Over-pressure? Couldn't extract case, Marlin lever won't lock anymore

Thank you all!

So, update: the gun didn't have any problem, it was just dirty ahah! I cleaned it and now it works perfectly. The extractor works again for some reason... I have no idea why it stopped working at some point. Perhaps it was just with some specific cases...

I shot a few dozens of both manufactured and handloaded cartridges, most worked well: lever locking correctly, not hard to extract...

Only a few manufactured cartridges caused the lever not to lock. I bought the Hornady Cartridge Gauge for .30-30 Win, and it turns out the ones causing the lever not to lock go slightly less deep in the gauge. I also bought the Hornady headspace comparator, and once again, the cartridges causing the lever not to lock have a slightly bigger (+0,020 in) headspace.

Thing is, even if these cartridges are slightly bigger/longer, they are still in the min/max range allowed (https://bobp.cip-bobp.org/uploads/tdcc/tab-ii/tabiical-en-page70.pdf).

Is it a common thing for a brand new rifle to be so picky about the cartridges dimensions?
 
It is not supposed to be like that. The rifle apparently has an undersized chamber. This is especially not so good for lever action, which requires a bit more headspace to work correctly.

If you shoot enough factory ammo, especially for critical tasks such as self defense or hunting, you may want to ask your gunsmith to ream the chamber a little bit larger. But if you most shoot your own handloads, you can just take care it with case sizing.

All is good. Glad it works out for you. Still be cautious with the super light loads. You are basically operating outside the envelope. I wouldn't feel comfortable doing the same myself.

-TL

Sent from my SM-N960U using Tapatalk
 
This is especially not so good for lever action, which requires a bit more headspace to work correctly.
Click to expand...


Where does this come from, exactly? WHY are you saying a lever action requires a bit more headspace? What rifles "require a bit more..."??

I would remind all that the OP's rifle is a Marlin 336 and the cartridge is the .30-30 Winchester.

The .30-30 headspaces on the case rim. Not the shoulder, the rim. The rifle's headspace is where the case rim fits. The fit of the rest of the case in the chamber is NOT headspace, in this case.

With a rimless case the fit of the case body in the chamber is part of the headspace measurement, with a rimmed case, it is not. The same is true with belted magnum cases, which headspace on the belt.

It is entirely possible to have a rimmed round rifle chamber where the shoulder is "too short" or "too long" and still have the rifle check out perfectly for proper headspace.

So, if you are using the term "headspace" to refer to the fit of the case body in the chamber, in this instance, it is technically the wrong term.
 
Is it a common thing for a brand new rifle to be so picky about the cartridges dimensions?
Click to expand...
No. Especially not rimmed cartridges like .30-30, where ammunition companies generally load to minimum dimension (or smaller) and firearm manufacturers generally lean toward maximum dimension chambers.

However, it is common for people to encounter issues with CIP ammo in SAAMI .30-30s.
I've never looked to see if there's a dimensional difference between CIP and SAAMI specs, but that's the first place that I would check if it was an issue.

There are a few cartridge where issues can arise when mixing CIP and SAAMI chambers and ammunition, because CIP or SAAMI rounded off a few decimal places for metric/inch conversions when standardizing their counterpart's cartridge; or there is an error in the conversion. Perhaps I'll take a look later, if I get some time, and see if .30-30 might be one of those victims.


Things like this happen. It was just recently discovered that two of the major chamber reamer suppliers in the US have been using different specs for 8x50mmR Lebel, without realizing it.
One is the Balle N chamber. The other is Balle D ... with an error for one of the body dimensions. (An error by CIP, at that.)
 
I ran through the CIP and SAAMI chamber and ammunition drawings earlier.

Most dimensions are right on, or within reason for unit conversions and wouldn't be problematic.

While some CIP max cartridge dimensions are really close to SAAMI minimum chamber - we're talking ten thousandths - I only found one discrepancy that could potentially be an issue with ammunition that is not CIP maximum and a chamber that is not SAAMI minimum.

CIP dimension P2, body diameter at the junction with the shoulder, is the sticking point (quite literally, probably).
https://bobp.cip-bobp.org/uploads/tdcc/tab-ii/tabiical-en-page70.pdf

The CIP dimension can be as large as 0.4118", down to 0.4059"; while a SAAMI chamber should be 0.4030" to 0.4050".

So, even with minimum dimension CIP ammunition and maximum dimension SAAMI chamber, that is an interference issue.

And, even when taking into account the longer body tolerance for a SAAMI chamber (moving the shoulder forward), there can still be interference. It is still likely to make contact in quite a few ammo/chamber combinations.

Now I know at least one reason why CIP ammo causes problems in some SAAMI chambers.
Hopefully, that's helpful.



*I've had 'sticky extraction' and cases sticking in the chamber with both S&B and PPU .30-30 ammo in SAAMI chambers. And it is a fairly well known issue in H&R, Marlin, Mossberg, and Henry chambers, with some complaints from Winchester owners, as well. ...Just CIP getting a little fast and loose with some dimensions and tolerances.
 
FrankenMauser,

You dropped a zero. 10.19/25.4=0.40118", or 0.4012" with SAAMI rounding (note the SAAMI drawing's 0.4013" maximum is followed by the parenthetical 10.193 millimeters.) All good to go.
 
Damn.
You're right.
I had to double check.
I even checked both calculators that was I using for conversions, to make sure it wasn't caused by something funky, like a floating point error.
And then converted 0.4118" to 10.46 mm, to see if I could have just read the wrong line.

Definitely appears to be human error.

I'm glad someone caught it, even if my face is a bit red.
 
Think sunscreen. ;)

Incidentally, it is so easy for humans to fat-finger a conversion, one of the things I really like about the web is you can search on "mm to inch conversion calculator" or conversion between any other pair of equivalent units and get a dozen specialized calculators to choose from. This one gives you all the forms of expression and has a swap button so you can convert in the other direction.
 
Its possible with low pressure loads to get an incomplete powder burn.

It takes a certain amount of pressure to make a powder light up and burn properly.

As you are improvising your own load,perhaps your load is too low pressure to get a proper burn.

Unburned powder granules in the chamber will dent the brass,and perhaps get cooked firmly to the chamber walls.

You are not using tested data,so,for safety,you are on your own...but parameters that MIGHT make a more complete burn include:

A larger charge of powder

A hotter primer

A roll crimp into a crimp groove in the bullet.

Your seater die is likely to be able to crimp.

I do not have any data to recomend what is safe..

If your bullet has a crimp groove,that would be the first thing I would try.

Beware pursuing subsonic rifle loads without a chronographand with variable and incomplete ignition is a very good way to get a bullet stuck in your rifles barrel.

Thats bad enough. Following it with another round into an obstructed bore can go very badly.

Good luck!

Sorry I've been busy and didn't see this sooner. FrankenMauser is most likely correct. Because this is a very low pressure load, the case mouth is not expanding to seal the chamber completely. This allows pressure to blow some granules of the powder back between the case and the chamber. I've seen the same thing happen with very light target loads in other guns.
Click to expand...

I've seen thi;s.too.Like mega lube dents. One case was a friend who built a 250 Sav Ackley. He started with light,short bullets and a light load.
 
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mehavey said:
You're only talking 12-13,000 psi w/ that (Quick)load.
As 44-AMP & Frankrnmauser observe, your chamber is a gravel pit.
Scrub/polish/Flitz the bejeezus out of it and get those chamber walls looking like mirrors.
Click to expand...
Glad to hear that you got things working by cleaning the chamber... It was mentioned earlier to polish the chamber to a mirror finish, but I wouldn't recommend going that far. While a very mild polish may slick things up some, the walls of the chamber should still be able to hold on to the cartridge as it expands through the pressure cycle.
If it works properly with just a cleaning, I would leave it there.
 
Chamber walls should as polished as reasonably possible.

The old bugaboo of "negative effects of increased bolt thrust" has been disproven
time, and time again. (In fact the ability of the case to move freely back against
the bolt minimizes case stretch, ...which is actually to your benefit)
 
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