M1 Carbine blast of gas in face

[nwellons]

A few months ago, my son mentioned getting gas blowback in his face once when shooting my M1 carbine. I fired about 100 rounds of factory type ammo with no problem.

I decided to reload with cast and was working down to a below minimum starting load to see how light a load I could still get the action to cycle.

On my last load of about 15, loads were weak, action cycled reliably but I felt a puff of gas against my forehead twice. When I examined the cases, two had a good bit of black carbon from the mouth to about 1/3 back on the case.

Am I getting too light a load to effect a good seal or does it sound like a headspace problem.

[Ford SD]

Not sure if im qualified to comment on your question
I have done some very light loads in a m14 rifle if that helps

Soot / black and lube covered brass is a sign of too light loads/ or wrong powder

when I had too light loads in the m14 I had falure to pick up another round
and after 10 rounds rifle was as dirty as after 300 or more cast loads that sealed the chamber.

I could be wrong but i would invest a few bucks (and piece of mind) in a new recoil spring

Then retest your loads starting above where you had soot/ black brass

some one with M1 experience will help more than I can

[waksupi]

Yep, put more powder in there. You are underloaded.

[JIMinPHX]

If lite loads give you blow back, also check to see if the chamber is worn out of spec. I've seen that before on an old Mauser. Factory ammo shot reliably, but my first gentle hand load speckled my face pretty good. The throat on that gun was more than .005" over max. Thank god for safety glasses.

[Larry Gibson]

You are very close to a dangerous situation with those loads. What is happening with those light loads is the action is opening slightly befre the bullet clears the barrel. With the short stroke gas piston system of the M1 Carbine the action can open and function as soon as the bullet passes the gas port. If the pressure is too low to keep the bullet moving the bullet will stick in the barrel an the action mat very well function and pick up and chamber another round.

Get the picture what happens next if you pull the trigger on the next round with the previous bullet stuck in the barrel??? Listed "starting loads" in manuals provide enough "umph" to get the bullet out the barrel. Going below those suggested "starting loads" can get you into problems with gas gunds, especially the M1 Carbine.

What load are you using?

Larry Gibson

[nwellons]

Thanks for all the replies, everyone.

I was using 2400 per the recommendation of an experienced reloader who works at a local gun store. The Lyman cast bullet book gave 11.0g to 12.5g compressed for a Lyman 115g bullet. When I checked the Lee manual, the never exceed load (10.3) was just above the starting load (10.2).

With my well-used carbine, I wanted to back down lower and lower and see if it would function. I am using cast boolits that run 102g while the closest boolit in the Lee manual is 112g. The carbine functioned well except for the blowback. I was using loads as low as 9.6g to see how low I could get before it failed to eject (or stuck a boolit.)

As to stuck rounds, I was watching for that problem and testing where I could see each shot impact.

Here are the results:

Using 11.1g - chrono was 1698 Oddly, this run had two blowbacks (gas in face) of 10 shots.
Using 10.2 - chrono was 1565
Using 9.6g - chrono was 1386
No blowbacks with the lighter loads but I just shot 3 of each to get fps.

Any further advice will be welcome. Because of the narrow load range in the Lee book, should I just go to another powder.

I always wear substantial eye protection when shooting.

[Larry Gibson]

Nwellons

Suggest a powder that ignites and burns more efficiently at reduced psi's. Might try Unique or Blue Dot. Keep checking for a stuck bullet, good for you to do that.

Larry Gibson

[MostlyOnThePaper]

I'm not home to double check, but I think the new Lyman cast bullet handbook had some data for a lighter bullet like that, 105gr comes to mind. From what I remember lighter bullets often use more rather than less powder than heavier ones.
Randy

[MostlyOnThePaper]

Oh,
After rereading your last post I see you are referencing the Lyman book, so duh, I guess that isn't where I read it, sorry.

Randy

[JIMinPHX]

Nwellons

Suggest a powder that ignites and burns more efficiently at reduced psi's. Might try Unique or Blue Dot.

It's been my experience that Blue Dot does very spooky things when you use it for reduced loads. I would not recommend going below a published book minimum load with Blue Dot.

[zomby woof]

I have the best results jacket or cast with 296/H110.

[dale2242]

I`m with zomby woof,
H110 was designed for the M1 Carbine.
H110/296 has always worked great with jacketed and cast for me.....dale