I have questions about a 9mm build

[AndyLate]

You find the Uzi pattern Colt mags easier to load? I really wanted the Endomag to work but it was just not reliable with my set-up. I was definitely surprised with the accuracy of my 9mm upper.

Andy

[TonyAngel]

The only magazines I have a clear recollection of dealing with are ASC and C-Products magazines and yes, I find them easy to load. I think the Glock mags are a PITA when you get past 20 rounds.

[JB2000]

As a data point, the BCG and buffer in my FM-9 on a mail scale is 21 ounces. FM (Foxtrot Mike) runs this with a 308 carbine spring. The BCG IS 14.5 ounces and the buffer 6.6.

[TonyAngel]

I put all of the parts that I originally listed together and put them on top of a Spike's multi cal lower using endomags. It runs like a clock and shoots very accurately.

[AndyLate]

I put all of the parts that I originally listed together and put them on top of a Spike's multi cal lower using endomags. It runs like a clock and shoots very accurately.

That's great! There really are advantages to the Endomag concept, the one I tried just didn't work for me.

Andy

[TonyAngel]

Andy, what's funny is that the one you sent me that was used and you said was messed up, worked fine for me. Based on my experience and all of the research I've done, I really think that it's a matter of the BCG. Apparently, the Faxon works really well with Endomags.

[AndyLate]

I would rather err on the side of caution - I am glad it's working for you. I am certain you are right about the BCG.

Andy

[TonyAngel]

Alright guys, I have a couple more questions. I have my 9mm running good, but am starting to think about tuning it to run the best that it can. I've scoured the internet looking for info about buffer/BCG weights and springs, but it looks like most of the info is for carbines with 16"ish barrels. From what I'm gathering, the longer the barrel, the more weight you need.

I'm running a 5.5" barrel. I removed the weight from the BCG so that I'm right at 20oz for my BCG and buffer combo, which is where I think I'm supposed to be. I'm running a Sprinco Blue spring.

Now, I'm finding out that most recommend an AR10 carbine buffer spring. I ordered one and installed it, and it's a good bit stiffer than the Sprinco spring.

I'm having a hard time reconciling all of this in my head. If I'm going to run a much heavier spring, why not just run a heavier bolt with a lighter spring.

Is anyone out there running a 5.5" setup? What are you running and what weight BCG/buffer/spring are you using?

[JB2000]

My Foxtrot Mike has a 5” barrel and runs a .308 carbine spring with a BCG and buffer weight of 21 ounces. It seems to cycle best with full power ammo. I haven’t had an opportunity to really benchmark what it will and won’t cycle because consistent supplies of powder and bullets are hard to come by.

[TonyAngel]

I’ve settled on a standard weight buffer spring. The weight of the spring only seems to make a difference upon closing of the bolt and the heavier the spring the more the muzzle moves.