Ejection Ports

Post by Spencerman

Here is something that has really bugged me for a long time now, which probably started with the Glock 17 when that came along, and has more obviously be viewable on newer firearms such as the Walther P99 in Tomorrow Never Dies and the HK USP Compact in the series 24. I was watching 24 earlier, and what it is, and it seems to only plague the more open topped semi automatics, is that silver bit on the front leading edge of the ejection port that slopes up for about the first third of the port. Why is this? I figure that it must have a reason, probably something to do with firing blanks from a live fire weapon, maybe something to do with the locating lugs of the barrel perhaps or something similar. You see it so clearly in Tomorrow Never Dies, but not the later ones as they use crappy blank firers instead of the real thing for the shooting scenes. Here is what I am talking about:



You can see that silver bit ever so clearly, it was plastered all over the poster even, but when you actually look at the gun it seems to just dissappear:



The next one is not quite so obvious, but you can still see that it is there, even on some of the poster art, but not all (It is clear on the season 5 boxset cover in the UK):



As I say, not quite so blatant, but it is there none the less, but not on the real thing:



I couldnt find an image that showed the Glock, but if you look at many films with it, I specifically recall it in Freejack, with Emilio Estevez, but there are many others that I have seen it in also, the names of them just escapes me. It is not that I dislike the look that this gives the gun, I do not, it does have a kind of nice cosmectic appeal to it, but I cannot imagine anyone going to that much trouble just to add a little cosmetic touch like that which is after all unrealistic. Maybe it is for safety reasons? Maybe it weakens the chamber enough that a live round could not be fired from it? I can appreciate that a well used gun can tarnish on the ejection port (and other places for that matter), but it doesnt wear away the metal like that, only scuffs it up a little. I had a few that ended up like that myself. Maybe it hepls the gun to be more reliable using blanks, or maybe it is only when they are using blanks of a certain strength? Hopefully someone will know the purpose behind this butchery and be able to put me out of one more of my petty little gun related miseries!
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Post by Doc

Not sure on the answer with this spencerman but Bauer`s going for the nose job the cheap way then

Is it possibly a visual aid to show the slide is fully foreward and presumably ready for firing ?

DOC
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Post by 2sharp

My take is that you're correct, you don't need to have the barrel and slide locked together when firing blanks, and you have less pressure to work with.

So i'd say that the milled, angled slope is to enhance operation.

I've seen a live Glock 26 that had a similar, altough not as severe modification to allow it to work reliable with a small suppressor.
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Post by figaro

Blank or live the pistol won't fire unless the slide and barrel are locked up (on a real steel modern handgun).
Blank with choke in barrel has the same pressure as a live round, sometimes more. You will need a choke to cycle the action on an automatic.
The only major modification on a pistol that I've seen was on the 1911 series, the chamber has to be milled wider for the fired .45 blanks to eject successfully, some people also clip the recoil springs to make them less stiff, but this isn't always necessary.
Some guns just never cycle well with blanks, Luger, Browning GP35 for example, in my experience, and that doesn't count for so much.

I've seen plenty of the milled/sloping chambers on live fire guns.
My guess it was for lightening the system, maybe after market barrels.
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Post by HueyJ

The P99, the H&K and the Sig family of pistols are all breech locking, rather than using lugs on the barrel such as the 1911 and GP35. the front edge of the square breech section provides the locking surface for the corresponding cut out in the slide. Removing that surface from the breech makes the pistol function as a blowback system requiring only the pressure of the fired cartridge to cycle, rather than a locked recoil system which requires the recoil impulse of a fired projectile to function. IE to function with blank rather than ball ammunition.
The modification of the pistols you've noted Spencerman is the equivalent of the removal of the locking lugs from the barrels for pistols such as the GP35 to make them function in the blowback mode. Of course since these lugs are inside the slide such modification is not visible in the way it is with breech locking designs.

Post by Kimbo

When a semi-auto pistol has a tilting barrel that locks up into a recess in the top inner portion of its slide...OR...in the case of a 92FS where it also has a delayed blowback design because of its locking lugs...in order for the pistol to work with blank ammunition, one MUST defeat the lock up or delay. Like the Walther PP and the PPK designs, they operate on a straight blowback design. In other words, when a .32 or .380 live round exits the barrel of the PPK and the PSI decreases in the chamber, the extractor helps control the rearward inertia of the empty case until it hits the ejector which kicks it out of the ejection port. Watch a PPK action/barrel when you pull the slide back and forth (with the mag out)...notice that the barrel doesn't move and remains static.

Now on a Glock pistol, since the top of its barrel locks up into its slide, there is NO way that the pistol will function with a blank round. Blank rounds do NOT have any recoil whatsoever...there's NO projectile. So, in order for one to make their Glock operate semi-auto with blanks, one must defeat the tilting barrel/slide delayed blowback design by professionally machining the metal on the TOP, FRONT portion of the "meatier" or chamber area of the barrel. If one will start milling a downward "slope" starting from 3/4" forward from the most rearward top portion of the TOP of the barrel...mill forward (towards the muzzle) only 7/16" and STOP there. DO NOT MILL ANYTHING ON THE LEFT, BOTTOM OR RIGHT SIDE OF THE BARREL. Buff everything you've done so it is all shiny. You can blue that milling to keep it from reflecting any light. Then, one must tap/thread the muzzle for 3/8x24NF down the muzzle about 1" deep. THEN, get about 10-3/8" set screws (that have the same threads) and start drilling the centers out of about 5. Start at about .230. Then, with ONE blank round in the magazine...shoot the pistol with the .230 set screw snugged into the muzzle and what you are shootin' for is to have the slide lock back. ONE MUST GO SLOW AND BE CAREFUL that you start with a very large oriface in the barrel....then, work your ways smaller until, like I said, the blank locks the slide back. THEN, go just ONE drill another screw ONE drill size smaller and snug that screw in the muzzle and your pistol will NOW work in a STRAIGHT BLOWBACK design.

I know...this got longer than I had planned...but, this machining to the top of auto pistol barrels (along with the milling off of the Beretta 92's locking lugs on the sides of its barrel) make those "Movie Guns" work semi-automatically with blanks. Machineguns and Submachineguns are converted the same way...straight blowback. Of course, revolvers and single shot rifles or pump shotguns don't need any modifications to operate their actions with blanks.

Hope this answered your question, Spencerman.

Let me know if you have any other questions...and I'll try my best to post a more concise answer.

Kim in NW GA.
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Post by Spencerman

Well, I think that that pretty much answers my question. Many thanks all of you. Now I am wondering if you can buy pre modified barrels for just this purpose. Swap outs as it were, so that you can just pop one into your own Glock and use it for blanks, pop your original barrel back in to use live rounds again? If so, what sort of place sells them and does anyone know what sort of regulation these parts would come under?
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Post by figaro

All of the rental houses in LA have stopped blank adapting guns that are not their own.
When I bought the adaptor for my 1919A4 from Guiette. (this is was the only time I've actually had to buy an adaptor, usually they are put together by a gunsmith fairly efficiently)
http://www.guiettemfg.com/catalog.html
It came with different sized chokes and two different sized round stops, and information on starting with the biggest hole and working backwards, to find the one that cycled the action most efficiently.
I didn't do the experimenting, I handed it all off to a gunsmith I'm afraid to say (chicken!).
Joe Swanson mixes magnesium into his blanks and they are very hot especially in .308, I didn't want any part of it possibly going wrong.
The other guns I have were all blank adapted by a gunsmith, you guys for the most part seem a lot more engineeringly advanced than I am.

PS. I still don't think the sloping part of the barrels you are talking about is to do with blank adapting, I will find a real-steel automatic with a sloping breech and photograph it, the hunt is on, ha.
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Post by kimbo

...that a semi-auto pistol with a delayed blowback design MUST have their barrels modified so that they will operate in a STRAIGHT blowback design. The later is the only way that a semi-auto pistol will run 100% with blank ammo. The Ruger P series semi-auto pistols have to be modified the same way as a Glock. A Beretta 92 or Taurus PT92 has to have their left and right side locking lugs milled off to operate in a straight blowback operation.

Then, as with ALL semi-auto pistols...the barrel's muzzle MUST be sized down (using a set screw with smaller hole in it) to allow enough PSI to spit out flame and also, work the action.

Yes, the "sloping" of the top portion of the Glock, HK, Ruger and any other pistol barrel (except the PPK and a few others) that has a delayed blowback design will have the same mods done to the barrel. Again, that "siny" portion on top is where the armorer didn't blue the steel again.

Hope this clears up any confusion.

Kim in NW GA.
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Post by HueyJ

DELAYED BLOWBACK pistols will require a different form of modification, dependent upon the system of retardation employed, and there are a range to choose from, H&K P7, Steyr GB, CZ52, all delayed blowback designs. all using different methods to delay opening of the otherwise unlocked breech, all reliant upon the pressure of the cartridge to shift the slide.

There would be no modification of the breech required since there is no locking performed by the breech.

Glock, Walther P99, Sig P22x, H&K USP, Colt 1911, Browning GP35, Tokarev T33 are all RECOIL operated designs all reliant upon the recoil impulse of a fired projectile, as described by the third law of Newtonian physics, to unlock the breech from the slide.

In those designs which are described as breech locking ie those that don't use corresponding lugs on the barrel and slide in the way that the Browning designed 1911 and GP35 do but rather a rectangular or square cross sectioned breech which locks directly by camming up into the ejection port cut out of the slide it is, as Kimbo says, essential to modify the breech in order to remove the locking function and allow the slide to move under cartridge pressure alone when used with blank ammunition.

The same modification in terms of mechanical effect is carried out when creating blank firing barrels for 1911s, GP35s et al by machining the lugs off the barrel, this however goes un-noticed since the portion of barrel affected remains concealed within the slide.

It's possible to demonstrate the difference between blowback force and recoil if you have access to a either a recoil operated pattern live firearm for those board members in countries where such items are permitted, or a sympathetically deactivated example for the rest of us.

Obviously having checked that the weapon is clear first, place down the barrel a wooden dowel of sufficient length to protrude from the muzzle when inserted fully and of small enough diameter to move freely. Now with the end inside the weapon butted up against the face of the slide push the dowel taking care not to exert any force on the muzzle of the barrel. This simulates the blowback effect, and there will be no movement of the slide, no matter how hard you push.
Remove the dowel and just with your hand flat on the muzzle push, this simulates the recoil impulse experienced by the weapon when a projectile is fired, and the slide and barrel will unlock.

If you do the same with a wooden dowel and a delayed blowback design you'll find that the slide moves when you push, although quite how hard you'll need to push will depend upon the particular design of the pistol, some like the H&K P9 which utilises rollers will require more than others such the H&K P7 which bleeds gas from the bore to keep the slide forward and so only has retardation when actually fired.

It may well be possible to find other designs of pistol which normally have a sloped leading edge to the breech, that simply means that they are not breech locking, they may achieve locking through another means, they may be delayed blowback in operation, they may be simple blowback designs, or they may even be gas operated. Not all pistols function in the same manner and consequently not all require the same sort of modification for use with blank ammunition.

But for the pistols which Spencerman enquired about, the modification that both Kimbo and I have described is the one required to permit blank firing, in conjunction of course with suitable choking to up the pressure sufficiently to 'blow back'

Post by figaro

This is great info.
Valuable and well thought out thank you, Huey, for taking the time.

I have four 1911's that are blank adapted.
2XSpringfield WW2 rep's.
a Model 80 Colt, and a genuine WW2 Colt.
None have had the breech modified (other than enlarging the port on the slide), all work just fine, but I'm sure they would work better with the breech work, I will look into it, thank you for the heads up.

There is a link to a site that is showing the teaser (work in progress) for my picture, "The Butcher" I think you can see the 1911's firing and also the 1919A4, for anyone interested.

http://worldfilms.com/home.cfm (click on "Play" next to "the Butcher" artwork.)

Enjoy,

JJ.
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Post by Claymore

Looks good Jesse, really looking forward to seeing this, you got a great bunch of actors there and there great looking gun fights.
finally got my hands on a copy of pit fighter, man pretty brutal, love the final shootout some great classic guns there . still trying to get the last sentinal but not succeded yet.

Post by figaro

Thank you so much Claymore, very, very kind words.
Pit Fighter was so low budget, but I'm proud of it, it was my first film to make money.
Strangely enough in relation to this thread, the Glock the girl uses kept jamming, look closely it turns into 1911 .45 throughout the gunfight, this was the only gun on set that didn't jam and was the same color, pathetic I know. But maybe if the Glock had the breech work done it would have been better.
The M60 could only shoot in bursts of 100, or it jammed, it got pretty hot.
So glad you liked it, The Butcher is a much more, polished, professional looking movie, it's a learning process you understand.
Again thank you.
Sorry to stray from the thread, hope no one minds too much.

Jesse.
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Post by Phil_D

Claymore, i think you will like the Sentinal, lots of gunfire and action
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