Lowering ES 260 REM load

[Ghostmoney]

I am working up a load in my 260 Rem and having issues with high ES, but great accuracy. Below is a 5 shot group with the 5th shot a called flyer as I got a little excited with the 4 shot group.
5BD6DECD-8599-4565-B012-9658C09580C6

This load had an ES of 56fps. The load is:
-43.6gr H4350
-Lapua Brass 1x fired and annealed with Amp annealer before sizing with .293 bushing for .001 neck tension
-Berger 130gr AR hybrid .010 off lands
-CCI 250 primer

Brass was all the same length, length to the shoulder was the same as virgin brass, and now being 2x fired the shoulders have grown .002 so will bump them back .001

I shot groups with 43, 43.2, 43.4, 43.6, and 43.8 all groups but the 43gr had above 50fps ES but it shot 1" group.

At this point should I play with seating depth to see if it lowers the ES? Load some at 43.6gr at .010, .020, .030, .040 off the lands? Try a different primer? or start over with a new powder?

With my 338 I was able to get my ES down to 10-12fps and would like to get this load down below 20.

 

[cohunt]

are you neck turning? no way to keep right at .001 neck tension with un-turned brass using the same bushing due to neck thickness variation

have you checked the ID of the neck on your brass after you size? I was using bushing dies and was getting + - .005" differences in "ID" that what the bushing should have sized it to even after neck turning and annealing --- I now size smaller and then use a mandrel die to increase the "ID" and I get much more consistent neck tension/sizing than just with a bushing

no sure this would make it better, but it is something to try out to see if it works for you

make sure you leave enough time between shots to let barrel/chamber cool, as increasing bbl/chamber temps can cause an increase in velocity

 

[Barrelnut]

I would try another primer. A magnum primer might be an issue in the smaller case with a powder like H4350. I would try Federal 210 or even F210M if you have some.

 

[Ghostmoney]

are you neck turning? no way to keep right at .001 neck tension with un-turned brass using the same bushing due to neck thickness variation

have you checked the ID of the neck on your brass after you size? I was using bushing dies and was getting + - .005" differences in "ID" that what the bushing should have sized it to even after neck turning and annealing --- I now size smaller and then use a mandrel die to increase the "ID" and I get much more consistent neck tension/sizing than just with a bushing

no sure this would make it better, but it is something to try out to see if it works for you

make sure you leave enough time between shots to let barrel/chamber cool, as increasing bbl/chamber temps can cause an increase in velocity

No I am not turning necks. I have not measured the inside diameter after sizing with bushing, but something I will have to check.

 

[cohunt]

No I am not turning necks. I have not measured the inside diameter after sizing with bushing, but something I will have to check.

lapua brass is better than others but usually still has a variance of at least .001" on neck thickness so the ID when using a bushing with no expander starts to vary--I found that using an expander mandrel die ( not the included expander ball that comes with the die set) seems to work best for me regarding uniform case neck tension

 

[L.Sherm]

As barrelnut said I would try non- magnum primers, then some more grip on the bullet .002-.003

 

[Jud96]

Try a different primer as a couple others suggested. I had this happen with my .308 Norma. I started off using Winchester Magnum rifle primers and my ES was all 50-60. I switched to Fed 215s and the ES went down to 10-15

 

[cohunt]

I agree, start with easy things like primers and neck tension before diving into neck turning...only try 1 thing at a time though

 

[Mikecr]

-Lapua Brass 1x fired and annealed with Amp annealer before sizing with .293 bushing for .001 neck tension

293 bushing to 263 neck IDs, means the necks would have to be >15thou thick.
Are they?

and now being 2x fired the shoulders have grown .002 so will bump them back .001

So you're not developing a load, but merely piddling with groups at different charges -from virgin brass. With this, don't you think everything is changing and unstable?
Also, shoulder bumping is not taken to new brass dimensions, it's taken from chamber fit.

At this point should I play with seating depth

You should do Berger's recommended full seating testing, and when your brass is fully fire-formed and stable, begin actual load development.
See where it goes from there

 

[J E Custom]

Low SD and ESs have always meant to me that the combination of Primer, power used, cases quality, bullet weight and case capacity have been good.

If poor SDs are present, i always look for different components in the same range as the ones i am using. I only change one component at a time, And clean the barrel between groups to give the new component an equal chance to show promise. If I find low SDs but poor accuracy I try different bullet brands of the same weight to test which bullet the barrel likes. great accuracy and poor SDs normally means you have the right bullet, but the wrong combination of load components. once I find a low SD and good accuracy combo I start trying different seating depths and neck tension to tweek the load (Find the best of both)

J E CUSTOM

 

[scottishkat]

My best accuracy with the 260 rem has been with Rem 9.5's 210M's are a close second but there has been a discernible difference long term over the course of hundreds of rounds. More than a few of those with H4350 but most with H4831sc.

Try another primer and then change seating that accuracy is awesome.

Good luck and shoot straight y'all

 

[ThrdKllr]

Standard primers for sure. Take the bushing out of your F/L die and size your necks with a Lee Collet Die. It sizes the necks on the inside regardless of neck thickness. Some combinations of components just will not produce low ES's. I get much better ES'S with RL16 in my Creedmoor.

 

[Ghostmoney]

293 bushing to 263 neck IDs, means the necks would have to be >15thou thick.
Are they?
So you're not developing a load, but merely piddling with groups at different charges -from virgin brass. With this, don't you think everything is changing and unstable?
Also, shoulder bumping is not taken to new brass dimensions, it's taken from chamber fit.
You should do Berger's recommended full seating testing, and when your brass is fully fire-formed and stable, begin actual load development.
See where it goes from there

Bushing is .293 OD of loaded round is .294

Not developing on virgin brass. Brass was all 1x fired. I have always fired brass 1x in a rifle then started development. I am not trying to take shoulder to new case dimensions I measured new case dimensions then fired brass 1x then measured again and noted the movement and then fired the brass a second time and now they have moved .002-.0025 forward. Will remove firing pin and check before bumping it back only enough to chamber smoothly.

How many times does the brass need to be fired before I can do actual load development?

 

[Canhunter35]

Weight sort your primers