Starting Point For Lands "Jump" on an AR15/6.5 Grendel

[RLinNH]

I have been loading for my 6.5 Grendel for a bit now. I have only focused on hunting cartridges though. So, as I have been ignoring this rifle for way to long. I want to start punching paper with her. With the appropriate bullets. Going to start off with some Hornady 123 Grainers. My question is this, as I am fairly new to the AR Platform precision game(all of my long distance precision guns are bolt action). As a starting point, what as general rule of thumb for a jump to the lands in an AR Chasis? And yes, I know that every gun has it's own fingerprint. Just looking for a comfortable starting point...

 

[FredHammer]

General rule is seat to mag length and then reduce COL to find precision.

 

[DHDeal]

As mentioned, magazine length will probably force your OAL. If you have some ability, you can get a PRI 6.8 magazine and cut and file the front so you can increase your ability to run a longer OAL. That may not be necessary however.

I have been shooting and loading the Grendel for many years and the 123's can shoot very well. I will put a 120 SMK or my favorite Grendel bullet of all, a Berger 120 BT against any 123 for accuracy. The 120's mentioned will allow you to get much closer to the lands which will give you more options in seating depth.

I do not find a Grendel hard to tune. A 120 or 123 grain bullet, 450 primer (or Wolf SRM) and 8208, LeverRevolution, or 2520 with a close to maximum load, and .025"ish off of lands should show something decent.

Just my experience but the 2 120 grain bullets I mentioned have always been more accurate than any others. That said, I have good luck with 107/108 grain bullets (exclusively using 8208) and 123 SMK or Scenar also shoot well. Not hard to find a good load IMO.