What do you guys see?

I

ivo

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I'm asking this question to see what some of the more experienced guy see if there are any patterns here and mainly to see how I can shrink these groups some.
The details are:
Trued Rem 700 in .260 AI with 29" 1:8 twist Gailard barrel
Lapua .243 brass once fired not touched other than uniformed primer pockets
CCI BR2 primers
COL is 2.875"
#s 1-4 are H4831 (47.5-49gr) with 130gr Berger hunting VLD
#s 4-8 are H4831 (47-48.5gr) with 140gr Berger hunting VLD
Weather was -13 deg C mainly calm @ 3400ft ASL.
Dist. 100m.

I thought about the only thing left to do is maybe turn necks and play with seating depth, especially because these Berger VLDs have been known to be somewhat finicky.
Any advice would be great.
Thanks,
Ivo

260_AI_Target.jpg
 
Rather than COAL, where do they sit in relation to the lands? I know there are exceptions to every rule, bu I'm tellin' ya, that Berger VLD's like being stuck about 15 thou past first land contact.

Are you familliar with "Ladder testing"?
 
ivo
It has been my experience that any group shot will have some human error in it.
The more shots per group, the more chance for human error.
Here's what I do:
-Clean barrel
-Load 10 rounds of a load. (all details recorded)
-Shoot one fouling shot
-Shoot a 3 shot group
-rest
-repeat for remaining 2 groups.
By shooting only 3 shot groups, you can reduce the human error for each group.
By shooting 3 groups, you will have a better average of what that load is doing.

The difference between a 3 shot group and a 5 shot group is... you.

Hope this helps.
 
I proof loads shooting 15 shot groups. Same as competition.

3 round groups tell you you may have something to work with, but it sure doesn't confirm anything.

Do some reading on ladder testing. This is a far more useful way to find accurate nodes.
 
(Ditto the questions on bullet position relative to the lands...)

Overall it looks pretty decent.

I am surprised (impressed) at the velocities you are getting with the 140 - I know that 260AI has a *bit* more powder capacity that the 260, bu still, wow, #7 and #8 are in 6.5-.,284 territory (not the limit of what a 6.5-.284 is capable of, but where most of them seem to be shot)

I am curious what is "wrong" with #5 and #6 (insofar as opening up to 0.6MOA and 0.7MOA is "wrong").

#7 and #8 both look good group size-wise, I'd be tempted to pursue #7 some more, the only thing about it that worries me is that its nearest neighbour #6 is a bit largeish. If you could find a way to "fix" #6, it would be pretty comfortable.

Also, ES looks promising on #7 and #8.

No pressure signs to speak of anywhere?

I've ignored the 130s because if they 140s work for you (as they appear to), why bother with the 130s, which don't perform as well?

I wouldn't bother spending any effort on the necks, there's not likely to be much payback there. I would spend some time exploring seating depth variations for the 140s in the 47.5-48.5 grain region.
 
Ian,
Contact with the lands is at 2.950" and they are seated at 2.875". My mag lenght is 2.900". Yes I am familiar with ladder testing, just I've always tested loads this way,
maybe time for a change.

Daniel,
The velocities are great and no there are no pressure signs to speak of, primers and bolt lift are fine. I don't know how the velocity and pressures may change as it warms up around here.
I bought this rifle from a fellow gunnut and with 139gr Scenars and 47gr of H4831sc he was getting2890fps...with 140gr Berrgers and the same charge of 47gr of H4831sc I am getting 3019fps. Altitude maybe?

I might make it out again this week, if not, I'll try the ladder test on the weekend.
Thanks,
Ivo
 
ivo said:
Ian,
Contact with the lands is at 2.950" and they are seated at 2.875". My mag lenght is 2.900"
Click to expand...

So you presently have about 75 thou jump (and are getting better-than-middling groups).

Do you have a requirement to feed from the magazine? If not, try less jump, in fairly coarse steps (see Eric S's article on jumping VLDs on the Berger website). I'd at least try 45 thou jump and 10 thou jump, to start. If you get better groups or better ESs, you've gained something.

primers and bolt lift are fine. I don't know how the velocity and pressures may change as it warms up around here.
Click to expand...

You could test with 1 grain more powder, just to be sure that you don't suddenly get too much pressure or have your groups and ES go bad. Don't want to unwittingly be just on the ragged edge.

I've not used 140 Bergers. I did find that 139 Scenars were noticeably larger in diameter than 142 Sierras - IIRC .2646" vs. .2640". Generally needed half to one grain less powder with the 139s than the 142s.

Altitude won't make any difference to MVs.

Using a different chronograph, or even the same chronograph set up differently, sure will.
 
I had no idea you could get 3,100fps+ with H4831sc from a 260 AI! WOW!
Gotta get me some then.
I found the Berger 140's like touching or being in the lands. Other than that accuracy wise you are there. Remember you have a long heavy barrel hanging off a Rem 700 action. Unless you have bedding under that barrel an inch or more you are most likely getting action flex. Don't expect 1/4" groups consistently.
How many rounds thru that barrel? Do you know?
 
I'm thinking those groups will shrink like your bung in a prostate exam if you jam them a bit.

They are showing tremendous promise though!
 
I am impressed and intimidated by your shooting, your rifle, your ammo, your optics and your arcane and mystical language as well as the number of posts you guys on this thread have.
I will skulk off now to shoot my factory guns and my factory ammo!
 
lejarretnoir said:
I had no idea you could get 3,100fps+ with H4831sc from a 260 AI! WOW!
Gotta get me some then.
I found the Berger 140's like touching or being in the lands. Other than that accuracy wise you are there. Remember you have a long heavy barrel hanging off a Rem 700 action. Unless you have bedding under that barrel an inch or more you are most likely getting action flex. Don't expect 1/4" groups consistently.
How many rounds thru that barrel? Do you know?
Click to expand...

I have an AICS stock on this rifle so no bedding and the round count is 205 now.

I'll keep tinkering with these loads and maybe even try the same loads out at 200m and see whats happening there, it might give me a better indication of where I should be concentratying my efforts.
 
Lex said:
I am impressed and intimidated by your shooting, your rifle, your ammo, your optics and your arcane and mystical language as well as the number of posts you guys on this thread have.
I will skulk off now to shoot my factory guns and my factory ammo!
Click to expand...

Always room for another over here on the Dark Side, Lex.... :welcome:
 
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