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Old September 21st, 2006, 13:31   #1
Raygis LasVegas
Join Date: Dec 2002
Location: Toronto
Star UMP -- Guide & Review (100 pics)

H&K UMP .45 cal
Guide and Review by Raygis LasVegas

Gun Name: Star UMP Version 2
Gear Box - Version 3
Magazine - 110 Rounds
Length - 680
Barrel Length - 195mm
Weight - 2630g
So far, here are some information regarding the different versions available:

Version 1: No body pins, fixed cocking handle, incorrect spelling on H&K trademarks.
Version 2: Body pins used, fixed cocking handle, blank trademarks.
Version 3: Body pins used, movable cocking handle, Correct H&K trademarks.

External Inspection

- Right side of handguard.
- Very strong polymers used for the contruction.
- Even with the ported handguard, I found it very difficult to flex the front section by squeezing it.
- Metal inlets are used for screwing on the accessory rails.
- Lower metal rail is included with the SMG.
- Front sling point is made from plastic. FYI, the Marui and CA G36C front sling point is made from metal.

- Right side of body

- ".45 auto" is engraved into the metal bolt.
- Here you can see the texture of the Star UMP body. I found this more appealing than Classic Army's CA36K.

- The UMP's bolt must be moved manually with your fingers to access the hop-up chamber. Because the bolt moves back less than 2cm, I found it difficult to adjust the hop-up wheel.
- Please, don't comment on my ugly thumb!

- Right side of selector switch.
- Star did a nice touch with realism by adding the receiver pins.
- Comparing Star UMP trigger guard with the CA36K trigger guard, Star's construction is much more rigid.

- Left side of hanguard.
- The serial number is nothing more than a non-unique silver sticker. Very cheap indeed!
- Cocking handle is non-movable.
- Plastic non-adjustable front sight and hood.

- Sadly, Star did not fill in the rectangle boxes with correct H&K trademarks.
- Here you can also see the silver sticker used as an indentification number.
- The bolt catch, selector switch, and trigger is made from metal.
- The mag catch lever is made from plastic.

- Detail pic of selector switch.
- The pictogram markings are pasted on. These will eventually rub off from use. I wished they were engraved then filled with paint such as those found on the ICS MP5 series.
- Great work on the pistol grip diamond texture.

- Stock release button is made from metal.
- There is a 1mm play within the stock when it is locked in position. I shimmed this space with electrical tape and now the stock locks tightly.

- The stock features a very nice cheek and recoil pad. These are made from rubber and actually functions preventing slips when shouldered. I like these a lot better than G&P's recoil pad found in there G36 battery folding stock.
- The plastic on the stock is very rigid and doesn't have any flex at all. This stock is much better than the Classic Army G36 folding stock.
- The seam line down the middle is very minimal. There is no way this stock can split apart even when attempted to flex upon.

- The stock retaining loop is a metal loop jacketed by polymer.

- Here you can see the two rectangle sections of electrical tape used to shim out the play of the stock when it is extended.

- Right side of UMP body
- Notice the folding stock locking bent forward of the ejection port.

- The stock locking bent is very rugid and can withstand extensive use.

- Here shows the process of how the stock is locked in place. Photo 3 show the stock being flexed upward over the locking bent.

- Stock being locked in place.

- Motor plate. The middle hole adjusts the motor height.

- Mag well and lower rail

- Plastic front sight and front sight jacket. I believe these parts are metal on the Marui G36C.

- Rear sight.
- Pictured here is the ghost ring sight being used. This has two settings... ghost ring and open cut.
- The rear sight jacket is made from plastic.

- Open cut CQB sight used.

- Open cut sight.

- Ghost ring sight.

- Sights aligned.

- Rear sight windage adjustment screw.

- Rear sight elevation adjustment screw.

- Top weaver rail.
- The two fixing points keeps the rail stationary.

- Top weaver rail.

- Here's a minor defect that I found in Star's moulding. Overall, the gun's construction was very well made without many burrs. Seam lines were present though.

- Markings on the UMP .45 magazine.

Field Stripping

- First remove the magazine.

- Unscrew lower receiver retaining screw.

- Push out lower receiver retaining pin.

- Rotate the lower receiver from the upper.

- Watch out for the wires if you have a battery connected already. Don't over stretch them.

- Lower receiver pivoting hook.
- This hook is very sturdy. However, I view it as the most delicate part on the UMP. When disassembling and assembling, you should take caution not to twist and break this area.

- Star UMP field stripped.

Removing the Inner Barrel

- Upper receiver.

- Underside of the upper receiver.

- Push in the inner barrel assembly.
- Rotate the assembly counter clockwise.
- The assembly will then spring out with a audible 'click'.

Gutting the Upper Receiver

- Detail shot of the 'bolt'

- Press the button to release the folding stock.

- Here you can see the shimming job I did to have the stock fit snuggly when locked.

- Pull the trap door down and then swing it downwards.

- I used a 9.6V 1200mah NiMH battery by Intellect. The battery pack consists of 8 cells. The gun can actually fit 12 cells in series. Because of this extra space, the battery has room to move back and forth. Shim the battery with electrical tape increases it's diameter and makes a snug fit when the battery is pushed in. If the battery is pushed in too much, you can always push the battery out from the front of the gun via the cocking tube.

- The cocking tube hole located above the barrel allows the user to push out the battery.

- The flashider can be removed by rotating it clockwise.

- The Star UMP features a true free floating barrel.

- To remove the barrel you must punch out the barrel retaining pin. You should use a proper spring pin punch instead of an allen key. I was too lazy to find the proper tools.

- Punch and push out the barrel retaining spring pin.

- Slide out the barrel from the upper receiver.

- Inside the handguard.

- Very long battery storage. Great for custom packs up to 12 cells in series!

Stripping the Inner and Outer Barrel

- Outer barrel assembly.

- Remove the grub screw.

- Grub screw removed.

- Unscrew the outer barrel from the breech block. The outer barrel has negative threads. Make sure you turn it clockwise to loosen.

- Negative threads are show here.

- Punch out this pin to remove the "hop-up centering piece".

- Pin being punched out.

- Hop-up centering peice removed.

- Removing centering piece. Make sure you reassemble the barrel as per these photos.

- A problem I had with the Star UMP was their outer barrel. Right out of the box, the barrel was loose. That was why I decided to take it down to every last bit. To solve this problem, I pre-drilled a hole where the grub would normally sit when the barrel was tightened. This allows the grub screw to grab onto a recess and not allow the outer barrel to unscrew itself.

Stripping the Inner Barrel

- Inner barrel assembly

- Remove spring

- Remove hop-up wheel retaining clip.

- Line up protrusions and prepare to slide off hop-up wheel.

- Sliding off hop-up wheel.

- Remove hop-up nub.

- Pull apart the brass barrel from the chamber to separate the two items. Pay attention to how the hop rubber reacts when removing the inner barrel. On one occasion I replaced the Star hop rubber with a Guarder one. For some reason, the Guarder rubber has a major air leak with reduced the velocity by approximately 120 fps. Luckily, my Star rubber was still in prestine condition when I removed it. I quickly installed back the Star hop rubber and gained back my initial velocity with the Action 360 fps sping.

Removing the Gearbox

- Unscrew the gearbox retaining screw.

- Retaining screw removed.

- Punch out the large body pin.

- Since the pin was externally visible, I did not want to scratch it during removal. For it's protection, I covered it with a layer of electrical tape cut to a circle.

- Electrical tape protecting the pin.

- Pin ready to be punched out.

- Place the selector switch between semi and full-auto.

- Wiggle the mechbox upwards and away from the lower receiver.

- Gearbox removed from lower received.

Disassembly & Inspection of the Gearbox

- Star used a shrink wrap to secure the motor wires to the side of the motor cage. During it's inspection, I cut away at the shrink wrap.
- Pictured here is the shrink wrap being taped together by me.

- The motor Star used was very whiny. So far with my experience, I prefer Classic Army motors ( CA M4A1, CA249, CA36K, CA36C ).

- Move the motor assembly.

- Pry open the front of the gearbox.

- Pry open the back of the gearbox.

- Insert a screwdriver and secure the spring guide.

- Slowly open the mechbox halves. Your left hand should be keeping the spring guide and piston assembly stationary. Your right hand should be opening the mechbox shell. Without my left index finger, the piston assembly (piston, cylinder, cylinder head, tappet plate) would fly to the right and possibly breaking something in the process.

- The gears used are XYT brand. These are commonly found in Cyma AEGs.
- Not that to diss Cyma and Star, but if those gears are found in cheap priced AEGs, than you can now understand where Star is making the profits since their AEGs are normally priced in the higher ranges.
- Star's cylinder compression was very inefficient. This was the blame for their piston head. The o-ring didn't match the cylinder size. Right out of the box, you'll have to buy a replacement piston head. I swapped my shitty Star one with a modified ported Marui.
- Another problem was the cylinder head. It had a major leak. I had to replace that piece with version 3 cylinder head from Systema.
- The Star nozzle also didn't form an air-tight seal. I had to shim the cylinder head with skotch tape. With the skotch tape applied and the diameter of the cylinder head increased, the nozzled formed a near perfect seal.
- In my opinon, Star's gearbox was a piece of shit. The user is required to replace $40 CND worth of internals to make the gun shoot efficiently.
- The only good thing about Star was that they included metal bushings that were shimmed correctly.

- The Star UMP uses a common Marui G36C nozzle. This nozzle is the same as the CA G36K.
- The green power spring seen here is an ACTION 360 fps spring.

- Here are some differences between a Star piston and an Area 1000 poly-carb piston.
- Star's piston is on the left. It is clearly thinner than the Area 1000.

Final Production Pics

- Lining up by the pistol grips

- Lining up by the pistol grips.

Contact info:
Gun Doctor Services: $45 for mechbox upgrades. Repair costs may vary.

AEG upgrades & repairs: $25/hr
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