Do You Add a BCM Extractor Spring?

[Dr. Bullseye]

Before we go down this rabbit hole. What is your experience level with the AR15 family of weapons? What type of buffer are you using in this rifle? What is the gas port sizing? Who makes the BCG and what spring is in there now? All of these things need to be looked at first.

Show me how to tell these things by looking at the rifle and I will gladly answer you.

[ggammell]

My action spring is 10 3/8 inches long. Again, I looked at the buffer for markings and found none. It has a white plastic type tip at the far end pointing towards me as I shoot but other than that I don't know how to describe it. I do not have 5000 rounds but I do have 2000 rounds on this rifle or more. If I replace the spring first, any recommendations as to brand/type?

BCM uses the stronger spring in their bolts. The BCM BCG is considered to have a good reputation. Another reason I am mentioning replacement is shooting steel rounds. I do not shoot steel but what if I have no other choice someday? I have read a stronger extractor spring helps in that situation.

Stop worrying about the extractor spring. 1:30-2:00 ejection is a function of how fast the BCG is moving when your extractor pulls the casing out of the chamber and the ejector kicks it out of the fun. The fast it moves the more forward the ejection pattern. Hit YouTube for full auto vids and you’ll see that the pattern starts out at 4:00 and ends up at 1:30-2:00 because the BCG is moving so fast.

So you buffer has no markings which means it’s pribably a carbine weighted buffer. You should try an H or H2 buffer. It provides more weight behind the BCG causing it to slow its cycle of operation. You action spring is within spec and there is no need to change it.

[sig1473]

Can you give me a source on this? I talked to a retailer who sold these rifles and Black Forge. They made several models of ARs. This retailer (I forget who this was, it was some time ago) went down the line with metal, chrome, and it all was correct for my rifle.

Per a retailer's site:
BLF BF15 Tier 2 M4 Rifle 5.56mm NATO 16.5 Inch Barrel Flash Hider MBUS Rear Sight Six-Position Collapsible Stock 30 Round Model BF15 Tier 2 M4 Tier 2 models meets all US military standards. Built with standard M4 accessories. Direct gas impingement operating system. Complete upper receiver includes A2 birdcage flash hider (1/2x28 threads) on a 16.5 inch M4 barrel with 1:7 NATO twist rate with an F-Marked A2 front sight post gas block. Barrel is made from 4140 Chromoly steel. 7075 T6 aluminum flat top A3 upper receiver with MilSpec 1913 picatinny rail system featuring M4 feed ramps. MagPul MBUS Gen 2 rear flip-up sight. Double Shield M4 handguard. M16 Auto/AR15 LEO bolt carrier group. Lower receiver: 7075 T6 aluminum forged lower receiver with standard semi-auto lower parts kit featuring a single stage trigger system. Six position collapsible stock with MilSpec buffer tube. Includes one 30-round stainless steel magazine with anti-tilt follower and owners manual. Item Number: BF15-556-T2 UPC Number: 741459537586

[Dr. Bullseye]

Per a retailer's site:
BLF BF15 Tier 2 M4 Rifle 5.56mm NATO 16.5 Inch Barrel Flash Hider MBUS Rear Sight Six-Position Collapsible Stock 30 Round Model BF15 Tier 2 M4 Tier 2 models meets all US military standards. Built with standard M4 accessories. Direct gas impingement operating system. Complete upper receiver includes A2 birdcage flash hider (1/2x28 threads) on a 16.5 inch M4 barrel with 1:7 NATO twist rate with an F-Marked A2 front sight post gas block. Barrel is made from 4140 Chromoly steel. 7075 T6 aluminum flat top A3 upper receiver with MilSpec 1913 picatinny rail system featuring M4 feed ramps. MagPul MBUS Gen 2 rear flip-up sight. Double Shield M4 handguard. M16 Auto/AR15 LEO bolt carrier group. Lower receiver: 7075 T6 aluminum forged lower receiver with standard semi-auto lower parts kit featuring a single stage trigger system. Six position collapsible stock with MilSpec buffer tube. Includes one 30-round stainless steel magazine with anti-tilt follower and owners manual. Item Number: BF15-556-T2 UPC Number: 741459537586

Can you please give me a link to this site?

[Dr. Bullseye]

Stop worrying about the extractor spring. 1:30-2:00 ejection is a function of how fast the BCG is moving when your extractor pulls the casing out of the chamber and the ejector kicks it out of the fun. The fast it moves the more forward the ejection pattern. Hit YouTube for full auto vids and you’ll see that the pattern starts out at 4:00 and ends up at 1:30-2:00 because the BCG is moving so fast.

So you buffer has no markings which means it’s pribably a carbine weighted buffer. You should try an H or H2 buffer. It provides more weight behind the BCG causing it to slow its cycle of operation. You action spring is within spec and there is no need to change it.

Thanks ggammell.

[ggammell]

Thanks ggammell.

You got it man. And listen to Iraqgunz. He might be a little gruff but he is the foremost technical authority on the site. I generally read any thread he posts in to gleam knowledge about how these guns work.

[Dr. Bullseye]

You got it man. And listen to Iraqgunz. He might be a little gruff but he is the foremost technical authority on the site. I generally read any thread he posts in to gleam knowledge about how these guns work.

OK, so looking at the Brownell's Catalog, a standard carbine buffer is 3 oz. From there upward is 3.5, 4.1 and 5.4 oz. I have no scale but Monday I can go to the local USPO and probably talk them into weighing my buffer (just to make sure). Then, if it is 3. oz, I should probably go up to 3.5, correct?

[ggammell]

OK, so looking at the Brownell's Catalog, a standard carbine buffer is 3 oz. From there upward is 3.5, 4.1 and 5.4 oz. I have no scale but Monday I can go to the local USPO and probably talk them into weighing my buffer (just to make sure). Then, if it is 3. oz, I should probably go up to 3.5, correct?

Atleast. Many will tell you H2 is the sweet spot.

If you can find just the buffer weights you can likely add them to your existing buffer with help from YouTube.

https://youtu.be/Bx0ttioOBgA

[Inkslinger]

OK, so looking at the Brownell's Catalog, a standard carbine buffer is 3 oz. From there upward is 3.5, 4.1 and 5.4 oz. I have no scale but Monday I can go to the local USPO and probably talk them into weighing my buffer (just to make sure). Then, if it is 3. oz, I should probably go up to 3.5, correct?

If your buffer has no markings on it, it’s a standard carbine buffer. You should probably be using a H buffer. I would put in the H and stop worrying about ejection patterns.

[SiGfever]

If your buffer has no markings on it, it’s a standard carbine buffer. You should probably be using a H buffer. I would put in the H and stop worrying about ejection patterns.

Agreed, if this is not enough, add the BCM Extractor Spring Upgrade Kit.