I'm not an expert by any means, but I'm far from being new to reloading. For whatever reason, a good 6.5x55 load is eluding me. I'm using RL22, remington magnum primers (all I could find), sierra matchkings 142gr, lapua brass, scott parker tuned scale, Forster co-ax press, and Forster ultra dies. My ES is not good at all. I shot yesterday and couldn't group to save my life. Averaging 1.5 moa. No it's not the shooter. I've loaded up 300 wsm and 7 mag and shot sub 0.5 moa. I'm shooting a Savage with a 28" criterion barrel in a bedded stock. My ladder group was kinda crappy to begin with as ES wasn't good then. Found a semi node and shot again. 45.5 gr had an ES of 61, 46.0gr was 29 and shot the best groups, 46.5 was 24 and 47.0 was 6 shooting the worst groups. This was with new lapua brass FL sized set to bump shoulder back 0.002 on once fired brass. Bullet concentricity was 0.002 and neck was 0.005 (I didn't neck turn these). Bullets are about 0.005 off the lands. What am I doing wrong? Is it my reloading, the powder, the primers, what? I know I need to at with seating depth, but will it make that huge of a difference because it never has in the past. Sad thing is, cheap wolf gold ammo that i used to sight in my scope shot better than my reloads!
I also run a 6.5x55 in a factory Tikka Varmint. My load is 47.5gr RL22, Lapua Brass, CCI250 Primers, and 140gr SMK average 2703. The ES (62) and SD (17) are higher than I'd like to see, but it shoots very well at 0.45 MOA. I've been able to narrow those numbers significantly by switching primers and trying different powders. I tested loads that would keep me in the same velocity node(~2750fps).
This method works with almost every bullet I have tried, not just Berger VLD's. Once you find the best seating depth for a given bullet, you can experiment freely with powder and primers. After seating depth, do your normal charge workup. I have found my load in 50 rounds or less every time I have used this method.
Try 37.5 grains of RL-15 under the 142. Not a maximum load by any means, and your velocity should be around 2,600 fps, but it was the standard test load used by Sierra for the 142s for many, many years. Assuming a good lot of bullets, any decently tuned 6.5x55 should shoot bugholes with this combination, no problem.
Nobody has ask this yet. What twist do you have in the barrel? If it is a 1-in-9 there could be your problem. Too slow for those long 142s. Could be your barrel just does not like the 142s or RL22. I have always had great success with the 4350 powders in the Swede. I have shot 45 grs Accurate 4350 with 140 gr Sierra Match, Sierra Game Kings and Hornady Interlock SPP in my M-96 sported Mauser with the 29" barrel and it shoots sub MOA and I average 2850 fps and this is according to Accurate is an under 46000 CUP load. I use Remington cases, Fed 210M primer, OAL 3.050 For a strictly target load for out to 200 yards for my open sight military M-96 Mauser 6.5X55 Swedes 37.8 grs IMR 4895, Rem case, CCI BR2, 140 gr Sierra Match King, OAL 3.050 runs in the 2500s fps but is one tack driving load.
With your load it could be something as simple as changing your primer make. I have had so so loads turn into bug hole shooter loads by just using a different primer.
Ain't getting a new rifle to shoot well fun especially when you can't get the stuff you need to do it with?