Author Topic: VZ61 upgrade.... flash hider & scope mount  (Read 14348 times)

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Offline guncats

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VZ61 upgrade.... flash hider & scope mount
« on: September 04, 2012, 01:23:52 AM »
just in case anybody might be interested.....






My scorpion is a fun pistol, but the iron sight is not exactly super easy to use. So I started this little project to add a reddot (still allows the use of irons as backup, though) and while I was at it, a flashhider.

Barrel threading: the VZ61 barrel is 12mm OD, I threaded it to 1/2"x28 (standard AR thread). Since the barrel is 0.7mm smaller than 1/2", the thread itself is undersized, though close enough for mounting a flash hider. I made threaded section extra long (3/4") so the flash hider bottoms out, it now fits very tight. I don't think it will shoot loose. Die, die-handle, and thread starter were from CNCwarrior.com. 
-Flash hider: Phantom for now, from CNCwarrior, $20. Might go to a type84 hider later.

scope mounting:
-The barrel clamping is done using a 1/2" double-lenght shaft collar, Mcmaster.com, #9658T6, $12
-Scope base: weaver #48076, $4, local sports shop.
-Spacer: the shaft collar is 1/2" ID, the barrel is 12mm OD, there is a 0.7mm difference, so I made a copper shim to put on the barrel (cut off a 45-70 brass).
-Scope: short/light weight reddot is needed. I am using a Millet SP-1 (1" tube). $60.
-Scope ring: in order to be able to use iron sight as backups, a see-through ring is a must. I ordered a set of weaver, it should arrive sometime next week. $20.

It is now just waiting for the ring (only needs one).
« Last Edit: September 10, 2012, 11:02:52 PM by guncats »

Offline JimThornTX

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Re: VZ61 upgrade, work in progress (flash hider & scope)
« Reply #1 on: September 04, 2012, 08:01:03 AM »
Never seen a modded VZ61 before. Looks like a fun project. Please keep us updated.  8)
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Offline guncats

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Re: VZ61 upgrade, work in progress (flash hider & scope)
« Reply #2 on: September 09, 2012, 10:09:26 PM »
Installed the reddot using a weaver offset see-through ring.





Range report:
-the good: aiming is easy with the reddot scope; there is no visible flash whatsoever, the phantom seems to work really well ( :);
-the bad: with the scope there is no more "if I do my part" excuses. With the bottom of the 10rd mag rested on the sand bag, steady shots are easy to make. However these "perfectly fired" groups are very disappointing. Average 4" or so. Tried RWS 71gr FMJ and Fiocchi 73gr FMJ, Fiocchi is a little better.

*Both of the groups shown below were shot using Fiocchi, 10 shots each, 25yd. I don't think it is a loose mount/scope issue, everything is tight.  7 shots in the second group are within 2", but why would the other 3 go so far away...And these are sandbagged groups! >:(  I can shoot better groups with my Browning buckmark, unsupported, one hand (bullseye style)........



So there we have it, folks, what a scorpion can do with a scope. I don't think it will shoot any better with a stock installed. This will be the end of my vz61 mod project. :'(

*other mods done so far:
- shimmed the rear edge of upper (it locks into the lower tight, no more wobble);
- installed polyurathane recoil buffer;
- polished the hammer/sear for better trigger feel
« Last Edit: September 09, 2012, 10:14:40 PM by guncats »

Offline Expat8

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #3 on: September 12, 2012, 02:39:11 PM »
Never seen a modded VZ61 before. Looks like a fun project. Please keep us updated.  8)

Indeed.. very inspirational :)
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- Scorpion EVO III S1
- VZ61 SBR
- Jericho 941 in 9mm and .41

Offline guncats

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #4 on: September 15, 2012, 09:44:48 PM »
Couldn't accept such bad accuracy from a fixed barrel pistol, I checked the barrel for problems.

-- the bore is not coaxial to the barrel. The top/bottom wall thickness are the same, but left/right wall thickness are off by 0.010", which tells me the crown might be off center if it was done on a lathe. So I re-crown the barrel using a ball stone. Went to the range again, and..... the accuracy was still the same, awefully huge groups.... :'(

-- next up was slugging the barrel to check the bore size. The slug measured .309, which seems correct. However, the slug slide through the last 1" of the barrel very easily, no resistance at all, which suggests this portion of the barrel is oversized slightly, and this is the most critical 1" for accuracy......  :'(

Knowing the barrel is likely the cause of bad accuracy and there is nothing I can do about it, I was, finally, able to give up. Overall, this scorpion has been a major disappointment to me, I am glad it was relativly cheap, I can probably still justify the purchase by calling it an "investment". All the mods are wasted effort, though. :'(

Offline Expat8

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #5 on: September 16, 2012, 06:52:34 AM »
%&*?  :(

how about a replacement barrel from czechpoint?

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- Scorpion EVO III S1
- VZ61 SBR
- Jericho 941 in 9mm and .41

Offline guncats

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #6 on: September 16, 2012, 02:35:02 PM »
this is a D-techink pistol, the barrel is as VZ as it gets and installed by VZ......... I don't want to take chance with another VZ barrel. 

Plus, I have not been able to find any solid reports on the VZ's accuracy, what I found in a google search is the typical internet write-up, the kind that claims "pretty accurate when I shot it with my elbow resting on a shaky falling-apart bench with 50mph wind blowing to the left... was able to hit a X size bucket at Y distance off-hand with regularity.... what kind of report is that?   >:(

Maybe 4"~6" 10-shot group at 25yd is typical for the VZ61  :-\

Offline Expat8

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #7 on: September 20, 2012, 02:40:38 PM »
Can't tell you yet about the shot grouping. I just received mine and will hopefully be able to take it to the range on Saturday. Maybe someone else here can give you more insight on this.

I recently read a book of a different topic and I stumbled about some lines about barrel threading. It says that if you have a rather thin walled barrel, like the Skorpion definitely has, it is very likely that the heat-treated steel sort of "relaxes/stretches" when you cut a thread onto the barrel. This "relaxing" is not equally occurring in all places thus resulting in the off wall-thickness. Thicker barrels don't seem to be affected, see bullbarrel versions of the Ruger MKII for example. I was thinking about a similar setup for mine, I will rather use a custom made clamp-on barrel sleeve to put a flash hider on. 

I'm sorry to put some more salt into the wounds dude but I thought maybe you would like to know why this happened. Just in case you do get another barrel eventually... It still is an awesome mod!  :)

Expat
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- Scorpion EVO III S1
- VZ61 SBR
- Jericho 941 in 9mm and .41

Offline guncats

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #8 on: September 26, 2012, 05:32:12 PM »
Don't think the barrel "scretching" is the issue, the 32 is a low pressure round to begin with, by the time it gets near the muzzle the pressure has dropped pretty low, I suppose.

What kind of group do you get from your new VZ61?

Offline bigj480

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #9 on: December 04, 2012, 10:44:40 AM »
How sure are you that the scope mount was not loose as a result of the spacer? I don't really care for the idea of using a spacer there, but I'm not expert. Why not just mount to the top of the receiver?

Offline guncats

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #10 on: December 18, 2012, 06:19:27 PM »
group size is about the same with scope or iron (apparently the aiming device is not the bottle-neck here).

The upper material is super thin, no way to attach a mount base (well, unless by welding). Plus, it is super thin, so it flexes.. Much more sturdy when the mount is directly on the barrel.

Offline Buckxo

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #11 on: January 14, 2013, 04:59:58 AM »
I used an HK 1/2x28 3 lug adapter on mine to use my Gemtech Trinity suppressor.

Works great!

Now if the Form 1 would just get here for the stock...





V/R

Buck

Offline cavegeo

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #12 on: January 21, 2013, 10:27:59 AM »
I used an HK 1/2x28 3 lug adapter on mine to use my Gemtech Trinity suppressor.

Works great!

Now if the Form 1 would just get here for the stock...


V/R

Buck

I have a question did you just thread the barrel to install this 3 lug adapter.

Cavegeo

Offline Buckxo

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #13 on: January 23, 2013, 04:45:09 PM »
Yes

V/R

Buck

Offline cavegeo

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Re: VZ61 upgrade.... flash hider & scope mount
« Reply #14 on: January 23, 2013, 07:45:08 PM »
Yes

V/R

Buck

Thanks that looks very nice, I am thinking I will do this to my Skorpion and Sterling and share a silencer.

 

anything