order of firing from guns

I was a .50 gunner for 3 years in the Army and rarely encountered any issues. We did headspace and timing checks when switching barrels or if we were unfamiliar with that particular weapon. To be honest I knew my weapon so well that I didn't even need to use the metal spacer to set the timing. Most malfunctions were feed problems with the links and I never saw a runaway .50. There may be a slight difference in the fire rate in some .50s but not enough you can really tell. We did warp a .50 cal once because we put over 3000 rounds through it in one night. It would still fire but would start jamming frequently but no Mustang would fire that many rounds through one weapon in a sortie.

Yeah? And you know what was known for jamming WAAAAY more frequently than the upright-mounted M2s as fitted to the -51D?

 

The Mk108 as fitted to the Bf109K4. When's the last time you had that jam under g-load?

Take it easy, man. I'm quite aware that reliability was one of the advantages that the .50 had over cannons, and I'm not at all suggesting that the Brownings have gun jams but not the cannons. I would hope (given my posting history) that it's fairly obvious that I was referring to realistic jams not being in the sim at all, and hoping that they would be introduced to all weapons.

As a matter of fact, my three favorite aircraft all use the Browning M2, so--though I am very fond of the 109 also--I'm hardly a "Luftwhiner" trying to get the fifties "nerfed." The reason I spoke of the P-51 specifically, and not the 109 & 190, is that I do not currently own the latter two modules (I've been unable to use a joystick since before their release, due to medical reasons, and so, thus unable to use them, I haven't been able to justify their purchase on my tight budget).

I think you would do well to take a few deep breaths and try to approach this subject with less of a hostile attitude. Please don't assume that anyone who says anything that could possibly be construed as contrary to your position, is a P-51 hater trying to get the aircraft nerfed. I do not dispute that such people exist, but I think they are far fewer than you suspect.

I was a .50 gunner for 3 years in the Army and rarely encountered any issues. We did headspace and timing checks when switching barrels or if we were unfamiliar with that particular weapon. To be honest I knew my weapon so well that I didn't even need to use the metal spacer to set the timing. Most malfunctions were feed problems with the links and I never saw a runaway .50. There may be a slight difference in the fire rate in some .50s but not enough you can really tell. We did warp a .50 cal once because we put over 3000 rounds through it in one night. It would still fire but would start jamming frequently but no Mustang would fire that many rounds through one weapon in a sortie.

I got a little time on a .50 cal too. 3000 rounds in one night is meaningless. 3000 rounds in 5 minutes is a melted barrel.

Also, you got lucky if you think you were so good as to not have to use a gauge.

There is a reason SMA published that article.

The chart IS the burst limits for the Aerial Weapon M2 .50 caliber as used on the P-51 Mustang.

Please don't assume that anyone who says anything that could possibly be construed as contrary to your position, is a P-51 hater trying to get the aircraft nerfed. I do not dispute that such people exist, but I think they are far fewer than you suspect.

It just amazes that this even has to be said.......

Moving on...

The head space and timing was set before each flight in a M2 .50 caliber equipped aircraft, even the P-51 Mustang.

Not true. Headspace and timing do not need to be "checked often"; and by phrasing it that way, you are (intentionally or unintentionally) implying that the .50 caliber M2 was less reliable, or more demanding of maintenance than other weapons of its class.

 

The only time headspace and timing need to be checked, are when the barrel is replaced. Once set, it is good to go until you remove the barrel.

 

It is, however, true that errors in setting the timing nut will cause the gun to run slow. Headspacing actually has nothing whatsoever to do with the rate of fire of the gun, but if it is set incorrectly (too long), AND timing is set incorrectly (too fast), it can cause a round to fire out-of-battery (before it's all the way in the chamber), which of course is a Bad Thing.

That's not exactly true. Just so you know where I'm coming from I'm retired, 22 years, from the army. I spent 16 years in the infantry, over half of that time in a scout platoon (reconnaissance). My last 6 years I spent in special operations.

The book says you only have to check the headspace and timing if you change the barrel. In practice, that doesn't work. More times than not, if you don't check it before going on mission you will have several guns fail because the headspace and timing is out. Through use, time, hard terrain and flying, it gets out of sync. If you follow the book you will most certainly end up with 100 lb paperweights on mission when you need a HMG. You will never find a combat arms unit that only checks the headspace and timing when the barrel is changed.

I'm now flying for my second airline.

I got a little time on a .50 cal too. 3000 rounds in one night is meaningless. 3000 rounds in 5 minutes is a melted barrel.

 

Also, you got lucky if you think you were so good as to not have to use a gauge.

 

There is a reason SMA published that article.

 

The chart IS the burst limits for the Aerial Weapon M2 .50 caliber as used on the P-51 Mustang.

 

I'd sure the weapon armorer or whoever did the install and maintenance for these planes checked them every time before they were installed. Personally we were issued the same weapon with the same 2 barrels every time so figuring out the timing wasn't an issue. All the way in and 3 clicks out for my weapon ... still remember it 15 years later. When you do enough night fire exercises you find out its important to know the timing of your weapon.

Mustangs only carried 400 rounds on the inner guns and 270 on the other weapons. I seriously doubt overheating was a serious problem unless they held the trigger the entire 400 rounds on the inner weapons. It just didn't happen whether you didn't have a sight picture that long or you used trigger discipline because there was no rearming.

Now I would like to know about gyro sight failure rate of the Mustang under high g's. I watched one interview with a pilot that mentioned it but haven't seen it anywhere else.

That's not exactly true. Just so you know where I'm coming from I'm retired, 22 years, from the army. I spent 16 years in the infantry, over half of that time in a scout platoon (reconnaissance). My last 6 years I spent in special operations.

 

The book says you only have to check the headspace and timing if you change the barrel. In practice, that doesn't work. More times than not, if you don't check it before going on mission you will have several guns fail because the headspace and timing is out. Through use, time, hard terrain and flying, it gets out of sync. If you follow the book you will most certainly end up with 100 lb paperweights on mission when you need a HMG. You will never find a combat arms unit that only checks the headspace and timing when the barrel is changed.

 

I'm now flying for my second airline.

Similar career paths, LOL! :thumbup:

I seriously doubt overheating was a serious problem

The guns you and I used were not encased in a wing and lightweight barrel like the fixed weapon installation of the P-51.

If it was not a problem and did not need to be done, burst limits would not have been published.

:thumbup:

Here ya go...

:gun_sniper: You go to SOTIC? Level II?

No, I went to Sniper School when I was in the scout platoon. I competed and deployed. I did run an in house SOTIC for the battalion I was in, well took part as an instructor. You know the SOTIC's are gone now and it's called SFSC.

I'm pretty sure it was nothing more than a name change, for whatever reason.

Sorry guys, we moved out side convo from the thread.

Ok, now that I actually have some time off to respond, I would like to say the following:

1) I don't care if you were, or are, in the army. So am I. I *also* used the .50 cal as a primary weapon system for a decade, am a gunsmith, and have a Browning M1919 (the .30 caliber clone of the .50) in my gun safe at home. I didn't mention any of that earlier, because it DOES NOT MATTER TO THE DISCUSSION AT HAND. You're falling back on a logical fallacy known as the "appeal to authority". Funny enough, some of the people *making* that logical fallacy on this thread spend a *great* deal of effort insisting that WW2 pilot's comments about their aircraft's superior speed/maneuverability/whatever are irrelevant, so... so is your opinion on the headspace and timing.

2) I suggest you re-read the field manual on operation of the M2 .50 caliber. If you have *ever* had an issue with the headspacing of the .50 wandering or becoming mis-set due to hard maneuvering aircraft/ bouncing across the terrain in a tank/ bumping the weapon, it is YOUR fault, because unless you failed to conduct your pre-combat inspections and failed to identify you had a broken barrel lock spring, this will never, ever, be a problem.

If the bolt is forward, it is physically impossible for the barrel to rotate in the barrel extension threads, because the barrel lock spring (the bit that goes in the headspacing grooves on the barrel and clicks when you rotate it during headspacing) is pushed in and prevented from allowing the barrel to rotate, by a camming surface on the inside of the receiver. The barrel locking spring can ONLY be unlocked from the barrel when the lug (the little "nipple") on the back of the barrel lock spring is aligned with the little hole cut in the right-side plate. (FM 23-65, 19 June 1991 edition, section 3-6: Headspacing and Timing, portion b: "using the retracting slide handle, retract the bolt until the barrel-locking-spring lug is centered in the 3/8 inch hole on the right side of the receiver")

The barrel will not rotate when the barrel extension is in any position EXCEPT the proper headspacing position. You're even supposed to verify that is true during pre-mission checks, if you're a competent operator (FM 23-65, 19 June 1991 edition, section 3-6.b.3: allow the bolt to go forward. Check the barrel for rotation. Attempt to turn the barrel in either direction. The barrel should not turn. If the barrel does turn, stop here and check barrel notches and the barrel-locking spring for damage). If you go out with a gun where the headspacing can wander, it's YOUR FAULT, because you didn't identify the damage and T/I the unserviceable part to your armorer.

THERE IS A REASON YOU HAVE TO HOLD THE BOLT SLIGHTLY TO THE REAR WHEN HEADSPACING. It is to allow the barrel lock spring to move out of the headspacing detent grooves. This is the same method used to ensure takedown pins don't come out of slide-action pistols. Again, IT IS PHYSICALLY IMPOSSIBLE FOR JOSTLING OR BOUNCING AROUND TO CAUSE THE HEADSPACING TO BECOME IMPROPERLY SET.

3) The timing nut is held in place by the friction inherent with a very fine-pitch bolt, spring tension on the nut, and most importantly, a detent spring. This is essentially the same thing that holds rifle scope settings in place (only, the timing nut has a lot less inertia trying to move it, because it doesn't have a scope prism attached to it). Scopes do not lose their zero due to recoil, and the .50 doesn't spontaneously reset it's timing, either. Even if it did, it would take more than wandering a couple clicks to render the weapon non-functional; it would simply fire slightly faster or slower. Unless the timing becomes VERY fast (causing a premature ignition) or VERY slow (causing the firing linkage to not engage by the time the bolt assembly and barrel extension is fully forward), it will not jam the gun even if it *did* wander, which it doesn't.

4) admonitions in manuals instructing pilots to check headspace and timing prior to any firing mission do not mean the weapon is prone to jamming because of a wandering headspace and timing. It is simply a check that is done prior to flight. The manuals ALSO tell the pilot to ensure the ammunition is properly loaded; this does NOT mean that the ammunition is prone to spontaneously dropping out of the feed tray. Manuals instruct pilots to check for hydraulic leaks, this does NOT mean the aircraft frequently develops leaks. It is a check. Nothing more, nothing less. Further, the ground crew will have (assuming that they're not on a mission surge) removed the guns, disassembled them, cleaned them, lubricated them, and reassembled them prior to the firing mission. Remember what I said about checking headspace and timing when the barrel is removed? Well, there you go. Has to be done before a firing mission. Not proof of any propensity for jamming.

5) Therefore, the only reason to believe jamming due to headspacing and timing happened, would be if the ground crew screwed up, AND the pilot skipped his preflight. We do not even have the OPTION to preflight the aircraft in DCS, so it would be stupid to penalize the players for assuming they messed up their preflight, and if we *really* want to model ground crew SNAFUs, we're opening a whole can of worms, because we would ALSO have to model things like forgetting to put any fluid in the cooling system, leaving spark plugs unplugged from the electrical system, failing to tighten bolts in the engine head or prop hub, and all kinds of other catastrophes. No. Just, no.

6) On a related topic, modelling failures due to worn-out guns or poor manufacturing tolerances is also a non-starter, because it would piss off players to be punished randomly for failures that are out of their control.... and would be much more of an impact on the German A/C than the allied ones. I don't know of any of the Luftwaffe virtual pilots leaping for the opportunity to fly an aircraft that spontaneously breaks and may or may not perform as expected every time. Also, modelling failures due to manufacturing errors and wear is mighty subjective. There is practically no way to do it without relying on what is, in essence, a GUESS on the frequency of the failure. I'm sure we all know that the community would NEVER be able to agree on the right frequency of failures, and that this would be an eternal bone of contention. Failures should be tied to specific, relatively predictable actions: the player should know that if they do action a, they risk failure b. If I push WEP beyond time limits, there is a chance I will seize my engine. If I allow temperatures to get out of nominal range, I will seize my engine. If I choose to shoot the Mk108 while maneuvering hard, it will jam. NOT just "gee, I hope my guns work this time".

7) Now, to those that said I was overreacting and acting "persecuted", there's a good reason for that: no one came on and suggested that we model realistic failure rates for ALL guns on ALL modules. I would have far less issue with that (though I would still opposed it because of the "punishment for nothing" issue listed above. It is also worth noting that some of the individuals on here trying to convince everyone that the .50 is jam-prone, have a track record of double-standards: trying to convince everyone that the P-51's speed should be reduced because "laminar flow suffers from the wear and tear of field use and minor surface defects". while simultaneously, in other threads, arguing that the Bf109K4 "must be modelled according to the factory specs, assuming that an aircraft has been built properly, because manufacturing defects, damage, competence of teh ground crews, and logistical availability of parts and fuel are all outside the scope of what DCS simulates" (paraphrased, because I have no intention of wasting hours poring through old posts). In short, they argue that we should model things that hurt the aircraft... but only for one side, not the other.

If we want to model failure rates on guns, fine by me. But only if we model failure rates for ALL guns.

But then, I think we would see a lot more whining from Kurfurst pilots who suddenly lose 80% of their firepower whenever they try firing their Mk108 under g-load, than we would see whining from P-51D pilots who lose 17% of their firepower once every dozen sorties due to random jams. So good luck selling that one.

It is the lack of cool down period requirement that is unrealistic.

You can fire 500 rounds from the M2 in one trigger pull without JAMMING the gun. The reason there is a scheduled firing rate (IE, that table) is NOT to prevent jams. It's to keep you from burning out the barrel or unintentionally firing ("cooking off") a round. The hotter the barrel is, the more material each bullet (and more importantly, the hot gases and unburned particulates) grinds away from the rifling as it passes down the barrel.

Letting it cool extends useful barrel life; it does not really have much to do with preventing jamming. If a Mustang pilot just laid on the trigger, those .50s would fire the full 400 rounds from the inboard guns without trouble. ...the "trouble" would come when the pilot then had to explain to his armorer why he needed a new set of barrels already. But whatever; if that's what the pilot needed to do to get himself and his aircraft home, ok.

Firing bursts longer than recommended may also lead to cook-offs, but those don't jam the gun... they just mean it fires unintentionally because the barrels are hotter than the ignition temperature of the propellant. The gun would still cycle that round just fine. It's worth noting that the high airflow and low air temperature associated with aerial mounts means they have much less trouble with cook-offs than do ground mounts. I would also say that the firing rates to prevent cook-off on Crumpp's table are *extremely* conservative. They are the recommended limit to ENSURE a cook-off doesn't happen, and do not mean that, if exceeded, a cook-off WILL happen (much like the WEP time limit for the Mustang is a "soft" limit; merely a recommendation, and does NOT mean that the engine will seize immediately if slightly exceeded.... though apparently THAT is in contention by the Luftwaffe-uber-alles crowd, too. Not that I'm going to name names.).

Barrel heat does make a huge difference in barrel life, though. Say you have two identical rifles (let's go with AR15s), call them rifle A and rifle B, and a bunch of identical ammunition.

Rifle A, you fire and fire and fire as fast as you can load ammo and pull the trigger until the rifling is worn out. For something like an AR15, this will take only around 1000 rounds to do. As in, after about 1500 rounds of this abuse, you are shooting a smoothbore musket with NO rifling.

Rifle B, you fire single shot, and allow one minute of cooling between each shot. This rifle will go for easily 20,000 rounds before the rifling starts to go. And by this, I mean that you won't have match-grade accuracy after 20,000. The rifle will have useable military-grade accuracy (6MOA or less) for up to 40,000 rounds if treated this way.

This does not, however, have anything to do with frequency of jamming.

P-51D series Maintenance Instructions say to the headspace and timing must be checked before each take off.

P-51D series Maintenance Instructions say to the headspace and timing must be checked before each take off.

 

you posted that one already.

Sorry...

:smilewink:

Just noting that the reason the headspace was checked by the pilot before each flight was because normally the weapons were removed and cleaned each day, regardless of whether or not they had been used, or after every mission:

(from)

And, of course adjusting the headspace occurred each time the .50 was assembled:

That the pilot was supposed to check the headspace before flight was no reflection on the reliability of the .50 cal Browning, it was simply part of the daily routine of keeping the weapon cleaned.

Just noting that the reason the headspace was checked by the pilot before each flight was because normally the weapons were removed and cleaned each day, regardless of whether or not they had been used, or after every mission:

Yes, you check the headspace after cleaning. However the instructions are quite clear.

Checking the headspace after installation of the guns is a separate event.

The basic rule with a .50 cal is check the headspace anytime you go to shoot it, have moved it, or your are not sure of it.

Just like the manual says!!

Comma emphasized...

:music_whistling:

Here is the burst limits for the Heavy Barrel Ground variant for comparison to the light barrel aerial weapon posted earlier in this thread.

(b) To control the rate of fire, the gunner may use single shot, slow,

rapid, or cyclic.

 

(6)

Single shot. Place the gun in the single-shot mode and engage the

target with aimed shots. The MG is accurate out to 1,500 meters.

 

Slow fire. Slow fire consists of less than 40 rounds per minute, in

bursts of five to seven rounds, fired at 10- to 15-second intervals.

 

Rapid fire. Rapid fire consists of more than 40 rounds per minute,

fired in bursts of five to seven rounds, at 5- to 10-second intervals.

[ame]http://www.bits.de/NRANEU/others/amd-us-archive/FM23-65C2(02).pdf[/ame]

Slow fire is the sustained rate of fire and what the weapon is designed to handle:

Maximum rounds fired per minute for slow fire rate = 70 rounds

Rapid rate of fire is used for emergencies for short periods of time. It is what is used for Final Protective Fires when the enemy is breaching your defensive parameter and in your trenches.

Maximum number of rounds fired per minute for rapid fire = 84 rounds

Yes, you check the headspace after cleaning. However the instructions are quite clear.

 

Checking the headspace after installation of the guns is a separate event.

 

The basic rule with a .50 cal is check the headspace anytime you go to shoot it, have moved it, or your are not sure of it.

 

Just like the manual says!!

 

 

Comma emphasized...

 

:music_whistling:

Crumpp, I believe that what the other guys are trying to get at is that while it is definitely correct procedure to check headspacing prior to each mission, that does not mean that the headspacing is prone to wandering out of adjustment. Rather, it is a reflection of the fact that headspacing is a go/no-go setting for the entire weapon system.

Just like I check the oil level of my motorcycle every day. I don't do it because it's prone to leaking, I do it because if something does go wrong, running the bike with no oil will almost immediately result in a useless bike.

that does not mean that the headspacing is prone to wandering out of adjustment.

Some guns do and some do not....

At least that was my experience.

Just like some bikes use some oil and some do not! :)

Some guns do and some do not....

 

At least that was my experience.

 

Just like some bikes use some oil and some do not! :)

Then "some guns" were incorrectly maintained and serviced by you, and you failed your squad, platoon, and service because you could not be bothered to do the correct PMCS on your weapon.

OutOnTheOP

The US Army is not wrong in it's instructions on when to set the headspace and timing as well as how to shoot the weapon.