Whats In your chamber?

I installed an M4 hop up in it and only modded one piece of the original ACR... I can still install the original hop up if I want, SUCCESS!

cool just got and flat-hopped my 3rd Lonex 70D for my ACR.

I tend to be rather conservative when upgrading my guns. I kept the stock ICS hop-up units (attached to a tight bore barrel)and upgraded the buckings and spacers to Matrix 60 degree (Blue). I've gone to great lengths to improve the air seal in each upper gear box. I've found that this works very well for me. My range and accuracy are improved and the amount of work involved is decreased considerably.

When the gun is new, yes that is a true statement. I'll play with it for awhile to see how well it works stock. I replace the  inner barrel and hop-up bucking first thing, I find These stock ICS parts on the weak side. I look at the air seal next. Depending on the type of play I got the gun for, I'll look at the upper gearbox, if it's for CQC, I'll down grade the spring, If for field use The spring strength will go up. I always check shimming and grease in the lowers, 'cause you never know.