Is there any reason to build a 270 Gibbs now? Considering the 270 wsm is around, are there any gains to be had by building this wildcat?
A friend of mine had one a long time ago and as I recall he was very pleased with the results. DW

A 270 Gibbs is not a 270WSM just like it wasn't a 270Wby. It gives up around 5grs of net capacity. It did give you a boost over a 270 allowing you to stay with the std boltface etc. In the long run capacity will normally win.

The 270Gibbs and 270Howell to me make more sense than the 270AI. My feeling if you are not going with a std them maximize your capacity from your parent caase. Loaded to the same pressure they will never match the 270wsm.

I looked at doing a 270 Gibbs some good information in Wildcat Cartridges Vol II on that case. 62gr/H-4831 with 150gr Sierra @ 3165fps test was done on that load in 1963.

I've got a Lilja barrel on my 270 and Lawton barrel on a 270WSM and I'm getting a 270Wby build with a Rock Creek barrel.

Reason I decided on the Wby I'm having the case headspace on the shoulder and no Wby freebore. It be throated so OAL 3.300" and I'll use alittle less powder maybe 3/4gr and get the same velocity as a standard Wby maybe alittle more shooting 150gr bullets.

I think with todays barrels/bullets/powder using a standard lenght action and not wanting to open the bolt face a 270 Gibbs be a good choice.

I've never shot a factory 270WSM but remember depending on who's actions etc you get your pretty limited on future build to the WSM line of cases. Well good luck

I was really impressed with the Gibbs line "until" I got a Chrony.........

quote:

Originally posted by Terry Blauwkamp:
I was really impressed with the Gibbs line "until" I got a Chrony.........

Was curious about the 270 Gibbs rifle used and what loads you used?

Remember.....Rocky Gibbs measured barrel length from the tip of the chambered bullet to the end of the barrel. Rocky's 26" barrel is your 29" barrel!

quote:

Remember.....Rocky Gibbs measured barrel length from the tip of the chambered bullet to the end of the barrel. Rocky's 26" barrel is your 29" barrel!

+1 My PDK case is about 2grs larger than the Gibbs. Based on my experience my velocities are about 2" shorter than what he claimed.

I have a 270 Gibbs getting 3225 fps with a 140 Sierra HPBT - 58.5g H4350, 25" Pacnor barrel. Not totally sure what a WSM will do with the same bullet but I was at the range with a guy with a 270WSM. His 270 WSM hand loads were only getting 2975 fsp with a 140g bullet. ALOT can be attributable to his hand load and his 24" barrel......

quote:

I have a 270 Gibbs getting 3225 fps with a 140 Sierra HPBT - 58.5g H4350, 25" Pacnor barrel.

That would be the fastest 270 Gibbs i've seen. QL calls that load closer to 3050.

quote:

Originally posted by tlp335:
I have a 270 Gibbs getting 3225 fps with a 140 Sierra HPBT - 58.5g H4350, 25" Pacnor barrel. Not totally sure what a WSM will do with the same bullet but I was at the range with a guy with a 270WSM. His 270 WSM hand loads were only getting 2975 fsp with a 140g bullet. ALOT can be attributable to his hand load and his 24" barrel......

I can see 3200fps with 140gr out of a 25" long barrel for the Gibbs. I'm getting mid 3200fps with my 270WSM and alittle over 3100fps with my
270 both rifle barrels are 25.5" long shooting 140gr bullets. I've had the 270WSM over 3300fps and I back it down.

Sound like a nice rifle.

quote:

I've had the 270WSM over 3300fps and I back it down.

Given that at 3,200 FPS the pressure is likely about 63,000 PSI this seems a prudent decision.

I bet your 270 & 270Gibbs loads are running higher pressure than your 270Wsm load.

quote:

Originally posted by ramrod340:
I bet your 270 & 270Gibbs loads are running higher pressure than your 270Wsm load.

I don't own a 270 Gibbs.

Are you saying that by build a rifle with a longer barrel that you should drop the velocity to what level of pressure are you talking about. How do you measure pressure?

Well the Gibbs looks cooler...

quote:

I don't own a 270 Gibbs.

Are you saying that by build a rifle with a longer barrel that you should drop the velocity to what level of pressure are you talking about. How do you measure pressure?

I thought you were quoting your measured velocity. I don't understand your second question. I was simply stating that from my experience with my PDKs and QL numbers if those were your actual measured results 3200 from a Gibbs was more than likely a higher pressure than mid 3200s from a WSM.

As to measuring pressure unless you have some real expensive equipment actual pressure is difficult. When I did a lot of my early wildcat work I was part owner in an Oehler system. Later work I had became friends with a Gunwriter in Mt Home Tx and he allowed me use of his system.

quote:

Originally posted by ramrod340:

quote:

I don't own a 270 Gibbs.

Are you saying that by build a rifle with a longer barrel that you should drop the velocity to what level of pressure are you talking about. How do you measure pressure?

I thought you were quoting your measured velocity. I don't understand your second question. I was simply stating that from my experience with my PDKs and QL numbers if those were your actual measured results 3200 from a Gibbs was more than likely a higher pressure than mid 3200s from a WSM.

As to measuring pressure unless you have some real expensive equipment actual pressure is difficult. When I did a lot of my early wildcat work I was part owner in an Oehler system. Later work I had became friends with a Gunwriter in Mt Home Tx and he allowed me use of his system.

Maybe this will help

"I bet your 270 & 270Gibbs loads are running higher pressure than your 270Wsm load."

Since I don't own a 270 Gibbs I assume your posting about my 270 and 270WSM. All Iwas m trying to find out how do you figure I'm running higher pressure with long barrels.

QL is your answer and some wildcat that never made it.

Now I know end of post.

quote:

Originally posted by tom holland:
I can see 3200fps with 140gr out of a 25" long barrel for the Gibbs.

Gentlemen.....One can read this statement two ways....let me interpret:
1. (If someone had a Gibbs) I can see (understand) 3200fps......

2. I (actually) see 3200fps with (my) Gibbs out of.....

From my perspective I can see how Tom doesn't have a Gibbs and Ramrod read it that he did...

I don't have a Gibbs either but can relate to Ramrods statement of a lot of pressure in the Gibbs to produce 3200 fps with a 140.....I won't even guess except to say quite a bit in excess of SAAMI specs for the standard .270 Winchester.....The Gibbs really does not have a lot more capacity.

I got 3200 with a 130 TSX and a max load of RL19 in my 270 win. with a 26 inch Shillin barrel until I shot it in warm weather. Had to back it down to 3150. DW

If you are already at 3200 with a normal 270 why worry about a Gibbs or WSM? I would consider a slightly slower powder like RL22 7828 or best MRP. Yes you will need to do some load compression.

The 270 WSM case is 7.5% larger than the 270 Gibbs case. 77 to 71 gr of water. The only presure limit that I have on the 270 WSM is 65K psi CIP. With the same bullet and same barrel lenght and the Gibbs is going the same speed the pressure have to be out the door on the Gibbs. Dose every one know how Gibbs cases are made? Because the shoulder is so far forward on a Gibbs case than on a 270Win case it can't just be firerformed. They used a die that held the 270 Win case and you filled the case up with oil and then hammered a plunger down into the case to do a smi-forming of the case and then firerform. The only time when you need a rain coat indoors to form cases.

quote:

Dose every one know how Gibbs cases are made?

There is another way.....neck up a .30-06 case to (say) .338 and then neck it down again to .270 but using the Gibbs die.

This results is a small but usable false shoulder and that can allow one to fireform the case.

One can also start with basic brass.....

I've read about the oil pressure forming and think it's more work than necessary.

vapodog; that is how I would do it now if I had to, but Gibbs did it with oil. Has every one heard about Gibbs flash tubes that he tried in some of his cases. It stuck up toward the neck of the case from the base and the powder was ignited in the middle of the charge and not at the base. He most likely saw it being uses in artiliary guns that had large cases.