.338 MAI with 160g Barnes XFB

Started by gitano, April 17, 2005, 09:22:56 PM

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gitano

As I said in another post, HB and I thought that given my experience with flat-based bullets, and the smaller case capacity of the MAI cartridge, the Barnes 160 XFB might be worth looking at.
 
So, using Load From A Disk software, (wish Ida listened to Ol' John about that software sooner), I came up with some experimental loads: 56, 58, and 60 grains of Vihtavouri N-150. I did get some other powder suggestions, but I thought I'd stick with N-150 since it was what I was using for the 200 Combined Technology Ballistic Silvertip.
 
To refresh your memory, the 200 grain bullet was doing about 2825 fps at the muzzle ahead of 54 grains of N-150. I was hoping to get a useful load over 3000 fps from the 160.
 
I got a request for "real" targets instead of my "processed" targets, so I'll provide both this time.
 
Here are the 'numbers':
 
56 grains of N-150
average velocity - 3023 f/s Standard Deviation - 13.3 f/s
max spread - 35 (Just for you John :) )
 
 
58 grains
average velocity - 3070 f/s Standard Deviation - 4.5 f/s
max spread - 11 f/s

 
 
60 grains
average velocity - 3174 f/s Standard Deviation - 12.0 f/s
max spread - 26

 
John has convinced me of the value of two 3-shot groups as opposed to one 5-shot group. I like larger sample sizes, and really dislike making any assumptions based on 3-shot groups. However, pooling two 3-shot groups, actually increases sample size by one, and more closely simulates a hunting situation. Testing the 160 this way proved very interesting.
 
Below you will find the "real" targets for the three charges. Following that will be some 'virtual' targets that break the groups down into two groups of three. It is quite interesting, but I'll save the details 'til later.
 
The top six holes are from the 56 grain charge, the middle six from the 58, and the bottom six from the 60.
 
Paul
Be nicer than necessary.

Kanibal

That bottom six is a great group.  That 160 Barnes would make a great deer or elk bullet.  Flying at a good pace as well.  You two should be proud with your creation.  What do you plan to do with it?  Do you plan on making more of the same or do you feel you need to experiment more?  I think you have got a winner.  Good job Paul and John.
-Richard
 
 

Brithunter

Hi Gitano,
 
      Well it looks like the 60 Grn charge might be the best, I would at least try some more groups with that one and see if that nice tight cluster shows up more often :D . Two groups is OK as an indication but I would have thought about 5 groups over a period or even 7 would show it's true potential better :cool:
 
      I am going to try a thing I read about some years ago using a "master target", you sight in and then put 2 clean targets up, one on top of the other marking the bottom one as Master. Then you shoot 2 groups on the top target and record the details, then filing the "master" away carefully. At another range session again put a new target over the master carefully aligned and with the same load & sight setting shot a group on the target, again writing the information down and saving the master carefully. Do this until you have shot about 20 groups on the master target over a period of weeks/months. It will show the rifles true grouping capability over a time scale.
 
     The "master" target in the article showed that some of what we may call fliers are not actually fliers but a normal part of the rifles grouping behaviour. I keep meaning to try this but never seem to get around to it :rolleyes:  which I really must correct.;) .
Go Get them Floyd!

gitano

There's more explaining to do. I shot the first 56-grain shot and checked for signs of pressure. (Oh yeah, the pressure gauge wasn't working. :( ) Since there clearly were none, I took a 58-grain shot. Again no signs of pressure at all, so I took three 60-grain shots. The 60-grain group wasn't too shabby, so I went back and shot two more of each of the 56, and 58 grain charges. In all cases, those first 3-shot groups are the three highest shots.
 
Since the 60-grain group was the best, I adjusted the 'scope accordingly, and shot the second 3-shot 60-grain group. Then went back and shot the second three-shot groups for 56 and 58. Clearly, the groups get better as the charge goes up. I like the second 3-shot group for the 60-grain charge.
 
Below are the 'virtual' targets for the 56 grain charge, and their associated statistics. There are four of them.
1) The 6-shot conglomerate as-shot.
2) The first 3-shot group.
3) The second 3-shot group.
4) The 6-shot conglomerate with the effect of differing scope settings removed.
 
In all cases, the black "holes" are from the first 3-shot groups and the red ones from the groups after adjusting the scope. Note the numbers at the bottom of the 'targets'. There's even a max-spead number for those that like that statistic. But do note the area of the ellipse. That's the most statistically useful number.
 
56 grains first.
 
Paul
Be nicer than necessary.

gitano

Gentlemen,
 
I was composing as you were posting. Please bear with me as I finish this, because I want to respond to your questions and remarks.
 
Paul
Be nicer than necessary.

gitano

Here are the 'virtual' targets for the 58-grain load.

Paul
Be nicer than necessary.

gitano

And here are the 60-grain 'virtual' targets.
 
I have kept the scales the same on all targets for easier comparisons. The largest group (56 grains) determines the max scale values, and for the tighter 58 and 60-grain groups it gets a bit small.
 
Paul
Be nicer than necessary.

gitano

OK...
 
It's clear from both the "real" targets and the 'virtual' targets that the best groupings come from the 60-grain load. It's also clear that they got better from 56 to 58 to 60.
 
That's 'good', but what does that mean with respect to the 200 grain bullet Combined Technology Ballistic Silvertip? Which is "better"?
 
Well, that question means I'll have to define "better", AND come up with an objective way to evaluate which is better. Since I'm not argueing with anyone about this, it's strictly a matter for my own use. As you might have guessed, I have both a definition of "better" and a way to objectively evaluate two or more bullet/rifle combinations to ascertain which is "best".
 
First the definition of "better". Since we are considering not only a single cartridge, but also a single rifle, things are easier to constrain. So... I'm interested first and foremost in accuracy. (Actually correctly referred to as precision.) All other factors and considerations are subordinate to 'accuracy'. Second on the list of factors defining "better", is delivered energy. In all there are eight factors I quantify to use in deriving what I call the Figure of Merit - hereafter FoM.
 
Below are the FoMs for the 200grain CTBS and the 160 Barnes XFB. There are two for each bullet. On is a based on a fixed range of 300 yds, my self-imposed maximum range. The other is determined by the characteristics of the cartridge, and to some degree the ambient conditions. In the second FoM, the bullet is allowed to move 6" vertically. Three inches above the line-of-sight, and 3" below LOS. This indicates a "kill zone" of 6" in diameter. (This is what I have chosen for me. If you wanna larger one, that's fine.) So, the max range is determined by where the bullet drops to 3" below the LOS after having been sighted in so that it is a maximum of 3" high. A "maximum-point-blank-range" (MPBR) standard.
 
I'll post these, then we can discuss what the various numbers indicate.
 
First the two 300-yd standards, then the 6" "kill-zone" standard.
 
Paul
Be nicer than necessary.

gitano

#8
First, let's compare the FoMs for the 300-yd standard.
 
200 CTBS - 1580
160 XFB.. - 1535
 
Pretty close, with the nod going to the 200 grainer. This is true, in spite of the fact that the 'accuracy' figure for the 160 (4.32 square inches) is better than that for the 200 (7.16 square inches). This is due primarily to the 200's ability to deliver more energy to the target. Consider the average kinetic energy over the entire 300 yards. For the 200 it's 2758 ft-lbs, while for the 160 it's 2675. Remember folks, this is the average ke. I chose to use the average so that no specific range would have to be arbitrarily chosen for comparison. Notice that the minimum KEs, 2086 for the 200 and 1913 for the 160, aren't too far apart, and that the 160 starts out with more energy than the 200. But statistically, the 200 is a "better bet" for any randomly chosen range (as in a hunting situation).
 
For you guys that like penetration, instead of looking at the KE numbers, compare the momentum values. (The BEST indicator of penetration.) Here it's a bit more dicey, as the two bullet types are not exactly alike, so relative penetration cannot be precisely predicted. However, the two bullets are similar enough to think that the penetration of the reviled "Ballistic Tip" would be at least that of the 160-grain "solid".
 
Drop at 300 is another matter. The 160 only drops 4.7" at 300 yds, while the 200 is down 7.3", in spite of a significantly higher ballistic coefficient. That 350 f/s greater muzzle velocity matters when it comes to drop.
 
Now lets look at the MPBR standards.
 
200 CTBS - 1694
160 XFB.. - 1600
 
Once again the 200 "wins" in spite of poorer accuracy. The MPBR for the 160 is 283, while that of the 200 is 262. 21 yds at 3" of drop. Not too big of a deal, except that 21 yards beyond 262, the 200 has dropped about 2 more inches!
 
Recoil is 18.1 ft-lbs for the 160 and 18.0 for the 200... no difference.
 
Anyway, you should be getting the picture now. In spite of its slightly better precision, the 160 bullet just falls short of the 200 in matters that I define as important. However, the FoMs are close enough, that I would choose the 160 if I 'felt' like it. They are for all intents and purposes identical in performance, except in trajectory.
 
This analysis also prompts me to try the 175 XFB out. While Barnes has quit making them, I've got about 150 stashed. Since I won't be using them in my .338 Win Mag, they might as well get tried in the MAI. I've also got some 185 XLCs. After I get all of these checked out, I'll have a good idea of the weight 'sweetspot' for the .338 MAI. :D
 
Finally;
 
BH, wrt the "master" target. I have never done that exact thing, but that is precisely what I do in principle with the digital analysis. I have over 150 bullet holes spanning some 15 years in my .338 Win Mag 'virtual' target.
 
Kanibal, my primary use of the .338 MAI will be for caribou and bear. I'd use it on moose, but I go moose hunting only when I get archery (one) or muzzle-loader (never yet) drawing permits. (Moose hunting is too much like work after you pull the trigger.) I'd take it sheep or goat hunting too, but I have "the sissy gun" (7mmSTW equivalent) for sheep, and the .308 Win for goats. I s'pose I'd take it for sitka-blacktails on Kodiak, but Kodiak's a rare event for me.
 
Just occurred to me that a head-to-head comparison with MY .338 Win Mag might be interesting. At least to me.
 
Paul
Be nicer than necessary.

LLANOJOHN (deceased)

Paul,

SUPERB, AMIGO!  JUST ABSOLUTELY SUPERB!!  I like the actual targets and appreciate the extra effort you have gone to!  Most interesting info on the 160's.  I would never have tried that particular bullet and the untuned rifle seems to really like it.  How is the fouling - slow or fast?

Package of bullets & brass coming to ya from Midsouth via USPS.

Ol' John..:D :D :D :D
Life Member-NRA-TSRA
Riflesmith-Bolt & Lever Centerfires Only
Left-Hand Creek Rifles
Mark Twain was right-"There is no such thing as too much good whiskey!"
My best advice.."Best to stay outta trees and offa windmills!"

Hunterbug

That 60gr load is very impressive! That should make a smokin carabou load. I can't wait to see some results on game when you guys get around to it.
Ask not what your government can do for you. Ask how your government can go away and get out of your life.
 
 
The unarmed man is is not only defenseless, he is also contemptible.
Niccolo Machiavelli

gitano

#11
Well, I was gonna say that 'God willin' and the creek don't rise', I was gonna get out bear hunting this week. However, it appears that God isn't willing and the creek may rise. Snow predicted for the next three days. :( All the pilots I am willing to fly with take a dim view of flying small, VFR (visual flight rules) airplanes in snow storms. (There's a big cold front coming in off the Bering Sea. It's 11 below zero right now in McGrath, a village about 250 miles west of Wasilla.)
 
This weather 'problem' is pretty frustrating, as where I want to go is only about 30 miles as the crow flies, (or in this case, PA-11), from my house. However, it will clear up... ('member what I said about my ability to predict weather? :eek:  ) When it does, I am going bear hunting. 'Course, then the bears will have to 'cooperate' too. With a little bit of luck, I could get both a black and a grizzly. That would be a great 'test' for the MAI.
 
Paul
Be nicer than necessary.

Hunterbug

I figure that if the pilot doesn't want to fly then you probably don't either. I once heard a saying that there are old bush pilots and there are bold bush pilots but there are no old bold bush pilots. Stay warm! Oh yea, it's supposed to hit 80 here today. :p
Ask not what your government can do for you. Ask how your government can go away and get out of your life.
 
 
The unarmed man is is not only defenseless, he is also contemptible.
Niccolo Machiavelli

gitano

Just got up and looked out the window... yes indeed it is snowing.
 
Paul
Be nicer than necessary.

fish

you go, git.
too bad the data wouldn't draw a second look from 24campfire, or i'd suggest you post it there.
then again, why not?

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