The Creedmoor Forum

Picked up a box of 139 gr Scenar bullets to try out of my AR-6.5 used CCI-200 primers COL of 2.800 and H4350 all charges thrown from a Redding. The numbers associated with the three shot groups are powder throw readings not grains. Saw pressure signs at the last load and stopped at that point and it was around 40 degrees F when I was shooting. I'm thinking I may drop back to around the 35.4-35.7 setting groups and see if I can't get my SD in the single digits around that area, 36.3 may be a better spot who knows sometimes feel like this is like reading tea leaves, but at least it is a methodology. FYI My powder throw readings with that powder run around 4 grains lower than the actual grains.

Redding setting of 34=38.1gr H4350
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Photos didn't turn out as clear as I would have liked.

I'm not the brightest bulb in the box and your insistence on using redding units, as opposed to grains is making my head hurt a little bit.  My pet load uses 3.4 gigawatts of H4350, you know a bit less than a tramoraldian cubit.     I think you might confuse others as well but probably no rush by the masses in my race to the bottom.   

Like Westside, the lack of charge data in grains makes this difficult, but, the third and second from last groups appear to have the same vertical.  If the velocity is good work with them.

And give us grains of powder nest time.

RMD

Was that 100 yards? I was under the impression that the OCW method needed to be done at 300 yards minimum to actually see the vertical dispersion. I know not everyone has access to those ranges, especially 1000 yards, but with the precision most rifles shoot these days, 100 yards makes it hard to discern a difference in load and shooter, you know?

Anwyay, I guess it is still safe to interpret the load with the least vertical dispersion as the load with the most potential to be accurate at all ranges. I'm a firm believer in the accuracy of a particular load to be the same all the way out until external forces can become significant (and that varies greatly depending on external forces, i.e. wind at 5, or 30 mph), or the projectile starts into the transonic range. That's further than I typically shoot, and actually, I've never shot at anything past the point where the projectile would become subsonic.

And weigh your charges!!! Don't make us do your conversion. We all work for a living, or did anyway. Just kidding. Good luck with your hunt for accuracy.

http://forum.accurateshooter.com/index.php?topic=3814361.msg36632185#msg36632185

Here is a thread on long range load development at 100 yards started by Eric Cortina on the Accurate Shooter forum. Its 112 pages long so you might want to grab a cup of coffee before you pull it up. There is some BS there but a lot of valuable info and insights are also scattered through out. Enjoy

Jerry

This is my target for my first ocw test. I shot 5 shot groups. This does give you somewhat of a picture of where to go, but will start digging holes in the paper. Do the 3 shot groups, or in other words, exactly what the ocw site says. Much becomes obvious  after you do it a few times. The horizontal dispersion is very apparent.  I'm not a very good shot and new to reloading for accuracy for long range.
 The middle shots are 42 gr of powder. I then went up in .1 increments, settling on 42.2



This is day 2 of testing. 5 shots is way too many when you get it closer to being dialed in.



This is after changing my seating depth only.



I just went thru this doing the ocw test for the very first time. after you get your load about right I would chrono to see exactly where your lowest esd is going to be also. This is actually very interesting to do. There is a huge factor in going up or down .1 grains.


This is my best 500 yard group I shot a few days ago.



Lastly, I would use some dots to show all your shots together instead of a regular target. I forgot who suggested I so that on here, but it tells a better story.

I always turn that target over and put 1"" or 2" dots on it for 300 or 500 yards. Aim small, miss small.

Wilson1911 very nice shooting

Thanks JVW2008 for the link

I like to run the OCW test at 100 yards first looking for the tightest group of groups. What I mean by this I look for multiple charge weights that have the same POI. I do this so that small changes in temp, powder lot number slight inconsistency in powder throws ect. have very small effect on accuracy if I change powder charge by .1 grain and my group changes substantially from the previous .1 gr I would not consider that charge area for final testing it may be a very good load but more than likely way to sensitive to small changes which is spicificly what I'm trying to avoid so that weighing charge weights is not needed. I also like to use a chrony looking for low SD if possible at the same time I find this saves me time and components. Then I move onto testing at 400 yards looking for the most consistant groups particularly in vertical. I suppose I could start at the 400 yard mark but that is not my habit. I have a 400 yard range at the house and 1000 yard at the farm. Sorry for the charge weights not in grains I didn't figure it mattered that much as most people are going to test their own loads. I did hope to start a conversation on the how and why others are doing there load development I'm always looking for more tips, tricks or tools to add to my accuracy toolbox.
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JVW2008

I just started reading that link the author uses a very similar method to what I'm looking for in my testing. I have also noticed the flat spots in velocity then a jump seems to me the SD grows to higher numbers during the jump phase then settles down again in the next flat area. Good stuff

I'm working on a similar OCW on a 26" MPA barrel. I worked from 41.5 to 43.6 grains of H4350 using a .025" jump to the lands with 139 Scenars. .3 grain increments.

There is definitely a node at 41.8gr as accuracy has been .3-.4 5 shot groups. SD just under 10. I think there may be another node at 43.3 or thereabouts.

I'm wonder how far people have been jumping the 139 Scenars? I picked .025" kind of arbitrarily, and will try others once I find my best charge weight.

I found the 139 Scenar, jumped 0.080", in MY chamber, with 42 grains H414, WLR primer, would readily print under 0.5moa, typically in the .3's. Rumbling along at 2750-2780, easy on brass.

Terry