John Masen M1 Carbine 5 round blocked Magazines, from Midway
I've been shooting the M1 carbine for a couple of years at 200 yards, perhaps 6 times a year.
Failure to feed is the problem which I currently attribute to 10 round mags. From Midway, I bought some 15 round magazines blocked to only hold 5 rounds.
Anyone try these?
This is a Fulton rebuild from a CMP S'G' barreled receiver returned from El Salvador or so as I understood. Nice rifle...often get ribbed trying to shoot at 200yds, but I figure if the Marines could land at Iwo with these, they might just be adequate. One fellow called out behind me, whether I had asked my daughter if I could shoot her gun and promised he would applaud if I got an 'x'. He was applauding within three rounds.
This time I discovered the trigger group pin had fallen out during reassembly, easy diagnosing on that issue; the last three rounds would refuse to chamber...
When you say "trigger group pin" are you refering to the pin that actually holds the trigger housing assembly to the receiver? This pin is located directly under the receiver's barrel hole. Assuming that you have the most recent pin, that pin should NEVER fall out as it is held in place by the stock. Perhaps you have a wrong pin in there. A hammer pin will fit in there, but is is a sloppy loose fit.
As far as the failure to feed issues goes, there could be several things causing that problem. I'll just mention a couple for now:
1. Try a USGI 15 rd. magazine with feed lips that are in perfect condition.
2. Use USGI 110 gr. Ball ammo.
3. Make sure the weapon has been properly cleaned and lubed, including the chamber.
4. Make sure that the gas piston is free and that the gas piston nut is tight and lightly staked in place.
5. Be sure that the op rod spring is in excellent shape, no kinks, rust, etc. and measures 11" or a tad more in length.
This should cover the vast majority of failure to feed problems.
Thanks for taking the time to reply!
I do understand the four details of which you mention and have tried to comply with all of them, except that I wondered about the opinion of some to John Masen's 15 rnd magazines, sold by Midway, which are blocked to hold only 5 rounds.
The correct pin term is 'Trigger housing retaining pin' as per the NRA magazine's recent two page blow up of M1 Carbine...and is the pin holding the trigger group to the receiver.
It must have fallen out during reassembly/cleaning. (who needs all those extra parts...)
The failure to feed takes a lot of fun out of shooting for a score. I'll persevere until I can make this a reliable gun. It was very nicely built up by Fulton from just a bare receiver so all parts are new and blued.
Getting it to Run Properly
Did the carbine ever function perfectly after you first got it back from Fulton? I was an Air Force armorer in the 1960's and a serious carbine collector/shooter for almost 50 years. I got a DCM carbine before I went into the AF in '65. Based upon my experience with them, I feel that there can not be much wrong with yours and you'll have it functioning properly soon. About how many rounds have you fired with it? Sometimes they just need to be "broken in" after a refinishing job (but that's usually park, not bluing).
I just thought of another thing or 2. Be sure that the barrel and receiver are in perfect alignment. There are almost always "witness marks" on the front bottom of the receiver and in the bottom of the barrel. When the barrel is screwed in properly, there 2 little lines will line up perfectly. If they are out of alignment, this could cause the op rod to drag some. Also check the bolt's right hand lug for and burrs, etc. Same for the "hump" in the op rod where the bolt lug rides in. Is the receiver's "feed ramp" nice and smooth? Extractor area clean? Extractor lip not broken? There should be a little "spring action" to the extractor too. Check the gas cylinder for a tiny crack too.
When it fails to feed, is the bolt riding on top of a cartridge that is properly seated in the magazine and then the bolt closes fully? Or does the action have a fired case or an unfired round stuck in front of the bolt somehow?
Check the magazine retaining lugs to be sure they are not damaged. Same for the magazine catch itself. It should hold the magazine in nice and tight to the top of the magazine well.
I loved troubleshooting the guns & working on small arms (especially with an unlimited supply of parts at my disposal!) as much as the bosses would let me. Many times though, they'd have me working on our squadron's aircraft guns or weapon release systems. Our F100C fighter/bombers carried 4 M39 20mm cannons and our F100F (2 seat jets) and only 2 guns, the space being needed for the rear ejection seat. I do miss those days!
Let me know how you make out with this carbine Sully. My gut feeling is that it's magazine or ammo related but I certainly could be wrong.
All the best,
PS: Can you remove the "block" from a couple of those magazines and them try them?
Thanks for the Thoughts!
The rifle has perhaps 1,000 rounds through it. I know I used the steel wolf ammo at first, but the extractor crapped out as the Russian lacquer caused the ammo to stick. I will replace the extractor just to test this part. May be worse than it looks. Use American Eagle Ammo now.
My current focus are on magazines. All are now numbered and have tried 'adjusting' some of the Fulton ones by opening the magazine lips a bit.
I believe the round that fails to feed is stuck between the front of the bolt and the nose of the round is not quite inserted into chamber. Without the trigger housing retaining pin the bolt rides above the cartridge, no surprise.
I am usually shooting XTC with other high power shooters, so can't easily do my thing to adjust. Will take M1 to local indoor range to try out the new mags.
Will print out your suggestions and examine the areas you mention.
Incidentally, my Dad's favorite plane he worked on was the F-100 sabre jet. I think he worked on the forward fuselage design, but I was just born at that time so just recall bits that I heard.
Dad worked on 'Speed Brakes", but I'm not sure those were for the Super Sabre.
Perhaps you'll enjoy this:
"Push Starting a fighter"
F-100 Super Sabre (The Hun) had a large chamber that accepted a large gas generating cartridge.
When ignited by electrical current, the expanding gas from the black powder-like pyrotechnic
cartridge drove a starter turbine that brought the engine up to a
self-sustaining RPM. This device eliminated an absolute need for using slower, bulky ground starting units.
On the other hand, the cartridge spewed out a characteristic dense cloud of choking black smoke,
often mistaken by inexperienced ground crews as a true fire emergency.
The powder charge for the ground start came in a big sealed can, and on opening and extracting the
cartridge, you'd find two small metal tabs on the bottom of the cartridge.
These tabs were the electrical contact that fired the cartridge when the pilot moved the throttle outboard to start.
As soon as a tiny RPM registered on the Tach, you brought the throttle around the horn to feed
fuel and ignition to the rapidly-building engine speed.
Sometimes, the big metal receptacle holding the cartridge would get so dirty from repeated use that the metal
tabs wouldn't make contact. Then the cartridge would deny firing, so the crew chief would smack
the starter receptacle with a wooden wheel chock, usually curing the device of any reluctance to detonate.
We'd often take a starter cartridge can along with us as an alternative starting method.
The story is told, of USAF Captain John Green who had stopped in at Memphis MCAS, in an F-100 way back in the early '70s.
(MCAS = Marine Corp Air Station). He was approached by Marine crewmen, who then asked what kind of plane
he was flying. Green's slightly lofty response called it a ' S-U-P-E-R S-A-B-R-E’.
The tenor of his reply merely generated increasingly puzzled stares from the inexperienced ground crewmen.
One of the ground crew said, ' Sir, I don't think we have tech data on this bird.
What will you need for start . . a 'Huffer*' . . or just an electrical jolt from our APU*?'
(* Huffer is a pneumatic air supply and APU is Auxiliary Power Unit)
The pilot's eyes glistened considering a practical jokers dream . .
but poker-faced and without pause . .
he turned to the young Marine crewmen and told them : "NEITHER ONE . . GUYS!
You've got me fueled up, so just pull all the pins and hand them up to me.
Then, get at least six buddies from the other crews to give me a brief shove toward the active runway.
After you get me rolling at a fast walk . . everyone just stand away from the tail pipe when I ' POP
' this SUPER Sabre's . . CLUTCH ! Then stand back and watch this 'thing ' start . . just by using the muscle energy you've
More and more puzzled glances from the ' greenie ' Marines . . all of their mouths opened a bit in wonder as they thought of something to
say. What else would a young Marine say ?
And " YESSIR ! Let's do it . . became their ringing response."
The Hun was pretty finely balanced on the two main gear struts.
When you tapped its brakes, the nose strut compressed so much that the F-100's nose took a dip,
just like our cars' hoods dipped when we occasionally ' clutch started ' following a dead battery push from our
buddies while ' drag racing ' our hot rods.
So now . . still doubtful . . six Marines are standing at the ready. .
but they're not about to confront an Officer to challenge him on his engine start procedures.
John further instructed them : " Just get me going at about a fast walk.
When we're going fast enough, I'll wave you all clear. And when you're clear of the aircraft, I'll just pop the clutch and be on my way.
And thanks for the fast turn-around ! "
Six husky Marines quickly shoved the Super Sabre to a brisk-stepping speed.
Green gives them an exaggerated arm wave-off.
The Marines let the bird go, then warily stood clear before the pilot made the ' clutch move' he'd warned them about.
He didn't disappoint them. John momentarily jumped on both brakes . .
dipping the nose to approximate ' popping the clutch.'
Simultaneously, he secretly pushed start button . . that generates a BOOM along with a HUGE CLOUD of BLACK SMOKE as the
F-100's engine whined to life.
A chuckling Captain Green headed out to the runway's takeoff end, while six puzzled Marines with their mouths slack in amazement,
appeared 'pinned' in the smoky wake.
You asked whether the blocks could be removed from the Midway Mags? Perhaps they could be, but that would make them illegal to use in CA.
I am just hoping for well operating mags that help me shoot XTC and don't bolox up...
Two mags of 5 rounds each make for a 10 round rapid string.
The little short 5 round mags from USA work in my two beat-up Inlands...I just tried one in my 'newest' old beat-up gun..worked fine.
Is your carbine 'bone dry'?....I've had feed issues/fail to return to battery issues with M1 carbines if they were dry.
I put a new GI recoil spring in my latest carbine because the spring felt weak...this before I ever fired it. Weak springs and dry gun seem to be the only things that cause me feed issues. I would presume Fulton installs a new spring on a rebuild huh?
I've got all sorts of 15 and 30 shot mags..some of the 15 rounders are pretty rough looking..and they generaly feed fine.
Here are things I have learned after working on the Carbine for maybe 30 years.
The first thing is the piston nut HAS TO BE one of the later WWII ones (or post war) that has more of a chamfer in it. That gave just a little more room for gas volume that is really required for reliable function. I ran into one Carbine that did not function reliably no matter what I did years ago. I talked to some older Armorers and they didn't know what was causing it. I pulled out my copy of TM 9-1276, The Cal. .30 Carbines M1, M1A1, M2, and M3 Rifles and that's where I learned of the different piston nuts. OK, the one in the Carbine that would not function was an early piston nut, so I got a later one and MUCH to my surprise, the Carbine went from not working hardly at all to working marvelously.
The second thing you must know is the piston nut HAS TO BE TIGHT. If it is loose, you will lose gas pressure too easily and the carbine won't function sporadically or hardly at all. Korean War Armorers have remarked they were ALWAYS retightening piston nuts on Carbines and that is probably on the Full Auto ones, especially. To KEEP the nut tight, YOU HAVE TO STAKE the piston nut in two places. If you get inside enough Carbines, you will notice some serious stakes that were put there by the Rebuild Arsenals. With those stakes, the piston nut almost never came loose. One thing I always check during inspections of Carbines is I use a Carbine Gas Piston Nut wrench to ENSURE the nut is tight and if not, I tighten it AND always STAKE the barrel so it aligns with two of the crenallations in the piston nut and that keeps the nut from loosening.
The third thing is REPLACE the recoil spring. On MOST Carbines I inspect, the recoil spring has been worn down too short. Just replacing that spring ensures many Carbines that don't function quite right will work fine later on. The NOS G.I. springs I run across are a little over 11 inches to a little over 11 3/8" and they always work. So if your spring is under 10 inches, you DEFINITELY need to replace it and usually if it is under 10 1/2" - then I replace it. Of course no matter what the length is of a used spring, it still may have lost enough tension that it needs to be replaced. If I notice the spring has been stretched or is worn on the wire or kinked, I also replace it no matter how long it is.
Gus and all,
I don't mean to hijack the thread, but about your advise to stake the gas piston nut.........I've read that a couple times now. It makes sense for an M2 that gets battered with the higher rate of fire. But I really haven't had trouble with mine getting loose, and I have a nut wrench and take it off pretty often to clean out the recess, and the wrench makes it easy to get it good and tight. It seems that if it were staked, it wouldn't get cleaned as often, and would start sticking before long. So if it's opened and cleaned regularly, wouldn't the staking over and over cause the metal to get weak? And am I cleaning the valve recess too much? It seems to start getting a visible build-up of carbon after only a couple hundred rounds.
thanks much, lee
Here we go again. Gas pistons almost never need to be removed and cleaned. As far as getting stuck, there is 30 or thousand pounds of hot gas pressure pushing in it every time the carbine fires. The piston DOES need to be staked on all carbines. If it loosens, well have you ever seen a barrel with a blown our gas piston nut? I wish we could put this issue to bed for good.