DTA Groupings Question and .260 Rem Reloading Frustration

[drn1234]

While doing my load development for my 260 Rem through a DTA I noticed a trend.

Take a look at the photo. I seem to shoot a few left inline then a few right inline. What am I going to cause this?
I was shooting off a bench with rear bag and bipod

My frustration is i cant get the 260 to group at all. I am trying different powder weights, different OAL, did a ladder test at 500 yds and just cant seem to get the groups to close up at 100 yds.

My .338 is like a laser and can hole in hole and I did not put 1/2 the time i did into the .260

Running 4831 around 2800 fps with SD at 10 and ES around 20

What do you think

 

[VKC]

What brass prep? Bullet? Etc? Work on COAL and look at berger 's website about seating length.


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[Dogtown]

I had the same problem with trying to shoot the 285s in my standard .338 barrel - wouldn't group no matter what I did. Switching back to 250s shot 1/2MOA, so I tried 300 Scenars (which I hadn't done in almost 5 years) and came up with an excellent load in no time. There seems to be no rhyme or reason to it; some barrels just don't seem to like certain bullets.

Have you tried different bullets? Actually, more importantly, have you played with seating depth or primers? When I was working up 136 Scenar in the 6.5x47 barrel I found a powder charge that was acceptable and a seating depth adjustment brought the group further down. But switching to CCI 450 magnum primers made the group just collapse in on itself. Why? I have no clue, but I'm not going to argue with the data.

 

[leadbullet]

Do you take you head off the stock between shots???

 

[Sako man]

While doing my load development for my 260 Rem through a DTA I noticed a trend.

Take a look at the photo. I seem to shoot a few left inline then a few right inline. What am I going to cause this?
I was shooting off a bench with rear bag and bipod

My frustration is i cant get the 260 to group at all. I am trying different powder weights, different OAL, did a ladder test at 500 yds and just cant seem to get the groups to close up at 100 yds.

My .338 is like a laser and can hole in hole and I did not put 1/2 the time i did into the .260

Running 4831 around 2800 fps with SD at 10 and ES around 20

What do you think

I run 4350 and Varget with 142 SMKs. Not worried about FPS as I'm getting at least 2720, SD of 9-10 and amazing groups. Most accurate 260 i have owned. Try coming down in charge so you can get 2700+ fps and I bet your groups tighten up. Im nailing stuff past 1300Y with authority so the LR factor is still there at that MV.

 

[lte82]

I have a custom 6mm barrel that will shoot vlds, hybrids, and non-vlds really well with very little tuning required, and even when not in a node the accuracy is still pretty decent.

My savage 338 lm will shoot terrible groups with the wrong load but amazing groups with the right load. It was difficult to tune as well. My guess is as good as yours why some are just finnicky with everything, and others shoot with seemingly no effort.

 

[drn1234]

Thanks everyone Sorry for the late response. Had some travel.

To answer some questions:
Using Berger 140 gr hybrid target bullets
4831 powder
Tried jammed, just at the rifling and backed off and they all shoot somewhat the same
Lapua brass, fire formed measured annealed and trimmed
Winchester standard rifle primers (cant get ahold of anything else
Does it make sense to try magnum primers. I have some of those for my .338

I have not tried another bullet yet but will see if I can find some to try.

 

[broke_again]

Try H4350 first. Then try 139 Scenars and Barnes 140 match burners.

 

[0311@LAR]

I second trying H4350.

 

[drn1234]

I finally found some H4350 and it arrives beginning of next week.
I also had a big score today and found Federal 210M primers.
Got 4,000 to try.

Hopefully the new powder will help out

 

[Dallas4rceMarine]

I use 43gr of H4350 in Lapua brass, Fed 210M primers and Berger 140gr Hybrids. I jump them .020 and get 2850fps and gun holds 1/4moa to a 1,000 no problem.