New rifle not cycling correctly

[Rickc]

So I'm finally getting around again to try and figure this out. I'm going to change my buffer to see if that fixes the problem. My question are:

Can I put my buddies buffer which weighs 5.1 oz and is 6" long in my lower which is collapsible with a 10.5 inch spring?

Can I put any weight and length buffer in my lower with out changing the spring and tube and stock till I find which weight works best? I'm gonna go head and say this is a noob question.

FYI: the buffer I currently use is a standard 3oz.

No you can't put.a rifle length buffer in a carbine buffer tube.

Yes you can put.a heavier buffer in your carbine without changing the spring. Most will recommend an h2 buffer with a grendel. This will slow down the cycling rate. Could be it is cycling too fast to pick up the next round

Another possible problem is.the way the mag is fitting.in the.mag well. It.could be.sitting a little low. Why not take the.lower it.works.with and with the bolt.locked.back insert a mag.and see.how the.round is sitting in relation to the feed.ramps and the back of.the mag where the bolt is going.to pick up the next round. Compare that to your non-functioning lower.