Thread: What in the world?

Greetings Moa Hunter and Dicko,
Yes Moa Hunter the plunger will hold the cartridge forward in the chamber on rifles with ejector plungers. However primers back out on my low pressure loads in my scoped .303. This rifle does not have a plunger ejector so the case being forced forward in the chamber is independent of ejector type. Yes Dicko the belt would hold the case to the rear of the chamber if the belt and chamber recess tolerances were tight. Unfortunately they are not held to tight tolerances, especially on cases that have a substantial shoulder. In practice the belt does not help. If the case is sized just enough to chamber another problem can develop. Minimal sizing can leave an unsized portion of the case body just in front of the belt with hot loads and some makes of cases especially with cases fired in another chamber. Even with the die hard down on the shell holder this may not be resized which can lead to hard chambering. Some of the die manufacturers offer a special die just to remove this bulge. A friend with a .308 Norma Mag used a .300 Win Mag die with the case sitting on top of the shell holder to remove the bulge. Unfortunately the belt on bottle neck cases can cause more problems than it solves.
Regards Grandpamac.

Originally Posted by grandpamac

If the case is sized just enough to chamber another problem can develop. Minimal sizing can leave an unsized portion of the case body just in front of the belt with hot loads and some makes of cases especially with cases fired in another chamber. Even with the die hard down on the shell holder this may not be resized which can lead to hard chambering. Some of the die manufacturers offer a special die just to remove this bulge.

Grandpamac,

I mostly set my FLS dies up so that a resized case created a very slight pressure on the bolt when it is closed. The idea being it reduces stretch and increases case life. I have never had a case stick in a chamber and i tend to load fairly warm. My experience would be that if your FLS die is set to bump the shoulder back your taking care of the bulge above the base.

When i have repurposed fired brass from military rifles / chambers in my .223, i may screw / work the FLS die further down in the press (bit by bit), until i get case to chamber and be able to just feel a little pressure on the bolt at close. The big O frame press will be camming over at this setup.

I have had cases come apart at the web twice and in both cases it was due to excessive resizing and repeated firings. Modern bolt rifles have way more extraction power than need to pull a stick case out of a clean chamber with a normal "warm" but not over load.

Originally Posted by Dicko

Grandpamac,

I mostly set my FLS dies up so that a resized case created a very slight pressure on the bolt when it is closed. The idea being it reduces stretch and increases case life. I have never had a case stick in a chamber and i tend to load fairly warm. My experience would be that if your FLS die is set to bump the shoulder back your taking care of the bulge above the base.

When i have repurposed fired brass from military rifles / chambers in my .223, i may screw / work the FLS die further down in the press (bit by bit), until i get case to chamber and be able to just feel a little pressure on the bolt at close. The big O frame press will be camming over at this setup.

I have had cases come apart at the web twice and in both cases it was due to excessive resizing and repeated firings. Modern bolt rifles have way more extraction power than need to pull a stick case out of a clean chamber with a normal "warm" but not over load.

Greetings Dicko,
I don't doubt your experience in this at all but it does seem to be a problem with some rifles and perhaps some makes of cases. The problem seems to stem from the rather generous chamber tolerances of some rifles and a thinner case head with some manufacturers. I had a ferret around on the inter web and found that the tolerance between minimum case and maximum chamber to the head space datum for the .30-06 is about 0.013 inches. This is about the same as the belt length tolerance. The min cartridge to max chamber tolerance for the 7mm Rem mag is about twice that at about .024 inches. So if the belt is toward minimum and the chamber toward maximum (which seems to be the rule rather than the exception with factory chambers) there can be a significant gap between the front of the belt and its recess in the chamber. If the case also has a thinner head then the body can bulge into the gap. This is what my friend found with his .308 Norma. Innovative technologies in the US offers a fancy collet die that deals with the problem which I imagine they would only do if there was demand.
No doubt a gunsmith could ensure any chamber he was cutting would be close to or at minimum thereby eliminating the problem. I suspect that most do. I have to admit right here that I don't own any belted magnums and have only loaded for one. This was a .350 Rem Mag for my son. I didn't have any problems and I don't think he has since he took over. He calls it his .350 Whopper Stopper. I have read about the problem in Handloader and knew what was going on when my friend had the problem. Perhaps you have been lucky.
Regards Grandpamac.