TM M733 snappy semi build questions

[SSPKali]

Morning all,

I have a new toy on its way in the form of a TM M733 “Colt Commando” Totally stock at the moment. I plan on checking how it runs as standard - accuracy, consistency and trigger response. No sense just replacing stuff for the sake of it! It will be run it on 7.4v as a CQBish semi-only and ~1J

Having said that I do like playing about in gear boxes so planned to check the shimming, maybe short stroke it by a few teeth (possibly 13:1?) and throw in a basic MOSFET (Gate NanoASR?) Possibility of an XT high torque motor if needed with the M120.

Unfortunately I spotted the Warhead base motors and wondered if one of those could remove the need for short stroking / 13:1 gears and faffing inside the gear box? Seems the high speed ones can mess up timing. I am after trigger response not high RoF / wankergun!

I have been deep in GBBR land for a while so advice from the ARG gurus appreciated!

 

[Hatchet]

I've done something similar recently. Perun Hybrid, 13:1 gears and base 27k motor. Seems fast enough for me - I generally run on 7.4v.

Could probably have just used a 35k motor, 11.1 and not changed the gears, but in some ways it's easier to get a slightly slower motor and have the option to increase speed (with gear or battery change) than it is to have one that's too fast and be stuck.

Ran it last weekend spamming semi all day and only used about 50% of a 1300mah battery.

 

[Adolf Hamster]

if you're aiming for a snappy build then you'll want a mosfet with precocking, something like a warfet or ab++ will be fine if you're not switching between semi and auto often.

the warhead is definately the motor you'd want for this, i'd go with a standard speed and as mentioned above if that's not enough for you then upping the gearing and/or battery voltage remains an open possibility.

 

[SSPKali]

if you're aiming for a snappy build then you'll want a mosfet with precocking, something like a warfet or ab++ will be fine if you're not switching between semi and auto often.

the warhead is definately the motor you'd want for this, i'd go with a standard speed and as mentioned above if that's not enough for you then upping the gearing and/or battery voltage remains an open possibility.

I was under the impression that the WH motor controller included AB? and might not play well with other mosfets? 
 

Perun AB++ looks like a cool little unit

 

[Adolf Hamster]

I was under the impression that the WH motor controller included AB? and might not play well with other mosfets? 
 

Perun AB++ looks like a cool little unit

Not unless they've updated something?

I know the build i had was running a titan with precocking and ab dialed up to "reasonable" (read: excessive) levels and it didnt have any issues.

All precocking is for the likes of the warfet/ab++ is just a timer that shuts the motor off a little later than the cutoff lever trips, which you can adjust the timing to get your desired amount of precocking.

 

[SSPKali]

So finished* the M733.

Warhead high speed motor, G&G 16:1 gears short stroked 2 pickup/2 release, metal bushings and shimed. Lightweight piston with 14tooth metal rack and new POM head, 3/4 cylinder. XT M110 spring and radiused the gearbox shell. E&C pistol grip as the TM one was uncomfortable and screws for motor cover very lose.
 

Macaron 50deg rubber and cylindrical hop nub with steel core from Firefly nub. Polished the brass barrel with Autosol and cleaned with Isopropyl alcohol.

Shooting 0.28g Warhead ammo (its preferred food from todays tests) at 275fps plus or minus 2fps tops. 30mm square grouping at 10m. 15rps in full auto with a 7.4v block LiPo, not that I will use that often.

Vortex red dot, Tacbelts minimalist sling, scout light on Magpul mount and 100mph tape to hold the switch finish off the gun.

Looking forward to running it next weekend at UCAP VENDETTA.

* for a given value of “finished” still looking at an E&C metal upper and lower receiver!

View attachment 103119



IMG_2039.MOV

 

[SSPKali]

Ran the M733 today at UCAP VENDETTA and it worked really well. Not quite the range of the MWS and I had one semi-lockup (at the worst possible time…so I switched to my USP and forgot the safety was on ?‍)

Trigger response and cycle time were plenty fast enough so no 11.1v or pre-cocking on the horizon.

Will be getting the E&C metal upper&lower receiver as the TM one while ok is a bit wobbly on the carry handle.

 

[SSPKali]

Not unless they've updated something?

I know the build i had was running a titan with precocking and ab dialed up to "reasonable" (read: excessive) levels and it didnt have any issues.

All precocking is for the likes of the warfet/ab++ is just a timer that shuts the motor off a little later than the cutoff lever trips, which you can adjust the timing to get your desired amount of precocking.

Turns out the precocking on a Perun AB++ uses active braking and causes issues with the Warhead motor, as does the burst settings which might give 1 or 2 shots…or maybe none.

Using the TM motor it worked fine, but the Warhead fought it and refused to play nice.

One to watch out for in the future.

 

[Leo Greer]

Ran the M733 today at UCAP VENDETTA and it worked really well. Not quite the range of the MWS and I had one semi-lockup (at the worst possible time…so I switched to my USP and forgot the safety was on ?‍)

Trigger response and cycle time were plenty fast enough so no 11.1v or pre-cocking on the horizon.

Will be getting the E&C metal upper&lower receiver as the TM one while ok is a bit wobbly on the carry handle.

I like the build!

I did have a couple of notes:

The shimming sounds just a teeny, tiny bit scratchy to my ears, so if you were going to be a crazy perfectionist you might be able to make it sound a little smoother. That being said, I wouldn't bother, personally. Not worth the time, in my opinion.

Second, you shouldn't ever really experience semi-lockup with the Warhead. Semi-lockup occurs when the piston gets stuck near the end of its cycle and the motor/battery doesn't have enough startup torque to overcome the increased spring strength and complete the cycle. The Warhead has massive torque, so either your battery is criminally underpowered, which seems unlikely, or you have another issue entirely.

Depending on the shape of the selector cam on the gears you chose, the cutoff lever may be having difficulty resetting every time. Certain newer gearboxes have this issue where the gun experiences "semi-lockup" with no lockup due to the shape of the cutoff lever... It's possible that the spec differences between the TM stock gears and the replacements are causing the issue.

 

[SSPKali]

I like the build!

I did have a couple of notes:

The shimming sounds just a teeny, tiny bit scratchy to my ears, so if you were going to be a crazy perfectionist you might be able to make it sound a little smoother. That being said, I wouldn't bother, personally. Not worth the time, in my opinion.

Second, you shouldn't ever really experience semi-lockup with the Warhead. Semi-lockup occurs when the piston gets stuck near the end of its cycle and the motor/battery doesn't have enough startup torque to overcome the increased spring strength and complete the cycle. The Warhead has massive torque, so either your battery is criminally underpowered, which seems unlikely, or you have another issue entirely.

Depending on the shape of the selector cam on the gears you chose, the cutoff lever may be having difficulty resetting every time. Certain newer gearboxes have this issue where the gun experiences "semi-lockup" with no lockup due to the shape of the cutoff lever... It's possible that the spec differences between the TM stock gears and the replacements are causing the issue.

Thanks for the tips, I have run it at several games and put 1000+ rds through it and not had any semi lock up - must have been a one off!

It does sound a little screechy in the video - certainly not that bad in real life, probably down to the cheap mic on the phone. I checked the shimming with all gears in place and the shell screwed shut (not just held shut with fingers!) and it was all spinning smoothly.