mrcylinder
Member
I've been reading about and seeing these CCU’s popping up, I have no idea just how many of these CCU's are out there but they come in many varieties/calibers for Glock and 1911s. The first thing many will notice is the versatility and being able to adapt them and make it their own. The idea behind these is not new but the way they, Mechtech have done it, can most definitely be appreciated. You are not modifying your firearm receiver at all, just using the receiver and turning it into a carbine. Federally legal, as technically speaking, you are doing nothing more than changing the slide and or replacing a barrel. The barrel being long enough and other agendas are met not to be a SBR. Just field strip the gun, using a Glock block or a Para block if needed and slide the receiver onto the upper, lock it in place with the slide stop and you now have a carbine in the caliber you chose to order. It will appeal to many, much of this review will apply to all and as such, many of the checks, fixes or tweaks, whatever terminology you choose to use. If it doesn’t exactly apply to a problem you are having, use your imagination and put your thinking cap on and hopefully, along with this information, you might just come up with something, or take it to a gunsmith. You void your warranty when making changes, so changes and safety is your responsibility and yours alone, DO NOT attempt or do anything you are not willing to accept the responsibility for!
I ordered one to give it a try and a closer look. After receiving the one I ordered, I opened the box and all the accessories were there that I ordered with it. The outside finish appeared to be well done and coverage was good. The fore grip piece which is on the basic unit was not there, as I ordered the full quad rails, which they installed, so if you want it, you will have to tell them when you order it. I just called and it was sent out.
The first thing I noticed was in moving the bolt handle back and forth; there was a very gritty sounding dragging movement. No amount of oil did anything but mask the sound a bit. So a disassembly was in order to see why. I thought I’d find some residue, probably due to machining of parts but instead a texture on the inside of the tube assembly that resembled a sand blasted or other media blasted surface, see photo, The white specs are from the terry cloth rag I ran through it. The rough surface just pulled some off all the way up and down the upper unit.
Media blasting can embed small particles in the metal that has to be cleaned out. The upper assembly (Bolt channel sub assembly as they call it) was full of pits from using what appears to be a once rusted piece of metal to machine it out of, see photo,
even the firing pin block was made out of very badly pitted and once rusted out appearing metal. See photo, the small pin is what holds the extractor in the firing pin block part.
In my experience these pits could have also been caused by chemicals and or exposure to salt or any number of things but none the less, in my opinion, a bad choice for manufacturing anything out of from the get go. The outer tube assembly was slicked up with some steel wool inside, trying not to remove any material just take the rough scrapping residue off the surface and clean out any blasting residue, then a very thorough cleaning, not much can be done about the pitted metal except a fine polishing with some 1500/2000 wet sanding with a light oil. I did no more than clean up the rough surfaces, oil it, put it back together to try and fire it. Well the first thing was two bangs, a stove pipe, removed and it went bang three times and another stovepipe, changed magazines, changed ammo to +P and it went bang more but the stove pipes still occurred. I tried three different 1911s; series 70 single stack, commander size single stack and the Para high capacity, all had their share of stovepipe type malfunctions. I also noticed how the outside of the shells were being blackened very badly with blowback, see photo, (note: these are basic blowback operated devices so some more than normal blowback or darkening of the shell might be seen)
The first case is before any changes, the second is a factory Winchester after, the third is a Longshot +P reload after and the fourth is a factory Fiocchi after fixes for comparison.
I noticed too, how many of the shells were being smashed like they were being pinched in-between something, beside the damage from the stovepipes. So I put a video on the action and saw how the shell was being dropped by the extractor on the way back and the movement of the bolt channel sub assembly was trying to throw the shell out, knock it out, sometimes being caught in-between the next round in the magazine and the top of the chamber, sometimes making it out. We shot about 80 rounds before frustration took over and we called it quits. I went to work on a complete disassembly, measuring things and an up close inspection, using the 1911standards for doing the measuring, as that is what it was made to fire. The first thing, was why the dark blacking of the case, excessive blowback even in a Blowback design?
In most firearms, I've found this to be a clearance problem, or in other words a headspacing problem and the mouth of the shell is not in the chamber headspace deep enough for the shell to expand and seal the gases off, thereby too much is coming back towards the rear, instead of pushing the bullet out the barrel. This could also be caused by a chamber being cut to large. In this case, the shell was not forward enough to be in the sealing or mouth portion of the chamber, it was .022 thousandths too far away even after allowing the maximum standards and clearance for a dirty chamber for a 1911. The spacer and or front buffer pad they call it, see photo,
was so thick, that the barrel was sitting too far away from the breech face/recoil face of the firing pin block, leaving a large gap. This is only a polyvinyl piece and you can use your imagination to come up with a thinner one, I cut one with the proper material needed to bring this one in. You will have to do some measuring to determine how thick to make yours and pay close attention to the barrel to firing pin block spacing, breech recoil face spacing and headspacing in the barrel. See
photos,
Before with large gap
After
I allowed .004 between the barrel and firing pin block and it seems to be working well. Again, check to make sure you have adequate headspacing before removing any of this space. For those that don’t know what I’m talking about, in other words, when in full battery and ready to fire, the shell must have some room to move back and forth in the chamber some, this allows for differences in shell lengths and for a dirty chamber. If you use a go, no go gauge to check it no problem. You DO NOT want these surfaces to come into full force contact as you have a 2lb piece of metal slamming the two together, along with the tension from the recoil spring and that will translate into damage for sure, so allow a small bit of space. Just don't use any thing for this pad that will deteriorate like paper or even rubber, as oil can swell rubber and then the pounding will cause a quick deterioration of the pad. Use a similar material as to what is in there. Another problem that was encountered here, was the breech recoil surfaces of the firing pin block were not even, it wasn't square. One side was .011 longer, so after moving the barrel back toward it, one side of the breech recoil face would hit the barrel and the top lug of the barrel and the extractor side were still back away from it, so some squaring up was in order. This is easily checked by removing the front buffer pad and sliding the barrel into the Bolt channel sub assembly and seeing how it sits. Upon measuring the width of the breech face itself, it measured .021 to wide. This is one of the worst deviations from ordnance specifications I have ever personally measured for anything designed to fire a 45acp cartridge however not much can be done except welding it up, re-cutting and or making one from scratch, so it is what it is. Also the recoil pin block as they call it had a strange taper to it, the breech face measured .501 but as you measure out towards where the barrel would be, and where the case rides towards extraction, it tapers for no apparent reason other than poor machining and parts matching to .506. Again not much can be done other than remaking the piece. You can see it in the photos above if you look closely. Once the thing was squared up and things were sitting in position better it was on to the extractor.
First measuring the tension in order to have a starting point. Using a .475 tension gauge and a digital trigger scale I measured 17.6oz, too low for any 1911 I've ever had. Trying to re-tension the spring, even reshaping the spring on the extractor was futile and only measured 20.4 oz and that was all I could get it to retain. I tried to reposition the extractor spring forward to gain some tension on the shell and only got it up to 22.1oz. Note: that a single stack might work with that tension and 7 or 8 round magazines but I was working with a Para double stack and it has a lot more magazine spring tension. I measured the square cut out in the firing pin block. grabbed an old 1911 extractor to measure, it was close enough to remove a little material and I went on to shaping it, see photo.
What I ended up with was a extractor I could tension and it would hold all I gave it, I set it at 32.4 oz. No need to dwell further on that point, yes, it worked and hasn't failed me yet with almost 400 rounds, so that’s a go in my book. What you do have to make sure of in making one is, that the cuts for the shell to come up from underneath are present and that they are polished up slick and that the extractor can jump over the bottom lip of the shell if it misses it coming up out of the magazine, without damage to the extractor, otherwise you could break it and have to start all over. Just like fine tuning a regular 1911 extractor for reliability. Note too how far their extractor sticks out toward the barrel and the space, see photos. Before and after extractor replacement.
Before
After
All the space meant the shell could walk .026 thousandths back and forth on the extractor and this doesn’t include the gap between the barrel and firing pin block above. When the firing pin strikes, it has to push it forward into the chamber headspace, if it doesn't go off right away, (before the recoil/barrel pad fix above) stop when it hits the case mouth, or the extractor hook, when it goes bang, it throws it back against the breech face, not good. I believe in the past this was called firing on the extractor in a 1911!?! The extractor also stuck out so far that once it started the fired case backward it was over half way off the opposite side of the breech face edge so it didn't take much for it to just fall off the extractor before ever hitting the ejector, many times being knocked off or dragged off by the next round.
Note: The fired case in this design is acting like a piston to push the large metal piece backwards, (the bolt channel sub assembly) once it’s clear of the barrel however the extractor has to do its job of holding the case until ejection.
I went on to measuring the barrel, the head space, the chamber and what I found was fairly good for a lot of today’s go bang low end firearms. I only found a .002 thousandths to large taper difference in the chamber and a few minor low spots but livable. Headspaceing was a just shy of the “go” gauge by about .002, which is another reason I allowed the space mentioned above. All the other measurements were within limits of a 1911 measurements. The rifling and all was pretty well done and where evenly cut, the barrel had a good throat cut into it within the 1911 specs in this one, so I won't waste time there. The barrel has more case support than a standard 1911 pistol barrel which is a good thing.
The barrel ramps were shaped similar to some of the older 1911s I’ve had, most newer ones are cut a bit different within the ramp area.
The strange notch out on the right is to clear the extractor that sticks out so far it would hit otherwise. At least before I modified the extractor. The ramps were both polished up like one would do for any pistol. The barrel is supported well when mounted in the outer tube like piece, with a large aluminum part pinned to it and eight small bolts. The barrel did exhibit some forward/backward movement when bolted into the upper tube assembly. The bolt heads are suppose to hold it in place as they screw down against the barrel support and the round head of the bolt sits down into the holes to secure it. The clearances are such that there is movement present between the bolt heads and the tube outer assembly in this arrangement. If you use the full quad rails the support ring up front will stop this play and secure it tightly in position. The firing pin alignment to the primer in the shell was pretty well aligned, see photo, and was striking with enough force for positive ignition. I’ve seen worse.
On to the large metal piece they call the Bolt channel sub assembly. The whole part was full of pits, except for the machined portions. The machining was pretty rough with a lot of sharp edges that needed filing off, deep gouges and machining marks that needed polishing up using various grits of sand paper. Most of the machining marks couldn't ever be removed, as the lines are too deep and you would ruin the piece if you tried to remove them all, so don't. Some areas you might can address is the bottom of the firing pin block, just be careful, just like in a pistol you don't want to try and remove any deep lines but a little polishing can go a long way. Another is the ejection port, this one had some very sharp edges, almost knife sharp and jagged, I took them out with a fine diamond grit file and polished the whole area up so there was nothing for shells to grab onto and hiccup the extraction and ejection process. Another is where the barrel rubs in the top of this part and the whole exterior with some wet sanding/polishing up 2000 grit paper as mentioned earlier.
See Part II
I ordered one to give it a try and a closer look. After receiving the one I ordered, I opened the box and all the accessories were there that I ordered with it. The outside finish appeared to be well done and coverage was good. The fore grip piece which is on the basic unit was not there, as I ordered the full quad rails, which they installed, so if you want it, you will have to tell them when you order it. I just called and it was sent out.
The first thing I noticed was in moving the bolt handle back and forth; there was a very gritty sounding dragging movement. No amount of oil did anything but mask the sound a bit. So a disassembly was in order to see why. I thought I’d find some residue, probably due to machining of parts but instead a texture on the inside of the tube assembly that resembled a sand blasted or other media blasted surface, see photo, The white specs are from the terry cloth rag I ran through it. The rough surface just pulled some off all the way up and down the upper unit.
Media blasting can embed small particles in the metal that has to be cleaned out. The upper assembly (Bolt channel sub assembly as they call it) was full of pits from using what appears to be a once rusted piece of metal to machine it out of, see photo,
even the firing pin block was made out of very badly pitted and once rusted out appearing metal. See photo, the small pin is what holds the extractor in the firing pin block part.
In my experience these pits could have also been caused by chemicals and or exposure to salt or any number of things but none the less, in my opinion, a bad choice for manufacturing anything out of from the get go. The outer tube assembly was slicked up with some steel wool inside, trying not to remove any material just take the rough scrapping residue off the surface and clean out any blasting residue, then a very thorough cleaning, not much can be done about the pitted metal except a fine polishing with some 1500/2000 wet sanding with a light oil. I did no more than clean up the rough surfaces, oil it, put it back together to try and fire it. Well the first thing was two bangs, a stove pipe, removed and it went bang three times and another stovepipe, changed magazines, changed ammo to +P and it went bang more but the stove pipes still occurred. I tried three different 1911s; series 70 single stack, commander size single stack and the Para high capacity, all had their share of stovepipe type malfunctions. I also noticed how the outside of the shells were being blackened very badly with blowback, see photo, (note: these are basic blowback operated devices so some more than normal blowback or darkening of the shell might be seen)
The first case is before any changes, the second is a factory Winchester after, the third is a Longshot +P reload after and the fourth is a factory Fiocchi after fixes for comparison.
I noticed too, how many of the shells were being smashed like they were being pinched in-between something, beside the damage from the stovepipes. So I put a video on the action and saw how the shell was being dropped by the extractor on the way back and the movement of the bolt channel sub assembly was trying to throw the shell out, knock it out, sometimes being caught in-between the next round in the magazine and the top of the chamber, sometimes making it out. We shot about 80 rounds before frustration took over and we called it quits. I went to work on a complete disassembly, measuring things and an up close inspection, using the 1911standards for doing the measuring, as that is what it was made to fire. The first thing, was why the dark blacking of the case, excessive blowback even in a Blowback design?
In most firearms, I've found this to be a clearance problem, or in other words a headspacing problem and the mouth of the shell is not in the chamber headspace deep enough for the shell to expand and seal the gases off, thereby too much is coming back towards the rear, instead of pushing the bullet out the barrel. This could also be caused by a chamber being cut to large. In this case, the shell was not forward enough to be in the sealing or mouth portion of the chamber, it was .022 thousandths too far away even after allowing the maximum standards and clearance for a dirty chamber for a 1911. The spacer and or front buffer pad they call it, see photo,
was so thick, that the barrel was sitting too far away from the breech face/recoil face of the firing pin block, leaving a large gap. This is only a polyvinyl piece and you can use your imagination to come up with a thinner one, I cut one with the proper material needed to bring this one in. You will have to do some measuring to determine how thick to make yours and pay close attention to the barrel to firing pin block spacing, breech recoil face spacing and headspacing in the barrel. See
photos,
Before with large gap
After
I allowed .004 between the barrel and firing pin block and it seems to be working well. Again, check to make sure you have adequate headspacing before removing any of this space. For those that don’t know what I’m talking about, in other words, when in full battery and ready to fire, the shell must have some room to move back and forth in the chamber some, this allows for differences in shell lengths and for a dirty chamber. If you use a go, no go gauge to check it no problem. You DO NOT want these surfaces to come into full force contact as you have a 2lb piece of metal slamming the two together, along with the tension from the recoil spring and that will translate into damage for sure, so allow a small bit of space. Just don't use any thing for this pad that will deteriorate like paper or even rubber, as oil can swell rubber and then the pounding will cause a quick deterioration of the pad. Use a similar material as to what is in there. Another problem that was encountered here, was the breech recoil surfaces of the firing pin block were not even, it wasn't square. One side was .011 longer, so after moving the barrel back toward it, one side of the breech recoil face would hit the barrel and the top lug of the barrel and the extractor side were still back away from it, so some squaring up was in order. This is easily checked by removing the front buffer pad and sliding the barrel into the Bolt channel sub assembly and seeing how it sits. Upon measuring the width of the breech face itself, it measured .021 to wide. This is one of the worst deviations from ordnance specifications I have ever personally measured for anything designed to fire a 45acp cartridge however not much can be done except welding it up, re-cutting and or making one from scratch, so it is what it is. Also the recoil pin block as they call it had a strange taper to it, the breech face measured .501 but as you measure out towards where the barrel would be, and where the case rides towards extraction, it tapers for no apparent reason other than poor machining and parts matching to .506. Again not much can be done other than remaking the piece. You can see it in the photos above if you look closely. Once the thing was squared up and things were sitting in position better it was on to the extractor.
First measuring the tension in order to have a starting point. Using a .475 tension gauge and a digital trigger scale I measured 17.6oz, too low for any 1911 I've ever had. Trying to re-tension the spring, even reshaping the spring on the extractor was futile and only measured 20.4 oz and that was all I could get it to retain. I tried to reposition the extractor spring forward to gain some tension on the shell and only got it up to 22.1oz. Note: that a single stack might work with that tension and 7 or 8 round magazines but I was working with a Para double stack and it has a lot more magazine spring tension. I measured the square cut out in the firing pin block. grabbed an old 1911 extractor to measure, it was close enough to remove a little material and I went on to shaping it, see photo.
What I ended up with was a extractor I could tension and it would hold all I gave it, I set it at 32.4 oz. No need to dwell further on that point, yes, it worked and hasn't failed me yet with almost 400 rounds, so that’s a go in my book. What you do have to make sure of in making one is, that the cuts for the shell to come up from underneath are present and that they are polished up slick and that the extractor can jump over the bottom lip of the shell if it misses it coming up out of the magazine, without damage to the extractor, otherwise you could break it and have to start all over. Just like fine tuning a regular 1911 extractor for reliability. Note too how far their extractor sticks out toward the barrel and the space, see photos. Before and after extractor replacement.
Before
After
All the space meant the shell could walk .026 thousandths back and forth on the extractor and this doesn’t include the gap between the barrel and firing pin block above. When the firing pin strikes, it has to push it forward into the chamber headspace, if it doesn't go off right away, (before the recoil/barrel pad fix above) stop when it hits the case mouth, or the extractor hook, when it goes bang, it throws it back against the breech face, not good. I believe in the past this was called firing on the extractor in a 1911!?! The extractor also stuck out so far that once it started the fired case backward it was over half way off the opposite side of the breech face edge so it didn't take much for it to just fall off the extractor before ever hitting the ejector, many times being knocked off or dragged off by the next round.
Note: The fired case in this design is acting like a piston to push the large metal piece backwards, (the bolt channel sub assembly) once it’s clear of the barrel however the extractor has to do its job of holding the case until ejection.
I went on to measuring the barrel, the head space, the chamber and what I found was fairly good for a lot of today’s go bang low end firearms. I only found a .002 thousandths to large taper difference in the chamber and a few minor low spots but livable. Headspaceing was a just shy of the “go” gauge by about .002, which is another reason I allowed the space mentioned above. All the other measurements were within limits of a 1911 measurements. The rifling and all was pretty well done and where evenly cut, the barrel had a good throat cut into it within the 1911 specs in this one, so I won't waste time there. The barrel has more case support than a standard 1911 pistol barrel which is a good thing.
The barrel ramps were shaped similar to some of the older 1911s I’ve had, most newer ones are cut a bit different within the ramp area.
The strange notch out on the right is to clear the extractor that sticks out so far it would hit otherwise. At least before I modified the extractor. The ramps were both polished up like one would do for any pistol. The barrel is supported well when mounted in the outer tube like piece, with a large aluminum part pinned to it and eight small bolts. The barrel did exhibit some forward/backward movement when bolted into the upper tube assembly. The bolt heads are suppose to hold it in place as they screw down against the barrel support and the round head of the bolt sits down into the holes to secure it. The clearances are such that there is movement present between the bolt heads and the tube outer assembly in this arrangement. If you use the full quad rails the support ring up front will stop this play and secure it tightly in position. The firing pin alignment to the primer in the shell was pretty well aligned, see photo, and was striking with enough force for positive ignition. I’ve seen worse.
On to the large metal piece they call the Bolt channel sub assembly. The whole part was full of pits, except for the machined portions. The machining was pretty rough with a lot of sharp edges that needed filing off, deep gouges and machining marks that needed polishing up using various grits of sand paper. Most of the machining marks couldn't ever be removed, as the lines are too deep and you would ruin the piece if you tried to remove them all, so don't. Some areas you might can address is the bottom of the firing pin block, just be careful, just like in a pistol you don't want to try and remove any deep lines but a little polishing can go a long way. Another is the ejection port, this one had some very sharp edges, almost knife sharp and jagged, I took them out with a fine diamond grit file and polished the whole area up so there was nothing for shells to grab onto and hiccup the extraction and ejection process. Another is where the barrel rubs in the top of this part and the whole exterior with some wet sanding/polishing up 2000 grit paper as mentioned earlier.
See Part II
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