Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Reloading

Reloading Techniques For Reloading


Reply

Using chronograph data to determine the best load????

 
LinkBack Thread Tools Display Modes
  #1  
Old 12-26-2005, 04:03 PM
 
Posts: n/a
Using chronograph data to determine the best load????

Any tips on analyzing chronograph data to develop loads????

Of course, low ES and SD at the desired velocity are the goal, but how do you analyze the numbers and what do they tell you???

Let's say your ES is too high......do you increase or decrease the powder charge......do you change primers, do you alter seating depth.....and how do you know what to do first and which direction to go????

Same questions for SD???

I'd appreciate a nudge in the right direction if there is a comprehensive article or FAQ concerning this subject!
Reply With Quote
  #2  
Old 12-26-2005, 05:18 PM
SPONSOR
 
Join Date: Dec 2004
Location: El Reno, OK
Posts: 1,930
Re: Using chronograph data to determine the best load????

I once loaded 13 different shells for my 300 RUM each increasing by .5 gr. I was going to do a ladder w/the 240 SMKs but it was too windy that day so I just set up the chrono and fired all 13 @ 100 yds. From 83 gr to 87 gr, I only noticed about a 50 fps increase in velocity. 87.5 gr brought a 20 fps jump as did 88 gr. The jumps continued w/increasing charges. What really impressed me was that all 13 rounds went into one hole that measured .850". The group was also much smaller before I noticed the jump in velocity. As the charge increased, my group opened up a bit to the right. Not sure why, but that is what it did.

I am going to try the same thing w/my 6BR when I get it back. We'll see if this was just fluke or if it actually works!!!
Reply With Quote
  #3  
Old 12-27-2005, 05:43 AM
Platinum Member
 
Join Date: Dec 2005
Posts: 2,114
Re: Using chronograph data to determine the best load????

My recommendation is don't use one. A chrony will tell you which load will make a bullet win the race to the target, but not how close together they'll arrive there. I would not try to get a given velocity. The same handload will produce different velocity in each of several rifles anyway, but can be very, very accurate in all of 'em.

Years ago I was part of a group of folks testing handloads for Sierra Bullets' then new 155-gr. 30 caliber Palma bullet. New Winchester cases were primed with Federal 210M primers. We tried several powders and charge weights thrown from measures; not weighed. AA2520 ball powder had the lowest charge weight spread, lowest muzzle velocity spread and lowest chamber pressure spread. AA2520 also produced about the worst accuracy. IMR4895 had a 3/10ths charge weight spread, average muzzle velocity spread and peak pressure. IMR4895 produced the best accuracy; tested at 2.8 inches at 600 yards.

The best primer today is probably PMC ones. They don't deteriorate and start producing higher muzzle velocity spreads within a year like the others.

Change powder charge weight by no less than half a grain to check a load's accuracy. There's no way to tell if you should increase or decrease the powder charge for best accuracy if you're below maximum.

Shoot at least 20 shots per group when you think you've got a good load; anything less isn't reliable enough to be meaningful.

Full-length size your cases such that you set the shoulder back a few thousandths of an inch.
Reply With Quote
  #4  
Old 12-27-2005, 11:17 AM
Gold Member
 
Join Date: Feb 2005
Posts: 564
Re: Using chronograph data to determine the best load????

Bart is 100% correct. The target must always be the final arbiter. And since you have to shoot the bullets to chronograph them anyway, why not just put the paper out there and believe it. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Chronographs are more of a distraction to me during load development. I find a load that shoots tight via my OCW method www.clik.to/optimalchargeweight and then--and only then--do I become curious as to the velocity...

Bart... your last name wouldn't be Bobbit would it? If you're Bart Bobbit you're a wealth of knoledge...

Just wondering. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Dan
Reply With Quote
  #5  
Old 12-27-2005, 04:30 PM
Platinum Member
 
Join Date: Dec 2005
Posts: 2,114
Re: Using chronograph data to determine the best load????

Yes, Dan, that's me. Joined this board to sell some bullets. They're all gone now but I may hang around for a while.
Reply With Quote
  #6  
Old 12-27-2005, 07:12 PM
Platinum Member
 
Join Date: Jun 2007
Location: Fredericksburg VA
Posts: 4,146
Re: Using chronograph data to determine the best load????

Disagee with Bart on this one and green 788. If you have a very accurate gun a chrono will help you find the tuning nodes for that gun. Just got to understand what it is telling you, if you don't then yes forget using one.

I use the ladder method to ID nodes by both grouping on paper and chrono results. Guess what, they normally match up, when a close powder charge range groups on a ladder it will also group very closely on velocity on the chrono. I can pick the tuning node in the MV range I want and normally pick a weight in the middle of the node to take care of any variances with temp or pressure spikes.

Green 788 OCW method works to find an acceptable load (ie .5MOA maybe in most guns) but it will not normally find the most accurate load for a really accurate gun (.25 MOA or better).

As far as PMC being the best primer for what I do not know. The equip list for matches sure do not back that up for being the most accurate across the board. The best is what works best in your gun.

F210s in most LR BR guns, RWS and even the Russian primers are the most common on the equip lists. As we test everything, we use the most accurate and I normally use F210 and RWS.

BH
Reply With Quote
  #7  
Old 12-27-2005, 07:21 PM
Gold Member
 
Join Date: Feb 2005
Posts: 564
Re: Using chronograph data to determine the best load????

The PMC's are Russian primers... FWIW. [img]/ubbthreads/images/graemlins/smile.gif[/img]
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Using chronograph data to determine the best load????
Thread Thread Starter Forum Replies Last Post
Load data .243 Ackley varmit load please ballie Reloading 5 02-22-2011 01:49 PM
Millennium Chronograph Versus Pact MK IV Timer & Chronograph Eaglet General Discussion 10 03-31-2010 11:28 PM
How to determine "best" load for long range shooting bgordon Rifles, Bullets, Barrels and Ballistics 8 11-05-2009 01:17 PM
chronograph & load development? dewiseman Reloading 4 07-04-2009 09:12 PM
Test results from 338 ST *pics and chronograph data* Black Diamond 408 Rifles, Bullets, Barrels and Ballistics 16 04-24-2006 10:08 AM

Current Poll
Do you archery hunt for elk?
YES - 34.35%
113 Votes
NO - 48.33%
159 Votes
Not yet, but I plan to. - 17.33%
57 Votes
Total Votes: 329
You may not vote on this poll.

All times are GMT -5. The time now is 11:34 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC