TM Hi-Capa Upgrade Part 1

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If you have read my review of the TM Hi-Capa 4.3 Custom, you’ll know that I was very happy with it. It’s beautifully made and it shoots very nicely indeed. However, I did wonder whether it might be possible to upgrade it for a couple of reasons:

  • One, I’d like it to shoot with a little more power, which would allow me to use heavier BBs, and,
  • Two, I’d like to be able to use Green Gas rather than HFC-134a. This would help with the first point, and would also mean that I’d need to have only one type of gas for my replicas.

My plan was to fit uprated parts and then to test for both power and accuracy with Green Gas.

I was fortunate during my research for the review on the Hi-Capa to come across Elite Shooting Centre in Bury in England. This small company is run by Mike Cripps, a man who knows a great deal about competition shooting and TM Hi-Capas. Mike was a member of the UK Squad at the World Shoot X in Bisley in 1993 and he won the very last UKPSA Competition using firearms to be held in the UK. When firearm law in the UK changed in 1997, Mike switched to shooting with airsoft pistols and in particular with TM Hi-Capas. He won the UK Open Championship in 2003, 2004, 2006, 2008 and 2009.

In 2004 Mike started Elite Shooting Centre (you’ll find a link to his website at the end of this article). Initially, this included a retail store as well as shooting ranges. However, in time the focus of the business changed to supplying parts for and building custom airsoft pistols for IPSC and pistol shooting. Mike only builds and provides parts for TM Hi-Capa pistols. Obviously, Mike is very knowledgeable about these pistols, and so I asked him for guidance when I was thinking about upgrading.

His advice was fairly straightforward – keep it simple and upgrade only using parts which are a straight replacement for stock. His recommendation was that I fit a tightbore barrel and upgraded hop-up rubber, an uprated loading nozzle and 120% hammer and recoil springs. Mike was kind enough to provide the parts needed to upgrade my replica, so, let’s see just how easy it is…

The parts

Mike provided several replacement parts for my TM Hi-Capa. These are:

  • Elite tightbore 6.02mm barrel
  • UAC replacement hop-up rubber
  • Gunsmith Bros. uprated loading nozzle
  • AIP Enhanced 120% hammer and recoil springs

Fitting all of these should simply be a case of swapping the uprated parts for the standard parts. None of it sounds too challenging, so let’s see how it goes.

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First, the replacement springs. The parts Mike provided come from Hong-Kong based AIP (Army International Products). The upgraded recoil spring should provide improved recoil effect from the blowback, though you should only fit an upgraded recoil spring if you are planning to use Green Gas – HFC-134a just doesn’t provide enough power to deal with an upgraded recoil spring.  The hammer spring will lead to a harder hammer strike, which will cause more gas to be released with each shot, hopefully providing improved fps. The downside is that this will also use more gas, but as the TM Hi-Capa is pretty frugal with gas, I’m prepared to accept that trade-off.

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Replacement AIP 120% recoil spring (top) and TM original (bottom)

Fitting the upgraded recoil spring was no problem – I just removed the guide rod, bush and spring from the slide, replaced the old spring with the spiffy new one and put everything back together.

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The hammer spring was little more tricky. The mainspring housing on any 1911 style pistol is in the base of the rear of the grip and it’s essentially a self-contained module which has to be removed to access the hammer spring. One useful tip is that it’s best to lock the grip safety in the engaged position before you remove the mainspring housing. The grip safety uses a leaf spring with fingers which can be bent or damaged when you re-fit the mainspring housing, but if you use tape or an elastic band to hold the grip safety in before you remove the mainspring housing, this won’t be a problem.

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Pin which retains the mainspring housing (arrowed). Masking tape is used to hold the grip safety down.

To remove the mainspring housing, all you have to do is drift out the pin in the bottom rear of the grip. The pin has a pronounced dimple on one side and that’s the side on which you should place your drift.

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Pin partway out.

With the pin removed, tension on the hammer spring will cause the housing to move around 1/8” down. Just slide it out the rest of the way down and out of the grip.

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If you then look into the top of the housing, you’ll see the dished top of the hammer spring pin and, coming from the left side of the housing, a small plastic pin which stops the hammer spring and pin from twanging out. All you do is push the small plastic pin to one side and the hammer pin and spring will come out.

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OK, I know it’s a little difficult to see in this picture, but if you look into the top of the mainspring housing, you’ll see the dished top of the hammer spring pin and the small plastic pin which pushes in from the side and holds this in place (arrowed)

This is one part of the job where you’ll need to be careful if you don’t want small parts springing off into the middle distance. When you push the small pin to the side, tension on the hammer spring will cause the spring pin and spring to twang out of the housing. Guess how I know that? And, if you’re working close to an open window where the light is good, you may be especially unlucky and the spring pin will bounce out of the window, on to the balcony and then down into the street one storey below. And you’ll then spend fifteen minutes looking like a complete dork as you wander up and down, scouring the street outside looking for the missing pin. Guess how I know that? And against the odds, yes I did find it. It’s lucky I live on a very quiet street! To avoid similar problems, all you have to do is make sure that your thumb or something else is over part of the opening at the top of the mainspring housing before you slide the small plastic pin to the side – this will stop the hammer spring and pin popping out.

u9New AIP 120% hammer spring (left) and original TM hammer spring (right)

Anyway, once the old spring is out, you just replace it with the new one and reassemble everything. Just out of interest, I put everything back together at this point and tried the slide and hammer. And yes, the hammer feels harder to cock and the slide is harder to rack. Nothing dramatic, but you can certainly feel the difference. Which is encouraging…

In Part 2, I’ll fit the tightbore barrel and hop-up rubber and replace the loading nozzle. And I’ll finally get round to doing some chrony testing and shooting with my upgraded Hi-Capa to see if these changes provide a notable improvement.

Related pages

TM Hi-Capa Upgrade Part 2 

TM Hi-Capa review

Refurbishing a Crosman Peacemaker

Links

Elite Shooting Centre

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