I would appreciate any information -loading data etc. on this cartridge.
See: http://cartridgecollectors.org/forum/viewtopic.php?t=27...11d57c6293560fd39bc8

Glenn

Volume 1 of P O Ackleys Handbook has a little data on the 257Condor using a 160 grain bullet in a 7 twist barrel, but the barrel length is not listed.

The data listed:
54.5 grains 4350 - 2920 fps
58.0 grains 4350 - 3305 "
59.0 grains 4350 - 3395 "

56.0 grains 4831 - 2730 fps
57.0 grains 4831 - 2920 "

I have been using a 257 Weatherby with a 7 twist barrel for about 1 year, and have chronographed various bullet weights up to and including the Wildcat 156 grain ULD (1.550 inches).

The new Norma 257 Weatherby brass has a capacity of 87.8 grains, and increases to about 90.8 grains after firing and neck sizing.

I estimate that the 257W would have at least 5 grains more capacity than the 257Condor which uses the shorter Norma 7x61S&H brass.

Based on my experience with the 257W, I find that the velocities of 3305 and 3395 listed above for 58.0 and 59.0 grains respectively of 4350 are unrealistic and way over the top.

I struggle to get 2900 fps with the 156 grain bullet using Norma 257W brass, and get about 2950 - 2975 with cases formed from 300 WM brass. Some of my data with the 156 grains bullet using a Krieger 26 inch 7 twist barrel:
Norma 257W brass
63.0 grains Viht N170 - 2791 fps (Max)
65.0 grains AR2225 (HRetumbo) - 2855 fps (Max)
69.0 grains H870 - 2881 fps (Max)
70.0 grains AR2218 (H50BMG) - 2871 fps (Max)

Remington 300WM brass
69.0 grains AR2218 - 2962 fps (Max)

Hope that the above is of some help. Brian.

Brian

What does that 156 gr ULD bullet look like? Is it two diameter? If not, what length freebore does your chamber have. Or do you seat it deep in the case?

Do you make them yourself or where do you get them?

Interesting information that you gave.

Ray

Ray, I will have to look up how to post a graphic on the website before I can display pictures of the Wildcat 156 grain ULD, 142 grain ULD, 130 BCFBHP, etc.

Richard Graves is the proprietor of Wildcat Bullets and lives in Alberta, Canada, and can be contacted at wildcatbullets@hotmail.com. He is a very busy man as he is a farmer, welder, and bulletmaker in that order, so there may be a delay in his responding to emails.

The 156 grain ULD is made using a tapered Corbin jacket, and is 1.550 inches in length, has a Sectional Density of .337, and a very high Ballistic Coefficient. Due to is construction and sectional density it penetrates extremely well.

My 257W is based on the Rem 700 LA, and I wanted the loaded rounds to operate within the constraints of the magazine length of about 3.650 inches. I also wanted the overall length of the loaded round to be 3.550 inches, to allow me about .100 inches for chasing the lands as throat erosion occured.

My gunsmith has throated the rifle so that the boat tail (.160 inches) of the 142 grain ULD (1.362 in) is projecting below the base of the neck. Consequently when the 156 grain bullet is seated about .010 from the lands, there is about .360 inches projecting below the base of the neck.

The amount projecting below the base of the neck does cause any problems, as the maximum load of 70.0 grains of AR2218 (H50BMG in US) only represents a load density of about 89%.

Luckily the Nosler 100 and 115 BT's are tough bullets, and withstand the 340,000 - 370,000 rpm that are generated at top velocities in a 7 twist barrel. The ability to use these bullet weights certainly increases the flexibility of the rifle.

However, the velocities I am achieving with bullets in the 100 - 156 grain range in the 257W when using Norma brass are only about 20fps more than what I achieve in my 25/06AI.

Using Remington 300WM brass has increased that 20 fps advantage by another 75-100 fps, and in the future I might at some stage try some Lapua or RWS 300WM brass to see if any more can be gained.

Hope that the above is of some help. Brian.

Ray, I just noticed a typo in my previous post.

I meant to say that "the amount projecting below the base of the neck does NOT cause any problems, as the maximum load of 70.0 grains/AR2218 only represents a load density of 89%. Brian.

Brian

Thanks for all that good information.

So I assume that the chamber throat is not much (or any) different than in a conventional rifle?

I'd like to see those long bullets if you get a chance to post a photo. I'll also contact Richard. But the current state of border uneasiness has just about halted all legal transfer of things such as bullets, brass, powder between the USA and Canada. (Note that I said "legal")

Thanks again.

Ray