7mm-08 Load development truoble?

[AndyW]

I have been working on load development for my 7mm-08 and I am having the same results no matter the bullet/powder combination;
Working up the ladder I will always get one charge that will cloverleaf 3 shots,3/8”), however ½ grain below that most accurate charge and ½ grain above that charge the group will be over 1” ? What I am worried about is this also being an indication that this load will be overly temperature sensitive because of this very small accuracy node within every ladder test I shoot? All bullets seated .010 into the lands with the exception of the TSX which are .030 out.
The load that has been the most stable so far is 47 grains H-414 w/ 140TSX .030 off the lands, 2930 fps. By most stable I mean that ½” grain on either side of the 47 grains it is opening up approx. 5/8" for 3 shots. I have never experienced this with any other semi-custom gun I own?

Caliber-7mm-08
Trued Remington 700
Lapua .308 brass necked down
Custom Button rifled, lapped barrel 24”
Macmillan Classic stock action bedded and barrel free floated
Bullets tested- 140TSX, 120TSX, 140SGK, 140Accubond
Powders- Varget, H-414. I am going to try Reloader 15 next.

Am I missing something?

 

[jb77]

Andy are all the loads that are accurate close in velocity, and how much velocity difference are you getting at half a grain up and down from your most accurate load?

There should definitely be another node somewhere below the maximum loading for that particular rifle/load combo.

It sounds like you may have another issue with your rifle. Cloverleafs are ok but with a good aftermarket barrel and a trued action and good handloads I would expect more.

Keep looking and good luck.

 

[65BR]

My factory 700 in VLS stock, pressure point removed will group one hole, 140 ballistic tips, 139 hornady's I 4064, jammed in lands with RP brass, no sorted, no case work.

Also, had very good accuracy 150 MKHP H380 I believe, perhaps 414, but IIRC, it was H380.

I would expect more also. Scope? Conditions? Don't rule out 150 and heavier matchkings. My gun shot a 1/2 group at 200 for 3 shots with Hornady 100gr, varget, you never know. Untrued action also. BBL cut to 21", but yours should be fine.

BTW, I had much more consistency with 4064 and Varget than 414 with 140 class bullets.

 

[tillroot1]

I had great success with RE 15, Lapua brass, 210 primers and 140 accubond, powder charges did not affect my rifle as much as seating depth. mine is a 7mm08AI. Ron Tilley

 

[Elkbane]

Andy,
Are you missing something???? Good question. I have had some experience with necked down 308 Lapua cases and TSX bullets that didn't give me the consistency I was looking for.

Foremost was that the TSX bullets had higher than normal weight variation.,Accubond's were really consistent - finally quit weighing them - Noslet Ballistic tips were better still). If you are shooting 3 shot groups, this may not be large enough sample size to express the natural variation in the finished load. Suggest you try 5 shot groups to confirm the trend you're seeing is not "random" variaton masquerading as true differences due to weight charge. When you test this, do it on weighed bullets to keep that constant. I went away from the TSX's as they were just too expensive for the weight variation I was getting.

Secondly, the Lapua 308 brass I necked down had a nominal length of 2.015" as compared with book trim length of 2.025" for the 7-08. This left me with "short" necks which limited my ability to play with seating depth,matching up the bands on the TSX bullets with the case necks)AND manipulating disctance to lands to increase consistency. I winded up just going back to Winchester cases.

Lastly, going from 3/8 to 1" groups with a 1grain spread,.5 each side of node) in powder charge doesn't sound abnormal. I usually do final testing in .2gr increments and can usually get a .4-.6 gr spread around a node to shoot reasonably consistent. Suggest you try smaller increments around your node than .5gr - again, using 5 shot groups.

FWIW I've switched to Varget for all my 7-08 loads. My best hunting loads are Nosler 140 BT's in Win cases, Fed 210M primers and 43.5gr Varget. Accuracy loads are WIn cases, Fed 210M primers, 130gr SMK's with Varget running from 43.2 to 44 grains,Not much difference in this range). All of these function fine in my chambers, a Browning A-bolt and a Savage with custom SSS barrel), but suggest you pressure test starting lower own in your chamber. Mine also like a "jump" of .017-.020" to lands.

Good luck with your load.
Elkbane

 

[hvybarrel]

You might try seating off the lands .005 - .010. That is where I have had my best results.

 

[BillK]

I don't know about you guys but I always use a magnum primer with ball type powders. I have always had trouble with regular primers with ball powder. I have always had great success with magnum primers and ball powder.

 

[AndyW]

Thanks for the advice guys!