Erma E M1 Carbine front sight

[Patrick Chadwick]

"I still need to work on cycling issues."

Me too. I have a beautiful 67er. But there is one major weak point in the design: no continuous ramp into the chamber. So any slight misalignment of the bullet as it enters the chamber causes the bullet to snag on the chamber edge. Try hand-cycling a few rounds and look at the bullet noses. Odds are there is a bit of scraping. Not only is this ballistically a bad thing, but the scrapings cause other problems, which are addressed below.

There are 5 things you could check/try:
1) Both the recess in the bolt head for the cartridge base and the slot for the extractor can become crudded up with a mixture of grease and lead scrapings. As a result, the cartridge base does not sit down squarely in the recess and the extractor may fail to latch properly. Cartridge guiding is impaired, and if the build-up is large enough, then ignition may be impaired as well. CLEAN the bolt head area as well as you can. As for the extractor slot: see 3).

2) The front "wings" on the magazine lips are often slightly bent. They need to be VERY carefully tweaked so that the bullet has the smallest possible clearance between the lips, without it being a rubbing fit. This improves cartridge guidance.

3) If you are now feeling a bit more confident, then clean out the extractor slot in the barrel. It is necessary to partially dismantle the rifle to do this properly. Be warned: do NOT just start taking it to bits. Things will fall off and disappear, and it could really spoil your day! There is good pictorial information on the internet for doing it correctly:
http://www.m1carbinesinc.com/carbine_em1.html
will help you a lot.

4) If you have got this far, then slide out the striker from the bolt and clean both it and the hole through which the striker passes. Crud in this hole + old grease or oil has a hydraulic braking effect on the striker, thus impairing ignition.

5) Having attended to points 1) to 4), try out as many different types of .22 ammo as you can get. Tip: forget the specialist 50meter target ammo. This is lightly loaded to provide maximum accuracy at 50 meters/yards, but can be too weak to cycle the action. Stick to standard ammo with standard loading.

[ltc]

Patrick, Thanks for your insight on my cycling issues. I think a good cleaning is called for. Have you ever seen anyone "break" the lower edge of the chamber mouth? The mouth is a perfectly square, sharp edge. I am continuing to proceed slowly so as not to do irreversible harm.

LTC

[CINDERS]

I liked mine allot and had lotsa fun with it sadly due to draconian and unconstitutional rambling laws were are now forbidden to as a hunter or average firearms owner to have Semi Autos of any type.......

[Patrick Chadwick]

...Have you ever seen anyone "break" the lower edge of the chamber mouth? The mouth is a perfectly square, sharp edge...
LTC

Indeed I am seriously considering doing that myself. In principle, all you would need would be a rat-tail Swiss or diamond file, and very, very carefully form a lead-in at the bottom of the chamber mouth. If you look at this area with the aid of an eyeglass, you will see that the edge is** chamfered, but only by a few tenths of a mm - just enough to accommodate the rounding between the rim and body of a .22 case, but quite inadequate for a bullet feed ramp.

Now on a center-fire rifle one would say that to open out this area could be extremely hazardous, leading to case-head blow-outs, or at least serious distortion. But since .22 cases are not reloadable, who cares about distortion as long as the case integrity is not compromised? The rim region of the case is anyway seriously distorted by the striker - that's how rimfire cases work! So I reckon that the chamber edge could be enlarged a few more tenths of a mm. To avoid the lead-shaving effect, the edge profile should not look like this

XXXXXX
XXXXXX
XXXXXX
XXXXXX

which, fortunately, it is not quite...
... or even this

XXXXX
XXXXXXX
XXXXXXXXX
XXXXXXXXX
XXXXXXXXX

but rather this

XXXXXXX
XXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX

In other words, a chamfer will still cause some shaving if it has a sharp edge. The edge must be rounded.

The real problem is: How can one achieve this without FUBARing the rifle????

On that, more later...

...I am continuing to proceed slowly so as not to do irreversible harm... LTC

And so am I !


** make that "should be" chamfered. Maybe your Erma is slightly different.

[Sentryduty]

In other words, a chamfer will still cause some shaving if it has a sharp edge. The edge must be rounded.

The real problem is: How can one achieve this without FUBARing the rifle????

Would it be possible to get a dremel rotary tool with a 90 degree attachment into the chamber? If so, I would start with a conical felt polishing bob and a compound, finishing with a polish, it should round the chamber lip very slowly without resorting to possibly ruinous bit based grinding.

I had a Norinco Type-97 NSR that needed the feed ramp reprofiled to run with non-Norinco magazines and undertook a similar smoothing process. The Norinco magazine fit tightly in the magazine housing and the rounds made a smooth jump to the chamber. Non-Norinco magazines would rock fore and aft which changed the presentation of the next round, often tipping into the feed ramp and ramming the projectile well into the case with extreme force. In my case I started with jeweler hand files and finished with Dremel felt polishing.

[Patrick Chadwick]

Would it be possible to get a dremel rotary tool with a 90 degree attachment into the chamber? If so, I would start with a conical felt polishing bob and a compound, finishing with a polish, it should round the chamber lip very slowly without resorting to possibly ruinous bit based grinding.

That's just what I was thinking of doing, but haven't yet summoned up the courage. Your success with the Norinco is encouraging.