Bullet to ~ 1020-1030 FPS was my goal).  The issue is that the ES and SD are always high. I’ve trickled charged precise drops into new brass and tested in several different guns, same issue. Even cracked two different lots of N320 in case it was a bad batch. Am I maybe so slow that I’m not getting a good “seal” at ignition? Should I try seating deeper? I’ve been at 1.125”.

This same Bullets with Titegroup is very consistent with ES and SD in the 8-15 range.

Thank you

Clint

[SI VIS PACEM PARRABELLUM]

Possibly you already have the answer to your question. Titegroup gives you the consistency your looking for but N320 does not. Do you suppose maybe N320 is just not suited for what you are trying to achieve? I guess if you are wanting alternative powders why not move on and try something else?

[Wobbly]

I'm surprised (and frankly puzzled) by your numbers and your issue... But what's most important in IDPA is accuracy. And we've noted several times that SD doesn't tell us anything about accuracy.

I'd say show us some targets. And tell us about brass and primers.

 

[timmy75]

my load is:

139gr LRN-FP
N320 3,2gr
COL 28,2mm
avg 920 fps
mixed range brass
fiocchi small pistol primers
SD is always ~10fps

[Bossgobbler]

I shoot USPSA. I load for a PF of 129-132 (124gn X 1050fps) and only look at my groups at 15 yards(1"-2") & 25 yards(<3").
125gn blue bullets, 3.8gn N320 @ 1.110 & 124gn  JHP PD, 4.1gn @ 1.100. 
 In shooting sports with moving and shooting, accuracy is more about sight alignment and trigger control.  You gain so little chasing low ES & SD numbers it's not worth the time.

[tdogg]

I'm with Wobbly on this, how does it shoot?  Velocity variation most likely doesn't affect accuracy until you get out there a bit (much longer than IDPA/USPSA distances).  Can you shoot a 3 inch group at 25 yards freestyle?  That's about the extent of the required accuracy for run-n-gun games.

What are your numbers with N320?  Are you concerned about making PF?  Is there anything about your process that would inflate the N320 velocity variation?  What do you do differently with Titegroup?

Cheers,
Toby

[Clint007]

Most recently it's mixed brass and Win SPP.  Accuracy has been fine.   TG works, yes, so I've no imperative to change to N320. But I've several jugs and can't shake this frustration about why I can't get the ES and SD to settle down. It's as much academic as anything. 

Loading hotter is wasting energy (and maybe a few hundredths of seconds per stage).   I can load so every round is >1008 fps to make chrono, but it'd be more satisfying if all my rounds were in the 1025-1035 range, rather than some at 1010 and others at 1070s.

I will experiment with careful shortening of the OAL a bit, then load hotter and see if the ES/SD settle down as I do that.

[Fuzzy Sights]

Use VV N320 in target loads with 124 gr Bayou Bullets.  ES is usually less than 15 fps.  There is one difference in that I only shoot Speer brass.  Bullets touch at 25 yds, when I do my part.  Not fond of copper wash bullets, have always had accuracy issues.  When I do use them it is for close range defensive practice where precision is not really required (45 feet at a IDPA target)  They will usually group 2 inches which is fine for a ASI match.  If I miss a head shot it is still my fault.

Best of luck on finding your load.

JW

[tdogg]

How's your OAL variation?  I'm wondering if Titegroup is more forgiving for OAL variation?  I don't see how that could be given it is "faster" than N320 and that should equate to more sensitive to OAL.

Have you characterized the charge variation between the two powders?  Maybe the N320 doesn't drop as well in your process?  Highly doubtful as Viht powders meter like water.

Any static issues?  Maybe try to wipe everything down with a used dryer sheet?  Maybe it's time to clean the drop/press?

Cheers,
Toby

[Clint007]

Thanks for your thoughts. Sort of ruled those factors out when I did a whole bunch of N320 rounds with a trickle charger on my gem pro scale that is accurate to two hundredths of a grain.  I had 20 or so rounds, new Starline brass, all viciously weighed the same within .04 grains and still had the issues.

My OALs are tight, also....

I dunno. I guess it’s worth retrying that experiment.



C

[tdogg]

Oh I somehow missed that in the original post.  The gempro is a good scale, I have one as well.  Good luck tracking this down.

Cheers,
Toby

[Ricca]

Did you try to use different primers?
I had a similar issue in the past and changing the primers solved my problem.

[Clint007]

Great point, thank you. I have not tried different primers. I used Winchester. That  is worth checking. I have a few federal match grade SPP I might donate to this experiment.

[Wobbly]

Great point, thank you. I have not tried different primers. I used Winchester. That  is worth checking.

In one of my numerous ammo tests, I ended up suspecting my erratic data was caused by Win primers. I don't think it went any further than that, but I was thinking that at one time.