Blank Adapter

[paintmanmatt]

I'm new to 1919's....I don't even have the gun yet (it's on order). I want to make my own blank adapter. I've been reading the threads and am planning on drill/tapping a booster and using set screw/bolt with hole drilled though it.
Does it make a difference, or is there any advantage of using a 1pc verses a 2pc booster?
For changing orifice sizes, wouldn't you just replace the set screw? Or would it be better to have a 2pc and change the booster? If the booster that comes with the gun was a 2pc, it would be a no-brainer, but I'm pretty sure it's a 1pc.

Thanks, Matt

[Lucky#13]

Bumping this for you today, since it's a day old. There are a number of guys here who can help. Hopefully some will chime in. Be patient for the responses as I am out of town and have limited access for a few more days. Only two of us here to approve posts and we do our best to be timely.

[gulf state gaurd]

I have been scheming on a better looking blank adapter. I have used my USGI one when firing .30 cal but have been scheming on one to fire 7.62 blanks also would like to have a not so obvious BFA on the gun for living histories. I'm not done my project but I have the major portions done. I had thought about using the allen inserts but have never trusted them not to fail and become a projectile. I'm working on one that all the parts mount to the inside so there is zero chance of them getting shot out if a part would fail. I marked a thick steel bar with the interior dimension I wanted to fit in the booster. I found a thread thimble to be the perfect diameter to fit nicely in the booster so used that as my pattern. I found the rough center of the circle and drilled it for the brass machine screws I intend to use as the orifices/inserts and then threaded it while I had the length of the bar to hold onto it with. I then rough cut the steel with a Sawsalls with a heavy duty metal blade. I then used a sanding wheel on my right angle grinder and rounded it to a circle.
At that point I realized I needed to put a bullnoze on the leading edge of the steel insert to fit it snug against the inside face of the booster.
I fit the first brass bolt in place in the insert and cut off the excess then sanded the end smooth.
I still need to cut the three other bolts i intend to make other diameter inserts and tap them with the respective sizes for various blanks.
I also need to figure out the final attachment of the inserts. I think I will put the insert into place holding it there with a large wood dowel and drill on either side of the booster in the channel for unscrewing the booster and tap them for a small diameter machine screw. Then I'll drill out the corresponding insert holes so the screws I intend to attach it with will screw in from the inside face attaching only to the outside face. That should enable me to only need to worry about tapping 2 relativey small holes in the hardened steel booster and of course tap it for the 2 screws to grab into. My goal is that unless you look closely the only immediately obvious alternation to the booster will be the two screw holes.

[ad5zo]

Blank Firing Adapter
A BFA blocks off the outlet of the barrel bushing to create enough back pressure to operate gun to cycle the bolt etc. There are lots of "how tos" and I adapted them to my needs and tools.

Simplified, I started with a 1/2" carriage bolt 1" long. I bored a 1/4" hole through the center along the long axis. This is the drill diameter for a 5/16" bolt. I threaded the head of the bolt for 5/16"-24 and only tapped to a depth to just allow the shortest set screw to rest flush with the top of the bolt head.

Used 4 set screws. One is not drilled, the others are drilled for 0.162", 0.149" and 0.128". There will be a bit of "leakage" around the 1/2" carriage bolt which should not be a huge factor ... especially as the idea is to releive some pressure. After all we are drilling a hole in the BFA. The 5/16"-24 set screw has a 3/16" allen head, which is smaller than the 0.162" hole. This was not a problem as the hole was drilled from the "bottom" of the screw and did not cut into the allen head flats.

I started with 0.162" as one of the blank distributors recomeneded that for there ammo. The three sizes will allow for some experimentation and the undrilled set screw will allow for another other hole size if the others don't work.

I will removed the zinc and parkerized it.

I hope to make a "T" wrench for the BFA instalation/removal ... one side will be 3/4" socket to attatch the BFA to the barrel bushing and one side of the handle will have a 3/16" allen wrench attached so the two tools will not be separated.

3/8"-24 Allen Set Screws work to might be better ....
Some set screws are hardened. I put them in a nut with a bolt on the other side to keep some of the heat away form the main part of the screw. Heat the exposed end. I use this method to drill them too ... makes it easy to hold in a drill vise ... e.g. the hex nut/bolt with the screw in th nut.

This BFA does show ... e.g. not a "Hollywood" but it works.

No photo ... I can't find my BFA right now.

Thanks,
TomE
ad5zo.com

[paintmanmatt]

Thanks guys, I've decided to go with Mr.Gadget's BFA. By the time I get a 308 booster (my 2pc is .718), set screws, and bits, I will have the BFA delivered to the house for same or even less if I were to tap the .718

BTW...my 1919 is built with the exception of the trigger package and it's enroute as we speak. Looks like I'll be test-firing this weekend!

[emmagee1917]

....If you made an end cap that was solid , no gas could escape out the front nor could anything break off and become a projectile. On the inside , a short cylinder could be made . This cylinder would enter a hole drilled into the end of the bbl at the muzzle. Gas from the blank would push against the cylinder , driving the bbl back. Varying the cylinder / hole sizes would adjust your gas preasures. Nothing would show from the outside. The cylinder would prevent a regular bbl from being inserted until changed out. It seems most people have spare bbls or shot-out bbls that could be used for this. Heck , you could even put a chamber in the cylinder with several small holes leading out to vent between the bbl and booster. A sleeve could be fitted to slip over the cylinder here , cut to expose a certain number of holes , change the sleeve , change the number of holes opened or covered , adjusting the gas flow.
Chris

[MR. GADGET]

This works good, plus it is easy..

Working to make 1919's mo fun, one projest at a time.........

[paintmanmatt]

Test fired yesterday. Mr.Gadgets BFA worked great! Once I got the headspace right, not a single misfire and gun cycled perfect......using the German plastic blanks.

[fourfifths1911]

i made one just like mr gadgets 4.00 dollars for the booster nut from oow and ten bucks for 5/8-11 set screws from mc master carr

[paintmanmatt]

Here's how she runs with German Blanks & Mr.Gadgets BFA. Just a short from a cheap Kodak.....but you get the picture.



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