Shot with Orkan last night. Getting closer to a clean dot drill
Thanks for that write up; there are some things you mentioned that really caught my interest.
You have mentioned your bag issue in a few posts, would you expound on that issue? Was it bag firmness or how butt sat on the bag, or something else entirely?
My rear bag is a little soft and I had a bad habit of loosening my grip on the bag right as I would pull the trigger. I was also playing around with a couple of different ways of using the rear bag on the DT SRS while using a 10rnd magazine.
Could you also touch on the shouldering issue you experienced and the fix?
This was something that I did and do nearly every time I first get behind the rifle. I would have it too far out on my shoulder (away from my neck). This would cause me to stretch my neck, and muscle the rifle a little bit. Compound that with it being out of my shoulder pocket and recoil would slide the rear of the rifle even further out to the right. After the first shot was a "yeah duh" moment and I would get the rifle in the proper position
I sure would appreciate hearing about these issues and steps taken to being overcome.
Your cartridge runout was of great interest also as I am unsure as to the cutoff measurement for accurate ammo. Was the runout introduction done during sizing or seating; or can it be attributed to the brass?
Runout was sorted into 3 groups. 0-.002, .002-.005, and .005+ (.010, .012... yeah that bad). This weekend I will be checking both sized and loaded ammo. The sized pieces I tested yesterday all looked to be pretty good, it wasn't until I had seated bullets. I have a different seater die now to use, so I'll get back to you on what exactly was causing me issues.
Here is today's dot drill. Quite a bit different than yesterdays! I did a couple of things different this time. I shot 10 rounds in a row, let the barrel cool and reloaded, then shot another 10. It's pretty clear that my first shot of each 10rnd string I wasn't behind the rifle properly. Once recoil proofed my position, I found I didn't have the butt tucked into my shoulder correctly. I held center for each dot, so I'm glad to know I've worked out a viable solution to my rear bag issues, though they tried to creep back up on me at the end!
Now, what was the drastic change? I noticed when I was loading that almost all my rounds were nice and smooth, but a few here and there would be clunky. I ASSUMED in the past that it was just that case, so I would set it aside to foul the bore. Today I became suspicious and put a few rounds on my concentricity gauge. The first one was...ok.. not that great but ok. I went back to loading and noticed it again... NOT ok... so far out of wack I could SEE the bullet bobbing up and down when I rotated the round.
I met up with Orkan later and told him about what I found. I checked my brass before loading and it didn't have hardly any variance, but once loaded it would be all over the place. I tried different ways of holding the bullet before I pressed it in, no change. My most straight case became my worst loaded round.
He took out his 21st century concentricity gauge with wheel and looked them over. Yep! Confirmed what I had found (and then some). He sorted out my rounds into 3 groups, ok, bad and terrible... and out of 101 pieces, only 35 made the cut (under .002"). Most were so bad it looked like the needle on his gauge was moving to skrillex music. At this point I suspect my hornady mic seater, but will look into other variables as well. To get an idea of what this can do to your groups, I present the following dot drill.
(shot left to right, then below)
Cold shooter (notice a trend I have? First shot goes left and up a touch. Working on it though!) Followed by a nice little cluster.
That's a pretty happy 5 shot group. Still working on rear support, but heck, I'm also using a chargemaster, and while it has been really good to me compared to others of it's kind, it still will give or take a little bit when weighed on a better scale.
Reloaded and let the barrel cool, got back down on the rifle and lookie here, another one off the left side! By the end of the day I caught onto what I might be doing, and proceeded to locking into memory how I need to setup to prevent it. Really wrecked what was to be a very tight 5rnd group that was also right on aim point.
After dot 3 I went and did my dot drill posted above. Since I only had 35 healthy rounds, I decided to see what would happen if I shot rounds that were both out of wack AND had variable seating pressures. Pretty ugly in comparison eh?
5 shots in that group on the dot. These were all rounds that seated well, but were in the middle group as far as what the concentricity gauge had shown. I decided to add a 6th shot to the group, for science of course. I stayed on the rifle, single fed one of the rounds that was "thrown out" due to being on the extreme end. Orkan said that I would see a difference on paper, and of course he was right.
Dot #6, below #5
For this 5 round group I selected 5 pieces from the outside group that was sorted. When I shot this they all felt and looked as good as when I shot #5, but the paper doesn't lie.
Even if I didn't have a concentricity gauge I could have found this out by simply rolling my cases on a smooth, flat surface and paying attention to the tips of the bullets... the bullets were bobbing that much!