TM 5.1 Hammer Problem

[safx]

I bought this gun off an ASC member recently
knowing the hammer had an issue of some kind.
I opened up the grip and set the leaf spring (3
prong) into the correct position but the hammer
only sets properly half the time. The other half,
it's following the slide forward after firing, and
creating a full auto effect...

I'm prettey sure the gun has an upgraded hammer
and recoil spring set. And the leaf spring is a tad
mangled from people trying to set it correctly but
still apears in decent enough condition to work...

If anyone knows what the cause is, and or what
part needs to be replaced let me know please and
I'll hold off buying a new leaf and sear.

Steve

[ILLusion]

Take out the hammer and take a picture of it. I'd like to have a look at it.

There should be two notches on the hammer. If the middle-one is worn down, it will cause the full auto effect. I've noticed this occuring mroe on guns that have aftermarket ALUMINUM hammers with upgraded hammer springs. The problem increases if the sear has been replaced with a steel one.


One way to test if the middle-notch has sheared off: do a slow manual hammer drop. (with your thumb releasing the tension after pulling the trigger.) If the notch is still there, the hammer should be only able to drop half way (unless there were modifications done to the hammer to do a proper working manual release.)

[safx]

Awesome, sounds right as alot of the bits
have been swaped out for bling silver.

I'll take her down tonite and get some pics
ready to send you bud, thanks for taking
an interest.

[safx]

Originally Posted by Endymion

Steve,

I have an almost-new sear you could borrow and try out if you'd like. I'll bring it with me tomorrow night.

Thanks bud, I'll get it off you tomorrow. I'll wait for ILLusion's
recommendations before I install it. Sounds like I might need
to buy a hammer as well lol

Fast responses.. sniff.. I feel the love...

(sorry for the double post, I didn't see Endy's before I responded to ILL, my bad)

[ILLusion]

See the attached picture to see what an intact hammer profile should look like.

1 - indicates the primary sear notch. This is what the sear locks against to keep the hammer retracted back fully

2 - indicates the intermediate sear notch. I never fully figured out the reason or purpose as to the existence of this feature - I've only noticed that if this feature is worn down you can a) manually de-cock the gun and b) the gun can full-auto temporarily

(PS - if you're looking to modify the hammer to allow a manual de-cock, there's actually a different part that needs to be filed down)

[MadMax]

Check to see if your trigger sear disconnector feature of the trigger group is working properly.

The disconnector is the funny tab sticking out the top of your frame on the right side just forward of the hammer (pistol pointing away with slide removed). When the slide recoils about 3mm, it's pushed down by a surface in the recoil block in the slide. When the disconnector is pushed down by the slide the entire piece moves down so the trigger loop does not bear against the hammer sear. The disconnector has a side protrusion which sits between the trigger loop and the sear. When it's pushed down by the slide, the trigger loop is decoupled from the sear so it allows the sear to rotate and retain the hammer even with the trigger pulled. The leaf spring pushes the disconnector upwards via a triangular feature at the bottom of the disconnector.

If the top of the disconnector is severely worn, it does not push down far enough do disconnect the trigger loop from the sear so the sear is not allowed to retain the hammer.

You can diagnose this problem by removing the hinged grip safety (sometimes called a beavertail grip) and manually actuating the gun according to the following scheme:

Remove the grip safety and test on an otherwise reassembeled gun. Put an empty magazine in the grip (no gas). Lock the bb follower down with a wad of paper so the slide lock doesn't lock the slide.

1. Cock hammer

2. Grip frame in a way so you can look into the trigger assembly

3. Pull trigger to release hammer and keep trigger pulled

4. Manually retract the slide slowly keeping the trigger pulled. Pull the slide upwards while pulling it back. This simulates a worst case condition where the slide pushes down on the disconnector the least because the slide is tended to the top of the rail grooves.

5. Look to see if the disconnector is pushed down far enough that it does not stack between the trigger loop and the sear. It should drop out allowing about 2mm of clearance so the sear reliably engages the hammer

If the sear does drop completely out of the way yet the sear still does not reliably engage, your rear bow on the trigger loop may be bent too far rearwards. On some custom tuned triggers, the gunsmith may have bent the trigger bow too far so the sear is pushed far enough that the hammer is not retained even with the disconnector depressed. Bend the rear bow forward slightly to fix this. Bending the rear bow rearwards reduces the small amount of play before the trigger loop starts to rotate the sear. A small amount of play is necessary to allow the disconnector to pop back up when the trigger is released to reconnect for the next shot, but it's possible to shorten a trigger action with some trigger loop tweaking. DO NOT FILE OR SAND TM Hicapa sears or disconnectors. While it is tempting to customise the shapes of various surfaces for super short sharp trigger pulls, you will remove the heavy chrome plating TM puts on their cast aluminum trigger bits. This finish is not cosmetic. It reduces friction and acts as a hard wear surface which is much more durable and low friction than bare aluminum (I wish WA would learn something from TM here).

Watching the trigger sears with the beavertail removed can also show other problems like a sear not rotating smoothly. If the leaf spring isn't doing it's job, the sear tip will not be sprung against the hammer engagement surfaces. If there's too much crud in the mechanism, the sear may not rotate freely.


I think that's about all I can think of that might cause your hammer to not lock back.

[safx]

Big thanks to ILLusion for his coaching over PM early on. Mad Max you're a genius— why are you wasting your time doing anything but designing guns for your own Canadian airsoft company? Oh wait... replicas, dang laws

So, after taking the gun apart and realizing the inners were all in top shape, I concluded she wasn't assembled properly, and just resetting the leaf spring wasn't enough, as the sear wasn't in the proper position all along. I set the sear so it catches the hammer for both clicks and now she's firing.

I was a little worried about opening up this gun because of past experiences with nightmare glock hammer block designs, but the TM couldn't be simpler or easier to take down and reassemble. Had a little snag with the hop-up (this gun has a hop ) being set too far so the bbs were trickling out (small scare)..lol, turned it off and blamo.

For anyone who has a TM Hi-Capa I'd recommend saving this thread as a web archive to your HD for future reference, these tips are pure gold!

Cheers, Steve

[Scooby Steve]

Originally Posted by safx

For anyone who has a TM Hi-Capa I'd recommend saving this thread as a web archive to your HD for future reference, these tips are pure gold!

Will do, as I'm thinking of getting a 5.1. Great info, guys.

[MadMax]

Originally Posted by safx

Big thanks to ILLusion for his coaching over PM early on. Mad Max you're a genius— why are you wasting your time doing anything but designing guns for your own Canadian airsoft company? Oh wait... replicas, dang laws

So, after taking the gun apart and realizing the inners were all in top shape, I concluded she wasn't assembled properly, and just resetting the leaf spring wasn't enough, as the sear wasn't in the proper position all along. I set the sear so it catches the hammer for both clicks and now she's firing.
*snip*

Yeah, the TM Hicapa is a very well engineered GBB. I'd say it's the most well engineered GBB in existance. The KSC Glock is pretty good, but I can tell that TM went through some lifecycle testing to refine it into a durable gun. I really hate changing KSC Glock hammer springs. I really like TM's material selection. Economical cast aluminum trigger components made durable and ultra low friction with an economical hard chrome finish. WA used to be the gold standard in GBB performance and reliability. They've stagnated and shown TM where to improve.

WA trigger design more or less copies the sear design from the real steel 1911 economising on materials (cast aluminum instead of investment cast steel) with some design changes. TM branches off on WA with a more elegant take on the 1911 design principle eliminating one spring (disconnector spring) with the triangle feature on their disconnector. TM appears to have noticed a common failure in WA sticky sear failures as they chrome plate their trigger bits and adjusted some engagement angles for more consistent performance. It used to drive me crazy when I'd have to take a WA GBB apart and change the engagement angles so the sear wouldn't stick to the disconnector. The WA disconnector could occasionally stick under the sear so releasing the trigger wouldn't allow the d'conn to slide forward and up and stack behind the trigger. You'd get annoying loose trigger issues which interfered with the firing of a second shot. Thump the gun on the side and the d'conn would reset. Aluminum on aluminum sliding surfaces is an amateurish mistake in product design. Al-Al does not wear well and you get a high coefficient of friction later in life. I would try to offset this with a good scrubbing of molybdenum or graphite powder but TM fixes this with beautiful hard chrome.

The WA triggers were the most tunable for ultra short light action, but they didn't wear as well. TM precludes some tuning tricks with chrome finish (you don't want to file it off), but you can still tweak the trigger loop.

And the hopup! TM Hicapa hop up is the best HU design in GBBs. Consistent and easily adjusted. They're not externally adjustable, but they're consistent enough that the trouble of disassembly is well amortized over consistent performance. WA has been struggling with HU design for years. They're really quite bad. WA has hit a design limitation in HU design. They appear unwilling to stick in a longer nozzle to push the bb forward to preload it against the hop up bump. As a result, their bb sits in a staging area against a rubber feature so the bb pops forwards and bounces off the hop up bump so you get inconsistent engagement with the HU. TM preloads the bb against a consistently set bump so you get solid AEG level HU performance. They've also gone through some pains to consistently register the inner barrel to the slide when the slide is in battery so the IB consistently follows the slide mounted sights.

Glad to hear you got your Hicapa working. It's a solidly engineered GBB for a pistol enthusiast. It's doesn't have the wide aesthetic appeal of a SIG226 or the 1911, but the bigass 0.45 doublestack replicating mag has a huge amount of gas for trippletapping performance. I think the TM hicapa mags have the highest gas/bb ratio of the TM GBB line. Only the WA 0.45 double stacks have similar gas volume:bb capacity. Compare blasting away with a 226 and a hicapa and you'll notice the difference if you compare side by side.

[JDM350GT]

u guys are lifesavers, i bookmarked this page for my 4.3 in the future