delayed roller bolt/fluted chamber...discuss...
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Jim Watson
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Do we get a piece of the diploma for writing your dissertation for you?
Bobarino
member
fluted chambers: if you're shooting high pressure stuff, they can ruin your brass and make it non-reloadable. the delayed blowbalck system sends more stuff out the barrel and not into the chamber and is great if you're using a suppressor. less noise coming out of the ejection port. honestly i'm not sure what the advantages are. i'm someone here knows.
Bobby
Bobby
Let me put in my $.02 before the confusion begins . . .
A peremptory note: The HK roller delay system ( a la G3, MP5, P9s) and the CZ52 (qua MG42) roller locking are NOT the same thing. Just because they use rollers doesn't mean they work the same way.
The HK system is a "delayed blowback" system (fixed barrel, no movement of slide and barrel together). The Cz52 roller locking is a "short recoil system" (barrel and slide locked together and move rearward together a short distance then separate) adopted from the German MG42 machine gun - it is a short recoil system that is no different from JMB's 1911, only the CZ uses rollers and a wedge to lock/unlock the slide and barrel together instead of a tilting barrel and lugs. End Note.
The Hk system depends on the fired case being able to freely move rearward to push on the breech. Unfortunately, casing walls tend to stick to the chamber walls during high pressure, preventing this. HK scores the chamber with lines so some high pressure gas can provide a buffer/cushion between the case wall and the chamber wall, thus preventing sticking and allowing the casing to freely move rearward. Because the CZ does not operate as the HK's do, it doesn't need the fluted chamber wall.
As far as advantages on HK roller delay - in handgun or subgun: fixed barrel, less felt recoil (see MP5). In rifles, can't think of much advantage as it's heavier and requires more machining. Originally it may have been seen as a cleaner advantage to gas operated rifles, but more modern systems (G36) render that concern obsolete, which may be why HK went to the G36 system.
I can't speak to the HS .380 or Colt .38 sp.
A peremptory note: The HK roller delay system ( a la G3, MP5, P9s) and the CZ52 (qua MG42) roller locking are NOT the same thing. Just because they use rollers doesn't mean they work the same way.
The HK system is a "delayed blowback" system (fixed barrel, no movement of slide and barrel together). The Cz52 roller locking is a "short recoil system" (barrel and slide locked together and move rearward together a short distance then separate) adopted from the German MG42 machine gun - it is a short recoil system that is no different from JMB's 1911, only the CZ uses rollers and a wedge to lock/unlock the slide and barrel together instead of a tilting barrel and lugs. End Note.
The Hk system depends on the fired case being able to freely move rearward to push on the breech. Unfortunately, casing walls tend to stick to the chamber walls during high pressure, preventing this. HK scores the chamber with lines so some high pressure gas can provide a buffer/cushion between the case wall and the chamber wall, thus preventing sticking and allowing the casing to freely move rearward. Because the CZ does not operate as the HK's do, it doesn't need the fluted chamber wall.
As far as advantages on HK roller delay - in handgun or subgun: fixed barrel, less felt recoil (see MP5). In rifles, can't think of much advantage as it's heavier and requires more machining. Originally it may have been seen as a cleaner advantage to gas operated rifles, but more modern systems (G36) render that concern obsolete, which may be why HK went to the G36 system.
I can't speak to the HS .380 or Colt .38 sp.
The HK systems ,P7 etc ,have a bolt that moves immediately when the pressure is the highest .Normally this would cause the case to separate since at the highest pressure the case mouth is tightly gripping the chamber.To prevent this the chamber is fluted [grooved] so that some gas escapes from the case and prevents a tight grip.
A peremptory note: The HK roller delay system ( a la G3, MP5, P9s) and the CZ52 (qua MG42) roller locking are NOT the same thing. Just because they use rollers doesn't mean they work the same way.
thats why i seperated them at the beginning ...
the high standard is a blowback (also their expermental 9mm) with a single flute in the chamber...
the colt has smooth almost stepped ring(s) to retard the lugless slides blowback...
thats why i seperated them at the beginning ...
the high standard is a blowback (also their expermental 9mm) with a single flute in the chamber...
the colt has smooth almost stepped ring(s) to retard the lugless slides blowback...
Hand_Rifle_Guy
Member
Innerspring...
You know...like a mattress. But I digress...
Hokay, fluted chambers. In HK's rifle, does the gas that's allowed to circulate through the flutes and all around the case immediately upon firing, and right through the 60-000 psi pressure peak:
A) alllow the case to move as neccessary to operate the action by adding a factor of lubricity to the chamber walls by acting as an air bearing and actually "floating the expanded case, or does it:
B) equalize the pressure on the inside and outside of the case somewhat, so that the case does not expand and grip the chamber walls during the pressure peak, facilitating action movement when neccessary?
And last of all, how does HK keep these high-pressure gasses from getting around the case that's sealing the breech when the rifle's design clearly allows some gas leakage?
I've never looked at one in any detail, so If someone knows, fill me in.
Now, the grooved chamber in a P7 pistol is a different order of business. Or is it?
P-7's are a gas-delayed blowback, using pressure tapped from the barrel operating against the multiple faces of it's gas piston set-up to hold the action shut until pressure drops emough to let the pressure remaing in the barrel overwhelm the gas-seal of the piston, whereupon the cartridge case becomes a piston that pushes the slide back to cycle the action. I could see wanting a fluted chamber to ensure pressure relief at a critical time, and also provide for less surface area for the brass case to get traction against, helping to ensure extraction/ejection. (Or, conversely, could the flutes provide extra ridges and edges for the case to get additional traction during a critical time segment to assist in delaying the blowback like the grooves in a Seecamp chamber.) Dunno which it is, me.
)
I've heard P-7's can run with no extractor. Blowback is blowback, fluted/delayed or not. Slide movement is initiated by the rearward movement of the cartridge case out of the barrel, or it doesn't happen.
That speaks well of HK design that such a complicated, closely-tuned balance of pressures should work as good as it does under all SORTS of different ammo conditions.
However, it is worth noting that A) .40-caliber P-7's don't like the pressure curves of some commercial ammo types, as they cause the guns to fail to cycle by holding them shut with high-pressure gasses, in effect delaying the action to a halt, and:
B) I've read accounts of P-7's being overdriven to the point that the cases were coming out of the gun shredded into little rosettes of brass as the high-pressure gas blasted the case away where it was uinsupported!
WITHOUT causing the gun any harm.. That's amazing right on the face of it.
And yet...The Heritage C-4200 Stealth Shadow pocket pistols in 9mm and .40 S&W have to all intents and purposes the same gas-delay system that the P-7 uses, but requires NO flutes in the chamber to assure functioning. So what is the fluting REALLY there for? Enquiring minds want to know!
Now I always thought MP-5's were just ordinary blowbacks, and here I find they're this contrived-up delayed-roller fluted-chamber Rube-Goldberg assemblage of operatiing principals. Does this complexity justify it self sufficiently via superior performance? Who-ever heard of a locked-breech submachine gun? No WONDER those darn things cost so much.
Other chamber "flutes" or rings, or what have you. The Colt AMU .38 Special autos. The Seecamp.
The AMT Automag II has thee sets of holes drilled into the walls of it's chamber before a tight-fitting sleeve is slid over it and welded on to finish the barrel. The one set is right in front of the end of the case, allowing gas pressure to relieve internal pressure on the case through the holes that are drilled in the chamber that the case grips the edges of during the high point of the pressure curve. After that it's strictly a blowback job.
High Standard had a gas-delayed blowback system? (That being the proper definition of ringed/drilled/rough chambers.) When was that?
I thought the only OTHER gas-delay system was in the Steyr GB. That one taps the barrel through a couple of BIG holes, and holds the slide shut by providing pressure against the greater surface area that was the back of the bushing until the case evntually wins and blasts backwards out of the fixed-barrel to run the cycle.
And NO, Rogack P-18's do NOT count.
You know...like a mattress. But I digress...
Hokay, fluted chambers. In HK's rifle, does the gas that's allowed to circulate through the flutes and all around the case immediately upon firing, and right through the 60-000 psi pressure peak:
A) alllow the case to move as neccessary to operate the action by adding a factor of lubricity to the chamber walls by acting as an air bearing and actually "floating the expanded case, or does it:
B) equalize the pressure on the inside and outside of the case somewhat, so that the case does not expand and grip the chamber walls during the pressure peak, facilitating action movement when neccessary?
And last of all, how does HK keep these high-pressure gasses from getting around the case that's sealing the breech when the rifle's design clearly allows some gas leakage?
I've never looked at one in any detail, so If someone knows, fill me in.
Now, the grooved chamber in a P7 pistol is a different order of business. Or is it?
P-7's are a gas-delayed blowback, using pressure tapped from the barrel operating against the multiple faces of it's gas piston set-up to hold the action shut until pressure drops emough to let the pressure remaing in the barrel overwhelm the gas-seal of the piston, whereupon the cartridge case becomes a piston that pushes the slide back to cycle the action. I could see wanting a fluted chamber to ensure pressure relief at a critical time, and also provide for less surface area for the brass case to get traction against, helping to ensure extraction/ejection. (Or, conversely, could the flutes provide extra ridges and edges for the case to get additional traction during a critical time segment to assist in delaying the blowback like the grooves in a Seecamp chamber.) Dunno which it is, me.
)I've heard P-7's can run with no extractor. Blowback is blowback, fluted/delayed or not. Slide movement is initiated by the rearward movement of the cartridge case out of the barrel, or it doesn't happen.
That speaks well of HK design that such a complicated, closely-tuned balance of pressures should work as good as it does under all SORTS of different ammo conditions.
However, it is worth noting that A) .40-caliber P-7's don't like the pressure curves of some commercial ammo types, as they cause the guns to fail to cycle by holding them shut with high-pressure gasses, in effect delaying the action to a halt, and:
B) I've read accounts of P-7's being overdriven to the point that the cases were coming out of the gun shredded into little rosettes of brass as the high-pressure gas blasted the case away where it was uinsupported!
WITHOUT causing the gun any harm.. That's amazing right on the face of it.And yet...The Heritage C-4200 Stealth Shadow pocket pistols in 9mm and .40 S&W have to all intents and purposes the same gas-delay system that the P-7 uses, but requires NO flutes in the chamber to assure functioning. So what is the fluting REALLY there for? Enquiring minds want to know!
Now I always thought MP-5's were just ordinary blowbacks, and here I find they're this contrived-up delayed-roller fluted-chamber Rube-Goldberg assemblage of operatiing principals. Does this complexity justify it self sufficiently via superior performance? Who-ever heard of a locked-breech submachine gun? No WONDER those darn things cost so much.
Other chamber "flutes" or rings, or what have you. The Colt AMU .38 Special autos. The Seecamp.
The AMT Automag II has thee sets of holes drilled into the walls of it's chamber before a tight-fitting sleeve is slid over it and welded on to finish the barrel. The one set is right in front of the end of the case, allowing gas pressure to relieve internal pressure on the case through the holes that are drilled in the chamber that the case grips the edges of during the high point of the pressure curve. After that it's strictly a blowback job.
High Standard had a gas-delayed blowback system? (That being the proper definition of ringed/drilled/rough chambers.) When was that?
I thought the only OTHER gas-delay system was in the Steyr GB. That one taps the barrel through a couple of BIG holes, and holds the slide shut by providing pressure against the greater surface area that was the back of the bushing until the case evntually wins and blasts backwards out of the fixed-barrel to run the cycle.
And NO, Rogack P-18's do NOT count.
Jim Watson
Member
The High Standard T-3 in the 1950s 9mm NATO trials vs Colt Commander and S&W M39 had a ringed chamber a la Mann, Seecamp, Colt .38 Mk III.
I had never heard that a G380 did, though.
HiPoint just has heavy pot metal slides running in straight blowback, no flutes, rings, or anything.
Astra 9mm Largo and Para straight blowbacks work ok, but Walther could not make a satisfactory blowback 9mm in two tries, the Model 6 and MP I.
Ever see a Kimball .30 Carbine delayed blowback pistol? Dang little delay, just a little straight line barrel travel. Cracked frames and company bankrupcy in short order.
I thought the Automag .22 magnum description in one of the gunzines was hillarious. The gas pressure back through those ports was said to press against the sides of the case and delay extraction.
Bruce Gray did some IPSC conversions on P7 M13s, with long barrels and compensators in the slide nose instead of hanging on the end of the barrel. Muzzle blast added to the gas cylinder delay for 9mm Major loads. He did not flute the chambers of his replacement barrels. I think he was shooting 158 grain cast bullets so as to make Major power factor with bearable pressures. Must have had to clean the gas cylinders frequently.
There is a Communist Chinese gas delay pistol. Has the Lignose Einhand cocking arrangement, too.
One of the custom gunsmiths made a gas delay gun that looks sort of like a 1911, but it never sold. So he designed an ugly modernical gun that you can buy at a high price; big feature piece with Ichirio Nagata centerfold.
NCG does gas delay conversions on 1911s. Their rep is spotty.
SIG made a roller locked rifle at one time. Roller LOCKED, there was no cam ramp in the bolt carrier, it was retracted by a gas piston.
I had never heard that a G380 did, though.
HiPoint just has heavy pot metal slides running in straight blowback, no flutes, rings, or anything.
Astra 9mm Largo and Para straight blowbacks work ok, but Walther could not make a satisfactory blowback 9mm in two tries, the Model 6 and MP I.
Ever see a Kimball .30 Carbine delayed blowback pistol? Dang little delay, just a little straight line barrel travel. Cracked frames and company bankrupcy in short order.
I thought the Automag .22 magnum description in one of the gunzines was hillarious. The gas pressure back through those ports was said to press against the sides of the case and delay extraction.
Bruce Gray did some IPSC conversions on P7 M13s, with long barrels and compensators in the slide nose instead of hanging on the end of the barrel. Muzzle blast added to the gas cylinder delay for 9mm Major loads. He did not flute the chambers of his replacement barrels. I think he was shooting 158 grain cast bullets so as to make Major power factor with bearable pressures. Must have had to clean the gas cylinders frequently.
There is a Communist Chinese gas delay pistol. Has the Lignose Einhand cocking arrangement, too.
One of the custom gunsmiths made a gas delay gun that looks sort of like a 1911, but it never sold. So he designed an ugly modernical gun that you can buy at a high price; big feature piece with Ichirio Nagata centerfold.
NCG does gas delay conversions on 1911s. Their rep is spotty.
SIG made a roller locked rifle at one time. Roller LOCKED, there was no cam ramp in the bolt carrier, it was retracted by a gas piston.
1911Tuner
Moderator Emeritus
New Discussion!
HenryD...You scallywag! I see where this is goin'.
Watchin' and waitin'...
HenryD...You scallywag! I see where this is goin'.
Watchin' and waitin'...
I tried to resist the temptation to post and failed.
The chamber fluting on a G-3 is necessary because the bolt does not rotate. Rotating bolts loosen the case in the chamber prior to extraction. Without some way to loosen the cartridge case you end up with what was a common problem with some single shot breechloading rifles: the extractor tears off the case rim.
As for that roller delayed blowback, inside the bolt is a seperate piece that the bolt rides on. This piece has angled surfaces at the front that push against the rollers, forcing them out into the recesses of the receiver trunnion. This force is provided by a very stiff spring. When the rifle is fired, providing the thrust vector (sorry, couldn't resist ) against the bolt the rollers are pressed inwards against that internal angled piece, overcoming the force of the spring and pushing the bolt carrier rearward. The bolt carrier is quite massive because it serves as a countermass, absorbing some of the recoil.
If this is confusing let me know and I will try again.
The chamber fluting on a G-3 is necessary because the bolt does not rotate. Rotating bolts loosen the case in the chamber prior to extraction. Without some way to loosen the cartridge case you end up with what was a common problem with some single shot breechloading rifles: the extractor tears off the case rim.
As for that roller delayed blowback, inside the bolt is a seperate piece that the bolt rides on. This piece has angled surfaces at the front that push against the rollers, forcing them out into the recesses of the receiver trunnion. This force is provided by a very stiff spring. When the rifle is fired, providing the thrust vector (sorry, couldn't resist
) against the bolt the rollers are pressed inwards against that internal angled piece, overcoming the force of the spring and pushing the bolt carrier rearward. The bolt carrier is quite massive because it serves as a countermass, absorbing some of the recoil.If this is confusing let me know and I will try again.
Not true, NMshooter. The fluted chamber, as others have said, is used to allow the case to move back without head separation when the action requires case movement during the period of high pressure, as it does in roller delayed actions. The fact that the bolt does not turn is really irrelevant, although a rotating bolt (like the M14) can provide a degree of primary extraction that a non-rotating bolt (like the FAL) does not have. The FAL, of course, is one case of a non-rotating bolt that does not use a fluted chamber; there is no need since it is a fully locked, gas operated action. On the other hand, the Tokarev is a fully locked action (very similar to the FAL) and does have chamber flutes.
Not all fluted chambers "float" the case in gas; some do not extend into the chamber throat, but merely reduce the size of the chamber walls to reduce case adhesion.
The P7 has a fluted chamber not because the case has to move to operate the action, but because the case is going to move some while the bullet is moving far enough forward to allow the gas to get to the piston and slow down the slide. The Rogak did not allow for this, plus its gas had farther to go, so it routinely tore the rims off cases; Rogak's "solution" was to grind the hook off the extractor!
Jim
Not all fluted chambers "float" the case in gas; some do not extend into the chamber throat, but merely reduce the size of the chamber walls to reduce case adhesion.
The P7 has a fluted chamber not because the case has to move to operate the action, but because the case is going to move some while the bullet is moving far enough forward to allow the gas to get to the piston and slow down the slide. The Rogak did not allow for this, plus its gas had farther to go, so it routinely tore the rims off cases; Rogak's "solution" was to grind the hook off the extractor!
Jim
max popenker
Member
While rifles are OT here, SIG also made true delayed blowback rifle, the famous Stg.57 / SIG-510, in civilian guise known as SIG AMT.
as for pistols, Russian 'Grach' trials featured some blowback operated 9x18/9x19 pistols (with added polymer recoil buffer under the barrel), as well as pistol with two-part blowback breech-block. Both lost to locked-breech PYa.
as for gas delayed production pistols, there's the Steyr GB, the Heritage Stealth (patterned after S-African ADP, IIRC)
1911Tuner
Moderator Emeritus
Here Eye Bee
HD asked:
come on now , haven't you ever wondered how a DRB 1911 would work out ?...
Nossir...Nossir...I'm stayin outta this'un, Henry. This'uns yours!
I've been in enough trouble with the other two...
HD asked:
come on now , haven't you ever wondered how a DRB 1911 would work out ?...
Nossir...Nossir...I'm stayin outta this'un, Henry. This'uns yours!
I've been in enough trouble with the other two...
"Floating-Chamber" is error. Correctly-Designed "Rimfire Conversion" (With all respect; "Marsh Williams") unneeded.
With Higher-Pressure Centre-Fire System, One does NOT "A Moving Force-Multiplier" ("Floating-Chamber") desire.
"Fluting" as Retarding-Mechanism, in particular "Blow-Back" actions laudable System.
With Higher-Pressure Centre-Fire System, One does NOT "A Moving Force-Multiplier" ("Floating-Chamber") desire.
"Fluting" as Retarding-Mechanism, in particular "Blow-Back" actions laudable System.
Yet, (My Opinion) needless complication. One could "Floating Chamber" to "Positive-Lock" key.......Then again "H&K Gas-Buffer System" to M1911 adapted. (There exists question as to "Room"; i.e. Where then does One PUT additional components?)
For "Sporting-Arm" perhaps some potential, Defence-Arm? Would reliability with Gas-Fouling question.
Compliments extended for ideas/questions!
For "Sporting-Arm" perhaps some potential, Defence-Arm? Would reliability with Gas-Fouling question.
Compliments extended for ideas/questions!
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