Has anyone used the 30 gibbs? Forming brass seems to be the biggest problem. The velocity claims seem to have a lot of "blue sky" to them.

I have one I obtained through a multirifle trade and it is in great shape and bulit on a high numbered Springfield 03 receiver. I am and considering having the breech cut and rethreaded so I can have it rechambered for something more useful. Any ideas?

My .30 Gibbs was my favorite rifle for about 30 years. It kept me in fresh elk meat 22 of those years plus two Shiras bull moose, an Alaskan DIY caribou, and a Mountain goat.

To make cases, I would first anneal the cases, then I would expand the case necks with a .35 caliber expanding plug that I made, then run the cases through a .30 Gibbs FL size die (from RCBS) which would create a small headspacing shoulder, then prime the cases, charge with 14 gr of Red Dot, and fill with corn meal, and shoot. Once the cases were formed, they reload just like any other bottleneck rifle case.

I loaded 180 gr Sierras for practice and 180 gr Partitions for hunting. I once shot 20 shots into a 1 1/2" group at 100 yds that chronographed an average of 2990 fps.

Unfortunately, I apparently overcharged a forming round using salvaged military bullets, and it swelled the chamber and broke the extractor. I had a gunsmith try to fix it, but he didn't get it 100%, and in the process, shortened the barrel about 1 1/2" so I retired it to the back of my safe.

IMO it would be a shame to rechamber it to something less useful.

The OP 'might' get more responses by posting in the correct forum.. The Medium Bore Rifles forum is where .30-caliber cartridges belong. No biggie, a common mistake....



.

quote:

The velocity claims seem to have a lot of "blue sky" to them.

This is typical for wildcats and "AI" is no exception.

My 30 Gibbs will be sheep hunting with me soon and I will give a full report. Fireforming cases is no problem and getting 3000fps with 150gr NP is a cinch, why a person would anything negative to say about a 30 Gibbs is beyond me.

Actually, the velocities claimed were usually attained. But what was not told was the excessive pressures required to reach them. Ackley sold the shooting community on the idea that somehow a straight-walled case would grip the chamber walls and reduce observed pressure. Even that idea is poorly supported by engineering realities, but these are not magic cartridges. To attain a high velocity with a limited volume case you need higher pressures (or special propellants) or a very long barrel - another trick Improved suporters used in their "hoax".

Today there is no mystery. All one has to do is look at the pressure-tested data by Nosler or Hornady to see that an Improved case loaded to the same SAMMI pressures exceeds the performance of its parent case by 0 to 150 fps. On average there is a gain of about 100 fps, not enough for anyone to ever notice in the field. But it made P.O. famous and he earned a lot of money doing rechambers.

OTOH the case shape of most Improved cases looks cool and may help to reduce case stretching. They work as well as standard chamberings do, and that's no surprise. BTW Nosler data lists 3000 fps for 150-grain bullets in the standard .30-06 case.

Improving the .250 Savage case is also an anomaly in the AI line - the parent case is highly tapered, and blowing it out makes a much larger volume increase than the typical '06 wildcat sees. Combine the larger case capacity with modern maximum pressures (53,000 CUP versus the original 45,000 CUP) and you get a significant power increase. So maybe P.O. wasn't entirely wrong......



.

I built my own family of cases Similar to the Gibbs just 280 brass and 40deg shoulders. I had about 2 grs of net capacity gain over the gibbs.

Remember Rocky would measure his barrel length from the front of the bullet. So if he claimed a 26" barrel then it was 29"+. A straight wall case like the gibs or AI hide the pressure it is still there. Looking at most of the gibbs max loads I have run through QL calculate in the 70,000+ range.

In the 06 style case in all my testing some with pressure equipment. Loaded to the same pressure you gain about 1% of velocity for each 4% of net capacity increase.

I sure wouldn't be loading a 03 action with a gibbs trying to reach posted Gibbs velocities.

Can some thing like a 7mm gibbs match factory 7mag data. Sure if the reloader takes the loads to his brass and rifle limits. Can a 7Gibbs match a 7mag loaded to same pressure. Nope.

If someone wants a Gibbs go for it. Just be realistic in your expectations.

As to forming a 30Gibbs. Buy 35 Whelen brass neck it down load and fire. No big deal.

quote:

Originally posted by ramrod340:
I built my own family of cases Similar to the Gibbs just 280 brass and 40deg shoulders. I had about 2 grs of net capacity gain over the gibbs.

Remember Rocky would measure his barrel length from the front of the bullet. So if he claimed a 26" barrel then it was 29"+. A straight wall case like the gibs or AI hide the pressure it is still there. Looking at most of the gibbs max loads I have run through QL calculate in the 70,000+ range.

In the 06 style case in all my testing some with pressure equipment. Loaded to the same pressure you gain about 1% of velocity for each 4% of net capacity increase.

I sure wouldn't be loading a 03 action with a gibbs trying to reach posted Gibbs velocities.

Can some thing like a 7mm gibbs match factory 7mag data. Sure if the reloader takes the loads to his brass and rifle limits. Can a 7Gibbs match a 7mag loaded to same pressure. Nope.

If someone wants a Gibbs go for it. Just be realistic in your expectations.

As to forming a 30Gibbs. Buy 35 Whelen brass neck it down load and fire. No big deal.

Once again, Ramrod makes a great post with sound info and logic.....his posts are quite worth the time to read!

Rocky was, let me say, pushing the envelope way beyond what anyone would in today's world of pressure transducers etc.

Fred Zeglin's excellent book "Wildcat Cartridges" has a whole chapter devoted to Rocky that will curl your hair a bit.

A 30-06 works fine, a 300 WinMag works fine. Trying to make the former into the latter just doesn't make any sense today.

For those that don't know what a .30 Gibbs is all about

I'm always amazed at the folks that will agree that there's little difference between the .308 Winchester and the .30-06 regardless of the considerable difference in case capacity but if one adds just a small amount of case capacity to the .30-06 it magically becomes an equivalent .300 Magnum.

Personally I like the .30 Gibbs case......but it's not what many think it is.....

A prudently loaded .30-06 will push a 180 grain bullet a bit over 2,800 FPS.....The comparison needs to start there.....

Yes thats why i use a 308w it so close to a 300mag
The only thing that differs is the speed of the bullet(and shooting distance) if you need more power get a bigger caliber.

quote:

Originally posted by vapodog:
I'm always amazed at the folks that will agree that there's little difference between the .308 Winchester and the .30-06 regardless of the considerable difference in case capacity but if one adds just a small amount of case capacity to the .30-06 it magically becomes an equivalent .300 Magnum.

Personally I like the .30 Gibbs case......but it's not what many think it is.....

A prudently loaded .30-06 will push a 180 grain bullet a bit over 2,800 FPS.....The comparison needs to start there.....

LOL, I always thought the same thing but was afraid to point it out.

quote:

LOL, I always thought the same thing but was afraid to point it out.

Heck I believed the hype for years. Built an entire family of 280 based shoulder forward blow out cases from 243 up to 416. In the same barrel( my feeling is that often the gain is more based on a different barrel than the improving) some with pressure testing best I could claim was a 1% velocity for 4% capcity gain at equal pressure. The Gibbs and AI cases do HIDE pressure so you normally end up loading hotter than you think you are. There are also those rare cases that the couple of grains of net capacity gain might allow you to pack in just enough SLOW powder to make a larger difference.

I still build and shoot mine because I can and I like to be different.

quote:

As to forming a 30Gibbs. Buy 35 Whelen brass neck it down load and fire. No big deal.

Ramrod beat me to it. As others have pointed out, you can start with .30-06 brass, but the extra necking up and then necking down will almost certainly require annealing, which is both imprecise and a pain to do.

If I had a Gibbs-chambered rifle I would certainly shoot it. There is nothing wrong with the design, but as with any "improved" case your velocity expectations should be for a very marginal increase at the same pressures, or attaining the same velocities at lower pressures. Wildcatters are famous for achieving their pre-conceived notions of increased velocities by simply adding powder until the desired velocity is reached. Hell, they could have done the same thing without going to the trouble of hogging out the chamber.

I wouldn't MAKE a new .30 Gibbs but if I had one I sure wouldn't spend money to change it. Back when Rocky was cutting those chambers few people had chronograps so a lot of hopeful thinking went into published speeds and to the degree they were fast came at the expense of some pretty high pressures. But we have a LOT more powder variety today and matching some of them to a bullet in the 180 gr. range should give you a very good big game rifle.

My pre-64 30 Gibbs was purchased 20yrs ago from a fellow in Florida who said he was from Idaho and the work was done by Rocky Gibbs. He wasn't trying to sell it to me it just came up in the normal gun,shooting,and hunting talk.
In any event mine shoots very good and I'm leaving to go sheep hunting in a few days. Ackley data in Nosler's manuals are a lot more realizistic than most of the published loads in the wildcat books. My sheep load is 62 gr H4831 using 150NP or 165 Horn SPT.

quote:

My sheep load is 62 gr H4831 using 150NP or 165 Horn SPT

Are you sure of that load? That seems like a light load for a 30-06 much less a Gibbs.

It's the most accurate load by far!!

Books by Hagels,Ackley,and Wildcats seem like I am using a mild load,but I consider most of their top loads Dangerous by far. This goes for most calibers.

I fully understand accuracy over velocity. Have you happen to run those loads over a chrony? Reason I ask your load calculates 42,000psi for the 150 @2751fps and 46,600psi @ 2743 for the 165. Just looking at normal Hornady factory ammo they list 2751fps for 150s and 2700 for 165s. So if QL is close to being right your Gibbs is loaded to factory 308 levels.

2890 fps with 165 Horn SPT 5 shot average

quote:

2890 fps with 165 Horn SPT 5 shot average

Interesting. QL is not normally that far off. Your velocity is more in the order of what it calculates for that load in a normal 06.

If it works then take it to the bank.