Call Tom Weimann at Backwoods Outfitters (717-684-2017) in Columbia, PA.
Columbia is the next town over from Lancaster. I am sure he will know all the places to shoot around Lancaster.
Tom's shop is small and great - if he doesn't have it he will get it for you - with great prices too. I would suggest that if you want/need anything give him a call a week or so before your visit - he will give you a price, and if you like it he will be sure to have it waiting when you get into town.
I was there yesterday (over an hour drive for me). Picked up a Trijicon scope and a Laser Genetics laser for a hunting trip to the UK. Saved a small fortune.
Good luck with finding clubs in Lancaster County that shoot ATA. You'll find plenty of places to shoot practice but very little ATA register.
Palmyra, Southern Lancaster and Conewago located in Elizabethtown are the only three that shoot any kind of register shooting on a very limited basis.
My two favorite places to shoot in that area would by Palmyra and Columbia Fish and Game. Palmyra is probably the most ATA oriented. Columbia has good membership base and a good turn out of shooters on their Wednesday night practices.
Listed are the trap clubs that I have attended the most during the last four years I worked in Lancaster county.
Conewago Rod and Gun located in Elizabethtown,
Columbia Fish and Game,
I never had the chance to shoot at Southern Lancaster. Hopefully some day I'll make it down. With working in the Lititz area the other clubs are just a little easier to drive to
If all goes as planned we will be shooting registered targets, at Southern Lancaster County Farmers Sportsmen (aka Quarryville)on Tuesday nights starting April 26. Until then we will be shooting practice on Tuesdays from 1:30 to 8:30
New Holland GC outside New Holland 17557. They shoot big 50 on Wed mornings in Spring and after the state shoot into fall. They also run a few ATA shoots during the year. I think it is on Peters Road, east and south of the town.