[749th tank battalion]

Hello all,

My question involves more of a headspace matter than the actual ammo(blanks) matter so i hope it makes sense in the Semi auto forum.

I am running a McGuire built Semi 1919a4 in 7.62x51. As a reenactor I have been running the German plastic 7.62x51 blanks bought from Tony gunsmith for years. My weapon has been headspaced accordingly for these blanks when using my blank adapter. I have a front cartridge spacer that is adjustable via a set screw and spring which eases forward or back according to the length of the blank.
I just came upon a ziploc bag of 200 Austrian blanks headstamped HP 91 L31A1 that i'd like to get rid of at a small public WWII demonstration coming up.
My question is, I have seen threads on here discussing live ammo headspacing consistently, but very few threads dedicated to blanks. Of the ones i found, most seem to mention the German plastic blank which i am already set up for. So, if i switch out to this slightly shorter blank I know i have to adjust my front spacer on the BHP bracket to accommodate it. But what about the headspacing. I have to perform headspace outside the weapon because I filled the hole on the Israeli LSP to make it look USGI, thus that hole won't allow the barrel lock spring to move inside the receiver with the little wrench i bought on here.
Right now i believe i am running my plastic blanks 3 clicks from the point when the bolt first closes into battery.
Are the concerns as great for headspace with blanks as with live ammo ?
I read in one thread that someone was operating their German plastic blanks 5 clicks out..... i'm just confused now

Has anyone swapped blanks manufacturers often enough to have advice on headspacing ?
an easy fix is just to use the plastics at this event, but they are dedicated to tacticals as I have 20,000 of them. for this lot of 200 Austrian i just want to have done with them and fire them off at this public display, thus my concern....:help:

Thanks for any help and or recommendations.

Cheers,
Andrew

 

[DanG]

headspacing w/blanks

Hi Andrew,
I keep my headspace the same, even when switching between blanks. 2-3 clicks out is fine. As you stated, you have to adjust the feedway spacer to account for the shorter blanks.
IIRC, those Austrian brass blanks are very underpowered, I had to close off most of the holes in a GI blank adaptor to get them to cycle reliably.
DanG

 

[749th tank battalion]

Thanks for your input DanG, I appreciate it.
My gunsmith told me after he blank adapted my weapon that how we headspaced it for the German blanks should be good for almost any blank as long as it wasn't super hot...because as he stated, the barrel wasn't sealed when using blanks like it would be with a live round plugging up the chamber. I dunno, I just felt i should ask.
He did create an adapter that uses a set screw going across the diameter of the muzzle (in the 7.62 booster) sorta like a plumbing shut off valve. He didn't feel comfortable using set screws that went in vertically and sat against the muzzle and could come out like a projectile. I can pretty much adjust the screw a thread at a time to create any orifice size per the power of the blanks i'm using.

thanks again
Andrew

 

[paintmanmatt]

I'm the guy that runs 'em 5-clicks out! :rofl: Mainly for speed and muzzle/shroud flash at night. I do tend to break stuff, so I would start out standard 2-3 clicks out and only add a click or two if they run a little sluggish. Don't even have to do that if you have an adjustable BFA.

Matt

 

[749th tank battalion]

thanks Matt,

I now recalled it was you who mentioned that in the older thread. I was surprised to even find a thread dealing with blanks and headspace, as most are focused on live ammo, deservedly so.
I have to say, I love the plastic, they function reliably for me since the first time Tony offered them on the boards. But these Austrian brass were an impulse buy at a gun show before I got tony's or Widener's POF blanks. and at only 200 rounds I just want to blast away so they are gone and can't ever get mixed in with the POF brass.

I used a center punch mark on the barrel locking splines to show where i'm headspaced for the plastic blanks on my A6 profile barrel...now i'll do the same with the full A4 barrel by headspacing it out of the gun at the 3 click mark and like you said, see how the Austrians perform with my orifice setting.

Thanks !

 

[Luke]

I bought the German plastic blanks from Tony years ago but they hardly fire they are almost like just a little more than the primer is going off has anyone had this problem. Some fire more than others. I fired them out of a bolt action Smile 7.62X51 with the same results.

 

[749th tank battalion]

the blanks i got from him seem to make a nice report when fired in my setup. It could be the orifice i'm running them at as well. The only time i seem to get a weak report is the first event i go to after disassembling and cleaning my weapon from the previous tactical. I have to get the setting just right again after taking the set screw out to clean the carbon buildup during cleanup.