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Problem with my M4, need help


trackstar55

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I have a M4 that I just ordered. I installed the full length mag tube from SOCOMGUY as well as the skeleton stock. Looks great right? Well, before I went to the range to test fire this beauty, I wanted to see if it cycled properly (figured I wasting my time, but what the heck).

 

Well, I filled the mag tube with shells. When it was time, I pulled the bolt back in one swift motion and let go in order to load the shotgun. To my suprise, the shell was still in the bottom area resting on the feed ramp that guides it to the barrel. The shell was resting perfectly horizontal on the feed ramp. The bolt "seemed" to be locked back. I was like, what the heck.

 

Then, with the slightest (and I mean slightest) touch, I touched the bottom of the feed ramp with my index finger and it snapped forward with authority and I was good to go. The gun was loaded. Just like a 11-87.

 

I tried cycling this shotgun several times and got the same results again and again and again. Is this normal. My M1 Super 90 does not have this problem.

 

I disassembled the shotgun, wiped it clean, re-lubed it, and reassembled it. Still have the same problem.

 

Oh, and when I rolled the shotgun to its side, the shell suddenly loaded. Like it is just a hair away from functioning properly. I just can't put my finger on it.

 

Any answers? I will try to get pics up

Edited by trackstar55
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You're likely experiencing the "m4 BCG shelf" phenomenon.

 

The m4, with a shell in the lifter under the BCG, can be pulled back and "set" on a shelf in order that it APPEARS to be locked back. It is in fact not locked back at all, and a bit of a jar will knock it off the shelf and down to the chamber.

 

I got a black thumb back in 2006 from a guy who handed me my m4 in this condition ... I assumed it was locked back (why wouldn't it be?) and I reached into the chamber to assess dirtiness level, and the slight jar caused the BCG to come forward onto my right thumb. I swear to god I almost shot that mother ******, the pain in my hand was excruciating.

 

Upon reading your post again, this is definitely your problem. The BCG "seems" to locked back, but in fact it is not. If it's locked back or fully racked, the lifter won't be triggered and you can rack it all day without causing any effect, setting it on the shelf each time.

 

It's a common mistake with people new to m4s, they are unfamiliar with the cartridge drop lever and how it function in relation to the lifter, bolt release and the racking/reset of the weapon.

 

I would suggest working your weapon some with it TOTALLY UNLOADED in order to get more familiar with how your weapon works.

 

When empty, rack your slide to the rear. Make sure it is LOCKED back, you can tell because the bolt release button gets popped out, and the cartridge drop lever is in.

 

Now press the bolt release. The bolt goes forward, the cartridge drop lever comes out, right? You can now rack your gun all day long without it locking back. You will find you can get it to rest on the shelf NEAR the back, but it won't be truly locked back, and any jarring motion will set it free. If you pull it ALL the way back, the lifter should be activated, but the shelf is prior to the lifter engagement point, so it all depends on how far you rack.

 

Now, making sure your gun is unloaded, either pull the trigger or press the cartridge drop lever. The bolt release button pops back out, and your gun will now be locked to the rear if you rack it.

 

If all the above hold true, you have a 100% normal m11707 and I congratulate you on your purchase. It takes a bit of getting used to, but once you do you'll find it's extremely effective and intuitive, just different.

 

-Duggan

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Long story short, first time at range, friend shooting slugs. Friend asks me if they are 3 inch shells and presents the shotgun to me with the carrier "locked" back.

 

I stick my finger in to the reciever to roll the shell over that is laying in the carrier (to read cartridge label then WAMMO!!!!!! Bolt releases and smashes index finger against the front of the ejection port. Blood everywhere. There is nothing more humbling then having your finger smashed like a a-hole when you are showing off your badass combat shotgun.

 

Glad you mentioned it Duggan. I bled like a pig all the way to the bathroom.

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Ouch. I didn't bleed that much, my thumb just got crushed and the nail turned all black and it hurt like mad for a week or so.

 

I just talked to the OP on the phone for awhile about his problem, the problem appears to be abnormal and he's contacting CS about it :(

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Ouch. I didn't bleed that much, my thumb just got crushed and the nail turned all black and it hurt like mad for a week or so.

 

I just talked to the OP on the phone for awhile about his problem, the problem appears to be abnormal and he's contacting CS about it :(

 

That's good of you to offer help. Question: I'm expecting an M4 by Tuesday. Does the M4 operate identically to an M1?

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