I hate to say it as you have this brand new rifle and all but you knew going in you would have to fix the ramps so......
What is wrong with these guys at STAG:evil: A rifle barrel extension and extended M4 ramped receiver, even if super shallow, is bad mojo for a AR to work properly This is especially true considering they say they do not use M4 ramped anything as I understand it. Yet here we have a shallow M4 receiver with a standard barrel extension.
As it's sometimes hard to completely visualize what something is suppose to look like I have posted pics below of different examples:
HERE IS PROPER M4 RAMPS AND HOW THEY SHOULD LINE UP. THIS IS ABOUT PERFECT. Many typically may be off a tiny bit and this would be perfectly normal but that's all. The Extension should never create a lip inside the receiver ramp. We will consider the one right below the gold standard. This is what would be considered perfectly matched up ramps
Here is an example of what a proper Rifle Ramp setup looks like. Standard /Rifle Barrel and Receiver Extension. It has no ramps on the receiver face and the barrel extension ramps meet up nicely with the receiver. This is what is considered OK for 5.56 rifle length AR system but not for anything shorter and the rifle length would also benefit from the extended ramps of the M4 spec. These are an absolute no go for the 6.8 as it needs deeper lower ramps because of how the bigger case and bullets line up and travel. Again not good for 6.8 but still better than what you have shown above. As can be seen they look nothing like what Mattro posted of his current one. Again this is not what you want a 6.8 to be but is an example of a proper rifle extension setup
Number 2 THIS A STAG 6.8 FROM ABOUT MID 2007 BTW
Now here is a receiver with very shallow ramps with a M4 *extended ramp)barrel extension. This is close to the same ramps your receiver has but your barrel has the rifle or standard barrel extension not the M4 BIG issue. Would have been even worse if the receiver had true proper M4 ramps which are deeper.
Now here is Mattro he has posted of his new STAG 7. As can be obviously been seen this is not even close to the way the STAG in picture number 2. This is a combo with the receiver ramps of number 3 (very shallow M4) with a barrel extensions like number 2 ( rifle or standard) As you can see the barrel ramps as they are meant to come to a tip right at the flat receiver face end up being inside the outside edges of the admittedly narrow and poor attempt at M4 ramps on there receiver. This makes a great place for the bullets and case mouths to get hung up. They are already having issues as they are going to hit before this on the receiver face as the receiver ramps are still to shallow. But if/when they make it to the ramps they still stand a good chance of being jammed or damaged further. You can clearly see how a bullet tip could get caught under the barrel ramp as it tires to follow the receiver ramp up or how it could catch the case lip of the mouth and or shave the bullet on that sharp edge, If slightly off to one side it could run into the barrel edge and get cocked in the extension. The only thing that could have made it worse is if the receiver had had proper deeper ramps the ledge would have been even worse. Funny thing is it may function OK with some of the different bullets depending on how a particular magazine lines up etc. but it's universally a bad mismatch in any AR in any caliber.
While STAG might be able to put out an argument that rifle ramps might be fine in there tests even though we have tons of evidence otherwise. There is no way that any knowledgeable person could say that obvious miss match is OK with a straight face. If they did I would run from any gun built by that person as the obviously do not know much of anything about how a gun is suppose to be built. It doesn't meet any spec like that.
What is need to fix this is: get a round file or Dremel with a cone shaped tip grinding stone end. Place it in the barrel extension ramp to see how it fills it. Find one that the lower wider part of the stone fits snug in the wide part of the ramp in the barrel extension. Start by grinding out the bottom part of the barrel extension so it matches up with the outside ends of those shallow receiver ramps. Once you have then making sure to keep the same outward angle of the ramps stat to draw them downward so it makes the ramps in the receiver deeper and brings the beginning edge down farther down the receiver face. You want to make it look like picture number 1. Once you have it down low enough make sure to get the barrel extensions ramp to match up by keeping the same angle as the receiver ramp and working the barrel ramps so the outside edges match up perfectly as does the angle of the bottom inside of ramps themselves. Hope that sort of makes sense. Just remember go very slow. You can always take off more as needed and you are only doing one gun. Once its off its off and you will have the make them even lower or deeper. Once you get them just right get some flitz or 800 or higher grti polish and using a dremel buffing wheel bring them to a mirror shine and slick smooth. The whole thing for a first timer will not even take an hour it may only take 10 mins all depends on your pace. Just always error on the side of not going to far.
Here are some other pic of ramps and how them can be slightly off or on. Now do not go and expect every AR you see outside of true customs to be perfectly melded together but they should not be off to an extreme when you could look at it and see a edge coming about a 1/4 of the way into the others ramp. They should be fairly close with only being slightly off. This is a reason why on my personal ARs and when I do customs ones I tend to use non M4 receivers and then cut them to match the barrel ramps perfectly and then take them to a mirror finish:
Good alignment but inside has a slightly different angle and comes down to point rather quick but still OK even if a bit shallow. The right side one does seem to be a tad off on the right edge but, it would likely not be much of an issue and would be every easy to fix.
Here is an example of what appears to be good ramps on both, when apart, but when put together they do not match up perfectly. They are somewhat misaligned as can be seen where they meet on the edges. This is normally not an issue and can happen at no fault of the assembler just simply specs of the parts or how the alignment pin hole was drilled on the extension. A couple of swipes with a round file would have melted them together.
Near perfect alignment
These are misaligned but still what one might see but I would personally fix with a couple of strokes of the file and polish as its just enough I would not want to chance it. The easiest to fix are ones like this as you already have the angels and size you are only touching it up. Just about anyone short of someone with no mechanical skills at all could do.
This one as posted above it almost like not making them. They are Ok on matching up/ Well at least the left side is the right side is a bit off still not too bad but very very shallow. For a 6.8 I would deepen and bring them down farther into the receiver as well as clean up the right side to match it up better.
What is interesting about all of this is that it does mean STAG does have access to CMT's M4 ramped, even if shallow cut, receivers. But rather than do something positive with it they are matching it up with a barrel with a rifle extension. If this is what most have been getting as of late it is no wonder there are so many reports of feeding an erratic accuracy issues with these. STAG gets mini M4 ramps and still FUBAR's it regardless.:roll:
Honestly I have heard good things about STAG CS on here so I would give them a cal. First ask if STAG uses Extended M4 ramped receivers on their uppers. Then send them the pics and ask them how you then ended up getting M4 ramped receiver and a rifle/standard ramped barrel extension. I think I would not send it in to be swapped out unless they say they are now using M4 ramps on both and will replace it for you with no delay. One-two week turn around max. Otherwise it will be no better as you will still have to cut the ramps. At least you have a small start guide like it is but only if you are going to do it. If you do not plan to cut the ramps then I would get it replaced with the correct specs rifle to rifle setup.