I need some advice. I'm attempting to work up a load for a Tikka CTR in 6.5 Creedmoor. I'm using Hornady brass, Hornady ELD-x 143 grain bullets, H4350 powder and CCI primers (have tried both standard and magnum). It seems that whenever I get to an acceptable group size (for me that is 1/2 moa), my velocity extreme spread/ SD gets bigger. When I get my velocity / SD number reduced , my groups open up (sometimes over 1 moa). I've tried adjusting seating depth, powder charge and primers and it doesn't seem to help much. Any advice anyone can give me as to what to try next would be appreciated.
- Thread starter SWWI Shooter
- Start date
Shoot your groups at distance. If they are still good then who gives a shit what the numbers say.
I've had others tell me that as well as "throw the chony away" and just look at group size but I would think that high extreme spreads of velocity would lead to high and low misses beyond 500 yards regardless of how tight my 100 yard groups are. Am I wrong on that?
At 500? Only if youre shooting extremely small targets. Shoot it on paper and get tangible results you can hold in your hands to see for yourself.
How large are your sample size for these SD group size correlations? If only 3-5 I dont think thats big enough to really say one way or another.
How large are your sample size for these SD group size correlations? If only 3-5 I dont think thats big enough to really say one way or another.
I go with group consistently over es/sd numbers. Testing another powder like Reloder 16 would be my recommendation.
One factor you did not mention is the chrono. What are you using? Is it reliable?
RMD
RMD
I'll generally run with the load that gives me the tightest ES/SD and multiple 5 shot groups under 1" at 100y.
I do this based on the gun games I shoot which require a higher level of precision and/or limited rounds on target. In my case, this means PRS and casual LR steel with ~1-2MOA targets out to 1,100yds.
If I was shooting service rifle or other gun games with very small targets at moderate ranges (300-600yds max) I might be more focused on teeny tiny groups and care less about the velocity spread as the range of said small targets may not be far enough for the velocity spread to come into play yet.
I think it's all a balancing act and what you choose to focus on will be based on the intended use.
I do this based on the gun games I shoot which require a higher level of precision and/or limited rounds on target. In my case, this means PRS and casual LR steel with ~1-2MOA targets out to 1,100yds.
If I was shooting service rifle or other gun games with very small targets at moderate ranges (300-600yds max) I might be more focused on teeny tiny groups and care less about the velocity spread as the range of said small targets may not be far enough for the velocity spread to come into play yet.
I think it's all a balancing act and what you choose to focus on will be based on the intended use.
How big of an extreme spread are you worrying about? 50fps? At normal 6.5 Creedmoor velocities, a 50fps spread amounts to 2" +/-. Will that make you miss your target?
What is your shooting game? BR, PRS, F-Class?
What is your shooting game? BR, PRS, F-Class?
The extreme spreads are running 30-50 FPS. According to the Hornady ballistics calculator for my bullet and approximate velocity, a 40 fps difference is a difference of 9 vertical inches at 1000 yards. I haven't gotten into any shooting games as of yet as I'm just getting started at longer ranges. I'm mainly a hunter and while I don't intend to shoot game at extreme ranges, being able to hit targets at 800-1200 yards will make the 300-500 yards shots on game that much easier. So at this point in time, I'm just having fun as opposed to competing.
Okay, so using your numbers and the average velocity as your input, you can hit a 9" tall target every time at 1000 yards, based on extreme spread alone. That's a less than 1 moa target. I consider that a pretty adequate result. I doubt that you can call windage within +/- 5".
Edit: BTW, my 2" spread comment above was based upon your reference to 500 yards before. My point still stands with regards to misses at distance. A 50 fps ES will keep you within 1 MOA at each distance. Are you better than that in your windage calls every time? What is your windage call ES? Sorta just kidding, but I think that you get my point.
Edit: BTW, my 2" spread comment above was based upon your reference to 500 yards before. My point still stands with regards to misses at distance. A 50 fps ES will keep you within 1 MOA at each distance. Are you better than that in your windage calls every time? What is your windage call ES? Sorta just kidding, but I think that you get my point.
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Point taken. Just trying to keep the variables to a minimum
Thanks for everyone's help. Got a lot to think about.
The main thing everyone is trying to convey is: see if you actually have a problem first before you go trying to find solutions.
Unless you want to for the sake of reloading. I do that myself. I find my most accurate seems to always have a 12-15 sd though unless I remove the high and low random spurts to skew the data or luck into a decent string. Every time I have ever put 25 in a string it goes up into double digits. So I live with it.
Unless you want to for the sake of reloading. I do that myself. I find my most accurate seems to always have a 12-15 sd though unless I remove the high and low random spurts to skew the data or luck into a decent string. Every time I have ever put 25 in a string it goes up into double digits. So I live with it.
Understood. I guess the message that's coming through from several of you is that the goal of a single digit SD is just that- a goal and not always obtainable in every case given the variables. Secondly, acceptable long range accuracy can be had even without a single digit SD. Thanks!
Now you've got it. If you are shooting bench you need to prep for bench. I.e. arbor press, weighing everything, measuring everything, turning necks Etc. Shooting prs/ steel/ most targets a low sd is nice, but practice and wind calls will get more hits. If you can get an acceptable vertical dispersion at your farthest target you are on top of it. The wind will most likely cause way more trouble.
With that said, go hang with some bench guys shooting 600-1000 yards to get chaotic low sd and groups. Its a pain in the ass with low returns to get a sub 1/2 moa 1000 yard group.
We all demand different levels of accuracy from our guns. Myself, I do strive for sub half moa at a grand. I want my load and rifle to repeat what it just did.
You did not say what chrono you use, I have a magneto and a labradar, the magneto is always with me. My magneto always reads low on the first shot, so i'll either shoot it on a diff gun, then swap or kick the first number out. All my rifles suffer from cold bore too, so the first 2 shots are not chrono'd. When your chono'ing, there is no point in aiming, close the bolt and pull the trigger, the chamber is warming up on subsequent shots and baking rds skews results. If you don't buy into this, capture your brass and you can feel how it gets warmer the more shots you take.
Like spife said, let your target be the judge, chrono numbers can get skewed quickly. I'd strive for a load that held vertical at the distance you want to shoot, it's all downhill from there.
Edit: You get your load to hold 2" of vertical at 1K, I'll guarantee you that your chrono numbers will tighten up.
