UK custom blank fire fabrication

Disclaimer, I know a forum is no substitute for proper legal advice/guidance, but I'm approaching this from a pure "first instance" perspective.
I am 100% aware that top venting blank firers with a complete barrel obstruction (usually a tungsten carbide insert that can't be removed) is the most reliable way of staying on the right side of the law when concerning blank firing replicas in the UK (also, VCRA considered).
I have spoken to reenactors who use custom made blank firers that follow this strict guidance, and these are fabricated for this specific purpose by individuals with the necessary skills and knowledge.
I am on a quest to produce functional replicas for the purpose of film production (rentals) through my company. I do possess the skill and knowledge (from a manufacture point of view) to make blank firers, but I have always been put off by the "readily convertible" restriction that could see me on the wrong side of the law (which, for the record, I want to avoid 100%).
Out of interest, what is deemed to be "readily convertible" in the UK? The main one that gets thrown around is "being front venting". I know some custom blank firers have special chambers that allow "forward" venting, but are legally allowed due to the angle not being completely parallel with the angle of the blank round. Top venting has always been the safest (from a legal perspective) and this is something that I can tolerate, with my visual effects and post production knowledge/skill making it possible to "correct".
Then there's the ability to chamber a live round. Blanks are shorter than live rounds and this could be another consideration. I'm thinking of 8mm pistol blanks which are cheap and readily available compared to "real size" blanks. As far as I am aware, the PAK 8mm blank round does not share dimensions with any existing (live) ammunition, which, I understand, is intentional.
Then there's material. Would a full steel construction be something that would make a custom blank firer readily convertible? If the pressure bearing parts like the barrel and bolt were made from a softer/weaker material, say aluminium, would this be deemed "not readily convertible"? I know replicas from Bruni are made from pot metal or zinc, but these also seem to have a hard material insert running along the length of the barrel to prevent being drilled out. This precaution would be something I would consider implementing too.
And finally, from what I have discovered, the barrel and chamber should be permanently fixed to the receiver so it can't be substituted for a live barrel.
I know this is a lengthy post but just to be clear, I'm looking to start a discussion or share ideas, not legal advice. I would definitely consult a specialist lawyer before any manufacturing takes place. Model guns are great but the cartridges are just a pain to maintain and are especially awkward when a client ends up losing a few. 8mm blanks are just the better option, if location is appropriate of course.

Blank firers are still a huge grey area in the UK and the cost of getting anything approved would be huge and time consuming. Top venting is to me a stupid idea and dangerous The 9mm pak MP40 had to have a plate put on it to stop people putting their fingers over the hole. Its amazing that the rest of Europe can have front venting blank firers but we cant and it all comes down to the police and government not wanting us to have anytype of firearm including airsoft.
Good luck it would be great if you could sort something out but you have a mountain to climb, still suprises me that there are a lot of retay blank guns still on sale and the authorities have not put more restrictions on them, i am sure they will find something to restrict them.

Hi Claymore, thanks for the information. It's funny you should mention the Retay blank firers because in recent years, the variety of 8mm/9mm blank firing pistols have shot up. I remember back in 2009 when I first purchased a Bruni Glock, that was pretty much the only VCRA compliant semi-auto blank firer that was available in the UK (back then I didn't have exemption for RIFs like I do now). Various UK retailers had a range of revolvers available in bright Orange like the Peacemaker, Python and Olympic revolver (which I believe was banned due to being deemed easily convertible at one point, if memory serves?)

Then, years later, they started to release more Bruni and Kimar blank firers (in both VCRA compliant and sensible colours). But Retay is an interesting one due to how extensive their product range is. However, I think they are flying a bit too close to the sun when it comes to their interpretation of the VCRA compliant colouring. They appear to use a muted (very desaturated) shade of blue, almost grey, for just a small part of the replica, definitely less than 50%. The VCRA (which I have read so many times over the years) makes it clear that the colour has to cover more than 50% of the replica and be a bright shade of the colour (blue in this case). For irony, I have read articles about criminal gangs in the USA painting their illegal live steel firearms in bright colours to make them look more like toys and avoid hassle from Law Enforcement.

Back to topic though. I have actually had the idea to purchase more commercial blank firing pistols and 3D print shrouds to turn them into carbine or rifle looking props. Some of the compact Retay pistol models could be shrouded by (for example) an M4/M16 magwell with a trigger bar extended back to where the actual M4/M16 trigger would be...Sort of like a reverse bullpup setup, if that makes sense. The charging handle on the upper would then be able to latch onto the rear sight so the slide could be cocked and the same could be rigged up for the slide latch. The only tricky bit would be the magazine. If the original blank firer's magazine catch was removed, and the magazine was inserted into a M4 style magazine shroud with its own catch, then this could work and maintain a realistic appearance and function. Overall, little to no modification to the original blank firer would have to take place (apart from removing some external bits) and this should keep things completely legal, avoiding the risk that building a blank firer from scratch would present. That is, assuming, the blank firing pistol has a UK test mark to show that it is compliant. I know all the blank firing pistols I own have this etched into them.

You certainly pick a dodgy subject . As much a I hate to say it, you really need to have a conversation with your local gun grabbing police firearms officer. The most important thing to bear in mind is not the material or the vent angle (the specific angle of the vent is how the front venting one’s are legal, think of it kind of like the blast goes up, then gets channelled back down and then back up again, a bit like a maze, so the blast is not straight forward), but to make sure that you do not get accused by the gestapo of manufacturing a firearm. This can believe it or not be over something as silly as having some pipe laying around that an overzealous uneducated police officer decides could be used to make a gun, think about poor old Mr. Luty.
With regards to your idea about casing a blank gun, look into something like the Asi or the Blow crazy mp5 thing that came out a while ago, that sounds like basically the same thing.
Again, check with your local gun grabbers, you do not want to be in a position where someone mistakes what you want to do. You can use real parts quite happily, as long as it is not prohibited ordnance, and no matter what you do, don’t even suggest that you are building them to hunt monsters or zombies, then you would be done for.
Ammo choice is important, and why most movie blanks are 9mm parabellum crimped blanks, because something like a 9mm PAK blank won’t feed reliably from a real magazine due to the dimension difference, they are shorter. Look at the Marushin XM177 or M16, they use cartridges that are like a spent .556 casing, and because of this the magazines have a shorter follower and an insert at the front so that they feed properly. I know it is more important when converting a real gun to accept blanks, but reliable magazines are one of the hardest parts of firearms manufacturing to get right if you are fabricating them from scratch, and in general real magazines are cheaper than blank ones.
You can get preloaded single use pfc cartridges, but they are like rocking horse shit to find. You may be better off thinking along the lines of can you print out cartridges that you can fire once and don’t have to worry about retrieving. What you can make then opens up a lot more because you are not making anything that has to handle any pressures, and can be far more realistic in their function.

Hi Spencer-Man, thanks for the information. To be fair, a conversation with a specialised police officer sounds like the safest bet. I guess intent is very important and making the authorities aware beforehand helps. I think for the time being, I am going to stick to Model/Cap Guns and custom Gas blowback shell ejecting replicas with simulated muzzle flash. Blank firing guns just seem to risky in the UK and not something I have the time to seek legal advice for right now. Maybe if I can expand my business with Model Guns and GBB replicas for now then I can approach blank firing in the future, and demonstrate 100% that my intentions are perfectly legal.

The funny thing is, with all this talk about the best way to simulate gun fire for film in the UK...Most of what I have provided for film production so far has been purely as a prop held by an actor or appearing on a table etc without actually being 'used'. Most films I have worked on don't actually need to show a gun firing. I get paid all the same so it doesn't bother me much.

And yeah, I've seen the crimped blanks. I'm pretty certain the 9mm PAK round is designed in such a way so the replicas it is used in cannot fully chamber a live 9mm or 9mm blank, since the crimped 9mm blank is longer and requires some of the chamber space that a bullet would normally fill. Also, like you say, they're mainly designed to feed from regular real deal magazines into (in most cases) real firearms that have been converted for blank fire use.

And believe me, I know all about the Marushin XM177 and M16 Model Guns (I own both). It's next to impossible to get reliable feeding using the Marushin 5.56 cartridges from real 30 round STANAG mags, due to the lack of the front bit which Marushin 20 rounders feature. On YouTube, Lucifer7922's excellent custom made type-x cartridges feature a dummy bullet so he is able to achieve very reliable feeding/cycling from a Marushin XM177 using real converted 30 round magazines.

Magazines, as you said, are definitely the hardest part to get right...Funny how they're not regulated in the UK. In all my years of tinkering with custom made replicas that could feed and eject dummy rounds or fire model gun cartridges, I have gone through so many headaches but I have pretty much conquered magazine design now. 3D printing technology has helped a lot...And I mean, a LOT.

I've seen the single use disposable PFCs but like you said, too rare to consider. If caps (And I mean the Japanese ones) were more accessible in the UK, making single use PFC cartridges could be a possibility I think. 3D printing could work, by using certain plastics. I did some experiments back in 2020 during the pandemic and had success with cartridges printed using PETG filament and a single 7mm cap. I made a forum thread here and I was able to cycle an MGC 1911....But then I ran out of caps and have not been able to buy any since. Also, 3D printing takes too long for something that will end up being disposable so I think injection moulding would be the better option to produce a large quantity.

I'll keep tinkering though, it's what I do best. I would love to one day come up with a disposable cartridge design that I can produce and sell for the equivalent of what you would expect to pay for a box of 50 8mm PAK blanks...Which is between £15 and £20 these days.

Just thinking about another option for you possibly, I know that you can get the files to 3D print the necessary parts, but you can buy really cheap Chinese toy guns that take little plastic bullet shaped objects that go in the magazine, but don’t have any chamber, and they use like a ratchet spring system to simulate the firing action and ping a shell out as you fire. I don’t know if I am describing them very well, but you most commonly see the Glock or 1911 looking pistols. They are the same type of guns as the laser target guns (just without the laser). They are available as many different models, some of them are pretty good, like the M&P40. I have also seen Mauser, cp99, pit viper, Sig p320, FN five-seven, cz75, AK47, plus a few others I can’t think of. I am not sure where you may be able to purchase them from, but you can easily find videos on the YouTube of them, just search for laser target pistol. They seem to range from about $5 up to about $100, and I remember seeing an American prop guy talking about them and going through the different Glocks he uses for different thing, from real guns to blank firing to airsoft and these things.
I have a CP99 laser target gun that I got a while back, cost me about £50, but it is great fun, just a shame it is based on the air gun cp99 instead of the real gun P99, but apart from being plastic, it’s not too bad, even has interchangeable back straps as well!

Ah yes, I have seen those shell ejecting toy guns with the mechanical blowback action and they look pretty good and would make extremely useful props for film. I have looked into how the mechanism works because for years, YouTube has been filled with wooden rubber band guns with shell ejection action that people had made from scratch. I wonder..if these Chinese toy companies came across these videos and decided to "borrow" the concept - either making the shell ejecting only models or the ones that have spring loaded bullets for shooting.

I did think about designing and 3D printing my own version that ejected shell and fired caps - that way the cartridges could be kept super simple and the blowback mechanism was mechanical, actuated by the trigger. Plug fire blowback cartridges are expensive and require a lot of maintenance, but if you removed that and made the gun do all the blowback work, it wouldn't matter so much if the simple cartridges were lost. At that point, they're purely a vessel for containing the cap rather than a self contained blowback piston.