Problem with first round loading

[legaleagle]

With one rifle and not the other, but all mags impacted, here is a thought. It may be thath te BCG is encountering impedence from the 2nd round pushing up hard, but if you load 19 rounds, there is enough room in the spring to allow the next round to push down enough to allow the BCG to go home all the way. This could be a few things. It could be that the mags sit higher into the mag well of that rifle. This would lend support to all mags having problem and thefact that you have to hard extract the round as described. It could also be that the spring has too many coils on it and it cannot flex downward enough to allow the BCG to slide over easily, kinda creating a bump for it to go over that makes things really tight.

Things to check:

After the 20th round (count them out to make sure you are not at 21 - many times you can get an extra round in and not realize it) can you push the round down still. About half the thickness of the round should be good. This will tell you if the spring is bottoming out and binding. If you want you could cut one coil of the spring and see if that helps. I would be leary to cut more than two coils as the spring may get too short. (Also, shortening a spring will make it stiffer or firmer, not softer). You could also try a new spring and see what happens.

On the spring again. If you can find a 20 round GI mag and it works, swap the spring and see if that works. Also count coils to copmare. You can also measure the diameter of each spring coil and add that together for the stack height. Do this with the problem mags and see if there is a difference to the GI mag. If the stack height is greater on the problem mag, your spring is taking up more room than the mag body has to allow the top round to push in a little bit.

Insert empty mag into reciver without upper on it. Measure the mag protrusion out of the top from the ledge of the receiver. You could caliperthis or put a tape line on it and visually measure on comparing receiver. Do the same for the bottom part of the mag from the bottom of the mag well. I would check this against other receivers to see if the results are the same. THe bottom measurement is not a likely to be determinative as the length of the magwell is not critical, it is the top ledge where it mates to the upper.

Again on the mage well. Remove the mag catch, spring and release button. Measure from the bottom of the catch cutout to the top of the receiver. (The bottom is thecritical measurement as the mag follower and round push up thus pushing the mag down agsint the mag catch which will rest on the bottom part of the cutout. If this is the culprit I would consult with Bowers Tactical on a fix. Machining on a reciever is a last resort to me and precision with a mill is a must. If the reciever is out of spec this is really the only true fix to make it work with other mags too.

Hope this helps. Let us know what you find out.



Look at feed lips to determine if the bolt is riding on them. I doubt this is the case as the remaining rounds 2-19 work fine.

[spleify]

Wow, absolutely great information here folks!

I will do some research and take some measurements over the next couple of days. I do have another rifle that this issue does not exist on, so I can make some comparisons.

I will post back with my findings.

Again, thanks so much!

[FireMoth]

I'd still like to take a look at the rifle, mostly the BCG.

The Carrier impedance described would be a good answer if it hadn't also happened with a 30rd Pmag. Pmags are true 30s, meaning you could fit 31 in them if you tried, to make sure they seat and feed. so there shouldn't be enough pressure to affect that. I have also never seen mag impedance on a bolt require pogo sticking the rifle.

I think mag impedance is probably a good part of the problem, but i think we should make sure nothing else is going on there as well. I've seen some strange things of late with even good carriers, so its worth taking a look at.

[spleify]

I know for sure I am not loading more than 20 rounds.

I handload all my ammo, and box them in 100 round containers, not only do I count them out but the ammo is in rows of 10 so its pretty easy to be sure I only have 20 rounds in.

I will do some checking on this and I will try and get down to the shop some time soon Rob.

Thanks again gents.

[FireMoth]

My intent wasnt to suggest you are over loading. Rahter, because a Pmag can typically take 31 rnds to give it slack to prevent this kind of malfunction, if it happened with a properly loaded 30rnd pmag, then there could be something rotten in denmark.

To wit, if it were a mag impedance problem, a pmag should at least have improved it. More over, mag impedance doesn't explain the round getting stuck, while a downloaded magazine works fine.

If you come by, bring the mags, so i can see if the carrier or bolt is marking them anywhere.

[spleify]

My intent wasnt to suggest you are over loading. Rahter, because a Pmag can typically take 31 rnds to give it slack to prevent this kind of malfunction, if it happened with a properly loaded 30rnd pmag, then there could be something rotten in denmark.

To wit, if it were a mag impedance problem, a pmag should at least have improved it. More over, mag impedance doesn't explain the round getting stuck, while a downloaded magazine works fine.

If you come by, bring the mags, so i can see if the carrier or bolt is marking them anywhere.

Will do Rob, I wasn't thinking you were implying anything, I just wanted to offer whatever info I could to help solve this mystery...lol

Thanks

[legaleagle]

I think I mentioned the overloading issue. Sorry, if I confused anyone, my intent was only to suggest and make sure you did not have an extra round jammed in, as this would be an obvious fix. My suggestions are based on diagnosis of issues to elmiinate and narrow the culprit.
Rob - I concur, it is definitely a good idea to let you see and fix if anything is out of spec and requires adjustment, especially, machining, or warranty, if it is available.