The savagery continues!

[feets]

It looks like I'm not done with my commercial 30 carbine project yet. When we last had it out, the slide was hanging up on the disassembly notch in the barrel. The fit was loose enough that the slide would drop down a wee bit and hit the bottom of the groove head on. It simply stopped the slide and resulted in a partially chambered round and a bolt in the middle of it's travel. This happened with both the original banana barrel and with the new Criterion.
Swapping in the slide from the Inland fixed the problem. It fit much tighter to the barrel.
I took plenty of measurements from each slide as well as the barrel and studied the problem.

My slide has notches that are not as long as the GI unit and they don't poke out as deeply either. The GI slide was .020" narrower than mine.


It had .037" of slop side to side. That's rattly-clanky loose. Ugly. Being the enterprising sort that I am, I addressed the issue. Out came the pen, notepad, and dial calipers. I made lots of measurements of all surfaces involved. Once that was done, I got nasty with it.



ACK!! He did what?!?!? Yes! I butchered the slide. It's a cast piece and there was no way I was going to attempt squeezing it in a vise. Instead, I burned a little metal on the tabs. A little roughing in with a Dremel tool had the tabs reduced from lumpy bumps to over-sized guides. The various files came out to play and things started looking even better. I'd work the tabs a bit then stop for measurements. When they started getting close, I'd test fit the assembly and polish them with the Dremel.

After a couple hours of fiddling this is what I ended up with:



The slide now has .021" of side to movement side to side. That's a 44% reduction in slop. Because it has to be tilted while installing it's not possible to get a perfect machined fit. I also had to allow for some expansion of the barrel when it gets hot.
Gun barrels are fairly soft as far as steels are concerned. My welds are much harder metal. That's the biggest reason I worked with the polishing wheel to fit the tabs. The smoother they are, the less wear they will impart on the barrel. I also plan on adding a little of the high temp gun grease I use on my M1A. Some of that in the rails will also reduce wear.

It still has a tendency to hang up on the notch. I beveled both ends of the left tab but it didn't completely stop the problem.
I know the tab on the back of the op rod is a bit under nourished.



Honestly, it's downright sloppy. I can almost pull the tab out of it's groove anywhere along the run. That's allowing the slide to rotate down on the left side.

Tonight, I'll attack the tab with the same mentality and see what I can do with it. Adding material to the top and inside of it will prevent the side from rotating and dropping into the notch. Fitting this end will be a wee bit trickier but I don't think it will take as long as fitting the front half.

My shooting group has a range day tomorrow. With luck, I'll be emptying magazines with impunity.


So, by a show of hands, how many of you firmly believe I've lost my mind?

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[DaveHH]

Ever see photos of the Afgan/Pakistani gun shops where several guys are busy with hand tools charcoal pits and files making guns from scratch? It may seem funny but it definitely can be done. I would say that 4140 steel is not as soft as one would think, so I think your welds are fine. I've always looked at these tabs and wondered how they last when used with just light oil. The design of one spring has to side load that slide and cock it to one side, which is why I grease the snot out of the carbine.

[feets]

I have a machine shop in my garage. The lathe and mill are marginal at best for work this small and tight. It seems a bit overkill to chuck some small rod stock in a lathe that will swing 14" pieces and make a trigger group pin.
The 4140 is not a squishy metal like 316 but it's not that difficult to abrade.

I took some good measurements of the tab on the end of the op rod and the run in the receiver. I figured out how much metal it would take to get it where I thought it should be. That's when the problem with my M1A came to mind.
The M1A has a sliding pin that holds the recoil spring guide. The stock was a bit of a loose fit and the pin could back out. When you changed the magazine the guide rod would run out the back of it's channel and prevent the new mag from being inserted. To correct this I dropped a tiny bit of epoxy in the stock. That cured the problem.
With that fresh in my head, I dropped the carbine action back in the stock. I thought I'd see if a similar trick would fix this little guy. The dropping slide problem went away without any further modification. Curiosity being what it is, I completely assembled the carbine to a ready to fire condition and worked the action again. The slide did not hang up in the notch.
I stuffed 15 dummy rounds in the original magazine and went bonkers with the action. Every round fed without an issue. it didn't matter if I went slow or played machine gun. There were no failures. That is something the gun would not do when I first brought it home.
I stuffed the dummies in a Korean mag and tried again. It had a bolt over base failure to feed on the 14th round on three separate attempts. The next Korean mag worked perfectly. My third Korean mag failed regularly on the 14th round as well. On one attempt it failed on the 15th round. All three Korean mags are new. None of them have seen more than a couple uses. I marked the two failure prone magazines with tape and will test them tomorrow.
I will hold off on the second round of slide modifications until after I run the carbine.

What are the chances that this, my very first "gunsmithing" exercise, has reached a positive outcome? I know there's a huge difference between slapping an action around by hand and letting the rounds do the job for me but it never ran this smooth by hand.

I guess it's time to clean it up, lube everything, and hit the range in the morning.

[fn111557]

Good Luck and have FUN!
Looking forward to a full range report tomorrow night.

[feets]

I hit the range this morning to run the carbine. I took a variety of ammo with me.
PMC ball rounds old enough to be in the camouflage box.
Federal Classic 110 gr soft points (again, pretty old).
Remington 110 soft points over 14.5 gr H110.
Hornady 100 gr Short Jacket (we call 'em Squishies) over 15.0 gr H110.
Hornady 110 gr V-max over 14.5 gr H110. These are too long for the magazine but I wanted to play with them.

Here are the handloads:



With the carbine cleaned, lubed, and ready to go, I got down to bidness. First up were the PMC factory ball rounds. If anything was going to run properly, it should be these. I loaded the factory mag and sent lead flying.
NO FAILURES OF ANY KIND!!!!

I then filled the "good" Korean mag and gave it a whirl. Again, there were no failures of any kind. It gobbled them up like candy.
One of the "bad" Korean mags was next. It worked great too.
I was firing at 25 yards from a standing unsupported position. Wobbling around on my own two feet, the accuracy was acceptable but nothing to write home about. Despite a few close calls, the bad guy lived to mock me another day.



With 45 of the 50 rounds spent, it was time to change ammo. Next up were the Federal factory loads. They ran through the factory mag just like they were supposed to do. I'll have to find those bullets. They were pointier than the other soft points and fed a bit smoother. This time, the bad guy wasn't so lucky. I got his attention on the first round then put one right in the kisser!



With 15 of the 20 rounds gone I moved on to my hand loads. The rounds had a couple hiccups. There were a few failures to feed with the other "bad" Korean magazine. Again, these were on round number 14 just like the hand trials. I also had some hitches with the other magazines. These I'll attribute partially to the bullet design. Those Remington rounds have a fatter exposed lead tip. They are catching on the top of the chamber. The lead gets displaced a wee bit allowing the edge of the jacket to hit the breech and cause a stoppage. I have more of these bullets so I'll play with seating depth to see if they will run better.

Moving to my "squishies" and the three good magazines everything was fine. Accuracy was on par with the other loads. There were no failures. I like these little things. The carbine gets a bit of a bark to it and actually has a bit of flash when fired. The little guy gets all frisky and acts like a big dog. It's kinda like a little bite size Chihuahua going after an intruder. Just adorable, eh?

I then fed my V-max rounds by hand and sent them on their way. Since the herd of big bad guys had been sufficiently thinned, I had to take on a little bad guy. It was pretty close. He got a shave and a haircut but will live to heckle me another day.



A cursory after-action inspection showed no abnormal wear marks or bad signs of metal to metal interference on the carbine. I have some things to do this afternoon so a detailed strip, cleaning, and inspection will come later. For now, I'm happier'n a puppy with two peters! The only thing I have left to do is replace the wobbly wont-stay-in-place rear sight. It's hard to be precise when your rear sight bounces around with each shot.

[JimF4M1s (Deceased)]

Just my opinion but, if it doesn't fit in the magazine, it wasn't meant for the gun.

[Bubba-7]

Now I think feets is crazy but wished he lived next door.

[Rustship]

He's a Hot-Rodder. Hot-Rodders are Crazy!

[DaveHH]

Well played

[feets]

Thanks guys. I've been having fun tinkering on this red headed stepchild.
As for the V-max long pointy bullets, they are the same weight as the ball rounds and the bearing surface is quite similar. They seem to be a wee tiny bit more consistent than the other rounds. I'll have to bag the carbine and try them from a bench to see how they run. It might be fun prairie rat medicine. I could use the carbine at typical carbine distances and the 22-250 to reach out farther. Naturally, the more traditional rounds as well as the squishies would be used for hunting piggies, cans, bowling pins, and those abominable smiley faces.

<~~~ There's one now! Where's the carbine?