Boat tails - vertical stringing

J

jan botha

Guest
Need help please!

Over the past weekend I shot two different make boat tails.Starting off by using a .256 neck size bushing from jam , then 5thou and 10 thou into the lands.The vertical stringing stayed with me.
Any suggestions on how to improve the verticals?
Thanks
 
Nick,
Yes the barrel is warmed up by the time I start the record target.
 
Powder Load

I would normally start with the powder load and get this right, before I started altering things like bullet jamb.

Kevin
 
i agree with Kevin, if this happened with a known good load, then you can try to add .2grs, if it's safe and see what happens to the stringing.
M.
 
Wow a .256 bushing...?

If your chamber is a .262 neck, and you have brass with .087 wall thickness, why are you using a .256 neck bushing...:eek:
Start over by setting your powder charge (N133) at 29.0 grains, then
try a .259 or .260 neck bushing and start with your bullet right on the jam and then make .003 adjustments out into the lands until the vertical goes away.
Note; if you are using a Redding sizer die make sure you are sizing about 2/3s of the neck length...
If that doesn't work...send me the barrel and I will shoot it unmercifully hard in the Texas heat..to teach it a lesson..:D
 
Thanks for all the input so far.

Jackie , the barrel is a Hart 6 groove ,stolle action.I use the local powder S335.Bullets are Cheeks 68gr BT double radius.

eww1350, sorry can't send you the barrel since it takes tooooo long to get a new one from the USA.(the icon should appear here)
 
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B_Tail Bullets

You can change the neck tention very lite, just enough so thhat you cannot pull the bullet with your fingers unless you pull extremely hard.

Lester
 
Jan,

I am using double radius 68 Ultra's, with N133.

It could be a quirk of the powder but my rifle liked the bullets jammed hard into the lands, like 20 thou longer than the depth to where they first touch the rifling. The land marks are at least twice as long as they are wide.

I know that Jackie found the same thing with this style of bullet. The shape of the ogive is such that they will quite easily "wedge in" and more engagement is needed to get the same resistance to moving forwards. The same can be observed when using a bullet comparator, it can be pressed onto the bullet much more than it will a more conventional low number ogive bullet with a more rounded profile in the ogive.

As the others have said, I'd look to fine tuning the powder first and then tweaking the seating depth. It has been my observation that seating will only rescue you from a relatively small amount of vertical but the powder will pull in quite a bit with just a 0.2 - 0.4 grain change.

That may not apply to your local powder and could be a quirk of N133 but it sure couldn't hurt to try a longer seating depth, more jam.

Bryce
 
Jan

I would try what Bryce said. When shooting the double radius bullets, you can cure a lot of problems by jamming the bullets to where the marks are darned near twice as long as they are wide. That is how I shoot the Bruno 00 with N133. The Cheeks is almost identicle to the Bruno.
This does not work with 8208. The powder you are shooting, I don't know.........jackie
 
Jackies right with the 8208. Might want to start with light land marks and come out from there. I was having some real trouble with genters Bt one time and it sure cleared up once I got out far enough. What is S335 in american terms?

Hovis
 
From all your valued input above I have decided on the following action plan:
1)Three different loads and three different lenghts for each load.
Load 1 = 52 clicks (28.6gr) -jam, +.010, +.020
Load 2 = 53 clicks (29.1gr) -jam, +.010, +.020
Load 3 = 53.25 clicks (29.3gr) - Jam, +.010, +.020
2)Use a .259 bushing
3)Federal 205 primers
4)Only have S335 (somchem) powder.According to Somchem's comparison s335 compares favourably with IMR3031, H355, R901 and N133.Slightly faster than N133 I believe.
Hope the wind will be gentle on Saturday.
Thanks again to you all.
 
Jan

3031, or at least the lots sold here, is quite a bit faster than N133, even faster than N130.
Have you taken any velocity figures with this powder?? I am really curious about it........jackie
 
Jackie

I have not done any velocity testing yet and will do so on Saturday.
I will post the results.
Jan
 
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