Bear Creek Uppers??

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KenC52
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Re: Bear Creek Uppers??

Post by KenC52 » Tue Nov 03, 2020 3:28 am

Called BCA today and they suggested it might a problem with the bolt. Emailed me a pre-paid UPS return label and said they would have one of their gunsmiths fix it. They reminded me that it has a lifetime warranty. If it all works out you can't ask for much more.

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dellet
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Re: Bear Creek Uppers??

Post by dellet » Tue Nov 03, 2020 10:24 am

All the signs of an out of spec chamber.

You could try a known low pressure sub load, but even sub loads can have enough pressure in a bad chamber to cause problems.

Photos and some measurements of the brass would be helpful.
300 Blackout, not just for sub-sonics.

KenC52
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Re: Bear Creek Uppers??

Post by KenC52 » Mon Nov 16, 2020 6:35 pm

Got an email from BCA last Thursday. Said their "technician" tested the upper using PPU steel cased ammo and was unable to duplicate my problem so the are returning the upper to me (should be here tomorrow). I wonder why they did not try some brass cased ammo? I understand that steel cases are not as malleable as brass ones and do not seal as well or as rapidly. I'm certainly not going to restrict myself to steel cased ammo. Plan to video tape my test firing when it gets here. If the problem persists (using my 3 different lowers and 3 different premium ammo) I will send them the upper and the video and request a new upper or a refund. Still can't believe the didn't try brass cased ammo.

KenC52
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Re: Bear Creek Uppers??

Post by KenC52 » Thu Nov 19, 2020 3:37 pm

Got the upper back from BCA and tested the upper yesterday. Tried 2 rounds each of 4 different types of brass cased ammo:
1 - Magtech 123 grain FMJ
2- Hornady 110 grain V-Max
3 - Sig Sauer 120 Grain Elite
4 - HSM - 125 Grain Pro Hunter

All functioned properly, including locking back the bolt on an empty chamber. 
There were some signs of high pressure however that are a bit concerning.
1 - All the brass ejected to the 1:00 or 2:00 position in front of the shooting stand
2- There were extractor gouges on the rim of the cases
3 - There were ejector marks on the base of the cases
4 - The primers were significantly cratered, to the point that you could feel a sharp ridge around the circumference of the craters
5 - The case mouths were flattened on one side indicating a very violent ejection
6 - Three of the cases had weird dents on the side of the neck

Not sure if this represents a dangerous level of pressure or not. These are all premier brands of ammo and should be well within the pressure specs for 300 Blackout. And I have no idea of a solution for the situation if it is indeed a high pressure problem.
Took some photos with my phone camera but can't figure out how to upload them here.

20X11
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Re: Bear Creek Uppers??

Post by 20X11 » Thu Nov 19, 2020 5:13 pm

KenC52 wrote:
Thu Nov 19, 2020 3:37 pm
Got the upper back from BCA and tested the upper yesterday. Tried 2 rounds each of 4 different types of brass cased ammo:
1 - Magtech 123 grain FMJ
2- Hornady 110 grain V-Max
3 - Sig Sauer 120 Grain Elite
4 - HSM - 125 Grain Pro Hunter

All functioned properly, including locking back the bolt on an empty chamber. 
There were some signs of high pressure however that are a bit concerning.
1 - All the brass ejected to the 1:00 or 2:00 position in front of the shooting stand Try next heavier buffer
2- There were extractor gouges on the rim of the cases Try next heavier buffer
3 - There were ejector marks on the base of the cases Try next heavier buffer
4 - The primers were significantly cratered, to the point that you could feel a sharp ridge around the circumference of the craters
5 - The case mouths were flattened on one side indicating a very violent ejection Normal
6 - Three of the cases had weird dents on the side of the neck Gouges from feed ramps- normal

Not sure if this represents a dangerous level of pressure or not. These are all premier brands of ammo and should be well within the pressure specs for 300 Blackout. And I have no idea of a solution for the situation if it is indeed a high pressure problem.
Took some photos with my phone camera but can't figure out how to upload them here.

KenC52
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Posts: 8
Joined: Sat Oct 31, 2020 7:16 am

Re: Bear Creek Uppers??

Post by KenC52 » Mon Nov 23, 2020 7:50 pm

Thanks Silent but Deadly.

Your info very helpful. Shared it with BCA and they agreed with your conclusions. I have ordered an H3 buffer from Midway USA which should be here this week. Then between my regular buffer (3 steel weights) and the H3 (3 tungsten weights) I can mix them till it is just right.

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