Someone have try (.264) 155gr Sierra match king on 6,5x55??
I had try with 142 SMK with 43gr of N160 at 329m (300y) (with my Sako 75 Varmint) ONLY with tripod my group was 5 shot in 1,57 inch.
With 155gr SMK i can do better? I gain more accuracy? Any proof or comment are welcome.

That is better accuracy that I get with my 6.5x55s.

But I can comiserate with you not wanting to put out $110 for a package of 500 bullets to see if they work in your rifle.

Those 155 gr bullets are made for 8" twist barrels. Is that what you have?

Yes my barrel twist is 1:8

FWIW, most of the long range guys are using 139 - 142 grain bullets. The 155s have a lower BC. I would avoid them just because most everyone that tries them goes back to the proven match bullet weight.

Martindog

You didn't mention which rifle you had. Mine is a Remington 700 Classic in 6.5x55 with a 1 in 9" twist. Bullet selection poses some dilemmas here. For example, I shoot the Sierra 85gr HP as well as the Sierra 160gr SPSP into .89" groups (5 at 100yds.). In other words both extremes shoot the same size groups. That baffles me, but I'm happy about it. Both the Sierra 140gr. SBT and the 142gr. HPBT Match do poorly, about 1.1" yet the Lapua Scenar 139gr. HP prints around .656". It's the only bullet in that range that's notable. In fact, the two best shooting bullets from this rifle are Lapua Scenars. the 108gr. HP prints .533" and the 123gr. HP prints .485". I use other supposedly accurate bullets at the range, but with less than stellar results.
These include the Nosler Bal Tips in 100 and 120gr., Sierra 120gr HPBT Match. All 3 group around .8". I also get .8" from the Hornady 129gr. PSP. So, in summary, the 3 Lapua bullets are the most accurate. All three are pushed along by VihtaVouri 550 powder. It seems to be a winning combination. Don't ask what the max OAL is. I still haven't reached it. Best wishes.

Cal - Montreal

Fellow silhouette shooters who use 6.5x55 use 155gn pills for rams and the knockdown rate is pretty impressive, probably from all the ice they pickup as they re-enter the atmosphere. Only kidding about the ice. But the trajectory is much more rainbowed than 140gn pills, more like the 180gn+ 308s.

Hornaday 140's with re 22 have shot well for me in an old oberndorf sporterized 6.5x55 mouse rifle. Shoots well under an inch for 3 rounds.What are you hunting with it? Good hunting. "D"

I use 140grs SCENARs and it works well for 450m headshots on IDPA targets, I thing it is the best possible target bullet on the market....