help to reduce es and sd

nowler · #1 04-02-2005, 12:28 PM

hi folks

was out on the range today with the chrono and am having alarmingly high es and sd in the 3 rifles i was firing. 6ppc, 22-250 and 308.

all are shooting ok accuracy wise, ranging from .2moa to .5moa with the various loads, but es of over 60fps in smoe loads and sd's in the 20's and 30's etc. etc.

i am confident my loading technique is good, prepped brass, turned, and all charges weighed on a 10-10.

any thoughts on things to try to improve this situation? should i be trying different loads or different primers???

many thanks for any input

derek

3sixbits · #2 04-02-2005, 01:00 PM

Do your rifles all have tight necks? How long since your last anneal on the necks? What kind of clearance are you giving the necks? Are you finish seating using the bolt (into the lands)? Have you checked the throats lately? Check the neck tension, did you try flipping the button upside down to get less neck tension? Unless you plan on shooting beyond 300 yards with and your groups are that good whats the worry? And last but not least, Chrony check, I would test the unit using ammo with know low ES and Sd in a known rifle. I use tested .22 lr match that I already have lot data on and see if the avs have changed. Clock speed slow (low battery), poor connections etc. Hard to say unless you check out some of the above mentioned items!

Brown Dog · #3 04-03-2005, 03:56 AM

Derek,

Shooting from a moving car is never easy.

Those are good groups, but to reduce your es you will have to ensure that your driver is maintaining constant pressure on the accelerator and not allowing the vehicle to drift towards (or away from)the chrono.

[img]/ubbthreads/images/graemlins/grin.gif[/img]

nowler · #4 04-03-2005, 10:41 AM

some of the rifles have tight necks, some don't.
i have never annealed the brass in the ppc, the 22-250 and 308 are only on their second firing.
ppc has clearance of 3 thou. 308 and 22-250 are a considerable amount more.
ppc is soft seated and pushed home into the lands, as is the 22-250. 308 is into the lands but with more tension...
22-250 and 308 are new and there are no problems with the throats.
chrony test is the first port of call then a change to cci primers...

i'll keep you's all posted.

nowler · #5 04-03-2005, 10:45 AM

[ QUOTE ]
Derek,

Shooting from a moving car is never easy.

Those are good groups, but to reduce your es you will have to ensure that your driver is maintaining constant pressure on the accelerator and not allowing the vehicle to drift towards (or away from)the chrono.

[img]/ubbthreads/images/graemlins/grin.gif[/img]

[/ QUOTE ]

we were using cruise control, maybe there's a fault with it? [img]/ubbthreads/images/graemlins/grin.gif[/img]

cheeky b**ger beige poodle!