View Full Version : Question about HTS parts and SRA...

July 19, 2007, 13:12
Originally posted by NFADLR
Not to discount your experience with the BATF but a Semi Auto Trigger plunger or a Semi auto selector would have made this situation have never happened.

When the G series FN FAL was imported BATF asked for some modifications before the rifle could be imported below is the link to the letter and the letter below the link showing the modifications requested.

When all of the kit guns started coming in people building them only concentrated on the 922R parts requirement and not the full auto parts that were on the rifle besides the Safety sear.

I understand that the rifle cannot run full auto without the safety sear but as cheap insurance If you can find it the Semi auto Trigger plunger and even if you have to use a DSA semi auto selector change lever its better than being hassled by a know nothing FFL or BATF agent.

The only reason I'm posting this info here is so others can see it and put these simple parts on their kit guns and be safe from BATF&E Agents messing with them and their lives.

In my experience the 80's para imports had the Semi auto trigger plunger. At one time Gun south also had the SA trigger plunger in their FN Parts list. Ive been looking for it for a long time but haven't been able to find anyone or company selling the SA version but here is the FA version as you can see this plunger has 1 concentric ring around the OD.

The SA plunger has two rings around the OD. The 2nd ring is closer to where the OD of the body tapers down towards the ball on the end.

I would appreciate it if someone that owns a 50.63 takes their Trigger plunger out and look and see if its how I describe it and if it is please take a pic of it and send it to me.

Below is the Full auto Trigger plunger. This is not what you want in your kit FAL's .

The pic below shows the R marked Semi auto Selector Change Lever.

I hope this helps.


APR 3 1961

Browning Industries, Inc.
719 First Security Bank Building
Ogden, Utah

Attention: Mr. John V. Browning


This refers to your letter of January 5, 1961, concerning changes
in design in order to remove your F. N. Browning light rifle,
caliber 7.62 mm, from the classification of a firearm as defined in
the National Firearms Act. A specimen of your rifle bearing serial
No. G 493 was submitted through our Salt Lake City, Utah office for
examination and testing by us.

It is our understanding that the rifle has been designed and made
in Belgium as follows to prevent full automatic fire:

1. The change lever is blocked in such a way that it cannot
be moved forwardly into full automatic position. The
change lever thus becomes a standard safety.

2. The trigger return spring plunger has been modified to
limit the rearward movement of the trigger, regardless of
the position of the change lever.

3. The automatic sear has been eliminated. As pointed out,
the automatic sear is essential to full automatic fire.
If, for example, the two modifications above had not been
made, the rifle still would not fire full automatic
without the automatic sear. The hammer has to develop
enough energy in its forward motion to give sufficient
indentation on the primer to fire the cartridge. When
the hammer simply follows the breech block and slide
forward as it would without the automatic sear, it does
not ever impart the necessary energy to the firing pin.

- 2 -

The F.N. Browning light rifle described above will not be
considered a firearm as defined by Section 5848 of the National
Firearms Act and therefore not subject to the provisions of said

In addition to the above alterations, the following changes in
design of the gun are suggested so that the conversion to full
automatic will be further discouraged:

1. The stud nearest the letter "A" indicating the position
of the change lever for full automatic fire and the
letter "A" should be completely removed from the left
side of the frame. In addition, the groove to the right
of the aforesaid stud for stopping the change lever
should also be eliminated.

2. The recess (cut out) on the top of the left side of the
hand grip should be eliminated so that the change lever
cannot be pushed forward any farther than the letter "R"
indicating regular fire because the recess indicates that
the change lever can be moved to another position.

We are returning the rifle submitted to the Investigator in Charge,
Alcohol and Tobacco Tax, 335 Federal Building, Salt Lake City,
Utah, for subsequent delivery to you.

Very truly yours,

Dwight D. Avis
Director, Alcohol and Tobacco Tax Division

Figured I wouldn't hijack the dude's thread, so...

What's the difference between the automatic sear and the semi-auto sear? Or... Is it two different parts?

What does this part look like? Anyone have a good picture of the HTS with and without the parts in question?

Again, I'm just curious... Probably shouldn't be... :\

- CK

July 19, 2007, 14:48
It's two different parts.

Here are some diagrams from Gunplumber's site:


The automatic sear (aka safety sear) is #7 in the top diagram, and the primary sear is #15 in the bottom diagram.

If you have a FA capable rifle, it works like this (if I have it wrong, someone will correct me):
1) When the operator pulls the trigger to the rear with a round in the chamber, the hammer cocked, and the selector on FA, the trigger disengages the primary sear from the hammer and the hammer falls, firing the round. The FA notch on the selector is deeper than the Semi notch, which allows the trigger to move further to the rear in FA mode. In this position, the nose of the primary sear is held clear of its corresponding notch on the hammer.
2) The rifle cycles and re-cocks the hammer, which is caught and held to the rear by the safety sear.
3) When the carrier moves fully forward into battery, it trips safety sear, disengaging it from the hammer. The hammer rotates forward, bypassing the primary sear ('cause its being held clear by the trigger), and fires another round.
4) This continues until the operator releases the trigger.
5) With the trigger released, the primary sear can now re-engage its hammer notch. When the carrier trips the safety sear, it releases the hammer onto the primary sear, which retains the hammer and stops the rifle from firing further.

In Semi mode, the trigger doesn't move as far to the rear, so the primary sear stays in position to catch the hammer when the safety sear trips, which only allows the rifle to fire one round.

In a semi-only rifle, the safety sear is missing all together. In semi mode, the primary sear catches the hammer as the carrier moves back into battery after firing each round. If you happen to have a semi-only rifle with a FA selector, and you fire the rifle on FA, the hammer will just follow the carrier all the way into battery, but won't have enough energy to fire the next round (unless something is broken or you have super soft primers). Having a selector that goes to FA can cause trouble with ignorant FFLs and LEOs, so it's best to fill the FA notch or replace the selector with a semi-only unit.

July 20, 2007, 04:15
**finishes writing notes...**

Thanks. :)

- CK