Can enyone tell me what the C.U.P. level is ?I can not get JD to answer this.

It is very possible that Jones does NOT know the CUP for the round. Many max loads have been worked up for the Contender on smoke, mirrors, mojo, and some have even used scientific methods.
Measured pressures get a little more expensive, though less so now with the advent of the model 43 ballistics lab from Oehler.

If all of you will chip in and buy me a model 43, a buncha powder, bullets, and Contender barrels, I will work up data for each of the chamberings/loadings!

Nice guy that I am

LouisB

Oh and a scope for each please!

Hint: My aging Accurate Arms loading manual gives pressures for the .309 JDJ loads it lists. As I recall, none of the loads exceed 45,000 psi, which I always found interesting. Top loads in the AA manual with 165 gr. bullets are around 2200 fps, yet through some twist of metaphysics, JD espouses a load or two that shoves a 165 gr. out at 2400 fps.

A call to Hornady could prove interesting. The question I have often wanted answered is whether they pressure tested any of his data they publish or if they simply did as Sierra did many years ago with Bob Milek's data and simply printed it without verifying what the pressures were.

Then there is the question as to what the Contender will routinely withstand.

There is a margin between what is prudent and safe and what you can get away with.

Without having pressure test equipment, flying by the seat of my pants I have come up with things that work, experientially.

While the strength of the case enters into the picture, with its thinner brass .300 Savage factory loads at about 46,000 psi are marginal..... very prone to extraction problems, ie., borderline too hot.

Yet I have shot many hundreds of rounds of factory .444 Marlin ammo test firing. .444 Marlin is about a 44,300 psi round and is flawless in the Contender.

One can shoot factory .307 Win. ammo, which crowds the 50,000 psi mark, in Don Bower's .30 Alaskan chambers and get away with it, but it is not recommended. If you section a .307 Win. case and a .444 Marlin case, you will find the .307s about half again thicker than .444s measured at the same point near the web of the case. However, the .307 brass appears to be much softer than .444 brass. Working with the same wildcat rounds made from both .307 and .444 Marlin brass, I have a hard time telling the difference in allowable pressures with each. .307s may have some advantage, but not much.

With any .444 Marlin based round, such as the .309 JDJ, a prudent pressure is about 45,000 psi, based on comparisons in behavior noted shooting approx. 45,000 psi factory ammo.... namely .250 Savage, .300 Savage, and .444 Marlin.... all with the same head size.

Much of the above was used as a basis for the max. pressure determination method I use and Don Shearer more scientifically refined.

What you can get away with most of the time and what is prudent can be quite different.

For the benefit of those who have not been there yet, there are articles about Contender pressures, including Don Shearer's work, on my site: www.bellmtcs.com

Mike

[ 01-27-2003, 12:49: Message edited by: Mike Bellm ]