5.7 MMJ Carbine PMC

Just to be sure, is the receiver ring correctly marked as 5.7? 

You might have just identified a new highest serial number? 

I will post pictures tomorrow. PMC is stamped behind the rear sight on the receiver but there is no caliber marking on the front receiver ring..

I believe that some PMC carbines never were rolled on the receiver ring. Jim will be able to expand on this. 

Wow, such history is amazing. I haven't broken the rifle down yet, but I will and take photos to show you what the receiver looks like.

I think your receiver may be one of the receivers left over when MOCO went out of business. Then later used by Plainfield Machine.

Regarding yours having s/n A844...

MOCO s/n's I have info on are A107 - A361. H&S s/n's I have info on are A423 - A615. I suspect Plainfield continued this sequence when they started using the Plainfield Machine name.

Plainfield s/n A129 and A164 are M2 .30 cal. carbines with the Plainfield Machine marking on the receiver ring along with the Cal. .30 M2 model number. Plainfield's first M2's used the A as a suffix (164A, 208A, etc), not as a prefix. Both of these M2's are consistent with all other M2's having the A as a suffix. During a time when Plainfield switched from the Z series to the numbers only and hadn't become consistent with their markings.

Plainfield s/n A711 is a .30 cal. carbine with the PMC markings like yours. Plainfield Machine Cal. .30 M1 was hand stamped a letter at a time on the receiver ring. I suspect this was one of the first Plainfield carbines. But one alone isn't enough to call it as the earliest Plainfield s/n versus a 5.7mm s/n used on a .30 cal. carbine..

I suspect yours may have been s/n'd as a .30 cal. carbine then later assembled as a 5.7mm. This would explain why it's a higher s/n than all the other 5.7mm carbines (X A002 - A356). It also fits the PMC markings and the machining of the receiver that is like the first hundred or so Plainfield carbines and unlike any of the other 5.7mm receivers.

Keep in mind yours is consistent with a leftover MOCO receiver during a time when Haas and Storck were just getting started as Plainfield Machine.

Take a look at the sides of your barrel in the area of the gas piston housing. The MOCO carbines had their initials there.





The initials were present or sometimes removed on some of the barrels used with the H&S carbines.





MOCO carbine barrels had 4 lands and grooves. Some of the H&S barrels were also 4 lands and grooves. Some H&S barrels were two lands and grooves (cut down 1903A3 barrels). This continued with the early Plainfield barrels then switched to 12 lands and grooves before they finally settled on 6 lands and grooves.

Hope this makes sense. I'm not ready to call yours a new high s/n for the 5.7mm carbines as I think it very likely it was initially numbered as a .30 cal. carbine.

Jim

Jim

Jim, Thank you for the information. I did have a local gunsmith inspect the receiver and barrel and he gives it a thumbs up. Exciting to have such a piece of history and I'll just leave it in the safe and shoot the tribute rifle I have. Not sure what type of value it holds other than being an interesting part of history and the Plainfield Machine Company. I will check the initials location and post a reply.

For the majority of people the commercial carbines haven't had the collectable values like the GI carbines have had. Their value has been as affordable shooters.

While history adds interest I don't foresee the history of the commercial manufacturers upping the value of their carbines, making them collectable, or worth preserving.

I think their real value has been and will be as providing people with affordable shooters and helping to fuel and sustain the interest in the .30 cal carbines. While at the same time they can be great for self defense and beginners.

If you're interested, here are some examples of the lands and grooves found on carbine barrels.

Two Lands & Grooves

These were surplus GI 1903A3 barrels made by Remington cut down to carbine dimensions. They were inserted into the rear half of a demilled GI carbine barrel or a replicated replacement. Gas piston housings were integral if a demilled GI barrel was used. If a replica of the rear half of the GI barrel was used, each of the commercial manufacturers had their own gas piston housing design and means of attaching it. These were very common with the early commercial manufacturers in the 60's. Erma's Mfg used them with all their carbines.

Four Lands & Grooves

Four lands & grooves were the standard for GI barrels and for most commercial manufacturers.

Six Lands & Grooves

Plainfield Machine made these their standard in the mid 1960's thru end of production. Continued by Iver Johnson after they bought Plainfield and operated out of the NJ location. Used by Iver Johnson in AR thru 1985. IJ switched to 4 lands and grooves in 1986.

Twelve Lands & Grooves

These were made for a couple years in the mid 1960's by Small Arms Manufacturing Co. in Bridgeville, PA. They didn't add the gas piston housing. Each commercial carbine manufacturer had their own design and means of attaching it. 12 groove barrels were used early by Plainfield, Universal, National Ordnance, and Alpine.

Jim

Yup, 6 lands & grooves. Maybe someone more familiar than I am with the 5.7mm cartridge can comment on the number of lands & grooves recommended for it.

Jim