Redneck Tight Neck
- Thread starter MHouser
- Start date
I think I get what you mean. If you resize '06 brass down to 308 the neck wall thickness should be considerably thicker than standard 308 brass (after trimming etc.). It would stand to reason then that the overall diameter at the neck of a loaded round would be greater and would fill up a sloppy chamber. I am not sure however if the thicker neck would be more prone to splitting or would need annealing more often. I also wonder if the neck might be too thick to expand on firing to seal the chamber from gases.
Yes you are but if the neck is to tight you run the risk of extremely high pressures if it won't let go of the bullet upon fireing.
If you do it you should anneal the necks and you should take a fired 308 casing from that rifle to measure the neck diameter then neck turn your formed brass so it is about .003" smaller when loaded.
You can have a go at it but unless your chamber is quite large at the neck I don't think you will gain anything and if you do you will need a bushing neck die or your brass necks will work harden very quickly if you use a FL die.
You can have a go at it but unless your chamber is quite large at the neck I don't think you will gain anything and if you do you will need a bushing neck die or your brass necks will work harden very quickly if you use a FL die.
I don't get why one would bother spending that time and effort? 308 brass is easy to get
I'm doing it simply to learn. I'm just getting into reloading and have done most of the standard stuff and figured it would force me to learn about annealing, neck and chamber sizes and tolerances, etc.
A) The following neck measurements were taken from standard .308 casings after firing them in my gun (i.e. once fired)...
Outside Neck Diameter: .343
Inside Neck Diameter: .312
Neck Wall Thickness: .015
Does this mean my chamber has a neck diameter of approx. .344 (i.e. .343 + .001)?
B) These measurements were taken from the converted 30-06 brass that I'm referring to in the post (full length sized, trimmed, etc.). Pre-seating the bullet and pre-neck turning...
Outside Neck Diameter: .338
Inside Neck Diameter: .303
Neck Wall Thickness: .017
I tried chambering the empty casing from B) in my gun and it chambered fine but needed a little extra force to close the bolt, not much though.
C) After seating the bullet in casing from B) above...
Outside Neck Diameter: .341 - .342
I tried chambering after C) and again it chambered fine. A little tighter again.
I guess I'm a little worried about firing it like this. I should probably neck turn right? Maybe take the neck size down from .017 to .016 to give me an extra 2 thou?
Am I on the right track or should I take it down a bit more to be safe?
Sorry for any terminology errors. Feel free to point them out where appropriate.
I don't get why one would bother spending that time and effort? 308 brass is easy to get
I have been reloading numerous calibres for about 25 years and have never bothered with what you want to force yourself to learn.
MHouser
The only time I ran into trouble with necks was case forming 30-06 brass down to 7.65 Argentine. The necks ended up tapered and were snug at the base of the neck for approximately 1/8 of an inch. I was lucky and didn't have pressure problems because I was fire forming them at well below max pressures with IMR-4350. This happened in the 1970s before I even had a good set of vernier callipers to measure the necks with, the fired soot on the case necks told the story.
Your chamber neck diameter will govern what will happen, you could find the necks thicker on your .308 by just switching case brands, like switching from Winchester cases to Remington .308 cases.
Below Remington at the top and Prvi Partizan at the bottom.
Also remember if you don't have a tubing micrometer or a neck thickness gauge like above you will get false neck readings measuring with other devices like vernier callipers. (Thicker measurement readings)
You can be chasing your tail worrying about the case necks if the locking lugs are not making even surface contact and the bolt face is not true to the axis of the bore.
Also bullet runout could be off even on a "tight neck" rifle making it a mute point if excessive.
Below the savage bolt can pivot and maintains equal lug contact and improves alignment and accuracy on a cheap commercial rifle.
The only time I ran into trouble with necks was case forming 30-06 brass down to 7.65 Argentine. The necks ended up tapered and were snug at the base of the neck for approximately 1/8 of an inch. I was lucky and didn't have pressure problems because I was fire forming them at well below max pressures with IMR-4350. This happened in the 1970s before I even had a good set of vernier callipers to measure the necks with, the fired soot on the case necks told the story.
Your chamber neck diameter will govern what will happen, you could find the necks thicker on your .308 by just switching case brands, like switching from Winchester cases to Remington .308 cases.
Below Remington at the top and Prvi Partizan at the bottom.
Also remember if you don't have a tubing micrometer or a neck thickness gauge like above you will get false neck readings measuring with other devices like vernier callipers. (Thicker measurement readings)
You can be chasing your tail worrying about the case necks if the locking lugs are not making even surface contact and the bolt face is not true to the axis of the bore.
Also bullet runout could be off even on a "tight neck" rifle making it a mute point if excessive.
Below the savage bolt can pivot and maintains equal lug contact and improves alignment and accuracy on a cheap commercial rifle.
MHouser:
I get what you're doing & I believe the reasons for doing what you are doing (accuracy, right). It has NOTHING to do with cheap brass. You are simply trying to duplicate a tight neck custom chamber situation in a factory / standard chambered rifle.
I have done this in both 243 Winchester & 22-250 rifles, both using 308 Winchester brass & forming dies. I, however, was required to neck turn the brass in order to allow the cartridges to fire without experiencing a high pressure gas excursion.
Essentially what you want to check is that the outside measurement of your newly-formed brass, with a seated bulleted therein, measures LESS than your fired brass. IF it doesn't, turn your case necks. Don't forget about brass springback as well.
ALSO, make sure you start with starting loads, as the internal capacity may be less, especially if you are using old military 06 brass.
Smoke your cases with a candle & then insert them into your chamber & you may determine why you are experiencing hard bolt closure, with or without your bullet. I suspect it may be at the newly formed shoulder of the cartridge.
Have a look at the articles here:
http://varmintal.com/arelo.htm
Jim
I get what you're doing & I believe the reasons for doing what you are doing (accuracy, right). It has NOTHING to do with cheap brass. You are simply trying to duplicate a tight neck custom chamber situation in a factory / standard chambered rifle.
I have done this in both 243 Winchester & 22-250 rifles, both using 308 Winchester brass & forming dies. I, however, was required to neck turn the brass in order to allow the cartridges to fire without experiencing a high pressure gas excursion.
Essentially what you want to check is that the outside measurement of your newly-formed brass, with a seated bulleted therein, measures LESS than your fired brass. IF it doesn't, turn your case necks. Don't forget about brass springback as well.
ALSO, make sure you start with starting loads, as the internal capacity may be less, especially if you are using old military 06 brass.
Smoke your cases with a candle & then insert them into your chamber & you may determine why you are experiencing hard bolt closure, with or without your bullet. I suspect it may be at the newly formed shoulder of the cartridge.
Have a look at the articles here:
http://varmintal.com/arelo.htm
Jim
