Safeties

Type I	Type II	Type III	Type IV
Push Button			Rotary

	Type I Push Button

The safety used at the beginning of production was a push button safety having a checkered pattern on both ends. Those used by Winchester differed slightly
from those by Inland as the latter's safeties (bottom row) featured a beveled edge around the checkered pattern. These safeties have no manufacturer marks.

	Type II Push Button

On 10 Aug 1942 U.S. Ordnance approved elimination of the extra step that added the checkering as a time and cost savings. The safeties were left flat faced.

	Type III Push Button

Pressure exerted at the rear of the Magazine Catch/Safety Plungers & Spring held the safety in the safe or fire position by engaging one of the two holes
inset into the safety on the earlier safeties. With time and use it was found the ridge between these two holes was inadequate for this purpose. By mid to
late 1943 the holes were replaced by two V shape cuts with a ridge between the two that prevented the safety from moving from the fire or safe positions.

Use of the Type III safety continued after the introduction of the rotary safety. Replacement of the Type III safety with a rotary safety was mandated with
the Model M2 in 1947 and all carbines in 1949.

	Type IV Rotary

The push button safety was switched to the fire mode by pushing it from right to left. It's location near the magazine catch sometimes resulted in troops
pushing the magazine catch and releasing the magazine instead of pushing the safety to the fire position. Springfield Armory designed and developed the
rotary safety to prevent this from happening. The design was adopted 7 Mar 1945.

Winchester and Inland had begun using the rotary safety concurrent to the later push button safety by the time the war ended. An Ordnance Work Order dated
10 Dec 1947 ordered the replacement of the push button safety with the rotary safety on all Model M2 Carbines. An Ordnance Work Order dated 16 Sep 1949
ordered the replacement of all push button safeties with the rotary safety on all carbine models.

Magazine Catch/Safety Plungers & Spring

The Magazine Catch/Safety Plungers & Spring consisted of a spring with a plunger at either end. One plunger engaged a notch in the safety,
the other engaged the rear of the magazine catch. The spring provided tension on the safety to secure it in the safe or fire mode while at
the same time providing tension into a cutout in the rear of the magazine catch. The tension inside the cutout helped retain the magazine
catch in place as the magazine catch spring pushed the catch outwards.

The overall length when production started was 29/32", approx. .90" (top). Time and use altered the length slightly.

To strengthen the pressure exerted on the safety and magazine catch the overall length was increased to 31/32", approx. 1.0" (bottom).
As with its predecessor time and use altered the length slightly. The longer version has been observed on carbines being assembled as
early as January 1944 and was used concurrent with the use of the shorter version.

An Ordnance work order dated 16 May 1945 directed Ordnance personnel servicing carbines to replace the shorter version with
the longer version in conjunction with replacement of earlier magazine catches with the M marked magazine catch (Type III).

The shorter version was replaced to the extent it has become far less commonly encountered than it's longer replacement.

Magazine Catches

Type I	Type II	Type III	Type IV

	Type I

Used at the beginning of production this first Magazine Catch featured vertical serrated edges.

	Type IA

On 10 Aug 1942 U.S. Ordnance approved skipping the step that produced the serrations to save time and cut costs.
The serration was discontinued by late February or early March 1943.

Type I magazine catches featured what is referred to as a "long face" (left). Sometime in early 1943
the face was shortened by eliminating the overhang producing what is referred to as a "short face" (right).
All magazines catches thereafter have the short face.

	Type II
Serrated magazine catches having a short face are believed to have been made by altering existing long face magazine catches with serrated edges as opposed being newly manufactured.
Some smooth long face magazine catches may have been altered to the short face but the majority of smooth short face magazine catches were of new manufacture.

Magazine Catches prior to the Type III had a rail width of .095"-.10". To eliminate the chance of binding
and increase reliable movement the rail of the Type III Magazine Catch and all that followed was changed to .065"-.07".

	Type III

The letter M (Modified) was placed on the face of the magazine catches having the thinner rail to easily identify them from their predecessors.
The M used by the majority of manufacturers was a sans serif font (top). The M on the face of the magazine catches manufactured by Wadsworth Watch
Company (for Inland) used a serif font (bottom).

The Type III magazine catch was used as early as January 1944. On 16 May 1945 U.S. Ordnance issued a work order to ordnance personnel servicing
carbines to replace all prior magazine catches with the Type III and all shorter safety/magazine catch plungers and spring with the longer version.

The quantities of various parts needed to maintain production levels and for use as replacement parts occasionally exceeded the capabilities of the prime contractors and/or their subcontractors. During WWII Ordnance contracted additional companies to manufacture various parts to meet these needs. These included Type III mag catches manufactured by Walt Manufacturing Company and Commercial Controls (formerly National Postal Meter).

	Type IV The M Marking

The Model M2 selective-fire carbine began development in May 1944. The design called for the development of a 30 round magazine along with a new magazine catch to
support the longer magazine. The design of the Model M2 was adopted 29 Nov 1944. The first 8500 30 round magazines were turned over to various Army facilities for
testing in April 1945. The new magazine catch design was identified by underlining the M on the face of the magazine catch.

The 30 round magazines included three nubs for holding the magazine in place.
As with the 15 round magazines two were located on the back of the magazine and supported by the magazine catch. The
third nub added to the 30 round magazine was located on the left side at the rear and supported by the addition of
a 90 degree arm on the end of the mag catch facing the left side of the carbine.

An Ordnance work order dated 16 May 1945 to their armorers servicing carbines directing the replacement of the plain face mag catch (Type II) with the modified mag catch (Type III)
indicated the mag catch with the underlined M was currently being supplied with the Model M2 Carbines and was acceptable for use on all carbines.

	Type IV Absent the M

An Ordnance work order dated 29 Oct 1952 to their armorers servicing carbines identified an M2 mag catch absent the M as currently being supplied with the Model M2 Carbines.

An Ordnance work order dated 25 May 1954 to their armorers servicing carbines directed all mag catches prior to the M2 mag catch were to be replaced with
M2 mag catches. The intent was to support the use of .30 round magazines on all carbines. By the time this order was issued the majority of carbines had
already been inspected. Many retained their type III mag catches.

Magazine Catch Plunger & Spring

The Magazine Catch Plunger and Spring remained unchanged throughout production.