ASG CZ75 Barrel Silencer Thread?

[Just_started]

Hi,

 

I'm new to the world of airsoft and BB guns.

 

I just bought an ASG PZ75 Dual Tone blow back pistol, which seems good fun, although I was surprised at the amount of noise it creates when firing, especially with a fresh CO2 cartridge.

 

I like engineering, so I thought I might make a silencer for it, since I'd imagine the neighbours wouldn't be impressed with the noise when shooting my targets in my back garden.

 

Does anyone know the correct thread for the end of the barrel please? I took the plug out and checked on the web and thought it may be a 1/2" UNF sine that seems a popular thread, however having checked the thread data for that, it would have 20 TPI, whereas as far as I can see using thread gauges, this thread appears to have around 25 TPI although it does appear to be a nominal 1/2"?

 

Any info gratefully received.

 

Thanks

[two_zero]

isn't 14mm crossthread the usual, at least in airsoft? why not look at some airsoft suppressors/suppressor compatible airsofts? try this site:) http://shop.ehobbyasia.com/

[straffham]

Several pistols have a 11mm female threaded outer barrel, King Arms and SHS do 11mm barrel adapters to accept 14mm threaded standard silencers (though places such as Actionhobbies and Firesupport I've checked in UK seems out of stock, I'm after one for my S&W Sigma grrrr), not 100% sure the CZ75 is the same but would think it likely, I very much doubt it would be an imperial size to be honest.

[Just_started]

Hi again,

 

Many thanks to Two_zero and Straffham for your help

 

I tried checking more sites etc, and although I could find silencers and adapters to fit them to certain models, nothing specific to mine so far, neither could I seem to find any specs for the cz75 showing the thread. So I gave up and just cut a custom thread to fit which seems to do the job nicely!

 

It's a male thread with major diameter of 12.55mm, pitch of 1.0mm and metric 60 degree flank angle. An odd mish mash, but it seems to work nicely and fits perfectly in the barrel.

[straffham]

Hi again,

 

Many thanks to Two_zero and Straffham for your help

 

I tried checking more sites etc, and although I could find silencers and adapters to fit them to certain models, nothing specific to mine so far, neither could I seem to find any specs for the cz75 showing the thread. So I gave up and just cut a custom thread to fit which seems to do the job nicely!

 

It's a male thread with major diameter of 12.55mm, pitch of 1.0mm and metric 60 degree flank angle. An odd mish mash, but it seems to work nicely and fits perfectly in the barrel.

Nice one, glad you got it sorted!

edit: is it the CZ75 Compact you have? Been thinking of one myself, seem a good price for the spec, also any chance ofsome pics of your handiwork?

[Just_started]

Nice one, glad you got it sorted!

edit: is it the CZ75 Compact you have? Been thinking of one myself, seem a good price for the spec, also any chance ofsome pics of your handiwork?

That's the one - the CZ75 Compact - feels quite nice - not too plastic feeling and has decent weight to it. Top slide is metal along with the necessary components, then the main body is mostly resin. I have no experience so nothing to gauge it against. The slide and barrel do have a bit of play in them, which I would imagine will affect accuracy a bit, but I'm not sure how accurate these are supposed to be?

 

I'll try and take some pics of the CZ75 and the parts I've been making tomorrow and post them

[straffham]

Nice one, I take it it is blowback rather than NBB then? Most of the full size CZ75s seem to. be NBB. Does it have an adjustable hop unit, or fixed?

[Just_started]

Nice one, I take it it is blowback rather than NBB then? Most of the full size CZ75s seem to. be NBB. Does it have an adjustable hop unit, or fixed?

 

Hi again - yup it does have blowback which was a feature I liked, although I think it makes it a bit less gas efficient and possibly a bit more noisy - I really hadn't realised just how loud a pop these BB guns would make!!

 

It has adjustable hop-up which is access via the case ejection port in the slide when you pull it back to cock it - not that I've tried that yet as I've not used it too much as a bit concerned at worrying the neighbours!

 

The silencer work has gone well - nice little project

 

It's just got the paint drying at the moment and then I'll reconstruct it and post a few pics of it being made.

 

Unfortunately I noticed that the outer barrel of the gun which has the female thread to accept the silencer is actually NOT concentric with the bore of the inner barrel. What this actually means is that as soon as i screw the silencer into place, I can see that it actually points slightly upwards. I guess this is probably due to cheap manufacturing and poor quality control of the outer barrel. Its not my thread and silencer, as it's turned, drilled, threaded all sequentially without removal from the lathe - I couldn't really make it non-concentric even if I tried! When I put the plastic end plug back (that is fitted as standard) in the barrel I can see that it also does not seat correct and true against the end of the outer barrel. This isn't a problem at all if you don't fit a silencer, however it will mean that the BB will simply collide with the sound baffles if I tried it, since the BB is coming out level and the silencer is tilted slightly upwards. I'd imagine that it will also adversely affect the spin on the BB and probably make it super inaccurate if the BB will even make it out, so i haven't even tried it with a BB!

 

This is fixable as I can make an end plug and epoxy a 6mm ID sleeve within it that IS dead inline with the inner barrel, or maybe I just use the gun as it is with no silencer - I can always convert it to fit another BB gun in the future!

 

I'll try and get pics up this evening if I can

[straffham]

 

Hi again - yup it does have blowback which was a feature I liked, although I think it makes it a bit less gas efficient and possibly a bit more noisy - I really hadn't realised just how loud a pop these BB guns would make!!

 

It has adjustable hop-up which is access via the case ejection port in the slide when you pull it back to cock it - not that I've tried that yet as I've not used it too much as a bit concerned at worrying the neighbours!

 

The silencer work has gone well - nice little project

 

It's just got the paint drying at the moment and then I'll reconstruct it and post a few pics of it being made.

 

Unfortunately I noticed that the outer barrel of the gun which has the female thread to accept the silencer is actually NOT concentric with the bore of the inner barrel. What this actually means is that as soon as i screw the silencer into place, I can see that it actually points slightly upwards. I guess this is probably due to cheap manufacturing and poor quality control of the outer barrel. Its not my thread and silencer, as it's turned, drilled, threaded all sequentially without removal from the lathe - I couldn't really make it non-concentric even if I tried! When I put the plastic end plug back (that is fitted as standard) in the barrel I can see that it also does not seat correct and true against the end of the outer barrel. This isn't a problem at all if you don't fit a silencer, however it will mean that the BB will simply collide with the sound baffles if I tried it, since the BB is coming out level and the silencer is tilted slightly upwards. I'd imagine that it will also adversely affect the spin on the BB and probably make it super inaccurate if the BB will even make it out, so i haven't even tried it with a BB!

 

This is fixable as I can make an end plug and epoxy a 6mm ID sleeve within it that IS dead inline with the inner barrel, or maybe I just use the gun as it is with no silencer - I can always convert it to fit another BB gun in the future!

 

I'll try and get pics up this evening if I can

.

 

One of these is certainly growing on me, yeah the CO2 guns are loud compared to normal GBBs. Interesting what you say about the threads not aligned with the bore, I did wonder about that, also glad you said about the size, I'd assumed my Sigma had a 11mm thread, measuring with my digital caliper was about right, but now I'm wondering if "about right" is going to fit!

Have you had a chance to chrono the gun? I'm guessing its too hot to skirmish with? In which case I'd need to modify the valve as usual or get a new one turned up in aluminium.

[Just_started]

You may find that yours is fine - measure either the major (male) or minor (female) thread with your digital vernier and then ideally use a thread gauge to check the thread pitch. You'll probably find it falls into the "metric fine" category - check this site for thread data to compare your measurements to:

 

http://mdmetric.com/tech/thddat3.htm

 

to check the concentricity (or otherwise) is a little more tricky. I could see it straight away visually, but then checked by popping a long straight 6mm bar carefully into the bore of the inner barrel and have a tube screwed into the thread. The bar should exit the tube in the centre, not off to one side. Obvoisly be careful sticking bars into the bore so as to not damage either the bore or the hop up which is down there!

 

I don't have access to a chrono so I have no idea how many FPS the BBs are fired at - would be interesting to have a test though

 

Not sure what you mean by too hot to skirmish? I haven't done any skirmishing anyway with it yet - really just target practice in my garden:) Do you have to modify these guns for specific skirmish rules etc?

 

Here are pics of the materials and the final silencer. You can probably see from the final article fitted to the CZ that there is a slight upwards direction from the non-concentricity of the inner barrel and outer barrel thread.......

 

 

[straffham]

You may find that yours is fine - measure either the major (male) or minor (female) thread with your digital vernier and then ideally use a thread gauge to check the thread pitch. You'll probably find it falls into the "metric fine" category - check this site for thread data to compare your measurements to:

 

http://mdmetric.com/tech/thddat3.htm

 

to check the concentricity (or otherwise) is a little more tricky. I could see it straight away visually, but then checked by popping a long straight 6mm bar carefully into the bore of the inner barrel and have a tube screwed into the thread. The bar should exit the tube in the centre, not off to one side. Obvoisly be careful sticking bars into the bore so as to not damage either the bore or the hop up which is down there!

 

I don't have access to a chrono so I have no idea how many FPS the BBs are fired at - would be interesting to have a test though

 

Not sure what you mean by too hot to skirmish? I haven't done any skirmishing anyway with it yet - really just target practice in my garden:) Do you have to modify these guns for specific skirmish rules etc?

 

Here are pics of the materials and the final silencer. You can probably see from the final article fitted to the CZ that there is a slight upwards direction from the non-concentricity of the inner barrel and outer barrel thread.......

 

 

Great pics mate, didn't realise you'd gone the whole hog of making an entire silencer, you've obviously got the equipment to do things like that, did you put foam rings in the silencer? See what you mean about the slight alignment issue, can it be sorted? By opening the exit bore of the silencer maybe, it does look quite tight compared to a commercial airsoft one? (Could be an optical illusion though.)

Cheers for the data link, my Dad was an engineer and knows his stuff with threads,pitch etc so will use his tools to measure mine up.

To be skirmished pistols have to comply with site limits just like AEGs, sniper rifles etc, usually its the same limit as AEGs so generally 328 or 350fps with 0.2g bbs depending on the site. CO2 pistols often put out around 400fps, but can be modded to bring that down by building up or replacing the floating valve in the blowback chamber. Some sites flat refuse the use of CO2 guns though which is a shame.

I really like the 75D, its stylish and that bit different to the usual Glocks, M9s, Sigs and Colts.