Im shooting a Remington LTR match 308. Im using a Nikon buckmaster 4.5 x 14 with BDCs. im using a standard scope base. Im shooting at 14 power from 100 to 500 yrds. Scope work awsome at these didtances. Problem is when I move to 600 yrds. I have to drop my power down to 4.5. The match Ive been shooting where shooting out to 900 yrds. At 600yrds. at 4.5 im doing fine, but very hard. At 900yrds. target looks like bird shit on stump. Have hit target but not all the time. People have suggested 20 moa rail. Im not familar with this rail or how it will work with the BDC. I could use any help to get me a higher power at 600 and 900 please, using same scope I hope.