For any application in my opinion.RL23 is probably the best powder for the 280AI, for F-class applications anyway.
I used to use 22 untill 23 came out.Reloader 22 rocks in the 280AI - my guess is that 26 will too. Don't forget H1000. 1-8 twist works well, as do the 175/180g pills.
If you have the synthetic stock, it will flex with some pressure, especially with a bipod! I could run 2 one dollar bills up to the chamber taper and the barrel would touch the 'noodle' stock with slight twisting off the bipod!! Dropped 3 thou brass shim in the lug cavity and used 5 thou on each side just past the lug and staying low!! This raised the barrel about 30 thou at the stock forearm!! The target grouping improved with no strings!!If i can run paper around the barrel. Does it still need opened up?
The barrel channel is not the problem. It is the flexing of the synthetic stock itself. Any downward pressure on the stock, side to side pressure of the stock, or any combination of the two will result in stock/barrel contact at the forearm end. I use the shiming method just in case I want to sell the rifle in its original form!!! Relieving the channel would cause a noticeable gap. The best method for opening the barrel channel is using deep well sockets and sandpaper!!!If you need to open up your barrel channel find somebody with a mill you use a Dremel and it will look like a 1 tooth beaver with a cavity
Why would you put fiber glass in a stock that already flexes??? Fiber glass is designed to absorb energy by flexing!!!!If its a cheap SPS factory stock installing pillars and filling in the voids with fiber glass helps alot if you wanna spend the time, ive done it and they shot well after that.
Like a boat, there are places on the boat repair where polyester resin is used where you need flex!! Other places, like the transom and junctions of other parts require the 10 times stronger and stiffer epoxy resins!!! If you want stiffness and strength, go with epoxies!!! Adding the filings increases stiffness and strength!!!Because it stiffens the forend.
Have you ever installed pillars and filled the voids with fiberglass? Theres a big difference in a gunstock and let's say an application like a boat.
If you haven't done it dont knock it untill you try it. Will other things work like epoxy's absolutely.