I searching many posts on the subject of FTL/cycle issues I came across this fourm and would like to get some feedback on an issue I had on my first time to the range with a new upper assy that I installed and problem experienced. Old upper was shooting just fine but accuracy was not sub MOA I desired. My gun started out from a Armalite rifle mid length gas system and standard rifle stock. Since the front sight was mounted to the barrel and wanted to have my new barrel free floated I have replaced everything on the new upper with the exception of the BCG. The new upper consists of Bear Creek Arsenal 16" carbine length 1:9 twist diamond fluted barrel, Smith Vortex flash hider, and Nordic NC15 extruded upper, carbine length low profile gas block, and Magpul free floated hand guard. As I stated earlier reusing BCG from old upper. Went to the range with it 2 days ago with the following results.
1) Pull charging handle, round racks as it should
2) fires round down range and spent round ejects at about 4 o'clock and about 8 feet away
3)FTL new round, short strokes with the bolt stopped about mid way with next round still in Mag, and fails to lock action back with no rounds in Mag
This was consistent will ever round fired regardless of load, any where from 50g Nosler to 62g SS109. Research has indicated that my issue is with the rifle stock buffer being too heavy to allow rearward travel far enough to be able to rack a new round. I have since replaced only the buffer to a H1 but have not been to the range again to try it out. About the buffer spring, it appears to be in good condition, well lubricated, is 12.25" long with 43 coils. I have a question? I am not wanting to replace the stock with a collapsible carbine stock, assuming the difference between a rifle and carbine springs has only to do with # of coils and length, should this set up fix my cycling problem, or should I install carbine length spring with a block installed inside the buffer tube to account for the differing length springs.
Thanks for any and all thoughts you may offer.
