Just Released.....MCARBO AR-15 Trigger Spring Kit! DIY 10-15 minute AR-15 Trigger Job that will give your AR-15 a smooth and crisp 4 pound trigger without compromising the reliability of your AR-15. This AR-15 Trigger Spring Upgrade is the only one of it's kind in this price range that will reliably shoot all types of civilian and military grade ammunition. Making it the best and most reliable AR-15 Trigger Spring Kit on the market. Click here to check out the new MCARBO AR-15 Trigger Spring Kit!