Taming the .260...


PDA






Afy
September 21, 2008, 10:52 AM
Finally making progress.

Went to the range today.. 3 loads to test
37.5 and 38 grains of N150 over Lapua Scenar 139...
and 38.7 Grains of N150 over a Lapua Scenar 123 (Load is arbitarily derived using Quickload and OBT)

Still shooting off a bipod using my left hand as a rear support. My bench has not arrived yet.

Here are the results...

http://i256.photobucket.com/albums/hh178/afy08/IMGP0349.jpg

Pretty furstrating. My 1st group of five with the 123 looked pretty much like the top left group. So for the second group I changed the way I hod the rifle. Instead of crossing my thumb over the stock I aligned it to the axis of the rifle... and voila..

http://i256.photobucket.com/albums/hh178/afy08/IMGP0351.jpg

Approximately 0.781 edge to edge

I am pretty happy for now... I do want to try this technique with the 139 loads as well. I suspect I am getting the fliers due to improper technique... or even jerking the trigger.

I did trim all my brass tot he same length, chamfer in and out, clean primer pockets etc...

On another front figured out my puffy primer issue with the 8x60 S as well. The load is indeed too low. Was using Privi brass.. brand new which is much thicker than RWS. And was getting soot to the base of the cartridge... :uhoh:

If you enjoyed reading about "Taming the .260..." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Guntalk
September 21, 2008, 11:01 AM
Without a really, seriously, stable rest, you are NOT testing loads.

Even the legs from denim jeans, cut off and filled with sand, are better than a bipod and using your fist to support the rear.

The rifle must be stable. If is it not, you don't know if the groups represent what the rifle/load can do, or if they just show how well or poorly you can shoot.

Afy
September 21, 2008, 11:08 AM
I know... but I am still awaiting the delivery of my supplies. And I do want to get out shoot... more than loading up a bunch of ammo that has no accuracy potential.

243winxb
September 21, 2008, 08:30 PM
Your rifle is showing great potential. Sand bag, high power scope will help. When your package comes in, you might want to use the bushing die without neck turning and no expander button as a test first. Right now you can measure your loaded case neck diameter and your fired case neck diameter. How much difference between the two is there? If the difference now is more than .008" you might not want to neck turn.

Bullet
September 21, 2008, 10:17 PM
When working for small groups I use this front rest for a H-S precision stock -

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RIBBRICO&item=04-2610&type=store

And a rear rest similar to these -

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RIBBRBRB&type=store


I find that the Short-Range 100/200 Benchrest Targets listed here work real good too, the ones with 6 targets on one page -

http://www.6mmbr.com/targets.html

Afy
September 22, 2008, 03:25 AM
Bullet: This is what I have ordered:
HM Rest (http://www.tiroccitan.com/hm-rifle-rest.html)

243 will measure and get back.

Bullet
September 22, 2008, 09:22 AM
Looks good, I bet your new rest will help tighten your groups.

Howard Roark
September 22, 2008, 10:55 AM
Looking better Afy.

I tested my .260 this weekend at a 1000 yard match. I shot one match with 142gr. SMK. The next match I shot Berger 140's. The components were the same with only the bullet being different. The Bergers shot almost 2 min higher than the Sierras. The shooters next to me were shooting Palma with 155.5gr. Bergers. The .260 shot inside the .308s for wind by 2 min. They were using up to 4 min of windage adjustment while I never used over 2 min.

There was a pickup that I and the guy to my right shooting a 6.5x284 missed. We both shot a 9 so the .260 wasn't too far behind the big gun. I didn't think to ask him how much windage he had on to begin with.

With the shorter bearing surface of the Bergers I think I can get up to 2 more grains of powder in there before problems. That will really put the Sierras to shame.

Afy
September 22, 2008, 11:43 AM
243WinXB: Measured the neck diameters.
Fired: .295 inch
Resized: .290 inch
Loaded: .291 inch

Dont know if the above is any good for your line of thought.

Howard thanks... I only wish I had more powders and components available and preferably cheaper.

243winxb
September 22, 2008, 12:57 PM
Measured the neck diameters.
Fired: .295 inch
Resized: .290 inch
Loaded: .291 inch Looks like you will be OK if you want to neck turn. I ask because i wanted to get an idea of what your chambers neck diameter is. With spring back of the brass, i would guess the chamber neck is in the area of .296" to .297" Does anyone know the SAMMI loaded round neck diameter? On line i find 2. .2969" and .2940" What is correct? http://www.6mmbr.com/cartridgediagrams.html#260REM http://www.stevespages.com/page8d.htm

Afy
September 23, 2008, 03:26 AM
Lyman lists it as .2970 as does Quickload

If you enjoyed reading about "Taming the .260..." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!