light primer striking problem

[browningautorifle]

The carbine will very likely stop firing before a case would be exposed enough to cause a rupture due to long head space.

Probably won't go into battery so the bolt won't turn enough to fire. Unless it's very worn...

[donki1967]

Considering my reloaded ammo seems to work well in my carbine yet, and that I am in the safe dimensions of the cartridge, I will continue to do so.
Thank you to all.
Regards

[Bruce McAskill]

The case length is so very important in the .30 carbine. The length of 1.280 has been around for a long time and in reality its too short. New factory ammo is set to the 1.285 length for proper head spacing of the cartridge. Trim to length is set about the same at 1.285. Trimming is mandatory with the carbine case and should never be longer then 1.290. If longer then a possible out off battery discharge can happen. The result is a destroyed bolt. The left side lug recess must be checked for damage too as a new bolt could be damaged by damage to the recess. But disregard the 1.280 case length.

[painter777]

1.280 is the minimum case length. This by default increases head space. I would find some ammo with case lengths closer to 1.287 or so, which is what most commercial ammo measures. In other words….longer cases move the primer closer to the firing pin. If the action is a little lose, short brass aggravates the problem. Minimum trim length is 1.280, but that assumes the action meets head space specs.

Page 1, Post #2, The 1st reply which was by Floyd had answered the issue. Followed/Backed by BAR.
Last 2 evenings, I measured the brass on 2 new boxes of S&B, Most every case measured 1.287". Longest were 3 that measured 1.288". Shortest were about 9 between 1.285" and 1.286".

Hats off to the members here. It's good to see so many chipped in and kept following to get the OP donki1967 up and running. It says a lot about the group here

To donki,
Do you remember back in July of 2014 when you were asking about the Rebuilt IBM in the NPM Hi-Wood stock with beautiful tiger stripe that a shop had for sale for $930.00.
To quote you: "The gunsmith is selling it for 930 $, prices are high in France"
That was 7 years ago now. Looking back, I bet you wish you'd of bought it considering what they bring today.
A link to refresh your memory or to give you that punched in the gut feeling:

https://www.milsurps.com/showthread....151#post303151

Safe Weekend All,

[donki1967]

Good morning,
Indeed I had the solution to my problem under my nose from the start and I made a mistake by not taking this info into account.
Nevertheless, these 54 contributions brought me a lot of knowledge about this rifle.
Best regards from France.

[floydthecat]

Just simple math. SAAMI specs. Allow 1.300 from the bolt-face to the cartridge base. That math’s out to 20 thousandths using the shortest spec. case of 1.280. Nothing other than that can be assured by design. If head space exceeds 1.300 and a cartridge of 1.280 in case length is loaded….no guarantee it’s going to fire by design. Sometimes it might depending on firing pin protrusion, but not designed to.

As long as one can keep the space below 20 thousandths, it’s suppose to fire and if the head space does not exceed 1.300 on any particular case length it should fire. Lengthening a case by .005 tightens head space by .005. If the action spaces at 1.302 on a case of 1.280 in length, you just reduced head space to 1.297 simply by lengthening the case.

I feel like many carbines are condemned for no reason at all and the fix is simply watch your brass and trim longer. Bruce is completely right…..stay away from 1.280 brass even if it is the spec. minimum.

[DaveHH]

A lot of carbine ammunition is actually too short to seat in the chamber as designed: chamber seats on the case rim at the front. So the cartridge is held by the extractor and fires that way. I ordered a quantity of Remington brass years ago. The case lengths were all over the place but none were too long (The dangerous exception). It all fired just fine as is. Which puts the lie to a lot of headspace enthusiasts.

[floydthecat]

I will purchase a carbine all day long that head spaces in excess of a field gauge, but I do have a limit. Some consider 1.301 and greater as junk…..those are the ones I will consider at a discount price (of course) after they have considered it defective. There is way too much forehead sweating, hand-wringing and barrel replacing over a action that might only exceed 1.300 by a couple thousandths.

Soldiers took this gun into battle and the powers-that-be wanted to make sure it worked on that short brass that could get out there, so they decided to condemn it on the safe side. It will shoot and be completely safe well past 1.300.