cutting ones teeth on a wildcat

[s&w 24]

WARNIG DO NOT COPY ME. DO NOT LOAD ANY ROUND LISTED BELOW. READ AT YOUR OWN RISK.



thru the strange trades beween S&W the senior and my self I ended up with his remington 721 in 30 gibbs (he admited later he was sacred to load for it).
The 30 gibbs is the second cartrige developed by Rocky Gibbs in the late 60's.
Tje cartrige is based on the 30-06 case that has been "improved" by removing any tapper to the case and instead of just changing the shoulder angle as with ackley type improved models the shoulder is moved forward to increase powder capasity. By increasing the case capasity and loading the 06 type case to 270 pressures some have gotten 300 H&H ballistics.

The first thing I had to do with the rifle is get some cases formed. In the book Wildcats that is a bunch of old articals from handloader and rifle magazines I read about the differing Gibbs cartriges and how these cases were formed. There was a hydrolic method involving dies I don't have, a method involving seasting a flat based bullet backward over a starting standard 06 load, and making a blank cartrige with pistol powder and cream of wheat.

The first case I tried to form I tried a charge of bullseye with a cleaning patch jammed in the case neck. The result was a half formed shoulder. Scratch that method. Next I tried a small charge of bullseye with malt-o meal filler and a wax plug to keep everything together. with some trobble with the extractor grabbing the case I managed to fire a few malt-o-meal specials. It worked ! On a few of the once fired cases there was case stretching just ahead of the web and I tossed them but I found a method that works.

After having 7 cases formed I went over to Gunstop to get some new W-W cases and a few 180gr psp 30 cal bullets to try the next method. using new cases and IMR 4895 I loaded up some base forward loads seating out the bullet so the base of the bullet pressed firmly into the lands of the BBL. since this was going to take a trip to the range I also figured out how to partial neck size the formed 30 gibbs cases in my 30-06 dies and made a few test rounds with the rem 180's and IMR 4895. Off to Bills gunshop north. After the R.O. giving the hairy eyeball I went off to my firing point and blasted away. The 30 Gibbs cases looked fine after the test loads, nice looking primers easy extraction. then off to the backward bullet loads. Five round down range and five cases that look OK.

After all this I found the malt-o-meal specials work best for case forming despite being told my rifle is stinking like burned oatmeal. I picked up some 165 ballistic tips and I'll have to add a crony to the shopping list. Once I have the above I'll let you know how it works.


P.S. if any of the MN metro mebers on THR would taqke a few pics of this project just PM or e-mail me.

 

[s&w 24]

at minimum 6 more grains 4350 fit in the new case. I got a crony last week at some time I'll post the velocity.

 

[EShell]

The "backwards bullet method", the "cream of wheat (filler) method" and the "bullet into the lands" method all give inexact shoulder locations and thus deliver varying headspace.

This varying headspace is why some of your cases (obviously) stretched. The rest are likely stretched, too, but weren't as obvious at this time. It will manefest itself later in headspace induced misfires (firing pin can't reach) and premature case failures (as they try to stretch to fit).

I've done a few wildcats that needed fireforming and some special circumstances that required special handling and I'd like to suggest another method for you to consider.

To get you .30 Gibbs done, I would suggest necking up your basic .30-06 brass with a .338 expander, then necking them back down with your Gibbs sizer until the case will just barely chamber.

This is accomplished by backing out your sizing die until it barely forms the case neck, test chambering the case, then very gradually advancing the sizing die to increase sizing amount until the test case just barely allows the rifle to close with a definite "feel" of resistance. Make sure your rifle's locking lugs are lubed to prevent galling. Once you reach this point, check the adjustment with another couple cases to be sure it's right.

Once I find this point, I usually leave the sizing die set here until I've fired then loaded that batch once. Depending on what I intend to do, I may fine-adjust this later.

This process produces a hard, exactly located "secondary shoulder", which WILL headspace precisely, to allow your new brass to be in the correct position (against the bolt face) when it is fired. Using this method with the neck & shoulder region of the case lightly lubed renders a perfectly formed, and perfectly headspaced case on the first firing - zero stretch, every time.

When a bullet is seated backwards, or against the lands, the firing pin blow is enough to move the whole deal forward, and the case head leaves the bolt face. Upon firing, the case head gets driven back against the bolt face, stretching the case and thinning the web.

I've successfully used this method to form .280 Remingtons from '06's, .30 Herrett & .357 Herrett from .30-30's, .35 Whelen from .30-06, .30-06 Ackley and 6.5-300Wby from .300Wbys, and to "recover" headspace errors produced in a T/C .35 Remington.

 

[Reed1911]

+1 to the method Eshell give great instruction on! I've yelled and screamed on this one until I was blue in the face, to no avail.

 

[s&w 24]

unfortunatlly .30 gibbs dies cost more than I payed for the rifle but when I get the spare bucks I'll call up redding for a set. The new winchester cases formed with cream of wheat have survived 6 loadings with a stiff hunting load with no case loss and tight primer pockets, that does not make that method perfect but it will do till my forming dies get here.

 

[only1asterisk]

I think you can get a set of Gibbs dies in stock for less than $100. Worth it. Necking down 35 whelen cases will headspace well for fireforming.

David

 

[Vern Humphrey]

The method of fireforming you were using works very well in a controlled feed rifle (that's how I fireform cases for Bigfoot Wallace, my custom '03 in .35 Brown-Whelen.) Unfortunately your 721 Remington is not a controlled feed.

The best advice is the last given -- neck down .35 Whelen cases to form a temporary shoulder you can headspace on for fireforming.

 

[s&w 24]

I forgot one small detail I started placing the case rim in the extractor and pressing the case against the ejector when closing the bolt insuring the case is supported by the extractor. This solved most of the stretched cases.

 

[Jet22]

I would try 300 Savage dies for both neck sizeing and bullet seating (after your case is fireformed). Dimensions are very similar to the 30 Gibbs other than the case length. Just don't touch the shoulder. If you don't have 300 Savage dies, try 308 Winchester dies. They should work OK also, but you won't be able to crimp...but then you may not want to crimp anyway!

 

[Vern Humphrey]

I forgot one small detail I started placing the case rim in the extractor and pressing the case against the ejector when closing the bolt insuring the case is supported by the extractor. This solved most of the stretched cases.

Very good solution.

 

[djl4570]

My first wildcat is a .244 Remington Ackley Improved. Improved cases can be made by fireforming the parent case in the improved chamber. My next wildcat is going to be a .222 Remington Kilborne improved.

The Gibbs case is longer to the shoulder than the .30-06. You have to properly form the brass for these to fireform well. The method described in the manual of cartridge conversions is to neck the case up to about .315 using a a larger expander ball. A .303 British or 8mm expander ball should do this well, then size the case using the FL .30 Gibbs die. This pushes a slight step in the now oversized 30-06 case neck so the case can properly headspace in the .30 Gibbs chamber. After forming the case you really should anneal the necks and shoulders. A well set up sizing die should give you about .003" interference closing the bolt. This holds the case on the small step at the the base of the neck securely in the chamber. Load and fire using full power loads.

Now, if you don't have the .30 Gibbs FL die you can set up a .30-06 neck sizing die to achieve a substitute result. You still need to neck the case up as before but you can use the .30-06 neck die to put a pseudo-shoulder on the case neck. Remove the expander ball and decapping stem from the .30-06 neck die, Set the die to fully size the .30-06 case neck, and back it out one full turn. The length from the case head to the base of the .30 Gibbs case neck is .057" longer than the same measurement on the .30-06 case. One full turn on the die is .071" so you need to screw the die in about .010" (.003" interference fit, remember). Setting this up requires patience and testing the sized case in the rifle for a bolt that closes with a bit of resistance. Once you get the die set up leave it alone. I would not bother running an expander ball through the case necks, even though the neck tension on the bullet is going to be higher than usual they should shoot without any problems.

Methods that involve headspacing the case on the extractor are going to give you problematic results because the case isn't long enough to fit squared up in the chamber. These cases are likely to be asymmetrically fireformed, more prone to incipient separation and less conductive to accuracy.

 

[JackOfAllTradesMasterAtNone]

Once these new 30 gibs brass are fire formed, would subsequent reloads be performed with just a .30cal neck size die?

-Steve

 

[djl4570]

Once these new 30 gibs brass are fire formed, would subsequent reloads be performed with just a .30cal neck size die?

Yes, I recommend using a Redding Bushing style neck die, I like the micrometer adjustable neck die. Only the top .050" - .100" of the neck needs to be sized, and only enough to grip the bullet. Use the largest bushing you can and still get enough neck tension to hold the bullet firmly.

 

[JackOfAllTradesMasterAtNone]

Not to highjack the thread, but...

And if anyone spouts off, and tells me to start another thread, I will gladly.

But here goes... I also load a suto wildcat.

30-338. That's a .338 Winmag necked down to .30cal. Very similar to 308 Norma. I have some RCBS dies for 30-338 that I use to get things close from .338Winmag brass, but once fire formed, I only neck size. I have found that a light load of 4064 is quite adequate to form the shoulder to the chamber. On roughly the 4th reload, I'm splitting cases just above the belt. They are warm loads. 66.5gns of 4350 with a Speer 180bt or 66gns pushing a Hornady 190bt. But the primers look good and the accuracy is minute of angle. Feeding and extraction is simple too.

Should I be full length resizing since I have the dies, or is neck sizing better? Wouldn't I be working the brass more if I FL?

As for loading for the 30gibs... It must be a bit of a challenge to move the shoulder forward...???
Being unfamiliar with the Gibbs line, I searched the web.

"Rocky Gibbs developed the Gibbs line of cartridges in the early 50s. Based on the 30-06 case, the Gibbs was in essence another presentation of an improved cartridge. Objective testing of the 30 Gibbs has produced velocities in the 2,900 fps range with 180gr bullets, 24" barrel. This is about 300fps lower than what Rocky claimed, however, chronographs and a better understanding of pressures have come forth in the intervening years.

Bottom line is that the 30 Gibbs, like the 06 Improved, will develope 50fps to 100fps over the parent cartridge in barrels of equal length under equal pressures. "

-Steve

 

[djl4570]

On roughly the 4th reload, I'm splitting cases just above the belt.

This should not happen in a bolt gun if the case is well supported at the shoulder when fireformed. If you let the case headspace on the belt then the entire body of the case will stretch to fill the chamber. If the case is supported on the shoulder at the base of the neck then the body of the case does not need to stretch, only the shoulder fireforms.

When forming your brass from .338 Win Mag, back your FL die out a bit until you get an interference fit closing the bolt. My .244 Ackley was set up with a .003" interference fit on the factory 6mm Remington case.

You should not need to FL size the cases after this.

Do you outside turn or ream your case necks after necking them down?