New Posts New Posts RSS Feed - ES and SD
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

ES and SD

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2009 at 00:34
jonoMT View Drop Down
Optics Master Extraordinaire
Optics Master Extraordinaire
Avatar

Joined: November/13/2008
Location: Montana
Status: Offline
Points: 4618
A few months ago, I got a chronograph. Today was my second time out with it and I paid more attention this time to these two stats. The ES for a five-round string on a new test load was 20 and the SD was 9 (for a .308 load which had a low of 2635, a high of 2656 and an avg. of 2645). Seems like that is pretty decent, if I'm not mistaken. I'll measure again with more rounds next time but as this load was fairly hot I didn't want to load up more than five. I didn't see any signs of excessive pressure.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2009 at 03:55
8shots View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar
Lord Of The Flies

Joined: March/14/2007
Location: South Africa
Status: Offline
Points: 5754
That falls within the 10% variance, which I understand is acceptable. What weight bullet are you shooting? If it is 155gr or less then you should be able to push the speed to 1750.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2009 at 11:40
John Barsness View Drop Down
Optics Optimist
Optics Optimist


Joined: January/27/2009
Status: Offline
Points: 785
8shots,
 
I believe you added another zero. 1% would be more like it.
 
In reality standard deviation isn't very useful unless a LOT more than 5 shots are fired, say 40 or 50. This is because 5 or 10 rounds don't provide enough reliability.  (Also, if you fire that many shots, SD will generally be about half of extreme spread--just as you experienced in firing 5 shots. Contrary to what many shooters believe, SD isn't some sort of magic number.)
 
Even then SD must be gauged against other statistics, especially the group on the target! In general I haven't found all that much correlation between SD and accuracy at normal hunting ranges, though it does become more important at longer ranges, due to differences in vertical impact.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2009 at 12:21
jonoMT View Drop Down
Optics Master Extraordinaire
Optics Master Extraordinaire
Avatar

Joined: November/13/2008
Location: Montana
Status: Offline
Points: 4618
Thanks for the replies. I will definitely be focusing on group sizes. The main goal with those measly five rounds was to see if I could safely get the velocity I want. One limitation in this regard is that the rifle has a 20" barrel. I'm shooting a 165gr. Accubond, which is pretty much my standardized round for antelope, deer, and elk unless I'm hunting in heavy cover, in which case, I use bullets more suitable for short-range shots. So I don't think I'll squeeze any more velocity out. Next time I'll load up 20 rounds and see if I still get the sub-MOA accuracy I've gotten @ 2550 fps.

It was kind of funny to just pull off the highway on the way to go fishing, mount the chrony and run a few rounds against a quarry wall 100 yards away. The only aiming I really did was to make sure I didn't blow the chrony apart. We were in a hurry and were thinking more about elk hair caddis than elk.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2009 at 19:26
John Barsness View Drop Down
Optics Optimist
Optics Optimist


Joined: January/27/2009
Status: Offline
Points: 785

I know the feeling about elk-hair caddis this time of year!

Sounds like a great load from a 20" barrel. To tell the truth, I fell pretty much good to go out to 400 yards with a load that gets around 2700 with a good spitzer.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2009 at 02:50
8shots View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar
Lord Of The Flies

Joined: March/14/2007
Location: South Africa
Status: Offline
Points: 5754
Originally posted by 8shots 8shots wrote:

That falls within the 10% variance, which I understand is acceptable. What weight bullet are you shooting? If it is 155gr or less then you should be able to push the speed to 1750.
 
Oops, thanks for picking that up John! Meant 1%.
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "ES and SD"
Subject Author Forum Replies Last Post
Bill would require all SD citizens to buy a gun Chris Farris Firearms 25
remington sps aac-sd 308 troweler Firearms 1
What muzzle brake for my Remington 700 AAC-SD? tmenold Firearms 9


This page was generated in 0.250 seconds.