Universal Locked Breech Style Barrel Testing Frame Project.

[arakboss]

One of the latest youtubers I have subscribed to, developed a universal handgun frame that he uses to test homemade barrels he makes. He calls it the UTAH pistol.

This has motivated me to build my own universal pistol that will accept commercially produced locked breech style barrels of various brands and chambered in a variety of cartridges. My initial thoughts are to use an AR15 receiver set but I haven't settled on that idea yet. The function will be single shot and most likely require unscrewing a collar to load, reload and to change barrels.

Why? For the fun of it.

Read More

 

[arakboss]

A Glock 30 might be an easier host to use for this purpose. I would need to devise a method to keep the slide locked during the firing process? The 45acp breech face and opening would allow for a wide selection barrels to fit. A small selection of bushings could be utilized to reduce barrel hole in muzzle end of slide. A various assortment of recoil spring lengths would help keep barrels in place.

I would probably have to modify the locking area in the frame so it didn't interfer with locking lugs on various barrels. I will play around with some longer barrels in my Glock 21 and see if that idea is feasible.

 

[bcp]

There are commercial designs to get ideas from. For example:

Universal Receiver, Universal Receiver Barrels, Single Point Cut Rifled Barrels

Universal Receiver Systems, Cut Rifled Barrels, Universal Receiver Barrels,

www.newlenoxordnance.com

https://sydortechnologies.com/wp-content/uploads/Sydor-Small-Caliber-Universal-Receiver-Datasheet_050819-2.pdf

Universal ballistic MINI test receiver

M2 Improved mini receiver is designed to accommodate anything from a 5,56 mm up to a 12,7 mm caliber. | ZPV Proizvodnja

www.zpvpro.com

Bruce

 

[arakboss]

One persons method of locking slide during firing:

 

[arakboss]

A hushpuppy device would be much more pratical.

 

[RX-79G]

A hushpuppy style lock would be a poor choice on a polymer frame.

However, you can always use your thumb on the back of the Glock slide. Depends if your "universal" tester is for rifle rounds or not.

 

[arakboss]

A hushpuppy style lock would be a poor choice on a polymer frame.

However, you can always use your thumb on the back of the Glock slide. Depends if your "universal" tester is for rifle rounds or not.

I watched a number of videos where the thumb or hand grip was used to prevent cycling. I am going to post some photos of barrel and slide features later this morning, hopefully you can pop back in this thread and help me determine what the features do

 

[arakboss]

A hushpuppy style lock would be a poor choice on a polymer frame.

However, you can always use your thumb on the back of the Glock slide. Depends if your "universal" tester is for rifle rounds or not.

I installed my factory G22 40 S&W barrel into my G21 slide and it seems to fit OK except for the barrel hood being to short and too narrow to fill the breech hole area on the slide. I nervously installed the slide on to my G21 frame and it fit and functioned, seemingly OK. I did not try to cycle any rounds through it.

I am not worried about the G22 barrel not fitting on the sides but the shortness in length could be a huge problem or not?



I am still trying to understand how the locked breech system works. My understanding is that this area of the barrel hood holds the slide back for a moment when a round is fired so that the case is not pulled from the chamber too early, is that correct?
Would having the gap as shown in the photo allow the case to be pulled early and risk having a ruptured case?



What are all of the functions of this lug on the barrel?

 

[RX-79G]

I installed my factory G22 40 S&W barrel into my G21 slide and it seems to fit OK except for the barrel hood being to short and too narrow to fill the breech hole area on the slide. I nervously installed the slide on to my G21 frame and it fit and functioned, seemingly OK. I did not try to cycle any rounds through it.

I am not worried about the G22 barrel not fitting on the sides but the shortness in length could be a huge problem or not?

View attachment 1256414

I am still trying to understand how the locked breech system works. My understanding is that this area of the barrel hood holds the slide back for a moment when a round is fired so that the case is not pulled from the chamber too early, is that correct?
Would having the gap as shown in the photo allow the case to be pulled early and risk having a ruptured case?



What are all of the functions of this lug on the barrel?


View attachment 1256413

I'll answer the questions later, but if you dont understand this simple system I think you should think again about all the stuff you're screwing with.

 

[arakboss]

I'll answer the questions later, but if you dont understand this simple system I think you should think again about all the stuff you're screwing with.

Hands on is a good way to learn, for me. Look forward to more info about the gap.

 

[RX-79G]

Hands on is a good way to learn, for me. Look forward to more info about the gap.

Recoil operated guns cause the barrel to move forward because the bullet is going down the bore and the slide is pushed to the rear by the blowback of the cartridge casehead. So the front surface of the barrel chamber block is what "locks" the slide to the barrel. The back of the chamber block is called the hood, and it controls headspace.

Since a Glock is controlled round feed, we know it is going to fire with the case head all the way to the rear against the slide breechface. Since there is a gap with the 22 barrel in the 21 slide, that gap represents "excessive headspace". In this case, what is likely to happen when you fire the gun is that the .40 case web area will be hanging out of the chamber by the amount of the gap, which will cause that unsupported web to blow out at the feed ramp, blowing the magazine out and fracturing the frame.

The forward barrel lug that you asked about has two functions: The rear angled section hits the frame locking block cross bar when the slide recoils and that forces the barrel down to unlock the upper chamber block surface from the slide. The similar angled area in the rear lug is what cams the barrel up when the slide goes forward. The other thing the front lug does is stop the barrel and slide from shooting forward off the frame by the front of it coming to rest against the take-down latch.

 

[arakboss]

Recoil operated guns cause the barrel to move forward because the bullet is going down the bore and the slide is pushed to the rear by the blowback of the cartridge casehead. So the front surface of the barrel chamber block is what "locks" the slide to the barrel. The back of the chamber block is called the hood, and it controls headspace.

Since a Glock is controlled round feed, we know it is going to fire with the case head all the way to the rear against the slide breechface. Since there is a gap with the 22 barrel in the 21 slide, that gap represents "excessive headspace". In this case, what is likely to happen when you fire the gun is that the .40 case web area will be hanging out of the chamber by the amount of the gap, which will cause that unsupported web to blow out at the feed ramp, blowing the magazine out and fracturing the frame.

The forward barrel lug that you asked about has two functions: The rear angled section hits the frame locking block cross bar when the slide recoils and that forces the barrel down to unlock the upper chamber block surface from the slide. The similar angled area in the rear lug is what cams the barrel up when the slide goes forward. The other thing the front lug does is stop the barrel and slide from shooting forward off the frame by the front of it coming to rest against the take-down latch.

If the extractor was not present (disabled) and or the slide was prevented from moving after firing (hushpuppy type slide lock device), would either of those prevent the excessive headspace caused by gap?

 

[RX-79G]

If the extractor was not present (disabled) and or the slide was prevented from moving after firing (hushpuppy type slide lock device), would either of those prevent the excessive headspace caused by gap?

Of course not.

 

[arakboss]

Of course not.

Let me guess the barrel would still move forward to close the gap, the brass case would be pushed rearward until it hit the breech face? Where does the controlled round feeding play into to causing the excessive headspace?

 

[arakboss]

I will work on an adjustable method to eliminate that gap. The gap will likely vary from barrel to barrel.

 

[RX-79G]

Let me guess the barrel would still move forward to close the gap, the brass case would be pushed rearward until it hit the breech face? Where does the controlled round feeding play into to causing the excessive headspace?

It doesn't. It just insures that the round will fire rather than be seated forward into the barrel.

I will work on an adjustable method to eliminate that gap. The gap will likely vary from barrel to barrel.

Your firing pin isn't adjustable, so the only way of addressing the gap is the front of the chamber block. But even if you could fill that it would not mean that the barrel is in the right place over the locking block. If it is too far back, it will either not cam up or will allow the barrel to pop down and out of battery.

All of that ignores the fact that you have excessive room side to side, and the barrel is under torque due to the rifling.


There is nothing good about what you are trying to do.

 

[arakboss]

It doesn't. It just insures that the round will fire rather than be seated forward into the barrel.


Your firing pin isn't adjustable, so the only way of addressing the gap is the front of the chamber block. But even if you could fill that it would not mean that the barrel is in the right place over the locking block. If it is too far back, it will either not cam up or will allow the barrel to pop down and out of battery.

All of that ignores the fact that you have excessive room side to side, and the barrel is under torque due to the rifling.


There is nothing good about what you are trying to do.

"There is nothing good about what you are trying to do."

That seems to be a theme among my ideas. I will give more thought to the host for this project.

 

[Papercidal]

I would look at a Thompson contender I've often been tempted to get one to use with a pressure trace system for pressure tasting loads.

 

[arakboss]

....

I would look at a Thompson contender I've often been tempted to get one to use with a pressure trace system for pressure tasting loads.

If I inherit a bunch of money from a rich relative that I didn't know I had, I plan on buying a contender and an entire suite of barrels.

For know I will improvise with the cheap stuff.