HKPRO Forums banner

1 - 20 of 31 Posts

·
Registered
Joined
·
276 Posts
Discussion Starter · #1 ·
This post only focuses on the prep/design of SEF and SEMI trigger packs. No sort of information for prep/design of burst packs is included. Sear designs not similar to the standard Fleming/Qualified/S&H design may have minor or major differences from what is described here.

First off, a little about trigger pack cages. The above named NFA registered sears were meant to be compatible with standard SEMI HK trigger cages with very little modification. The NFA registered sear is held in place by the elbow spring axle. The sear geometry is different than the factory SEF sear position. SEF cages can be converted with small modifications.

Here's a comparison of a SEMI cage on top and a SEF modded sear pack with NFA registered sear on the bottom.


The areas circled in red is where a small amount of the SEMI cage may have to be milled away to allow full movement of the sear on its axle. NFA registered sear shown in SEMI cage.


SEF cages require the existing factory elbow spring/sear hole to be welded up (red), new elbow spring hole drilled in the factory SEMI position(green) and then the front of the cage milled to fit the semi auto shelf.


Here's a picture of a Fleming sear in an SEF pack, notice there is no cage shelf to impede the movement of the sear on its axle.


Either type of prepped cage is perfectly acceptable. When finished, the geometry of the internals are identical.

Full auto packs have a higher trigger stop than semi auto packs. This can be overcome with the proper hammer.
 

·
Registered
Joined
·
276 Posts
Discussion Starter · #2 ·
Secondly, let's go over the full auto specific parts you need in for the sear ready pack.

1) Full auto hammer (more on this later)

2) Release lever (not present in SEMI packs).


3) Full auto distance sleeve (SEMI on top, SEF on bottom).


4) Modified full auto elbow spring.
 

·
Registered
Joined
·
276 Posts
Discussion Starter · #3 ·
There are two basic designs used to create a sear ready pack. The modifications to rest of the pack as a whole is dependant completely on these two characteristics:

1) Using a factory full auto hammer as-is.

2) Using a factory full auto hammer re-cut for a registered sear.


Let's run down the above two methods in more detail:

1) Using a factory full auto hammer as-is. (Not the best way)

This is the less-desirable sear ready type pack for several reasons. One reason is that the factory hammer is not designed with an ideal profile for use of a registered sear. The hammer rides high in the pack when it is cocked which can lead to a number of problems including light primer strikes. This design also has a slightly higher ROF than factory full autos. With this design, you will need to do several other modifications to the sear pack.

They include:

a) Milling out/removing the trigger stop to allow extra trigger travel (circled in red)


b) Grinding down the front of the trigger "sear" (not to be confused with the NFA registered sear)
 

·
Registered
Joined
·
276 Posts
Discussion Starter · #4 ·
The second method is much more desireable.

2) Using a factory full auto hammer re-cut for a registered sear. (the BEST way)



With a properly re-cut hammer, you do not need to make any other modifications to the prepped cage or other internal components other than the FA elbow spring.

The trigger stop can remain in place and the trigger sear can remain untouched. The ROF is very close to factory HK full autos and the hammer cocks at a more factory correct geometry.
 

·
Registered
Joined
·
5 Posts
excellent post! You should call it "All the questions you wanted to ask about sear ready packs, but were afraid to ask."

thanks!
 

·
Premium Member
Joined
·
3,978 Posts
VERY well done, thanks for the info....
 

·
Registered
Joined
·
9 Posts
Ted said:
So which manufacturers use the first method and which use the second method?
I believe Curtis Higgins of S&H used method 1 when he installed my sear in a SEF pack and later, a Navy pack. He welded a steel plate to raise the shelf on my sear so that it holds the hammer at the factory setting. It has worked great for 12 years.
 

·
Premium Member
Joined
·
11 Posts
ARPORRO1: I am confused. Are you saying he welded something onto your transferable HK autosear? Does that affect its functioning with other caliber setups? Absent some catastrophic failure crisis, I don't think I'd have the guts to let someone weld on an $11,000 bit of metal. Thanks.
v/r
TED
 

·
Registered
Joined
·
9 Posts
Ted said:
ARPORRO1: I am confused. Are you saying he welded something onto your transferable HK autosear? Does that affect its functioning with other caliber setups? Absent some catastrophic failure crisis, I don't think I'd have the guts to let someone weld on an $11,000 bit of metal. Thanks.
v/r
TED
The converted pack with sear works well in a MP5K PDW, MP5-N, and a MP5/40. I haven't tried it in a .223 or .308. When he welded the new shelf to the sear, it was only worth $550.00 :). It's only tack-welded on -- it can be restored to original fairly easily, I believe.
 

·
Registered
Joined
·
12 Posts
DUH!??!?!?!?

$550.00????????!?!?!?!??!?!??!??!? HOLY NINNYMUGGINS!:eek:

I paid more than that for my last tank of gas! heh. Just Joking on that one but holy crap! That is amazing,.. .I wish I would've been born just a schoche' earlier. (not sure though, cuz then we'd still be in the 80's).

550,... grumbles and slams laptop shut..

:74:
 

·
Registered
Joined
·
276 Posts
Discussion Starter · #19 ·
I am not familiar with this ruling. Are sear ready packs controlled now?
There was a blurb written by the ATF on it a couple years back.

It's really ridiculous because depending on which way the pack was prepped, it may or may not be capable of a slam fire malfunction.
 
1 - 20 of 31 Posts
Top