What is the most overbore cartridge YOU HAVE USED?

[Calvin45]

Don't know if this goes here or on reloading forum, but figured I'd ask…

What is the most overbore cartridge you ACTUALLY have experience with? The craziest hot rod, the biggest case to bore ratio, the most ridiculous magnum, this worst barrel burner….

What have you learned from it? Would you do it again?

I know everyone on these threads makes jokes about a .17-50bmg or references the .22-378 eargesplittenloudenboomer experiment by ackley…I don't care about those. I don't know of a single person who has ever done such a thing in any serious effort. I'm trying to avoid that and learn about people's experiences and learning from actual field rifles in very overbore factory chamberings or more so truly impractical but still useful wildcats. I'm entertaining the thought of one myself.

@ButterBean @Fiftydriver @MagnumManiac i know you folks off the top of my head have played with some big cases pushing small bullets….

 

[Calvin45]

If swamplord was still here I'd be pickin his brain too for sure.

 

[cape cove]

I guess for me it would be the 257 Weatherby---7mm RUM and 30/378

 

[MagnumManiac]

The worst for me was the 7RUM, the throat erosion was like watching your fuel gauge go down on a long trip…
The other was the 505 Gibbs, 150g of powder to achieve 2150fps with a 600g bullet.
My 416 Rigby based wildcats are pretty overbore, but with super slow powders, the returns are worthwhile. In the beginning, early 2000's, powder choice was difficult. I had a powder here called AR2214, it was used in 50cal and 20mm cannon shells, it was a powder between Retumbo and H50BMG and ran 120-128g in my 338-416 Rigby Improved 45° with bullets from 265g to 323g obtaining velocities above 3000fps. Similar numbers in the 375-416 Rigby Improved 40°.
The 300-416 Rigby Improved 35° ran 118g of AR2214 with 230g Berger OTM, but that was later around 2009/10. My supply of that powder was diminished by 2012, it was no longer supplied to handloaders' for a long time by then. I miss being able to buy surplus powder by the keg…
Many say the 7STW is overbore, but with the powders available today, there is no powder that will give diminishing returns like there was prior to H1000 and Retumbo. As long as you can fit enough powder and still increase velocity, overbore isn't a real thing.

Cheers.

 

[just_jon]

7mm STW. At some point in my life, I decided burning 30% more powder for a 5% increase in velocity over the 7RM seemed like a really good idea.

 

[Calvin45]

7mm STW. At some point in my life, I decided burning 30% more powder for a 5% increase in velocity over the 7RM seemed like a really good idea.

What barrel lengths for each cartridge? Also I didn't think the STW was that much bigger, looking at them it doesn't seem 30 percent bigger but that's good to know! What charge weights?

 

[Hugnot]

8 twist 6mm-06 - blew up 87 Vmax's. 105 grain at 3,300 fps. Nasty hot after 3-5 rounds. Not too bad at 1 shot per minute. I replaced barrel with a 6.5-06.

 

[ButterBean]

22-06AI and the 257 STW, I still have the 22-06AI

 

[MtPockets]

22-06AI and the 257 STW, I still have the 22-06AI

257 STW???

What kind of performance did you get out of that? How about barrel life?

 

[Calvin45]

22-06AI and the 257 STW, I still have the 22-06AI

What happened to the STW!?!?

 

[duckhunter175]

Chronological order- 7RUM, .257wby (1-7.5t), and now a 6PRC

 

[just_jon]

What barrel lengths for each cartridge? Also I didn't think the STW was that much bigger, looking at them it doesn't seem 30 percent bigger but that's good to know! What charge weights?

Actually, both were shot in the same barrel. It was initially a 7RM that I later rechambered. With a 140 grain bullet and RL22 I run 67-68 grains in 7RM versus 80-81 grains in the STW.

 

[M16]

Mine was a 257 STW. I have a couple of hundred rounds down the barrel and it still looks remarkably well.

 

[Calvin45]

Actually, both were shot in the same barrel. It was initially a 7RM that I later rechambered. With a 140 grain bullet and RL22 I run 67-68 grains in 7RM versus 80-81 grains in the STW.

Oh that's useful! Apples to apples comparison, same barrel even!