Consistent ammo comes from Eley, RWS and Lapua.
They all make ammo that has a lot number that means something.
The quality of their tested ammo relates to accuracy and within that lot is repeatable.
Their ammunition falls into three categories . . . good, better and best and with that comes increases in price.
Their testing procedures identify the best within their testing procedures.
Eley produces Match grades identified as TENEX, MATCH and TEAM. Their testing rates TENEX as the best.
The lot numbers on the box identifies a particular production line and the lot number produced within that year.
A lot number might have 30,000 - 35,000 rounds produced with a single billet of lead.
It is possible that progressive lots from a particular line would produce TENEX (06-218), MATCH (06-219) and TEAM (06-220).
What ELEY identified as TENEX shot to their standard in their four test rifles; With MATCH only three rifles shot that lot to their standard and less that that was TEAM. This is not to say that TEAM wold not perform better in your rifle.
A test conducted about four years ago identified a lot with a better average in my rifle. Four similar lots were tested without the tuner. Over time I have purchased between 10 and 15 thousand rounds of this lot number only because my supplier is special.
Once the first order was received, the tuner was re-installed and setting established. While some have settings for 50 yards and another for 100 Metres, I have not gone to that extent.
Tuners should make good ammo better, better ammo better and the best better there are no guarantees.
The theory behind tuners has merit IMO but only one is installed on one of by rifles . . . a Remington 40XB, with a Lilja barrel, a 2 oz trigger set at 4 oz, a MacMillan BR Stock and a Leupold Competition 45 x 45 scope. It can be beat but for the rest of my life it will have to do.