Accuracy question

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magnum338

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I have a 338 Win Mag that's doing funny things with the Barnes TSX bullet and I hope someone can come up with an idea that I have not yet tried. Here's the problem:
When I am trying to sight the rifle in at the bench I get groups through whose centers you can easily draw a straight horizontal line using a ruler. However, the groups is spread out over several inches. This, when I try to let the barrel cool for several minutes between shots.
It never did that for lead core bullets regardless of manufacturer.
I am open for helpful corrective suggestions.
Thanks!
 
While it sounds like a rifle/barrel problem possibly....E-mail Barnes, you'll find them quite helpful. Have your load data or ammo info handy.
 
What you describe isn't normal for ammo problems, which usually result in these situations:

1. Large groups;
2. Vertical stringing;
3. Smallish groups with flyers;
4. Keyholing.

Sounds like either a scope or mount problem to me. Remove the scope and check base tightness. If they're tight, try another scope.
 
Thanks to both of you. Your responses parallel about what I was thinking and I'm glad someone else has the same ideas.
I'll certainly give them a try.
 
I'm getting a similar problem when I shoot Barnes out of the 8mm vz24. Let me know what you find out, as the info could help me as well.
 
I reload and have seen a simular grouping issue with them as well. I'm no ballistics expert but have heard the same thing from a number of individual's. The problem is most likely due to the sectional density of solid copper bullets. Although Barnes makes an excellent bullet for the hunting purpose, they really don't group as well as a quality lead core bullet, in my opinion.
Post your question on the reloading forum and I'll bet someone there will also address sectional denisty as a possible cause.
 
Also, you said it never did this with lead core bullets. That right there eliminates scope, rings, or an issue with the firearm.
 
You know, there's another aspect to this that I had not mentioned for some reason(?).
I have been teaching hunter education for many years in Cal. As a part of my sections on firearms I have, for years, caught fired bullets from my '06 and 338. I line up several 1 gal milk jugs, filled with water and capped and shoot down the line. I have been able to catch 4 out of 5 lead core bullets, several of the Barnes with hollow tips (the MSX?) but never the TSX with ballistic tip. They invariably veer off to the left and get lost.
I'm wondering if this is related to the accuracy problem I'm having.
By the way, the junior in my class who scores highest gets the mushroomed bullet.
 
I have had simular results with the Barnes TSX bullets in a 7mm08. I not saying you should try this, but the groups tightend up to under moa when the load was at MAX! and just off the lands. This was to close for comfort for me. Have not used that bullet in that rifle since. I do shoot these in my .223's with no problems with middle weight charges.
 
I didn't really mean to get a discussion started on Barnes bullets but I've had several interesting experiences with them and might as well mention them. One that comes to mind was with my 220 Swift.
The first time I loaded Barnes "Varmint Grenades" they grouped in 1/2". Wow, I thought, I've got something here so I loaded another batch and fired them about 2 weeks later, expecting like groups. What a disappointment; they wouldn't stay within an inch and a half!
Well, there's an old statement; "when all else fails read the instructions." So I read my Barnes loading guide and found what might be the answer. They say that the copper in those bullets is softer than in others and may cause metal fouling in chunks, and the barrel must be thoroughly cleaned after shooting.
Well, a reasonable cleaning with a copper solvent seems to have done a lot toward getting the accuracy back. The next session after this cleaning and the groups are close to 1/2" again.
Anyone else have a similar experience?
 
What rate of twist in your barrel and what .338 TSX bullet are you using?

Keep in mind that solid copper bullets are longer than lead ones (they have
to be to meet up the grain) so you need faster rates in some of them.


Barnes TSX - 338 Caliber

Diameter Weight Description S.D. B.C. CAT#
.338" 185-gr TSX BT .231 .352 33843
.338" 210-gr TSX BT .263 .404 33845
.338" 225-gr TSX FB .281 .386 33846
.338" 250-gr TSX FB .313 .425 33848

Lapua
.338" 285-gr TSX BT .356 .585 33850


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istmarine is 110% correct. The heavier the bullet, the longer it has to be. When you change from lead to copper, the bullet HAS to be longer. to equal the same weight. Your rifle needs a faster rate of twist to make it shoot. A very common problem with older design rifles. Even when shooting heavier weight / longer bullets, many rifles don't have the twist rates to spin the bullets fast enough to stabilize the heavier round. Case in point, a customer brought us a Sako 7MM Rem Mag. Won't shoot the 165 gr ammo. We told him he would have to rebarrel the rifle with a higher rate of twist to make it shoot. He decided that he didn't need to shoot heavier ammo. Wise choice.
 
Thanks for the suggestions guys. What you say is absolutely correct.

However, how can that explain why the shot dispersion is only horizontal? If it were a bullet stability problem, resulting from inadequate twist, I would expect random dispersion in all directions. Is that right, or am I overlooking something?

Twist rate is why I've been loading only the lighter weight 210gr. My load is 68 gr IMR4350 with WLR primers, Winchester brass. I've also been experimenting with different seating depths because Barnes suggests their bullets be loaded to provide a "generous" jump to the rifling. It's a bit rough on the shoulder so I don't shoot it every weekend.

I think an email to Barnes is indicated.
 
hummmm.... using a 210 grain should not required a lot of twist even with the solid coppers.
Now this might sound a little crazy but are you sure is not the scope?
I have seen this many times in my life either bad mounts or scopes going bad and the magnums can do the damage to them.
...Just thinking.
 
It hasn't been mentioned, but my experience with Barnes is that they like to be seated further than you would think usual away from the throat. I've seen them start to group at .050" shy of the lands. I usually try to get .010" to 015" away, but the Barnes don't seem to like that.

A couple of guys I know have had good grouping start at about .035", so if you haven't tried that, it may work for you.
 
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