Load development PRS rifles

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MartyK2500

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I am currently going through new load development as I wanted to group under 1/2 moa @ 100M.
Was wondering with PRS guys, do you guys use OCW (optimal charge weight) load development and use a resistant load even if not the most accurate?
Do you guys load develop on a shinny clean bore with a few powder foulers or do you develop with a coppered barrel to simulate field conditions?
 
Coppered bore, develop your load under the same conditions that you would be shooting a match under.

I ladder test to get the smallest ES, then tweak OAL to shrink the groups if necessary (it rarely is).
 
I charge to 0.5 increments and just shoot groups as it essentially give the same results as an OCW. I start 0.020 off the rifling. I then tweak the load with smaller increments and finish off by moving closer/farther from the rifling.
 
The 6.5 Guys have an article on their blog about their load development process.

There is a discussion of OCW at distance vs using a chronograph and the things to consider.

I think once you are shooting at distance human error can become a concern so I have taken to a method similar to theirs. I shoot for groups at 100 with the chronograph going. I look for good groups and good SD/ES numbers. A good group does not always correspond with good ES/SD numbers and vice versa.

When I did load development for my 6.5X47 I had one load that had an SD of 2 and an ES of 5 but the group was terrible (~1.00MOA). I thought I was maybe having a bad shooting day so I tried that same group with 3 more 5 round groups - it would not shoot. I went to the next charge weight which had good groups (~.4MOA average - probably across 5 or 6 5 round groups now) but a slightly worse ES/SD I think something like 9 SD and 20 ES over 20 something rounds.

I finally validated the round at 300M with a 10 round group and it worked with a .6X MOA group. It is not a BR or F-Class quality load but it seems to be working for me.
 
http://mysticprecision.com/category/tech-reloading/

A few articles that will help you along.

Test as you compete... tune the load with fireformed cases... test as far as you can with 200yds being a min.... 300yds being ideal.

Be consistent in your shooting. use wind flags and watch the mirage.

I know that chronograph output watching is all the rage right now.... if you want to do this, invest in a good chronie. magnetospeed and labradar are easy to get... another is out but have never used it... uses 2 chronies.

I just let the target tell the tale... it never lies

Jerry
 
My process has always been identifying the min and max load. I don't bother with minimum charges as I want some good velocity and accuracy.

I start somewhere near 30% over minimum. Then in something the size of a 260 case, work up in 0.3gr increments. Usually I end up with about 6-8 charges to test. I load up three of each charge.

Then I shoot 3 shot groups and measure velocity. Ideally i'm looking for something that groups well (200+ yards) and has good ES and SD. Then I will go a step further and plot all of my results using the averages and error bars representing the ES. I look for the flat spots in my plot that indicate velocity in-sensitivities to charge weights (or pressure) and low ES's. That way any small errors in reloading practices are not so detrimental to POI. If I see pressure signs I stop, brass life is also a consideration.
This is the latest load development I did. You can spend hours upon hours tweaking loads, or you can settle on something reliable and acceptable and go practice more; I always lean towards the latter.

 
Honestly, if you're using one of the more popular calibers and a quality barrel/action, you're going to be damn close with what everybody else is using.
39.6 of 4350 has been money in every 6xc I've seen... just load a touch hotter/cooler and see what works best.
 
I didn't realize the chrony would play an important role in load development.
Just relied on what was punched on paper.
Purchased a magneto speed 10 weeks ago but still ain't here yet, will have to check with grouse river whats up with that.
This is the copy/paste of formula I am using in 308 with 178gr bullet and varget


Using Max load of 43.8
-------------------------------
10% of Selected Max
Load 1# # # # # Sighter 1# # # #39.4
Load 1 + 2%# # #Sighter 2# # # #40.2
Load 1 + 2%# # #Sighter 3# # # #41.0
Load 3 + 2%# # #Group A – 3 Rnds# # # # 41.8
Load 3 + 0.7%# #Group B – 3 Rnds# # # # 42.1
Load 3 + 0.7%# #Group C – 3 Rnds# # # # 42.4
Load 3 + 0.7%# #Group D – 3 Rnds# # # # 42.7
Load 3 + 0.7%# #Group E – 3 Rnds# # # # 43.0
Load 3 + 0.7%# #Group F – 3 Rnds# # # # 43.3
Load 3 + 0.7%# #Group G – 3 Rnds# # # # 43.6
Load 3 + 0.7%# #Group H – 3 Rnds# # # # 43.9
Load 3 + 0.7%# #Group I – 3 Rnds# # # # 44.2

By the way, I now never load pass 43.6gr, as the first time I had used this table I was getting pressure signs at 43.9gr


Seems also like my 100M load development needs to be pushed out more.
I will make use of the 200M berm next time.
I will also wait until my barrel has let's say 150 rounds of powder/copper fouling before going at it.
Just cleaned it, as accuracy was declining after 450 rounds untouched.

I didn't think of making use of a wind flag for load development Jerry, just made the best of a calm day, i'll try it to see.

How long do you wait between strings? Full cool down?
 
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Test as you compete... if you need to hammer 10 to 15 rds in a relay, test to make sure your load will work at the start... and end.

Often factory barrel tuning changes as it heats up.... a load may be great at 3rds, not bad at 5rds, yuck at 10rds. Maybe it is not the load... but good notes and repeated testing will answer this question.

I try and shoot my "best" load under a variety of conditions to make sure it will handle the varying conditions I might see in a match.

But when starting, I will do 2 or 3rds per powder charge increment... watch the target and see how the grouping evolves... compare to barrel heat.

Then I will test again but mix up the better charges so they are used at varying barrel temps... in time, you will find the best load that is also the most stable for the amount of heat your barrel will see in a stage/relay.

Lowest vertical, most consistent grouping... may not be the absolute smallest group but as long as it will stay the same day in, and day out, that is better then a load that is great one day but varies another.

Jerry
 
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I seat a bullet .005" off the lands, get a load off quick load that matches barrel time then shoot over chrony adding powder in .2 increments until I get my sd below 10 then shoot paper and 9 times out of ten the groups are more than satisfactory. That one time out of ten thought the group will be crap so I usually try a different powder and get the results I'm looking for.
 
Again today I find myself agreeing with Jerry in that I let the target tell me what is and what is not working. While I have a Magnetospeed chrony the fact is that I rarely use it other than to have a rough idea as to how many fps to enter into a ballistic program. I simply prefer to shoot a series of five-shot groups at 200m to establish a load which I will confirm over several outings to my shooting spot and then ensure that the same load works out to 500m. Old-fashioned I know but it works for me.
 
Alright, seems like I have my work cut out for me!
I can load up all my charges as usual per my table, but mix the order up from outing to outing.Allow the barrel to stay warm between relays.
Take plenty notes, and test them out at 200.

Looks fun though, since competition has not bit me yet, it will be an excuse for many range trips!
 
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