MLC Posted July 24, 2017 Report Share Posted July 24, 2017 Good people of the forums, I built a 308 using mostly Aero Precision parts (full parts list below). I put a box of regular Federal 308 through it and the buffer face is scratched where the bcg touches the buffer and where the buffer retaining pin hits the buffer face. The bolt face is a bit discolored too. It doesn't feel like a physical deformation, but it looks like the brass on the back of the round rubbed coloring onto the bolt face. I talked to Aero Precision, who suggested the gun is overgassed and I need to use a 3.8 oz buffer and standard 308 spring. I called Luth-AR, who also suggested its overgassed. While I don't necessarily disagree with the diagnosis as I'm no expert, but the remedy sounds weird given that I'm using a 5.2 oz buffer and the spring that came with the kit. Any suggestions, to include "quit being a worry wort" or "do what they said" anyone has would be greatly appreciated. Lower: Aero Precision LPK: Aero Precision Buffer, Spring, Tube and Stock: Luth-AR MB1 kit for 308 Upper: Aero Precision BCG: Aero Precision phosphate bcg Barrel: 16" Aero Precision with mid length gas tube Gas Block: Brownells .750 low profile Gas Tube: Brownells mid length gas tube Muzzle Device: Wilson Combat Q Comp Quote Link to comment Share on other sites More sharing options...
sketch Posted July 25, 2017 Report Share Posted July 25, 2017 that seem prety dry from the pics.. ?? for the buffer it looks like it ate some paint.. on entry nothing in the bcg that strikes the middle on the buffer unles major shifting.. when you close your upper on the lower the upper scrapes the buffer. common on tight tolerance. whats your regular load of federal and where did your empty brass land from the shooting position? did you hit the target? im just thinking.. no expert.. they are here and so are you! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 25, 2017 Report Share Posted July 25, 2017 (edited) The Marks on your Buffer seem to be the BCG scraping the finish off it upon closing the Upper onto the Lower , as said above . Your Buffer should never touch the Retaining Pin when Rifle fully assembled ( the BCG pushes it back upon assembly ) , only when Upper Receiver is pivoted up off the Lower will the Buffer come to rest on that retaining Pin . You can file a very slight angle at the very bottom of the Pin Channel on the back Of the Bolt Carrier or just try to de-burr it to take the sharp edge off , but I see nothing abnormal , except that marking , run her wet to break in . Some finishes on these friction components will wear off quickly sometimes . Has the Head Space been checked ? Edited July 25, 2017 by survivalshop Quote Link to comment Share on other sites More sharing options...
MLC Posted July 25, 2017 Author Report Share Posted July 25, 2017 I lubed it up the same way I do my AR-15, but I'll be more liberal with the CLP next time. i was shooting indoors so couldn't really say where the brass was going, but I hit the target pretty well. The ammo in question was Federal Premium 168 grain FMJ. Just regular old red box I bought at the range because I'm dumb and didn't get any prior. i headspaced it using a go/no go gauge set and it is with in spec. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 25, 2017 Report Share Posted July 25, 2017 If you look at the orientation of your Bolt , the marks are in line with the feeding portion of the Bolt , where they contact the Base of the case . If its a Nitrated Bolt , that should just brush off . I don't think I have ever seen marks like that from a Bolt Carrier on a Buffer face , normally , as you know , the Buffer face will have a ring on it from the BC , but that would be with a higher round count number . Here is one from my 308 Carbine & has many thousands of rounds through it , don't see any BC markings like yours , replaced this one because I got a new one to test & thats in there now . This one is still serviceable . It is a real DPMS Buffer . Quote Link to comment Share on other sites More sharing options...
MLC Posted July 26, 2017 Author Report Share Posted July 26, 2017 That is good to hear about the bolt face. I'll give it a more thorough scrubbing when I get back to the home state. Could a too long buffer spring be the culprit? I'm about 80% certain I measured it when I built the gun but I can re measure it. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 26, 2017 Report Share Posted July 26, 2017 Not sure , you will have to count the coils & measure the length , the marks on your Buffer Face have to be from the Pin Channel on the end of the Bolt Carrier , looks like they beveled all around the back ,but not where the Channel is , thats whats leaving those marks on the Buffer Face. Quote Link to comment Share on other sites More sharing options...
MLC Posted July 26, 2017 Author Report Share Posted July 26, 2017 I talked to my wife about cutting our vacation short so I could check this and in a fit of unreasonable obstanance, she had the audacity to say no. However, I will count coils and measure when we get back. I appreciate the explanation about the source of the vertical scrape marks. My big concern was the marks where the retaining pin hits the buffer face and how to make that stop happening if it needs to stop. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 26, 2017 Report Share Posted July 26, 2017 I hope its not hitting that Retention Pin when assembled , that would show there is an issue with Receiver fitment . If the first photo in your series is of the BCG in full battery , like it would be if a Cartridge is fully chambered & ready to fire , the BCG will push the Buffer off that Retention Pin & its only hitting when the Upper receiver is Shot gunned for cleaning & inspection .Easy to see when you close the Upper Receiver onto the Lower Receiver . When the Buffer hits that Retention Pin , it usually bends or breaks it , & yes we have seen that here , but not with Aero Receivers . Quote Link to comment Share on other sites More sharing options...
sketch Posted July 27, 2017 Report Share Posted July 27, 2017 11 hours ago, MLC said: I talked to my wife about cutting our vacation short so I could check this and in a fit of unreasonable obstanance, she had the audacity to say no. However, I will count coils and measure when we get back. you dog you.. you have the bug lol. happy wife, happy ( shooting) life . shes a keeper! we will be here when you return! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 27, 2017 Report Share Posted July 27, 2017 9 hours ago, survivalshop said: I hope its not hitting that Retention Pin when assembled , that would show there is an issue with Receiver fitment . That's not it, brother - those instances will always look like this: Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 27, 2017 Report Share Posted July 27, 2017 Tubb Carrier Weight System fixes that, just with the CWS body, and no weight in it. If that was the issue. It adds 0.080" length to the back of the BCG, pushing that buffer off the retaining pin when the receivers are closed. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 27, 2017 Report Share Posted July 27, 2017 2 hours ago, 98Z5V said: That's not it, brother - those instances will always look like this: No doubt there are different levels of how hard the Buffer hits , we have seen here , on this forum, them bending & breaking , But the photos you show are correct on how they mark the Buffer . I can't remember the one Receiver manufacturer that we had several issues like this , it was many years ago . Quote Link to comment Share on other sites More sharing options...
MLC Posted July 27, 2017 Author Report Share Posted July 27, 2017 5 hours ago, sketch said: you dog you.. you have the bug lol. happy wife, happy ( shooting) life . shes a keeper! we will be here when you return! Lol! I do indeed have the bug. Putting that thing together was a hoot! Shooting it was just as good. It sounds like I'm worried about nothing, which is always better than the alternative. If it's safe to shoot I'll do so after double checking that everything measures to spec. Here's a question out of pure academic curiosity. Those pics of the chewed up buffers have those marks all the way around. Are the buffers rotating in the tube during shooting? i appreciate all the help and I'll let you know what happens! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 27, 2017 Report Share Posted July 27, 2017 5 hours ago, MLC said: Are the buffers rotating in the tube during shooting? Yes ,they normally do . Quote Link to comment Share on other sites More sharing options...
MLC Posted July 30, 2017 Author Report Share Posted July 30, 2017 I'm back and did some checking and measuring. What I measured is below. The BCG is 8.75" (minus the bolt) The buffer is 5 3/16 and weighs 5 1/4 oz Spring is 38 coils and 12.25" Buffer tube length(internal) is 9.75" The bottom of the bcg where the pin channel is felt like there was a small bur, which explains the scraping on the buffer face. Everything seems to measure to spec according to manufacturer websites. I took a close look at the retaining pin and it isn't bent and doesn't look damaged. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 30, 2017 Report Share Posted July 30, 2017 (edited) 34 minutes ago, MLC said: The buffer is 5 3/16 and weighs 5 1/4 oz Spring is 38 coils and 12.25" Buffer tube length(internal) is 9.75" Buffer length is correct. 5.200". Buffer internal depth is correct for a Rifle Receiver Extension. That spring is off - the coil count is somewhere between 308 rifle and AR15 rifle coil counts, and the length is short. AR15 Rifle springs are 12.75" - longer than what you have. AR10 springs are another inch longer, over that. What you're referencing almost looks like an AR15 Carbine spring, just an inch longer... IMHO, that part is suspect, and if it were mine, I replace it with a Genuine Armalite AR10 spring, part number EA1095, and see what you get... Reference material I use - click the pic, it gets huge... I can't see that causing the issue you're seeing there, unless that spring is weak and the BCG is slamming the crap out of that buffer once it's in the back of the extension... Edited July 30, 2017 by 98Z5V Quote Link to comment Share on other sites More sharing options...
MLC Posted July 31, 2017 Author Report Share Posted July 31, 2017 I don't see the spring being the issue either, and I'm beginning to wonder if there is one or if I'm being a worry wort. The spring is to spec according to LuthAR, but it could be weak. Is there a way to tell beyond looking at the back of the buffer? It looks fine, by the way. On a second note, you mentioned the Armalite spring. My theory is there's no such thing as Armalite vs DPMS standards for these springs. Is that correct? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 31, 2017 Report Share Posted July 31, 2017 10 minutes ago, MLC said: My theory is there's no such thing as Armalite vs DPMS standards for these springs. Is that correct? They have different Spring spec's . I really don't see what your issue is , down sizing to a lower weight Buffer is not correct if over gassed . How many rounds have been shot through this Rifle ? you will get all kinds of marks on both the Buffer & Bolt when rifle is fired . Any malfunctions ? FTF FTE ? Quote Link to comment Share on other sites More sharing options...
MLC Posted July 31, 2017 Author Report Share Posted July 31, 2017 At first the "issue" was the marks on the buffer looked weird to me, and I was (overly it seems) concerned about the marks where the retaining pin hit the buffer face. Only 20 rounds thus far, no FTF or FTE. The idea of it being overgassed came from the folks at LuthAR when I called them asking if this was normal. When I got a hold of AP they said the same thing. I didn't think a lighter buffer sounded right either. That's why I came to the experts. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 1, 2017 Report Share Posted August 1, 2017 The Armalite EA1095 spring - what are you gonna lose, really? You ever hear about anybody using the Armalite spring, and it causes an issue?... Never... Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 1, 2017 Report Share Posted August 1, 2017 3 hours ago, 98Z5V said: The Armalite EA1095 spring - what are you gonna lose, really? You ever hear about anybody using the Armalite spring, and it causes an issue?... Never... He doesn't have any issues with the Buffer Spring he has , its why I asked if he had malfunctions. His concerns of the marks on the Buffer , are not a concern , except for the Burr's on the BC channel making them . No idea why both those manufacturers gave that kind of info . Damn Armalite pushers , you guys won't be satisfied till all 308AR's are made by Armalite Quote Link to comment Share on other sites More sharing options...
MLC Posted August 1, 2017 Author Report Share Posted August 1, 2017 Sounds to me like maybe I've been worried about nothing. I guess the best thing to do is keep shooting it. Purely for the purposes of observation and scientific study, of course. I really do appreciate all the great information, even though some of it MAY have possibly been Armalite leaning. ;) Quote Link to comment Share on other sites More sharing options...
unforgiven Posted August 1, 2017 Report Share Posted August 1, 2017 I replaced Aero's recoil system with Armalite tube,spring ,buffer and my M5 has run without issue. Quote Link to comment Share on other sites More sharing options...
MLC Posted August 1, 2017 Author Report Share Posted August 1, 2017 What kind of issues were you having with the Aero recoil system? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.