Load Development

Since having my rifle returned to me, I have taken it out three times, with the purposes of doing some load development, chronographing my loads to find out standard deviation and finally, to start tracking more information than the reloading log books can record. I’ve got a bit of a gallery below (unfortunately not really in any order), showing a number of loads using both Berger 175gr OTM Tacticals and Sierra 175gr match kings. I started with the previous load that I had, and worked around that range of powder for the SMK’s. With OTM’s – I knocked it back a couple grains and did up some loads in .5gr increments. It was evident to me, immediately, that the OTM’s were favored in my rifle, and looking over the nodes at 43gr and 43.5gr, that I had a good area to start in.

I took the two nodes, split the difference and started reloading some rounds at different seating depths – to see where the sweet-spot was for this load. I measure to the ogive when I reload, using the Hornady comparator tool to find the lands, and go from there. My starting depth was 3.16″, it fit my magazine, and was not too tight in the chamber. I moved from there in .01″ increments down to 3.09″. Using 5-round groups at each depth, I fired my loads – and you can see (I’ve listed as much info on the photo as possible) how the group opens up at 3.16″ and 3.09″, but right in the middle, it really tightened up. 3.13″ was the evidenced sweet spot with a 5-round group size of .493″ – to date, my best group. There was 1 outlying round outside the group, that I know was user-related to cause it to not be part of the overall group (flier if you want); but beyond that fact, I have a load that I feel will do well.

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Piggy-backing on some advice from Ryan – ‘perfect practice makes perfect’ – I had decided that once I got the new barrel on, that I would be practicing and shooting as if it were a match, using match ammo and trying to make sure that I (as the shooter) was doing all that I could to be consistent. This string ‘felt’ right – more on that shortly. The only addition to this was that I was shooting through a chronograph. The results of the string were excellent once I did some calculations – as you can see below, are the velocities and standard deviation (which, upon further research – is a very important number):

2663 fps 2653 fps 2673 fps 2652 fps 2641 fps 10.83697 SD fps

Looking over this, and the other groups brought up questions – for example – if I have a group that is printing poorly (over MOA) but the SD of the velocity is very good (sub-10 fps deviation) – why is it not shooting better. I don’t have an answer for that yet – but I intend to research as much as possible to find that out. Looking at the velocity and SD of the group that I chose as the one to work off of, the SD is around 10fps. This is indicative of match ammo and unobtainable by factory ammo – Bryan Litz speaks about this fairly heavily in his books – pure velocity doesn’t give you enough information to go one if you are searching for precision and accuracy. I was happy – as this translates into a +/- 10fps difference shot-to-shot and the less difference in shot velocity, at longer ranges translates into a more consistent point of impact VS point of aim.

IE: at 1000 yards, a faster velocity means a higher point of impact VS. a slower velocity round – and this isn’t necessarily visible at 100m but is extrapolated hugely at 1000.

I love to read and research – specifically I like to know why something happens or why something doesn’t happen – so this has lead me to picking up a number of books on ballistics and do a lot of research on the subject. If it weren’t for the math – physics would be so much fun!

Brief book reviews

Continuing from above, one of the books that is really hammering home the lessons I have been learning is a book by Bryan Litz – Accuracy and Precision for Long Range Shooting. He details a number of shooting scenarios using a number of different rifle bullets, and how different errors (human and otherwise) affect the bullets travel. His WEX Test (Weapons Employment Zone) is a comprehensive analysis of ballistics of a given projectile, and can model how things like rifle cant or a poor wind reading translates directly to your hit percentage over given ranges. It’s a very technical read, and incredibly interesting to me. If you are looking for a greater understanding of ballistics – it’s worth a read.

The thing that resonated the most for me, is in the first chapter:

Precision and accuracy are two different things and need to be treated as such. Precision is making small groups, accuracy is knowing where those hits are going to go before taking them.

The other book that has been a great resource is Handloading for Competition – a really good in-depth reloading guide that focuses on anything and everything from prepping brass, to consistent, repeatable steps for loading. It really digs into the tools and methods you can use to get the best ammo possible out of your capabilities. It touches on a number of different choices and ways of doing things, but at the same time – he gives his opinion on his tried-and-true methods of getting good rounds. Glen Zedicker has a good background to support his methods and his writing style is definitely not technical. Hard book to come by – but worth picking up if you can find it.

Finally – have a read over at RifleTalk – Bob has a ton of great articles on precision and competition shooting, and frequently does reviews of gear that are incredibly thought out and easy to understand. His reviews are catching the attention of some blogs in the US.