So today I just started putting some new parts in my G&P M4. I put in a Lonex Hop Up Chamber, Lonex Soft bucking and a madbull 6.03 black python version II. I had to trim down the side tabs on the hop up chamber as they were too wide to fit in the upper receiver of my M4. I got everything together finally and went out to shoot and I wasn't really seeing much of an improvement in range, but a bit of an improvement in accuracy. There are some strange things now that are happening with the gun. First off being when I reassemble the receiver I have to pull down with a decent amount of force for the chamber to fit against the nozzle. In return, when I remove the upper receiver now, the inner barrel and hop up chamber stay attached to the gearbox as shown in the pictures below. In order to get the chamber out I have to wiggle it around. Is this sitting too tight on the nozzle? Also, one thing I noticed is I am getting lower FPS. I have no chronograph to show exactly how much, but I was at an OP on Saturday and the gun shot around 415-425. It had no problem piercing the bottom of a Coca-Cola can. However now it can pierce through both sides of the can (I know that is att least 280 as my TM FAMAS could do that) but it no longer pierces the bottom of the can, but leaves a decent sized dent. If anyone could give me some insight if something is off here, that would be great. Thanks!