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Fire forming 30 gibbs

 
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  #1  
Old 09-09-2004, 03:15 PM
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Join Date: Sep 2004
Location: Jamestown, ND
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Fire forming 30 gibbs

I just got a 30 gibbs rifle from my dad's estate. I was told that I could use standard factory loads to fire form the cartridges. Will this work? Are their any dangers in firing factory loads in my rifle? Thanks for your help.[*]null[LIST]
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  #2  
Old 09-09-2004, 04:01 PM
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Join Date: Aug 2004
Location: Arizona Mountains
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Re: Fire forming 30 gibbs

NO NO NO Please do not attempt to fire standard 30-06 cartridges in a Gibbs chamber. This will create a dangerous headspace situation that could wreck your rifle and you. In forming Gibbs cartridges you have to create some way to hold the cartridge tightly against the bolt face. There are a couple of ways of doing this but they require handloading techniques that a casual re-loader is usually not aware of.

Before you do anything, make certain what the chamber dimensions are. Do you have any brass that may have been fired in the rifle? If not get to a good gunsmith and have him amke a chamber cast.

Once you know exactly what the inside of the chamber looks like you can then find the safest way to form brass.

Talk to a shooting buddy who is familiar with fireforming techniques. Talk to a good gunsmith. Proceed slowly.
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  #3  
Old 09-09-2004, 04:16 PM
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Re: Fire forming 30 gibbs

Thanks for the info. I do have a few shells that have been loaded and fired in the past. I have also been reading about using red dot and cornmeal with a wax plug. It supposedly fireforms perfectly...
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  #4  
Old 09-09-2004, 07:55 PM
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Join Date: Sep 2002
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Re: Fire forming 30 gibbs

you can use a HEAVY for caliber bullet,..and seat it WELL into the lands. This will push the case firmly against the boltface and hold it in place. Then the forming will take place as it should. DO NOT short seat bullets when fireforming/"blowing out" a case. You want the brass needed to extend the body of the case to come from the NECK (flow backwards) instead of from the case head area (flowing forewards). The extra brass HAS TO come from somewhere,..the correct area is the neck and NOT the casehead.
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  #5  
Old 09-11-2004, 01:22 PM
 
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Re: Fire forming 30 gibbs

A Carlson,

I have 5 drawings of the 30 Gibbs and they are all different from each other. The implication is that there are probably at least as many different chamber reamer drawings as well. Cast your chamber and get someone with lots of reloading experience to assist you as you get started with the 30 Gibbs.

If you use 30-06 cases, you should neck them up to .338 first then neck them back down to 30 caliber a bit at a time to create a false shoulder. Check the case for a tight (crush) fit as the bolt is closed. Lock your sizing die at this point.

An article by Roger Stowers in "Wildcat Cartridges", states that with a 180 grain bullet seated firmly into the lands, a load of 50 grains of IMR-4895 will create the right amount of pressure to fill out the sharp shouldered case.

The illustration of the Gibbs below, I think is incorrect. The shoulder per Rocky Gibbs was set at a 35 degree angle. The overall length is short as compared to my other drawings, also. It just points out that there are differences between sources and they need to be checked.







[ 09-11-2004: Message edited by: Crispin Goodall ]

[ 09-11-2004: Message edited by: Crispin Goodall ]
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  #6  
Old 09-11-2004, 01:40 PM
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Join Date: Sep 2004
Location: Jamestown, ND
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Re: Fire forming 30 gibbs

Thanks for the sketch....but I tracked down your sketch on reloadbench.com and this is an ackley improved....i am looking for information on a .30 gibbs... thanks for trying... [img]images/icons/smile.gif[/img]

[ 09-11-2004: Message edited by: A Carlson ]
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  #7  
Old 09-11-2004, 02:51 PM
 
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Re: Fire forming 30 gibbs

Well, you need to look again, since this drawing is listed at both The Reload Bench and Steve's Pages as the 30 Gibbs with a 27 degree shoulder. The Ackley shoulder, when done by Ackley, is set at a 40 degree angle.

If you had read my entire post, you would have understood that I don't believe that it is a correct version of the Gibbs anyway due to the overall length and the shoulder angle. These two drawings were done by Dave LeGate for Rifle and Handloader magazines and taken off of fired cases. The contention is that the measuring was not very accurate. The newer drawing done by Dave is very close to what most of my chambers cast to. It is all that I could find quickly for posting.

But since you now seem to be an expert on both the Gibbs and the Ackley, you can ignore both of these posts and continue on your merry way.
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