Fire forming 30 gibbs

A Carlson

Sep 9, 2004
Jamestown, ND
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
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.
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...
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.
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 ]
Thanks for the sketch....but I tracked down your sketch on and this is an ackley improved....i am looking for information on a .30 gibbs... thanks for trying...

[ 09-11-2004: Message edited by: A Carlson ]
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.
I am sorry. I didn't mean for my response to be so abrupt.I appreciate the help and by no means consider myself an expert. In my defense....the first posting that I read had only a diagram...for some reason your words didn't show up...when I read it again after more research, the rest of your post magicly appeared. You got me.....what caused that to happen. Anyways, I did go back and look at reload beanch and found the information you were talking about and so much more on general reloading...I thank you very much for heading me in the right direction.
I was in the process of editing my post and checking the pictures to see if they were going to show up correctly. It is a drawback to this forum format, you can't proof a post before committing to the post.
safe way is to use false shoulder to avoid any headspace problem because headspave is far deeper ( longer ) on Gibbs case

on fresh 30.06 case
neck up to 8 mm or 338 with a expander as lyman M die use for lead bullet
run the in the Gibbs full sizer and resize the neck up to get a two stage neck with a little shoulder , that allow to lock the headspace and you avoid any case breakake

you can to purcahse 30.06 straight case from Z HAT and form step by step with straight case you get formed case at thg eright lenght

good shooting

I like using 35 whelen brass to fireform for a 30 gibbs. It will give you a longer neck than when using 30-06 brass. You probably wont have to turn the necks but it gives a little thicker neck if you want to turn them enough to clean them up. I size them down to 338 and then just enough of the neck down to 30 so the bolt closes with a little resistance.
I use the same method as Jerry T. except I skip the part about the cream of wheat. I use about 20 grains of Bullseye or Red Dot and a little piece of toilet paper to hold the powder against the primer. No more than a quarter sheet per round. Won't fill out completely but enough that you can use the case for a regular load to sight in and test. I wouldn't trim until after the first full power load.
Played with the 30 Gibbs for a few years and really like this round. You will need to fireform brass properly to work in that chamber. I use the cream of wheat method.

As was mentioned before, you need to expand the -06 brass to 338 cal. Then run the brass through a '-06 die to reduce the neck back down. You simply keep running the brass into the die deeper until it chambers with firm bolt pressure. I like the bolt to meet resistance about 1/3 before full close. That way I know the brass is solidly against the bolt face and chamber.

I use 15 to 17gr of HP38/Win 231, any LR primer, and fill to base of the neck with cream of wheat. Stuff a piece of paper towel in the neck to keep this mess in place and fire the brass. What pops out is a 90% formed case. The shoulder will be moved but not sharp yet.

Prep this case as normal. I use a 308 Lee Collet neck sizer and spacer to size the neck. Any 30cal neck sizer will work. I don't like FL sizing if I don't have to.

I found H4350 Extreme and 165gr SST to be a wonderful combination. I also used CCI BR2 primers. My loads were getting 3000fps out of a 26" barrel with very good accuracy. You can use starting data for the '06 and just work up till you get the accuracy and vel you want. I was able to go faster but accuracy fell off. Was still a pretty toasty load.

Below are pics of the brass I used. If you have any questions, feel free to ask.


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