My MechTech and G20, mags, and ammo of choice as of Feb 2016

DenStinett · February 11 2017 03:36:02 PM MST

I found that if you break the hard corner on the Glock Block it allows the Round to ramp into the Chamber cleaner
(sorry for the lousy Cellphone Pics)

cwlongshot · February 13 2017 07:15:25 AM MST

Jazz,
Something you need to realize when loading for different actions ESP locked breech blow compared to back actions like the MECH is they react differently and can give you different results IN-directly associated to pressure. Its MORE WHERE the pressure peak is... meaning the bolt comes back WITH recoil... so some powders are going to give you these smiles when they really are no near high pressure. Brass cases are designed to HOLD POWDER. NOT withstand pressures, this is why you get smiles. The bolt is opening BEFORE peake pressure allowing the brass to smile... Different powders will allow the performance you desire without the smiles.

CW

jazzsax8 · February 14 2017 04:53:22 PM MST

CW

I agree and one of the recommended loads I tried was 8.0 Longshot with the 220gr Xtreme bullet at 1.260. Potentially dangerous in my rifle but shoots fabulous in my G20 KKM 6". What else is anyone loading for theirs that has worked out to be great? I have some CFE Pistol on hand that needs to be tried. I put a small .035 washer under the feeding block that really tightens things up that should prevent the bullet from nose diving into the barrel ramp that could have caused bullet set back with excessive pressure. Spoke to M.T. and my 2 year old feeding block is the same dimension as the current ones. My block was doing a little up and down tilt when you pushed on it that it no longer does. The underside gap on their block is too long allowing that to happen unless you tighten it up against the barrel like I did.

Jazz

Keiichi · February 14 2017 08:06:28 PM MST

jazz - that might be a difference in the tolerance or dimention of the lower... I don't have any of the looseness or tilting that you describe.

What generation Glock do you use? Mines a Gen 4...

I have noticed that even between two lowers of the same generation, one of mine is more reliable than the other. Haven't really investigated why, though.

jazzsax8 · February 15 2017 07:02:10 AM MST

I am using a G20 SF Gen 3. After installing yours, lock the bolt back and reach into the action with a pencil eraser touching the block and see if it does not rock up and down just a little. Its not a lot but mine does move exposing the barrel ramp edge just enough to allow my plated bullet nose to dig in. It might only happen once in 30 rounds but the result could be catastrophic in the event the round now chambers setting the bullet back. I measured one that did not chamber FTF that went from 1.260 to 1.170! This might explain the two rounds leaving half the case in the chamber and one round swelled up at the head so large it was incredible it did not blow up.

Keiichi · February 15 2017 06:07:36 PM MST

Yep, checked again using the method you suggested, and checked both of my Gen 4 G20 lowers (one's from a G40, but... same difference...) - no detectable movement of the Glock block using either lower. It's tightly wedged in there between the lower and the bottom of the barrel.

Not sure what to tell you...

jazzsax8 · February 17 2017 04:00:31 PM MST

Hit the range yesterday and put 50+ rounds through it with only one FTF. Again the plated bullet nose caught the barrel feed ramp and hung up. Good thing it did not chamber as the OAL went from 1.260 to 1.185! I tried the M.T. on another G20 SF and the movement was less but still there. Measured the Glock locking blocks and my older one has probably shortened a little due to lots of rounds fired. It measured .312 where the newer one was at .320. My M.T. block underneath gap measures .377! If this gap was shortened to .325 it would snug things up where it would no longer teter totter in place. I also noticed if it installs rearward there is a larger gap exposing the bottom of the barrel ramp. Push it forward and it looks like a smoother transition.

Keiichi, measure your M.T. block to see if its .249 thick with the same gap of .377 underneath please.

Keiichi · February 17 2017 10:06:48 PM MST

I'll have to pick up a caliper to measure them... probably something I should have at this point anyway.

Give me a few days, and I'll get back to you with measurements.

On the .377 measure - is that the gap between the top of the receiver shelf the glock block sits on and the bottom of the barrel? I'm having a little trouble following exactly what it was you measured (sorry ${$default_smiley_smiley}$ ).

jazzsax8 · February 18 2017 07:42:54 AM MST

K

Thanks for asking. Its the gap that is front to back. I did not measure its depth but I was able to get a small washer .035 up next to the magnet that tightens things up preventing the tilt however even with it in place its possible to mount the M.T. block rearward due to the front to back slop that exposes the bottom of the barrel ramp somewhat. I know the fix would be to simply use jacketed bullets vs. the cheaper plated/coated/lead but this thing is such a joy to shoot and can really eat up the rounds.

Keiichi · February 20 2017 06:25:27 PM MST

Here are the dimensions as measured by my new digital caliper:

jazzsax8 · February 21 2017 08:49:38 AM MST

K

Thanks for taking the time to measure. Mine is like yours and M.T. gave me similar measurements. Are you shooting jacketed only bullets? I am pretty sure that is the fix for my problems as it would be less prone to digging into the barrel ramp. Since the glock locking block is only .320 the underneath gap of the M.T. block slot is way too long at .380 to provide a closer tight fit.