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Discussion Starter · #1 ·
I have an opportunity to purchase a Custom 1903 Springfield chambered for "30 Gibbs". I am not familiar with this cartridge and would like to hear from anyone that has information about it, I.E. forming brass, reloading data etc.

I would also like to hear your opinions concerning how it compares with the 30-06 ACKLEY, and would it be possible to ream the existing 30 GIBBS chamber out to 30-06 ACKLEY IMP.

Thank You

· Registered
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30 Gibbs info

I have been shooting the 30 Gibbs for a year and love it. It is my long skinny magnum (performance very similar to the WSM - the short fat magnum).

The Gibbs has the shoulder relocated so that there is a 0.25" neck. all in the Gibbs family share this characteristic. The shoulder angle is 35deg. You can make this easily from '06brass or 280/270 brass and trimming slightly if needed.

The cases are formed by first necking up in size to say .35 or .338. Then the brass neck is reduced to 30cal forming a secondary shoulder. The brass is resized so that chambering this brass in the Gibbs chamber is a firm fit. The fireforming load is approx 17gr of HP38/Win 231, and cream of wheat filled to the base of the neck. Any LR primer will work. I also put a small piece of paper towel into the neck to hold the COW in place. Fire the case and you will have cases with an almost sharp shoulder. The first full powder load makes nice cases.

I shoot 165gr SST w/ moly over H4350extreme lit by CCI BR2 primers. I have used Fed, win and LC69 cases to good effect. I actually prefer the LC69 because of its toughness - very accurate too.

Out of my 26" barrel, I can get 3000fps, with 3100fps as max vel (very, very hot) and lousy accuracy. I usually load to 2950 to 3000fps and both brass life and accuracy have been excellent.

How well does this shoot? With the above receipe, I am shooting 5rds into 1" to 1 1/4"at 250yds. My rifle does have a match barrel and a short throat (OAL to fit mag and bullets are just off lands when chambered). All brass necked sized using a Lee collet neck die (308win die and a spacer), and bullets seated with a Forster BR 308Win die. You must have straight ammo to shoot accurately. I also neck turn enough to skim 80% or more of the necks.

I have never used a '06 AI so can't compare performance. Also, don't know if these loads are over pressure. They are warm but work in this rifle. Compared to my '06 at 2700fps and the same SST bullet, I have gained a significant amount of performance for LR shooting. I use this Gibbs to shoot clays at 700yds+ and 9X9 plate at 1000m. Don't hit everytime because of wind doping but enough to make things very interesting. Not bad for a hunting rifle.

Most reloading manuals show '06 loadings of 165gr bullets to 2900fps. I have never seen such a rifle, at least one that was both fast AND accurate. Most seem to like 2700fps or so.

Hope this helps you get inspired...


· Banned
44 Posts
Well, It's sort of a tradition with me to start my activity on a new forum by reviving a long dead discussion, so here goes...

No, you cannot ream a 30Gibbs out to 30-06 Ackley Improved, but you probably can ream
a 30-06A-I out to 30Gibbs.

The A-I is an "Improved" cartridge meaning that Factory ammo can be chambered and fired.

the 30Gibbs is a "true" Wildcat, so brass must either be partially formed to make it fire safely.

Roger Stowers recommended in handloader #143 using
50.0grains of IMR4895 behind a 180grain bullet seated out to firmly touch the rifling as a fireforming load.

Of course you could do it the hard way and expand the neck out to .338 then form a false shoulder with a 30cal neck sizer
to enable you to fireform them

Brass temporarily formed for fireforming should take some effort to close the bolt on...

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