I was down at the drugstore today and I found a March 2003 Gun World Magazine, which had an article on an Ed Brown rifle in .50 Peacekeeper, which as you all know is one of the closely related family of cartridges developed by necking the .460 Weatherby cartridge up to .510".

Looking at the performance table on page 78, it appears that once you adjust for the different bullet weights and barrel lengths, the .50 Peacekeeper is loaded to exactly the same performance level as the .500 A-Square loads from the A-Square manual. This gives me much more confidence in the A-Square data.

Furtber, it is reported that Ed Brown had tested barrel lengths out to 30" then cut back to 23", and he had found an average velocity loss per inch of 17 fps. A 700-grain load at 2208 fps is listed.

Given an increase in powder capacity for the .510-.505 Gibbs case of 25%, and a velocity increase of 25% of the increase in powder capacity, we can expect to see a performance improvement of 150 fps with the 700 grain bullet and the 23" barrel to 2360 fps or so. It's now possible to consider in which cases the longer and larger case is worthwhile.

Yep, that's pretty good data. The average velocity loss from 30" to 23" may well be 17 fps, but it may be around 25 fps per inch from 23" to 27" in my experience with the .510/460 in two different rifles, both with McGowen stainless 1:10" twist barrels. Two different rifles, I wasn't cutting off the same barrel, so I have added another variable.

The smaller 510/460 case packs enough whack for me. It is my personal punishment with a smile limit.

I'll just stick to my 500 jeffe...

SDS, a 700 at 2350 is going to get your attention, in an unbraked, 11# rifle.. that's right there with the 585 nyati, but the recoil SPEED will be much faster in a hopped-up 510/505.

another issue is pressure.. but that's going to be a long way, uphill, after the recoil battle....

and bolt thrust... I aint an expert in it, I am certain someone can dig up the formula for you.

go with the 510/505... have the throat cut long, and have a ball. But, those pull bullets are for practice and target shooting.. NOT compeating with the BMG boys, imnsho
jeffe