As an option you can add this to cart and send in your barrel along with your trigger job. By sending in your barrel or adding this to your new barrel purchase, we can perform some basic service, cleaning and replace the locking bolt spring with our HD Bellm, you can actually hear the difference it makes when you close your barrel. Changing out this spring is not difficult if you know what you are doing, but do it wrong and you can break locking bolts, slotted roll pins, etc. Don't take a chance, let the pros take care of it for you. Spotting a potential problem is difficult if you don't know what to look for. My trained eyes will look over your barrel carefully, I'll check the lockup before and after the spring change verifying correct engagement. If you purchase an oversized hinge pin, I can perform a fitting and installation. I will also make suggestions based on the barrel and it's usage for barrel tuning. Please do not ship with the scope, we prefer the scope and rings be removed as well as any accessories added. It's ok to ship the barrel with receiver, just be sure to package well and insure just in case.