Im building a 6mm ARC AR15. And I am really excited about the prospects of having it all finished and running smoothly. I was at the range today shooting the first few rounds throo the barrel to break it in before sending it off for nitriding. But ... after sending a round down range the empty case sticks n the chamber. with a bit of extra force I can extract the casing. This happened 12 out of 12 times. On examination of the casings all of them seem to have two “scratches” on the neck parallel to the long axis of the case. Any input would be appreciated.
Those scratches are probably from the round feeding. Did you use a chamber brush to clean the chamber before fireing it?
Take a sharpie marker and color the neck and shoulter of the bullet, hand feed it into the chamber, let the bolt slam home using the bolt catch release.
Now eject the round and take a picture of it showing any marks on the blacked out area of the case and post it. Also tell us more about the ammo, is it factory or reloaded?
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03-07-2021, 03:16 AM (This post was last modified: 03-07-2021, 03:25 AM by Lemonaid.)
Use a bore scope after cleaning with attention to the neck area in the chamber. If there is a gremlin there, careful polishing can sometimes fix it.
Note that the case neck expands after firing and can encounter sharp edges on the way out as the ejector pushes it to one side.
Look for brass color at the sharp spots on the feed ramp edges or elsewhere in the barrel extension.
03-07-2021, 03:22 AM (This post was last modified: 03-07-2021, 03:22 AM by alwie.)
(03-07-2021, 03:16 AM)Lemonaid Wrote: Use a bore scope after cleaning with attention to the neck area in the chamber. If there is a gremlin there, careful polishing can sometimes fix it.
This is a brand new custom barrel, so if I can’t figure it out I will be calling the barrel maker.
Just for fun couple of ideas...
1. In that cycle of load a round with the bcg slamming, don’t shoot but measure it before and after chambering to see if the bullet is pushed back in or scored with lands (ie, sticking in chamber).
2. Do you have a second type of round to try? The 105’s when first released by hornady had a tendency to stick in the chambers b/c hornady sez they loaded them too long, at 2.24 or so... nowadays they load them to 2.200, opinion of some of us on here is that some chambers are actually too short, but no one wants to admit that.
May or may not be linked to your issue but could be part of it somehow.
03-07-2021, 05:38 PM (This post was last modified: 03-07-2021, 05:56 PM by alwie.)
(03-07-2021, 07:43 AM)grayfox Wrote: Just for fun couple of ideas...
1. In that cycle of load a round with the bcg slamming, don’t shoot but measure it before and after chambering to see if the bullet is pushed back in or scored with lands (ie, sticking in chamber).
2. Do you have a second type of round to try? The 105’s when first released by hornady had a tendency to stick in the chambers b/c hornady sez they loaded them too long, at 2.24 or so... nowadays they load them to 2.200, opinion of some of us on here is that some chambers are actually too short, but no one wants to admit that.
May or may not be linked to your issue but could be part of it somehow.
#1 no setback after hard chambering a 105, COL is the same.
#2 The 105s virgin COL = 2.200 measured with calipers
I also have one box of 108s which i will try when i get to the range again.
03-09-2021, 10:14 PM (This post was last modified: 03-09-2021, 11:28 PM by alwie.)
Today I shot the factory 108 Match rounds and had the same problem as with the 105 factory ammo .... case sticks in chamber. Looked more carefully at the spent casings and i think that I have signs of over pressure on all of them .... flat primers and ejector marks on base head.
I didn't see this asked (since I went through similar fun)... is the bolt cycling on firing? if not, my first thought is that you aren't getting enough gas.
I started mine of with the AGB closed and opened a bit at a time to get it to reliably function. Those first rounds with no gas were no fun.
03-10-2021, 06:04 PM (This post was last modified: 03-10-2021, 06:05 PM by alwie.)
(03-10-2021, 05:27 PM)Ihmsa7br Wrote: I didn't see this asked (since I went through similar fun)... is the bolt cycling on firing? if not, my first thought is that you aren't getting enough gas.
I started mine of with the AGB closed and opened a bit at a time to get it to reliably function. Those first rounds with no gas were no fun.
I dont have the gas system connected, no gas block and no gas tube. Was yours sticking with the gas off? I am just breaking it in before sending it out for nitriding.
(03-10-2021, 06:04 PM)alwie Wrote: I dont have the gas system connected, no gas block and no gas tube. Was yours sticking with the gas off? I am just breaking it in before sending it out for nitriding.
If you don't have the gas system connected it can be hard to extract a fired round. I have issues running a side charger 6.5 Grendel without gas and getting them to extract. I did it to see how well it would work till my gas tube in.
(03-10-2021, 05:27 PM)Ihmsa7br Wrote: I didn't see this asked (since I went through similar fun)... is the bolt cycling on firing? if not, my first thought is that you aren't getting enough gas.
I started mine of with the AGB closed and opened a bit at a time to get it to reliably function. Those first rounds with no gas were no fun.
I dont have the gas system connected, no gas block and no gas tube. Was yours sticking with the gas off? I am just breaking it in before sending it out for nitriding.
Yes, I needed to mortar it to get the bolt freed up. once I opened up the GB... it would throw brass farther than my 223. After that, I now have a cut down fishing net to catch my brass for my load development work
09-12-2022, 02:11 AM (This post was last modified: 09-12-2022, 02:12 AM by alwie.)
Panshovevo, I had H&M Blacknitride+™ done on 3 AR barrels. They have ISO certification. I am not sure what method they use, but I am happy with the results.
Thanks Alwie. Much appreciated.
In case you didn’t see my thread, Ballistic Advantage told me an AR barrel couldn’t be treated after assembly of the barrel extension and drilling the gas port. I had emailed info@blacknitride.com and asked their opinion, but never got a response.
I’ll try a different contact. If all else fails, a local guy I did a bunch of consulting and testing for on a greaseless gun project is advertising a surface hardening service that supposedly works on barrels.
09-14-2022, 12:27 AM (This post was last modified: 09-14-2022, 12:27 AM by alwie.)
(09-12-2022, 03:37 AM)Panshovevo Wrote: Thanks Alwie. Much appreciated.
In case you didn’t see my thread, Ballistic Advantage told me an AR barrel couldn’t be treated after assembly of the barrel extension and drilling the gas port. I had emailed info@blacknitride.com and asked their opinion, but never got a response.
I’ll try a different contact. If all else fails, a local guy I did a bunch of consulting and testing for on a greaseless gun project is advertising a surface hardening service that supposedly works on barrels.
Mine where all “assembled” and broken in before I got them nitrided.
Pan, the best contact for technical questions at H&M Metal Processing (BlackNitride.com) is "Bear" or Pat. Though they're busy, they're friendly and knowledgable. H&M's office number is (330) 745-3075.
The deal with nitriding an assembled barrel is that the one metal in the barrel extension and the other metal in the barrel might have different rates of expansion under the extreme heat of the salt bath process. I don't know, exactly, what happens when this happens, but the nitriders recommend against it.
Alwie, sounds like you had your assembled barrel nitrided as a unit and had no problems?
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