There's bad news and good news. The bad news first.
 
Got a chance to get back to the range yesterday. Took John's MAI, Rick's .338 Win Mag, Larry's .338 Win Mag, and my .45-70 Buffalo Classic.  Great day for shooting.
 
Based on the preliminary range data, John wants me to shoot two groups of three shots each for each of three charges - 53, 53.5, and 54 grains of Vihtavouri N-150. I did. I processed the data in a way that produced 3 targets for each of the charges. A 6-shot group (the combined 3-shot groups) and one each for each of the 3-shot groups. For clarity, I'll post the graphs and numbers for each charge in a separate post. (In this thread, just in sequential posts.) Here are the numbers and graph for the 53 grain charge.
 
Since no one seems to be interested in the equations, (that's just fine with me - I only presented them for those that wanted to see how I derived the numbers), I've condensed the equation sheet to just the pertinent data. The "Average Point of Impact" is the center of the x-axis (windage) and y-axis (elevation) points of impact in inches from the Point of Aim. In other words, the center of the group relative to the Point of Aim. "Max Spreads" are the windage and elevation maximum spread of the actual bullet holes. "Length of X and Y Axes" are the max dimensions of the 95% prediction ellipse, and the "Area of the Ellipse" is the area in square inches of the 95% prediction ellipse.
 
Paul

53.5 grains.
 
Paul

54 grains.

Paul

Oh yeah, I forgot to post the velocity data. Again, I'll spare you the individual values and just post the means and standard deviations.

200 grain Combined Technology Ballistic SilverTip
53.0 Grains of N-150
Grand Mean (n=6) 2764
St. Dev. = 19.8
 
200 grain Combined Technology Ballistic SilverTip
53.0 Grains of N-150 (group "a")
Grand Mean (n=3) 2769
St. Dev. = 23.5
 
200 grain Combined Technology Ballistic SilverTip
53.0 Grains of N-150 (group "b")
Grand Mean (n=3) 2759
St. Dev. = 18.7
 
200 grain Combined Technology Ballistic SilverTip
53.5 Grains of N-150
Grand Mean (n=6) 2783
St. Dev. = 17.0
 
200 grain Combined Technology Ballistic SilverTip
53.5 Grains of N-150 (group "a")
Grand Mean (n=3) 2783
St. Dev. = 22.1
 
200 grain Combined Technology Ballistic SilverTip
53.5 Grains of N-150 (group "b")
Grand Mean (n=3) 2783
St. Dev. = 15.3
 
(No, those aren't typos on the MVs - they were all the same.)
 
200 grain Combined Technology Ballistic SilverTip
54.0 Grains of N-150
Grand Mean (n=6) 2813
St. Dev. = 14.8
 
200 grain Combined Technology Ballistic SilverTip
54.0 Grains of N-150 (group "a")
Grand Mean (n=3) 2817
St. Dev. = 17.4
 
200 grain Combined Technology Ballistic SilverTip
54.0 Grains of N-150 (group "b")
Grand Mean (n=3) 2809
St. Dev. = 14.0
 
As you can see, these groups are clearly nothing to "write home about". To be honest, I was genuinely concerned. Even the "extracted" 3-shot groups weren't really very good. Furthermore, I had been seriously concentrating on making the best shots I could, and I'm fully capable of at least MOA precision. Things weren't looking good as far as I was concerned.
 
Now the good news. :D
I didn't clean the rifles as soon as I got home, and even when I did get to it, I saved the MAI for last so I could give it a "good going over". When I grabbed the rifle, it sounded like it 'rattled' a little. At first that was no big deal as I always store rifles with the bolts open, and Mauser's bolts really rattle. But it didn't quite sound like a bolt rattle. I grabbed the 'scope and gave it a good shake. It was really loose. Upon closer examination, it was so loose I could actually see the movement of the bases if I shook the rifle.
 
In order to install the pressure hardware, I had removed the 'scope but not the bases, when I first got the rifle home from John's. I didn't notice any looseness in the bases when I re-installed the 'scope, and indeed, the scope was still tight to the bases, but all four screws in the bases required at least a full turn to tighten back up to the proper level. Gee, you think that might have something to do with the poor accuracy observed? In fact, I'm amazed that I was able to get the groups I did! Actually it's too bad I wasn't "all over" the targets at the range. Had that been the case, I would have realized something was wrong at the range, and I could have salvaged at least some of the shots.
 
Anyway, I think the bases must have "shot loose". I re-tightened the screws, but I didn't put any Loktite on them yet. I'll keep an eye on them, and if they shoot loose again, then I'll Loktite them.
 
So, most of the accuracy data is useless or almost so. I'm hoping that the fact that I got almost "acceptable" groups with the 'scope seriously loose bodes well for the 'real' accuracy. You'll be among the first to know. :)
 
Paul

At least you have complete velocity data.

Now that the appearant sourse of the problem has been discovered you have to get back out to the range. Oh yea, and poor John's heart can start beating again. I'm sure that he was less than impressed with the accuracy thus far.

Quote from: HunterbugNow that the appearant sourse of the problem has been discovered you have to get back out to the range. Oh yea, and poor John's heart can start beating again. I'm sure that he was less than impressed with the accuracy thus far.

"AH-HA!".......the little unexpected gremlins of Murphy's Law raise their little heads!  Now you know why gunsmiths and experimenters are bald, tend to stare off into the distance, experience unexplained physical "twitches", mumble to themselves and sometimes seek solice in a bottle of booze!  ............................. the vertical dispersions were starting to bewilder me as that is indicative of extreme spread in velocities and the SD's were not showing that.........duhhhh!  Well, I can put the electric paddles back in their box but getting that "greasy stuff" off my chest is going to require a shower.  Hey!........it is SATURDAY!!!  Kill 2 birds with one stone.........!  Always have to look on the bright side of things as the loose screws are probably the "culprit"!  (I hope).

Paul--good going amigo!  The velocity data was good and what I was hoping for.........Look forward to the next update and hopefully better news........How did the other "boomers" do?..:D :D

Ol' John..:D

"Rick" was shooting his rifle with my handloads for it, and it did fine. Good, 1 to 1.5 MOA  3-shot groups  - 2.5 MOA 5-shot groups.
 
"Larry's" rifle did "OK" too, but nothing better than 2 MOA. The loads were probaly a little too cool for this rifle as they were middle values and it has a large chamber. I'm going to crank up the charges about 3-4 grains and have another look. The truth is, I really don't expect much better than 1.5 MOA from Barnes' XBTs. I've personally never gotten them to shoot better than that, and most other folks I consider reliable have said the same thing. Also, I've got a serious feed problem with these 185 XBTs. The meplat catches the leading edge of the feed ramp, and any more muscle on the bolt is only going to seat the bullet deper. I'm gonna increase the seating depth and see if that helps, but recall, that I'm already 25 thousandths off the lands as it is. The good new is, from what I understand Barnes' "X" bullets "like" to be off the lands. We'll see. If this next batch doesn't work out, I'm gonna try to talk him into using the 210 Partition. It's an excellent bullet for the "penetration" he wants, and it shoots very well in every .338 I know of.
 
Maybe by the next time I get the MAI to the range, I'll have the pressure hardware installed.
 
Paul