KS is spot on with tapered pins. Schleicher pins have no taper whatsoever, just rounded ends. If the spars aren't in perfect alignment, the pins clunk hard into the rear spar. I tapered the pins on my Genesus-2 so that the last 3/4" gently tapered down 1/8". With a little dab of lube on the tapered area and a twisting motion, the taper will force spars into alignment. If your pins go completely through both spars and stick out the rear, then it is safe to taper them in the excess area. You can also make a tapered pin out of aluminum. With the aluminum pin in, raise or lower the fuselage (or tip) to bring the second pin into alignment. With the second pin in, then remove the aluminum pin and insert the steel pin.
JJ