PCC Sub Gun Omnibus Thread

The Glock and most other delayed-blowback pistols have a light-weight moving barrel that is enclosed most of the time. This does not scale as well to a 16" rifle barrel that is often 1) exposed and 2) much heavier. Most people would not want a rifle where the barrel touching something causes it to malfunction, I should think.

Anyone used the Taran +11 round extension for the MPX. I probably should have asked before I ordered.

erwos said:

The Glock and most other delayed-blowback pistols have a light-weight moving barrel that is enclosed most of the time. This does not scale as well to a 16" rifle barrel that is often 1) exposed and 2) much heavier. Most people would not want a rifle where the barrel touching something causes it to malfunction, I should think.

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Ahh - tilting barrel does not equal direct blowback. Well my Walther PP and PPk/s seem to be direct blowback. I don't see any locking mechanism and the barrel is fixed. Sooo - same question still applies And I guess the same answer does as well; does not scale up.

Speed3 said:

Anyone used the Taran +11 round extension for the MPX. I probably should have asked before I ordered.

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These have a pretty good reputation.

calicojack said:

Ahh - tilting barrel does not equal direct blowback. Well my Walther PP and PPk/s seem to be direct blowback. I don't see any locking mechanism and the barrel is fixed. Sooo - same question still applies And I guess the same answer does as well; does not scale up.

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Those pistols are in .32ACP and .380ACP. As you said, same answer: doesn't scale.

*double tap*

Yeah was not thinking about the fact that most pistols use a tilting barrel locking design (even my LCP II mouse gun does I think). A tilting barrel / locked breech rifle with a 16" barrel would be something else.

calicojack said:

Yeah was not thinking about the fact that most pistols use a tilting barrel locking design (even my LCP II mouse gun does I think). A tilting barrel / locked breech rifle with a 16" barrel would be something else.

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https://www.yrsinc.com/product/roni...kit-with-igb-16-barrel-for-glock-17-19-22-23/

It definitely is something else, amazed this works as well as it does.

Awaiting the Stribog A3 release intensively.

Sent from my SM-G960U1 using Tapatalk

calicojack said:

Yeah was not thinking about the fact that most pistols use a tilting barrel locking design (even my LCP II mouse gun does I think). A tilting barrel / locked breech rifle with a 16" barrel would be something else.

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Tilt the bolt instead, then you have an FAL's action.

calicojack said:

Ahh - tilting barrel does not equal direct blowback. Well my Walther PP and PPk/s seem to be direct blowback. I don't see any locking mechanism and the barrel is fixed. Sooo - same question still applies And I guess the same answer does as well; does not scale up.

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Which is easier to rack the slide? Your 9mm Glock or .380 PP/PPK/PPKs?

Even though it is a less powerful and pressure round, the .380 are harder to rack, as they have a much stiffer spring.

FYI, Glock is a 16 pound per inch spring. Walther PP is 20 pound per inch.

9mm is 35,000 psi, .380 is 21,500 psi.

calicojack said:

Ahh - tilting barrel does not equal direct blowback. Well my Walther PP and PPk/s seem to be direct blowback. I don't see any locking mechanism and the barrel is fixed. Sooo - same question still applies And I guess the same answer does as well; does not scale up.

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Figure there is about .1sq inches of area between the case head and breech face, X 380s "lowly" 21.5KPSI =a peak of 2,150lbs of force. That 20# spring has no chance in hell of holding that back, and if the full force was imparted on the slide, or bolt, it would basically explode.

Blowbacks lock by the friction of the case in the chamber, the pressure expands the case, locking and sealing it in the chamber, then as pressure drops as the bullet is leaving the barrel the brass shrinks back, and it basically acts as a piston aggainst the bolt face "blowing it back", once it has moved about 1/4" back enough pressure has vented out the barrel, and around the case that only inertia keeps the bolt/slide moving rearward against the spring to complete extraction. Spring pressure has little to do with the ammount of force the rearward moving case imparts on the bolt in the short "powered" part of the blowback cycle. That is almost entirely a balance between the bolt/slide mass, and the pressure curve. The spring can slow the slide and keep it from bottoming out harshly as it coasts rearward, but the mass, and only the mass is what determines the initial rearward bolt/slide velocity in the first place, as the force imparted on it is relatively consistent. When the breech face and barrel are locked together in a locked breech short recoil system(AKA browning tilting barrels used by GLOCK), the system is no longer reliant on the residual chamber pressure to power it, and instead recoil powers the barrel/slide rearward a short distance as the bullet leaves the barrel, it unlocks as chamber pressure drops to 0, the slide continues to move rearward to complete the cycle from inertia only, there is less mass required to counter the force, and less spring pressure required to slow the mass of the bolt moving rearward. Delayed blowback just essentially delays blowback until the chamber pressure is lower that it would be without it, so less force is imparted, but the force is still imparted primarily from the chamber pressure in a fixed barrel, and not the equal/opposite recoiling force of the bullet leaving the barrel.

OK, my Taccom extreme short stroke bolt and delayed blowback recoil system came in today. I took a few minutes off of WFH to install it in my QC10 Glock lower build.

My pre-range hot take is that there's something to this combo. The stroke is clearly shorter, and the DBRS' magnets are doing SOMETHING to slow down the bolt, because you have to really yank hard to get it moving. It is not at all the same feeling as the constant heavy pull you've got with a standard blowback system. The ESSB has a slot milled in it to allow LRBHO to continue working even with the short stroke, which it seems to do fine in my limited testing. I would say the most annoying part so far is that you need to remove the buffer detent for the DBRS to install, so there's a bit of backend work involved with the lower. You also need to pull the rear weight out of the bolt.

I think it's perhaps a tad misleading to call it delayed blowback - after all, in the end, you're still overcoming the inertia of the bolt and buffer system, it's just that the buffer system now has magnetic retardation involved to increase the inertia. But it DOES remove quite a lot of weight by removing it from the bolt and the usual super-heavy buffers you see in 9mm ARs. From that perspective, assuming it works with live ammo, it may indeed be a better mouse trap and a way to re-equip older blowback guns to better compete with RDB / roller-lock / piston (MPX) guns.

Then again, one definition of delayed blowback is "do things other than increase the weight of the bolt/buffer or the spring strength to delay the bolt from moving back", so I guess you could argue it is delayed blowback from that perspective. Semantics are fun!

erwos said:

OK, my Taccom extreme short stroke bolt and delayed blowback recoil system came in today. I took a few minutes off of WFH to install it in my QC10 Glock lower build.

My pre-range hot take is that there's something to this combo. The stroke is clearly shorter, and the DBRS' magnets are doing SOMETHING to slow down the bolt, because you have to really yank hard to get it moving. It is not at all the same feeling as the constant heavy pull you've got with a standard blowback system. The ESSB has a slot milled in it to allow LRBHO to continue working even with the short stroke, which it seems to do fine in my limited testing. I would say the most annoying part so far is that you need to remove the buffer detent for the DBRS to install, so there's a bit of backend work involved with the lower. You also need to pull the rear weight out of the bolt.

I think it's perhaps a tad misleading to call it delayed blowback - after all, in the end, you're still overcoming the inertia of the bolt and buffer system, it's just that the buffer system now has magnetic retardation involved to increase the intertia. But it DOES remove quite a lot of weight by removing it from the bolt and the usual super-heavy buffers you see in 9mm ARs. From that perspective, assuming it works with live ammo, it may indeed be a better mouse trap and a way to re-equip older blowback guns to better compete with RDB / roller-lock / piston (MPX) guns.

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I'll be very interested in your range report. Have you a RDB gun to compare it to?

teratos said:

I'll be very interested in your range report. Have you a RDB gun to compare it to?

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Unfortunately not. I do have a roller-delayed rifle that is a pretty soft shooter, though. The idea behind the Taccom system is to have less mass bouncing around to reduce sight bounce, which is how I'll be evaluating it.

erwos said:

Unfortunately not. I do have a roller-delayed rifle that is a pretty soft shooter, though. The idea behind the Taccom system is to have less mass bouncing around to reduce sight bounce, which is how I'll be evaluating it.

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Good. The reciprocating mass is the major flaw in a 9mm AR. I’m certainly interested in solutions.

teratos said:

Good. The reciprocating mass is the major flaw in a 9mm AR. I’m certainly interested in solutions.

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cant be any worse than a standard blowback, right ? LOL

erwos said:

OK, my Taccom extreme short stroke bolt and delayed blowback recoil system came in today. I took a few minutes off of WFH to install it in my QC10 Glock lower build.

My pre-range hot take is that there's something to this combo. The stroke is clearly shorter, and the DBRS' magnets are doing SOMETHING to slow down the bolt, because you have to really yank hard to get it moving. It is not at all the same feeling as the constant heavy pull you've got with a standard blowback system. The ESSB has a slot milled in it to allow LRBHO to continue working even with the short stroke, which it seems to do fine in my limited testing. I would say the most annoying part so far is that you need to remove the buffer detent for the DBRS to install, so there's a bit of backend work involved with the lower. You also need to pull the rear weight out of the bolt.

I think it's perhaps a tad misleading to call it delayed blowback - after all, in the end, you're still overcoming the inertia of the bolt and buffer system, it's just that the buffer system now has magnetic retardation involved to increase the inertia. But it DOES remove quite a lot of weight by removing it from the bolt and the usual super-heavy buffers you see in 9mm ARs. From that perspective, assuming it works with live ammo, it may indeed be a better mouse trap and a way to re-equip older blowback guns to better compete with RDB / roller-lock / piston (MPX) guns.

Then again, one definition of delayed blowback is "do things other than increase the weight of the bolt/buffer or the spring strength to delay the bolt from moving back", so I guess you could argue it is delayed blowback from that perspective. Semantics are fun!

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I wonder it that will work in a QC 5 set. No LRBHO of course, but I can live with that if it lives up to expectations.

outrider58 said:

I wonder it that will work in a QC 5 set. No LRBHO of course, but I can live with that if it lives up to expectations.

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No reason it wouldn't work on that platform that I can think of.

erwos said:

No reason it wouldn't work on that platform that I can think of.

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Cool. I'll wait for your report.

AAFG opens for members only on Friday. I think I'll take my Banshee out for a good cleaning.