So I have a Spikes 16 inch 22lr upper.  My stamps came back and I want to have it chopped.  It doesn't use gas impingement right?  So does it matter how short I chop it?  Anything I need to know?   Im guessing ADCO has done many of these so any advice would be appreciated before I send it off.   I was thinking 10.5 or 11.5 since thats what my 556 will be.   Thanks

Green.