Re-posting here from M1 / M1A forum, as I think this is the more appropriate spot.
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My first WWII rifle, just in from AIM is a National Postal Meter M1 Carbine, Ser # 4,283,XXX with adjustable sights. It's a mixed parts gun, which I understand is very common.

Details:

• The barrel is Underwood, with bomb marking, dated 12-43.
• The bolt is flat, not round, and marked "N"  with two parallel dash marks on the left lug.
• Sights read "L.R.C.O." with a number.
• The front band is labeled "J.M.Q."
• Mag release has a stamped "W".
• Trigger housing is labeled "SG".
• Front sight is marked "EU".  
• Safety is swivel type and marked "JAO".
• The stock has only an "L-A" marking in the sling well. Nothing else. Does anyone know what this means?

The upper hand guard has a 10 stamped on the underside.  Could the stock have been sanded at some point or replaced in a foreign land along the way, given the lack of proof markings. The wood looks to be walnut and is in nice shape, definitely not dinged up like one might expect with a rifle of this age.

Also, today I made a neat discovery via Google - the rifle spent time in Austria with the Rural Police, as the trigger pack is stamped with an LGKT marking and four digit number. From WWII to post-war security is a pretty neat story.

All in all I'm happy. I can't wait to get a Garand at some point, and then maybe another M1 from the CMP.  Most of my experience is with black rifles and tupperware. The WWII stuff, with metal, wood, and character seems to have a lot more soul too it.

That there is a true story

I have one marked " Bavarian rural police".  It appears to have been lovingly cared for by whomever carried it. Guns maked like yours bring pretty good $ on gunbroker.

Jim from this site will tell you all about your carbine.  Contact him and take picks of everything.  He emailed me back detailed notes about my Bavarian after I emailed my pics.

Bavarian Carbines


This was Jim's reply to my pics of my IBM Carbine:

++++++++++++++++++++++++++++++
3724341
   receiver manufactured by IBM between Jan and Mar 1944

INTRAC, KNOX, TN
   Carbine was imported by INTRAC of Knoxville, TN from Austria in 1993. It was sold wholesale or retail by Tennessee Guns of Knoxville, TN 1994-1995.

LGKNÖ 1492
   Landes Gendarmerie Kommand NiederÖsterreich, inventory number 1492. While in Austria, this carbine was assigned to the Gendarmerie (rural police) in the lands of Lower Austria (state/province). This area is located to the southwest, west, and northwest of Vienna. Between 1945 and 1955 this area was within the Russian Occupation Zone.

In 1956 Bavaria sold at least 2013 of their U.S. M1 carbines to the Austrian Gendarmerie. The Austrian Gendarmerie bought them to add to the 8000 they had received as part of what Austria received from the Americans, at the end of the occupation of Austria in 1955. The reason the Austria Gendarmerie wanted the additional carbines was events in Hungary involving the Russians and communists, better known as the Hungarian Uprising.

Hang tag: Gendarmerieposten, 2243 Matzen, Bezirk Gänserdorf, Nied. Österr., Revlnsp Weiss
   The carbine was last assigned to Senior Inspector Weiss at the Gendarmerie post in the village of Matzen-Raggendorf, Gänserdorf District, Lower Austria. The Austrian Gendarmerie used the U.S. M1 carbines until 1992. You can assume Herr Weiss was the last person it was assigned too.

Bavaria Rural Police
   The Bavaria Rural Police were known to the Germans as the Landpolizei. Today, they are the Landespolizei. Between Feb 1946 and Jul 1947 the U.S. Army military government in Bavaria (OMG Bav) issued 14,647 U.S. M1 carbines to Bavaria, for use by their various police agencies. The Bavaria Rural Police marking you see on your rifle, was on the orders of OMG Bavaria. You can read more about this, and the rural police, here: http://www.bavarianm1carbines.com/bavaria.html

WWII
   Given the manufacture date of your carbine's receiver, it was used in the European Theater of WWII, after which it was turned over to the U.S. Army Ordnance personnel as the GI's departed Europe. Ordnance placed them in supply depots in Europe, pending a decision on disposition. Those carbines given to Bavaria, were removed from these storage depots, where they had been since the U.S. soldier that carried it, turned it in. There is no way to determine which American it was issued too, or their unit. During a time of war these records were not required to be maintained.

Your Carbine's Parts (the one's I can make out the markings)

Barrel
   IBM Corp. 9-43 with U.S. Ordnance bomb inspection proof

Barrel Band
   type I
Barrel Band Swivel
   type IA, marked KV-B, band and swivel manufactured by Knapp & Vogt. Mfg. Co. for IBM

Slide
   type IV, marked I, manufactured by and for Inland

Rear Sight
   type III adjustable, I.R. Co. 7160060, manufactured by International Register Co., used late production carbines and as a replacement rear sight. The number is the Ordnance part number.

Stock & Handguard
   of German manufacture, the LP in script indicates Landpolizei (Bavaria Rural Police)

Bolt
   flat bolt, need markings for further details

Trigger Housing
   type IV, marked BE-B, manufactured by an unknown subcontractor for IBM

Safety
   type IV rotary, used in late production as a replacement safety

Magazine Catch
   M2, used on M2 carbines, and as a replacement safety on M1 carbines


Comments
   Last 4 digits of serial number (4341) on bolt, slide
   1318 inside stock at barrel band & inside handguard
   2390 inside stock slingwell & inside handguard

Your stock is a very interesting one. The wood in the area of the slide is what is known as a "high wood", covering part of the slide arm. This is the first German stock that I've seen that's a high wood. Normally, the cut is lower, exposing the slide (low wood). The grain of the wood on your stock, is not something the American's used. The LP in script, on the bottom of the hand grip, is normally reserved for non-American manufactured stocks used by te Bavaria Landpolizei.

The 1318 on the inside of the stock at the barrel band and under the handguard, were put there by Bavaria. The stock was on another carbine, before yours. The 2390 inside the slingwell and under the handguard, could have been put there by Bavaria or Austria. It indicates the stock and handguard were on a 2nd carbine, before yours. This isn't unusual.

The 4341 should also appear on the rear of the trigger housing at the top.

Lower Austria commonly switched the safety to a rotary safety, the mag catch to a 30 round mag version, and the rear sight to an adjustable model. Often they upgraded the barrel band to the later model with the bayonet lug, but not always. That barrel band and swivel you have are the early version and highly sought after.

Jim