Short chamber advantages?

[DLCrocket]

So I have a Savage 12FV in .243 AI barrel by E.R. Shaw. After several firings on my brass, I couldn't close the bolt on several of them. Using a Redding full length die with 40° shoulder, it had no effect on the brass shoulder. Had a machinist take 0.010" off the die face and still no shoulder bump. Called Redding and they said I must have a shorter version of chamber. Is there any advantage to having a short vs longer chamber?

 

[Rat Rifle]

How was the Head Space set ?

 

[L.Sherm]

How was the Head Space set ?

Thats were I would look first

 

[DLCrocket]

How was the Head Space set ?

Good question. It was done quite a few years ago by a friend. All I know is he had go no-go gauges.

 

[Rat Rifle]

Good question. It was done quite a few years ago by a friend. All I know is he had go no-go gauges.

That’s the first indication of the problem.

 

[DLCrocket]

That’s the first indication of

That’s the first indication of the problem.

Thanks. The barrel is scheduled to be rechambered so perhaps this gunsmith will set headspace correctly.

 

[swd]

I’ve seen sizing dies need as much as .027” off the bottom to have any shoulder bump. Could be short headspace or a long die. Checking headspace is the first step.

 

[DLCrocket]

I’ve seen sizing dies need as much as .027” off the bottom to have any shoulder bump. Could be short headspace or a long die. Checking headspace is the first step.

Thanks swd.

 

[linebaugh]

I am puzzled by the long and short version to start with. Second this is still not making sense in my head. Chambered fine with new brass for X amount of firings and then got hard? Wondering how it chambered at all if it's the "short" version.

I dare you to ask for prints of the short version and the long version.

Anyway. Are you sure it's a shoulder issue and not a clicker issue on the base?

 

[doctorh]

If you have a 45 acp sizing die,run a piece of brass 243 ai thru it.it will resize base to very close to original brass.if this doesn't work ,it's some other part of fire case causing your problem.If this doesn't help,give me a call.2764941063 Doc Whitley.

 

[DLCrocket]

I am puzzled by the long and short version to start with. Second this is still not making sense in my head. Chambered fine with new brass for X amount of firings and then got hard? Wondering how it chambered at all if it's the "short" version.

I dare you to ask for prints of the short version and the long version.

Anyway. Are you sure it's a shoulder issue and not a clicker issue on the base?

I guess I'm assuming that after several firings and only neck sizing that a few cases grew to where the shoulder needed to be bumped back. As far as the long and short chambers, the Redding guy is the first I've heard that not all 243 AI chambers are not the same.

 

[ebb]

"Perhaps this gunsmith will set the headspace correctly?" WOW

 

[JSH]

Others will disagree I am sure. When you get off the beaten path or even semi wildcat, I set my headspace to what my dies tell me too.

 

[gunsandgunsmithing]

Maybe the next smith will be of help and I strongly suggest fl sizing after every firing. You only need to bump them a couple of thou.
Anymore, "bolt won't close" has a broad definition to different people. It used to mean it wouldn't close with normal cycling of the bolt...something obvious. Nowadays, if some people feel the slightest resistance, that may be their definition of the bolt not closing. It has become more subjective than ever before. Internet is great for creating something to argue about when it should be simple and clear.

Not sure about the op in this case but unfortunately, a better mental image of the issue might be of help...or not. Hard to believe it went several firings and the problem just appeared though. Maybe I'm misinterpreting something too.

 

[DLCrocket]

I am puzzled by the long and short version to start with. Second this is still not making sense in my head. Chambered fine with new brass for X amount of firings and then got hard? Wondering how it chambered at all if it's the "short" version.

I dare you to ask for prints of the short version and the long version.

Anyway. Are you sure it's a shoulder issue and not a clicker issue on the base?

I'm not sure what you mean by clicker issue.

 

[Rat Rifle]

I'm not sure what you mean by clicker issue.

When the bolt handle is at the top of the ejection cycle, there is a definite “click”. Caused by the brass swelling bigger than the chamber.

But, with Savages, because of the design of the Primary Extraction, they tend to “ciick” anyway.

Might not be something You need to be concerned with right now.

 

[tmwinds]

When was the last time you measured and trimmed your brass?

 

[FeMan]

.......... Is there any advantage to having a short vs longer chamber?

I can only think of potential negative consequences in a short chamber of not being able to sufficiently bump shoulders. I cant think of any positives.

I can see how this can happen and have experienced it myself. When sized brass is fired, it expands against the chamber and rebounds slightly as the pressure bleads off. When it is sized, it is compressed in the die and then rebounds (expands) slightly as it is removed from the die. On each successive cycle of firing and sizing, the rebound amount decreases as the brass work hardens. After three or four firings, the shoulders reach somewhat of a steady state condition. With no die adjustments, the shoulders will tend to drift froward on each of the first few firings and tend to settle in.

One thing I might suggest if you cant screw the sizing die any deeper is to look at case lubrication. Cases with too little lube on them absorb a lot of the strain from the press in sidewall friction between the case and die. if you have poor lube or too little of it, the friction can eat up a lot of the compressive force and result in shoulders being pushed back less. An illustration is the highly polished and nitrided sizing dies. They reduce the friction and the variance created by the lube and give much more repeatable sizing results in my experience. .

 

[DLCrocket]

When was the last time you measured and trimmed your brass?

Never had a problem with case length. After four or five firings and neck sizing they run 2.035 to 2.038.

 

[DLCrocket]

I can only think of potential negative consequences in a short chamber of not being able to sufficiently bump shoulders. I cant think of any positives.

I can see how this can happen and have experienced it myself. When sized brass is fired, it expands against the chamber and rebounds slightly as the pressure bleads off. When it is sized, it is compressed in the die and then rebounds (expands) slightly as it is removed from the die. On each successive cycle of firing and sizing, the rebound amount decreases as the brass work hardens. After three or four firings, the shoulders reach somewhat of a steady state condition. With no die adjustments, the shoulders will tend to drift froward on each of the first few firings and tend to settle in.

One thing I might suggest if you cant screw the sizing die any deeper is to look at case lubrication. Cases with too little lube on them absorb a lot of the strain from the press in sidewall friction between the case and die. if you have poor lube or too little of it, the friction can eat up a lot of the compressive force and result in shoulders being pushed back less. An illustration is the highly polished and nitrided sizing dies. They reduce the friction and the variance created by the lube and give much more repeatable sizing results in my experience. .

Thanks FeMan.