Jump to content


Photo
- - - - -

1921 Actuator


  • Please log in to reply
17 replies to this topic

#1 The1930sRust

The1930sRust

    Respected Member and Board Donor

  • Moderator
  • 1939 posts
  • Gender:Male
  • Location:Confederate, Kentucky
  • Interests:Thompsons, obviously. Proud West Hurley 1928 and Savage M1 owner, cave explorer, and KSP trooper (retired). Also interested in 1920-1930 American history. I appreciate all Thompson models and their owners.

Posted 01 September 2003 - 11:44 AM

Several weeks ago I was fortunate enough to obtain a 1921 actuator assembly. It consisted of the actuator, pilot, and two each buffer tubes and springs, and some extra buffer disks.

user posted image

As far as I can tell, it is totally unmarked. I had been tinkering with the idea of having a standard 1928 actuator modified to the specifications of the 1921, in order to speed up my 1928 just a tad. PK suggested the modification, and even sent me an image of such a beast.

user posted image

Having come across the real McCoy negated that option. I did, however, purchase one of PK's hybrid 1921-1928 buffer assemblies. I was worried about the purported design flaw of the 1921 actuator (lots of metal on metal contact), and the possibility of it damaging the softer metal of the West Hurley receiver.

user posted image

PK's hybrid buffer, utilizing a special buffer disk, itself is a piece of work, and was a perfect fit of course. I got a chance to get to the range today and try it all out.

user posted image

I ran nearly 300 rounds though it all, without a hitch. Although I have not been able to quantify the speed of the new actuator, it is definitely faster. It just sounds cooler! The overall action seemed smoother, too.

Here is a short 3 MEG .MOV file of the gun running through 50 rounds.

1921 actuator video
  • 0

#2 full auto 45

full auto 45

    Respected Member

  • Board Benefactor
  • 4584 posts
  • Gender:Male
  • Location:Looking over your shoulder right now
  • Interests:Thompson's, Any Machinegun, Harley's and scuba diving. In that order.

Posted 01 September 2003 - 12:15 PM

Great video work Chris. Looks like the actuator is slipping but moving to fast for the camera. Good work.
  • 0

#3 LIONHART

LIONHART

    Long Time RKI Member

  • Regular Group
  • 2785 posts
  • Gender:Male
  • Interests:Thompsons of course. All Manufactures and Models.

Posted 01 September 2003 - 12:55 PM

Nice video of your Chopper Chris!
  • 0

#4 First Sergeant

First Sergeant

    Respected Member

  • Regular Group
  • 757 posts
  • Gender:Male
  • Location:South West Ohio

Posted 01 September 2003 - 01:54 PM

Chris,

Great pics but I can't get the video to open.....any suggestions?

Chuck
  • 0

#5 ausrotten

ausrotten

    Member

  • Regular Group
  • 26 posts

Posted 01 September 2003 - 02:02 PM

i think you need quick time. well, thats what mine loads it up in.
  • 0

#6 PK.

PK.

    Technical Expert

  • Board Benefactor
  • 1567 posts
  • Gender:Male
  • Location:CO, USA
  • Interests:Full time gunsmith who loves Thompsons, 35+ years experience.

Posted 01 September 2003 - 02:26 PM

Minor correction; the buffer disk shown in Chris’ post and noted as an SRT part is actually of my own manufacture. They are different but similar and the mistake is certainly understandable.
  • 0

#7 The1930sRust

The1930sRust

    Respected Member and Board Donor

  • Moderator
  • 1939 posts
  • Gender:Male
  • Location:Confederate, Kentucky
  • Interests:Thompsons, obviously. Proud West Hurley 1928 and Savage M1 owner, cave explorer, and KSP trooper (retired). Also interested in 1920-1930 American history. I appreciate all Thompson models and their owners.

Posted 01 September 2003 - 02:38 PM

Yeah, sorry 'bout that. I thought you said that was what you used. Or maybe I recall you mentioning them as replacements for the 21 buffers. There goes my brain again....

Yes, the video requires the www.apple.com free Quicktime viewer.
  • 0

#8 Zamm

Zamm

    Respected Member & Artist

  • Regular Group
  • 831 posts
  • Gender:Male
  • Location:Long Island, New York
  • Interests:Thompsons, and all their goodies!<br>Obsolete Victorian Photomechanical processes,<br>Etching, Engraving and all Printmaking,<br>Entomology, specializing in Coleoptera,<br>Arachnology, specializing in Theraphosidae.

Posted 01 September 2003 - 03:14 PM

Chris,
Weeeeeeeeeeeaaaaaaaaahhh !!!!! Gad that thing is fast!!
Amazing view! Your an artiste!
Zamm
  • 0

#9 ausrotten

ausrotten

    Member

  • Regular Group
  • 26 posts

Posted 01 September 2003 - 03:15 PM

thats a very clear video! nice work mate.
  • 0

#10 PK.

PK.

    Technical Expert

  • Board Benefactor
  • 1567 posts
  • Gender:Male
  • Location:CO, USA
  • Interests:Full time gunsmith who loves Thompsons, 35+ years experience.

Posted 01 September 2003 - 03:20 PM

We did discuss SRT Chris, they are the only ones I know of who make replacement disks for the ‘21 buffers (the little red ones as shown in your photo, except I think theirs are gold color as the 28 disk show is). So you are not loosing it as badly as you might think! tongue.gif
  • 0

#11 Norm

Norm

    Long Time RKI Member

  • Board Benefactor
  • 2514 posts
  • Gender:Male
  • Location:Memphis, TN
  • Interests:Thompsons (of course), Electronics, Physics, History, Mechanics, Collecting License Plates.

Posted 01 September 2003 - 04:00 PM

I love the video! The Tommy-Cam! laugh.gif

What size drum was that you emptied? A 100 or 50?

Norm

  • 0

#12 Johnny.45

Johnny.45

    Long Time Member

  • Regular Group
  • 201 posts
  • Gender:Male
  • Location:Arizona, U.S.A.

Posted 01 September 2003 - 05:03 PM

Chris,

That looks like a great setup. The 21 actuator and PK's Mod 21/28 buffer pilot is a great addition to your 28 WH. I'm trying to collect as many spare 28 parts as I can, and now I'm going to look for those 21 parts that PK is manufacturing.
Thanks for sharing the information on the 21 parts kit.

Outstanding,
Johnny
  • 0

#13 The1930sRust

The1930sRust

    Respected Member and Board Donor

  • Moderator
  • 1939 posts
  • Gender:Male
  • Location:Confederate, Kentucky
  • Interests:Thompsons, obviously. Proud West Hurley 1928 and Savage M1 owner, cave explorer, and KSP trooper (retired). Also interested in 1920-1930 American history. I appreciate all Thompson models and their owners.

Posted 01 September 2003 - 05:03 PM

Norm:

That is a 50 round L drum. No C's yet! Couldn't possibly afford to feed one now....

Johnny:

PK's actuator made to '21 specification/hybrid buffer system is the way to go for pepping up a 28 for sure. I think if you supply the 28 actuator, he'll do the rest...

I also did some quantitative analysis (always wanted to say that) of the videos, and it empies a drum in 3.01 seconds (give or take). Eyeballing it, that is around 900 RPM.

Also, there is an unusual "lunge" (or perhaps it is a "lurch) as the last round plays out. I don't recall feeling this with the 1928 actuator.

Zamm and everyone else, glad you liked the flick!
  • 0

#14 full auto 45

full auto 45

    Respected Member

  • Board Benefactor
  • 4584 posts
  • Gender:Male
  • Location:Looking over your shoulder right now
  • Interests:Thompson's, Any Machinegun, Harley's and scuba diving. In that order.

Posted 01 September 2003 - 08:28 PM

That's pretty good. I clocked my "L" drum at 3.83 sec. or about 785 rpm. Amazing what you can come up with on a video and some editing software.
  • 0

#15 PK.

PK.

    Technical Expert

  • Board Benefactor
  • 1567 posts
  • Gender:Male
  • Location:CO, USA
  • Interests:Full time gunsmith who loves Thompsons, 35+ years experience.

Posted 01 September 2003 - 09:07 PM

With all due respect, I must take exception to the term “Speed Actuator”, it is much to reminiscent of the terms used to sell dangerously lightened parts by others in the past.

Lets be clear; the actuator shown in the photo I sent Chris and displayed at the beginning of this post is a 1928 Actuator that has been machined into a “by the print” ’21 style. It is for all intents and purposes identical dimensionally to an Actuator as supplied by Colt for the 1921 gun. No magic, no mirrors. Installed with a 21 recoil spring and either an original 21 buffer system or a hybrid buffer system, the function is as originally designed for the 1921 gun.


  • 0

#16 Walter63a

Walter63a

    RKI Member

  • Regular Group
  • 1430 posts
  • Gender:Male
  • Interests:Guns (Thompsons, Lugers, and Walthers mostly), History, Politics, Education, Nature, etc.

Posted 01 September 2003 - 09:38 PM

Chris, that's great video work. Thanks for sharing. smile.gif Regards, Walter
  • 0

#17 The1930sRust

The1930sRust

    Respected Member and Board Donor

  • Moderator
  • 1939 posts
  • Gender:Male
  • Location:Confederate, Kentucky
  • Interests:Thompsons, obviously. Proud West Hurley 1928 and Savage M1 owner, cave explorer, and KSP trooper (retired). Also interested in 1920-1930 American history. I appreciate all Thompson models and their owners.

Posted 02 September 2003 - 05:22 AM

Paul:

Boy! I've just screwed this post up from top to bottom! Thanks for keeping me in line. OK, I actually used the phrase "deleted term actuator" to draw attention to the old "speed bolts" to suggest this is the right way to speed up a 1928. I may even add a section in the FAQ about this, as the speed bolts are listed there I think. Anyway, next time I'll use a more appropriate term. How about "modified actuator/hybrid buffer system"? MAHBS? blink.gif
  • 0

#18 First Sergeant

First Sergeant

    Respected Member

  • Regular Group
  • 757 posts
  • Gender:Male
  • Location:South West Ohio

Posted 02 September 2003 - 07:25 AM


Got the video to work, thanks for the download info.

Good shooting there Tex (Chris) looked and sounded great. Thanks for a trip to the range but without the cleaning.

Chuck
  • 0