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Posted: 4/29/2007 5:25:02 AM EDT
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I have a relatively new (less than 1000 rounds) SBR wearing a CMMG 10.3" SG upper and an AAC M4-2000 suppressor. This week I noticed that the front of the ejection port was developing some scratches, and upon closer inspection brass dings on the delta ring were apparent. I tore down the bolt and checked the ususal suspects. The ejector had full travel with no snags and good tension, and the extractor was good as well. I did notice, however, that the extractor spring had come with a blue insert instead of a black one, but I had installed an "D" ring to increase the tension a bit. I fired Remington 55gr practice ammo, Hornady TAP 60gr, and IMI M855 with and without the can, and all showed the same forward ejection pattern. The M855 wasn't as far forward, but it was still under 45 degrees by a good bit and missed the delta ring by only an inch or so. As an experiment, I replaced the stock extractor spring with a Wolff extra power spring and removed the "D" ring. The problem persisted, however. I then took the stock spring without the "D"ring installed and the problem was somewhat alleviated but I don't know how much I trust a simple stock spring on such a short platform. This is a working gun that I carry daily which is why I immediately added the ring when I bought it. This past week was definately the most that I had shot the rifle since acquiring it a few months back, but the ejection issue is new so something has changed. I say this because the ejection path would have been something I noticed before, and because the rear of the ejection port does show the classic wear on the leading edge of the brass deflector so at one time the brass was going there. Additionally, there was fresh brass transfer there from the school's first day of shooting so the issue is a new one, not just one that I never noticed before. Any help is appreciated. Saleen |
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If the gun is functioning normally beyond that issue, sounds like an ejector weak or binding. I would pull the ejector and check for broken or worn spring (read: replace while out). Also for freedom of movement of ejector in the hole. Use light lube on it as well (a drop of lube and plunge it up and down several times after cleaning). Also, if that does not fix the problem, you might try switching the gas tube to a "Fat Boy", to increase dwell time to unlock and slow the carrier down a tad, if not already installed. 
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I'll try the heavy ejector spring, but the current one isn't binding (at least not with me compressing it with a punch) and it's lubed. As far as the fatboy is concerned, this upper has the secondary gas port (SG designation) about midway down to help retard the opening of the bolt carrier group. I also have a Colt "H" buffer installed. Can you recommend a source for the plus power ejector spring? Saleen |
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Well, no i can't. Simply due to the fact that i don't know that they make one. You do not want too much ejector tension either, tends to cause other problems. Try this (operation of ejector) Remove BCG, with an empty case, hook the rim under the extractor and pull the case over to compress ejector. Now, with extractor side facing away from you, and holding the case by the neck, let the case go. The case should flip out about 5 feet from about 2 1/2 feet above the floor. It should leave the bolt smoothly and not hang on the extractor. If it barely flips off, then there's you problem, if not, then we will have to figure out why the case is still on the bolt when it starts forward. Edit for content. |
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Pull the extractor and check the bearing edge of the claw and the rim relieve section for burs. If burs are found, they use a file and remove then. This could be the only problem, and as for the stronger extractor spring, you can go with a Colt M-4 black insert, or a Wolf extra power spring so you can drop the O-ring band-aid. Note: use you fingernail and check for burs. With the can, you are getting more back pressure, and may have to go to a H-4, SMG, or even a MGI buffer to compensate for the extra back pressure (even over the top of the pig tail (read lack of buffer stall, and it sling shot'g off the back of the receiver extension instead of stalling). Also if you are finding that without the can, you do not need the O-ring, the rig is at the verge of over functioning with the can. Note: when you pull the can, you will loose the additional back pressure, and may need to drop down to the lighter buffer to get the rig to cycle correctly. |
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