superdown,,,, here's the range report

[onesonek]

Well, I finally got some testing done with this new 6.5-257Rob.AIR Encore barrel.

First off, there isn't much for data on this round, so I was going from experience with various AI's, and at first had some puzzling results.
I elected to start with 1 gr. over max using H4831 .260 Rem data and the 125 gr Nosler Partition for my main deer bullet. As this case has a capacity is 1/2 way between the .260 and 6.5-06 cases.

On my initial 49 gr load, the velocity was about 250 fps over what I had expected. The cases extracted ok, but on the 3rd round, there was a slight hint of stickiness on opening. I went  ahead and fired the 49.5 gr load,,,and it was pushing it. I quit there and went pulled the rest of the load ramp. From there I backed off 2 full gr., and 47 gr. proved still to be above what my hopes had been.  Accuracy wasn't too bad, but I'll have to admit, I'm not the worlds best shot and also I haven't had much trigger time in all winter, so i know I wasn't at my best on the bench.
I did shoot the 47.5 gr. load, but group had opened up some.
I think the 49 gr. is absolute max in this barrel (17" Pac-Nor 9" twist polygonal OTT chambered). The some what puzzling part of why the one round was ever so slightly sticky, is I checked that lot of bullets and found .0005" variation in diameters. And that is also why I'm getting more variation in velocity than I had hoped. I'm happy with the 47 gr load in general, I would like to see that velocity spread tighter, but that's likely due to bullet diameter issue. Then too, I would like to see  a higher load density, than I'm getting with the H4831. Still I'm getting better velocity then I had hoped when I decided on building this barrel. I can only assume  that between the tight OTT chamber and possibly a tight bore, that I'm in the .260/Swede realm of data, and getting the velocity I am.. I really from experience would have guessed it top out in the 52 gr. with this powder bullet combination.
I think I'll get some more trigger time in and play around the 46.8 - 47.2 charge weights and see if I can't tighten up the numbers some. Then change from 100 yd zero and set up for point blank range on a 4" target. Then too, I might pick some RL22 or VV 165 and play around some more.

Sorry, kinda hard to read that pic, right is 47 gr.  H4831 2769 fps avg., 22fps spread, .472 group,,,left  47.5 gr. 2807 fps avg., 39 fps spread, .703 group


Dave

[onesonek]

(Follow-up using R22)

Well, I just had to try another powder and R-22 is it.
First off I came to the conclusion, before I get overly concerned with accuracy,I need to get the rust out my shooting mechanics. as I said, it's been a long spell without shooting and playing with a new barrel,,I'm just not fully concentrating on all aspects.
Ok enough of my excuses
 I started out with 47grs of R-22 and the same 125gr. Nolser Partition, and worked up to 49.5 grs.
Nothing spectactular at the low end as I kinda figured. At 48.5 grs I got a pretty good group, with a good velocity avg at 2741, and a spread of 8 fps. I can live with that, but I pressed on.
Now at 49 grs. my 1st round went into the same relative position as 48.5 gr charge did. But the next 2 were 1 1/4" left but touching,,,,,shooting machanics,,,I had changed my grip??? velocity on that charge was 2740,2781, and 2754 fps.
The next load 49.5 grs. went first 2 touching with the 3rd a flyer?? 2" left,,,,I'm still thinkin rust, and lots of it. But still, I'm getting excited with the R22, no pressure signs at 49.5 on the first 2 rounds and readings of 2837, 2818, and 2898. That last reading has me a little dumbfounded. The only thing I can think of, is that somehow I bumped the powder trickler in taking the pan from the scale and didnt notice,,, possibly getting an extra 1/10 or whatever. That higher reading did have a tad bit of stickiness to it on opening.
But I'm excited and curious,,,I head home and load another 3 with 49.5 to recheck, and then a 50.0 gr run.


Back at the pit, I set up again, and fire the 49.5 again,,,,,came in 2803, 2809, and 2801,,,,I'm smiling like the 48.5 again...till I look through the spotter,,,,looks like buckshot.
Now I start checking the gun over real close,,,everything is fine and tight.
 
Is it me or the load,,,,I wouldn't bet a plug nickle one way or the other.   Oh well, move on the the 50.0 gr. charge. But now I'm curious so I look in the spotter after the 1st round,,,,It's dead center in the ring ,#2--12:00 touching , #3 just off at 3:00
But faint pressures signs started showing
Not bad enough that I wouldn't sweat it I don't think,,,just brass life be shorter.
But I decided I'll get some more 125 NP's in and play around the 48.5 - 49 gr range,,,I'm pretty sure I could improve the 48.5 group of .496" . That velocity range of 27-2750 fps is about perfect for my wants and needs.  But I'm still thinkin I need to polish off some rust, the consistancy just don't feel "there".
Any how the pic is of the cutoffs from cluttered old h4831 target, and then the re-shoot of the 49.5 and 50.0 gr this afternoon.
       

Dave

[superdown]

  Dave thanks for the range report i really enjoy reading about unique cartridges also looks like you found a powder that works well. It doesn't look like you have to much rust to worry about ! it's going to be funny when i can finally get back out the range with my encore still have to get my 44mag bbl sighted in. you may have to do some load testing on a few coyotes and such over the summer . Justin

[Steve P]

That is good shooting by any standard.  Way to go!. 

You made comment about your bullets being .0005 difference which isn't too bad.  Who did the throat on your barrel?  Did they give you the dimensions?  Tight throat?  Have you measured neck diameter of loaded cases?

Per your description of good, good, then sticky extraction, sounds like maybe a neck thickness problem.  Get a bullet that is on the larger size and a case with a little thicker neck and you could wind up with the sticky extraction you describe. 

I have a 6.5BR and I am using Lapua cases.  They are a little more expensive than the Remington, but we still turned the necks and found quite a variation. 

Just another option to look into.   Sounds like you have a shooter there.  Enjoy.

Steve 

[onesonek]

Necks are turned Steve,,,that's not saying I have the neck diameter correct for the .2638 bullets, That aspect didn't occur to me, and it's possible I have them turned a little tighter for the one(s) that ran .2633 The one thing I didn't do is weight case to see how much variation is there. This Norma brass while coming from the same order, has some physical appearances than make be believe they could be 2 different production lots also. Which might have more to do with it than anything. Then there's the low load density issue with the H4831 ,,,,may not be helping much either.
OTT did the chamber, and his tolerances tend to run pretty true and tight.  All in all I very happy with the barrel and the results  with the 125gr. NP's, even though it was built around tha 130 gr. Accubond. I haven't shot a load ramp for them yet. That's for another day,,,,,comming soon I hope.

Dave