Tips and Tricks
Tips and Tricks:
On this page, we are going to look at some ways to optimize the GFD AR-17HMR upper to your specific lower.
First, let me say what it is and what it isn't.
We have designed the upper receiver with the gas system to operate on a wide variety of lower receiver setups. We have seen anything from the Novenske Laru ilk; to polymer 80% lowers made with a mildly sharp Dremel tool- freehand. Brand new out the box, to the truck gun that has been handed down from cousin to cousin. Some people are decidedly meticulous in cleaning and oiling, others are content to run a patch down the bore annually if they remember it.
We do a good job, with most of our uppers working out of the box. However, sometimes some tweaking is in order.
One thing you can do is make sure the bolt is well oiled when new. We have attempted to make this an accurate system as most targets are going to be small and field accuracy is necessary for the intended task. We have kept tolerances fairly tight for this purpose. So some break-in is necessary. We are looking at some of the new Nickle Boron, Black Nitride coating on the market and have them out in the field with good results. Just use a light oil like CLP, Rem oil, or similar. Once things are working just keep things lightly oiled like you would on normal firearms. By the way, it is not recommended you lubricate the cases of ammunition. It is not necessary and promotes dirt in the chamber. You should have things running in the first 50 rounds or so.
Perhaps, after breaking in your weapon is still short cycling. Many things can influence this- different triggers, hammer spring rates, small variances in manufacturing tolerances between mil-spec parts, tight or loose fitting buffer tube, variances in ammunition -even from lot to lot.
Most of these issues can be addressed by clipping a few coils off of the buffer spring. Start with 2 and go up to 5 or so to balance the spring weight with the individual system.
Another check is to make sure the gas tube is aligned with the gas key in the bolt. To do this remove the bolt and charging handle. Remove the locking bearings and insert the bolt without the rollers in place, there should be little friction between the gas key and gas tube as you slide into battery. This is especially important if you have changed hand-guards or removed the gas block.
Make sure the locking cups on the side of the receiver are tight. Locktight in place if they are loose.
If it still isn’t running like a sewing machine. Get in touch with GFD inc.
I hope this helps.