the mag was probably designed for a remington type action. tikkas generally only work well without modification with AICS metal feed lip mags or the factory mag. Plastic AICS mags wont fit unless grinded the feed lips way dont and it kind of becomes pointless
as long as its a new t3x stock it should have two mounting holes that are threaded. you can get ether a Salmon river solution rail or a mountain tactical rail that will attach without modifying the stock
I would suggest not worrying about the rules or details and just get out and shoot some matches. Just worry about having a gun your allow to shoot ie under the speed limit mainly something that is not going to damage seal and is safe to shoot.
The different divisions is real only important at...
I would suggest shooting a couple matches to start and ask as many people about their set ups and if you can shoot them before you start buying. If you are not concerned about buying things twice and have the funds the bravo is a great starting point
take the 243 and find a local club match and go shoot and have a bipod for your rifle. the rest of the stuff you will be able to barrow. let them know you are brand new and they should be very willing to help you out.
by changing out those pieces is not going to amount to much weight savings. the bravo has an aluminum back bone from the tang to the end of the forend.
If you have a tikka the echo is mostly the same but has less aluminum so it weights a little less
I have used it and it works great for dry fire practice.
The big advantage to the roll up poster is that the target array is the same for each. So if you are practicing from different heights you do not have to move your target poster up or down while practicing.
They do sell single target...