Home Forums Hunting & Shooting Ask The Gunwriters 270 GIBBS vs. 270 Winchester

I'm looking for real-world velocity differences between the two. Anecdotally, I've heard anywhere from 100 fps to 200 fps difference while at the gun range but I have yet to read or see anyone who actually has some data.

Also, can the 270 win be fired in the 270 GIBBS? Is it like an AI or is it way more...?

Ackley kept the same shoulder. Gibbs moved the shoulder forward.
You can't fire form a gibbs. Once people found out the pressures
he was running Gibbs lost popularity.

Don't know about the last sentence, but I'll take yur wurd fur it!

The Gibb's rounds as well as classic Ackley-Improved cat-tri-ge's both use 40-degree shoulders in the nearly straight blown-out cases. I suppose there's "value" in knowing how to stuff the brass with still-more powder, but in a .277 cartridge its seems the easier and more sensible [practicle] thing to do is either shoot the .270Win in a rifle with a 24 or 26in tube (vs. 22 inches) to gain extra velocity, or jump up to the .270 Weathherlie or 7mm Rem Mag.

Ken Waters ("Pet Loads" Wolfe Publishing fame) did four article on the .270WCF over his career. Last article specifically on 24-inch .270's as that was O'Connor's bread n butter combo. Waters was quite surprised he gained over fifty feet-per-second per inch!! Going to a 24in tube! (but he only used two test rifles in that article too, the other 2nd rifle had a 22in bbl and was used in a previous article or two).

Shooting a .270Gibbs? One needs to ask whether all the hassle and extra risk (pushing the pressure envelope and that basic .270WCF case to EXTREMES) is worth "maybe" an additional 200fps over the standard .270 Winchester?

Twas me I might choose a .270Win in a 24inch rifle (to gain up to 100fps velocity) if I was still shooting that particular round. The .270Win is indeed a great hunting round and it indeed kills very very well! Whether in a 22" rifle, 24" or even a carbine.

Ive got a 25Gibbs and a 270 Gibbs. I dont shoot them a whole lot but I have killed deer with each one. Ive never had any problems with them but yes they are more work. We have fireformed our brass too with a few grains of powder and some cream of wheat. The choice is totally up to you but the deer I have shot with mine did not react any differnt than the deer I have shot with a 25-06 or a 270 Winchester.

Just to be clear, yes or no to fireforming from a 270 win to a 270 Gibbs?





Which is it?

I owned a 7mm JRS at one time, and a 338Hawk too. They both use 30-06 brass with the shoulder set forward, just like the Gibbs.

You do fireform brass, but it is not simple like the Ackleys (where you can just fire standard ammunition and it forms to the Ackley shoulder and case taper).

For the Gibbs cases, there are two (or three) options:

Seat the bullets out long (hard into the lands so that closing the bolt takes some effort). The bullet maintains the headspace during fire forming. I cannot comment on this method, because I never used it. Seemed a little scary to me, but it is probably fine.

Otherwise, neck the virgin brass up (two calibers is recommended) and then back down but just far enough so that a false (forward located) shoulder is made on the neck. Again, the false shoulder is located such that closing the bolt on a round requires some effort. The false shoulder maintains the headspace during fireforming. This is the method I used. It really is not difficult (just sounds like it). For a 270 Gibbs you could probably just start with 30-06 brass and skip necking it up.

Otherwise, the cream-of-wheat method mentioned. I never did this either, so I cannot comment on it. Not really sure what maintains the headspace using this method, but I believe that just a few grains of a fast powder (bullseye) is used, and the pressure spike is fast enough that the brass never gets a chance to move (don't quote me on this - it's mostly a guess).

My 7mm JRS was a 700 KS stainless that had the action and bolt body beautifully skelletonized. It is probably the nicest SS/synthetic rifle I have ever owned. But I don't own it anymore. Just a bit too much work for this lazy SOB.

Today, I'd probably just buy a 270WSM or 7WSM and be just as happy.

Quite a nice advantage being able to buy commercially loaded ammo versus having to make every round you want to fire!

I'm going from memory here but in a factory 24 inch Winchester barrel and using 4831 powder, the standard 270 Winchester would do just over 2900fps with a 150 Hornady. The Gibbs would do just over 3000. The 270 Weatherby about 3150. This was in the same barrel at similar pressures (judged by miking the case head).
My grandfather fireformed 270 Winchester factory ammo in his Gibbs until a case separated and blew the FN extractor out and away. He took the rifle back over to Rocky Gibbs for repair and got a lecture on headspace which he never forgot.
Gibbs did load to the limit of the brass and specified different maximum loads for different brass. He cautioned shooters that the top loads were only usable in some lots of brass. Many of his clients ignored this instruction and, consequently, many ran into trouble. In many cases, it seemed like Rocky over-estimated the intelligence level of his clients!
I have, from time to time, thought of chambering a Gibbs for myself but have always resisted the urge. It just hasn't seemed worth the effort. GD

Not being worth the effort puts the Gibbs concept into five words.

Other than just fo the fun of it, why not just go to a larger case, e.g., 7mm Rem Mag, 270 WSM or 270 Weatherby. It is a lot easier to reload a standard case than to fire-form cases like the Gibbs.

Yet we worship the 280 AI. We are a fickle bunch!

The Gibbs mandates one more trip through a die when setting up the brass initially, but really, is it that much more hassle than an Ackley? In fairness you can of course buy 280AI brass today which makes this somewhat moot.

And no, I don't own a Gibbs. Never saw the point.

Hmmmmm. Maybe just take that Nosler .280AI brass and neck it down to .277 Now that's a niche that needs filling and could once and for all make demand for the .270 Gibbs go away. The .277 Shootem. I like the sound.

The 6.5x280AI is available . . .

I think Pac-Nor chambers it.

But a 6.5X280AI Shootem . . . now that would be REALLY cool.

150 fps I gained was certainly not worth the hassle of fireforming, the expense of the chambering work nor the turnaround time.

If all you're looking for is 1-200fps, why not get the Hornady superformance ammo in standard .270?--Bill

I've never tried Hornady's "light mangle-um" fodder, never saw the need!

And since my words were 'borrowed' to put bewtween quotes, I AM NOT one of those nimrods who see's the need for the .280AI, either.

However I do shoot the .280 in a singleshot with a 26in barrel. SUPERB CARTRIDGE! And rig.

Gonna try to work up ONE load using the 160 grain Accubond, as the single goto load for EVERYTHING I'd ever kill in the Mtn States; mostly mulies, pronghorns, whitetails, the occassional b-bear, and some elk.

Easiest answer to gaining that 100-200 extra MV is to adopt the WSM in either the .277 or .284 bores.

A better bullet selection goes with the .284.

And also pointed out above, either short-mag is MUCH easier to reload for as well as find new fodder on a retailer's shelf. Problem solved! With more time and jack$$ to spend hunting!!

I can't stand it anymore. The .270 Gibbs has at most 10% more case capacity than the standard .270, which does NOT equate to 150-200 extra fps at the same pressure. Instead it would result in about 75 fps. This is according to the 1/4 rule: Any increase in case capacity with cartridges of the same caliber results in a potential increase of 1/4 as much velocity AT THE SAME PRESSURE.

The "wildcat" syndrome rarely follows this rule, because when most people obtain a wildcat rifle, they load it up until the first "pressure sign" shows up (usually an ejector-hole mark on the case head) and then back off the load a grain. Since ejector marks usually don't show up until presure is at least 70,000 psi, backing of a grain might bring the load back down to just under 70,000. NATURALLY this increases velocity considerably over the typical 60-65,000 psi of factory ammo or handloads using tested data.

To get another 150 fps AT THE SAME PRESSURE as the standard .270 Winchester, we have to go to the .270 WSM case, which has about 20% more powder room. To get 200+ fps more we have to use the .270 Weatherby, which has 30% more case capacity.

I have seen these "comparisons" of factory rounds and various wildcats over and over again. Some people even compare the fairly wimpy ballistics of some factory ammo with that they get by super-stuffing an improved version. One guy even published an article about how he got 250 fps more by "improving" his .35 Whelen. This was a comparison between the 2400 fps Remington 250-grain factory load and what he got by loading the hell out of the AI to get 2650 fps.

The thing he missed, however, is that the .35 Whelen Improved only results in about a 4% increase in powder room, because there isn't much shoulder to blow out. This translates to a 1% increase in potential velocity when (again) the two rounds are LOADED TO THE SAME PRESSURE. And 1% in any .35 Whelen load is about 25-30 fps.

17 Gibbs gets an extra 331 fps...

Mule deer, thanks for that post. Several years ago there was an article in Handloader or Precision Shooting, that showed that increasing case capacity, did not necessarily increase velocity, because you now had to put MORE powder in it to get back to the initial velocity. Also, some rounds, like the 270 and 25/06, already over bore and all the available case capacity can't be used as it is. Even Ackley himself said this in his book Handbook for Shooters and Reloaders. Back in 1968, when on my honeymoon, I stopped in Viola and visited Rocky Gibbs, and when I left had enough doubts about claims on the velocity increases, to not want one. I have several Gibbs cartridges here for display, but can't see going to all the problem of making them up (he had a hydraulic system he advised using), when if you wanted more speed, go to the next larger round. About 6 years back there was a real comprehensive article in Precision Shooting on the Ackley cartridges too, and maybe 10% achieved enough additional velocity increase to be worth it, and then you had to say, why get a 30/30AI, when you can just go to the 308?

Again, thanks for the post.

Cuzz 94 Winchesters don't come in 308?