(duplicate post on the Big Bore forum, by the way)

Well, I finally arrived at a light practice load that works in my double rifle. 75 grains of IMR 3031, Fed 215 primers (probably not critical), Bell cases (ditto), some dacron fibers on top, and a Hawk 350 grain .035 bullet, diameter .474 (NOT .475).

I've had problems getting the breech to close without forcing it. Between chamfering the case mouth and the slightly smaller bullets (custom order from Hawk - nice folks!), this cartridge loads easily and shoots to the regulated point of aim at 50 yards. More or less, anyway.

Shot a box of them today, and was absolutely having a wonderful time. Thought I would share. I got the loading data from this forum, and my only improvement was the chamfering and the slightly smaller bullets, apparently needed for my Chapuis.

Hope this helps some other folks. As for me, practice is looming ever larger as both enjoyable and necessary. I leave August 28th to go use the 470 for real. :>

HT,
Thats the old recipe that ringed many a chamber btw...

I would suggest 44 grs. of XMP 5744, with enough dacron to pack solid and a 500 gr. lead bullet...that will normally zero in most guns...

I take Mr. Atkinson's observations very seriously. So please take my recipe with a large dose of caution.

Here's what I found out about chamber ringing -- article by Norm Johnson (http://www.schuetzen.net/chamber_ringing.htm)

"The use of wads and fillers to hold the powder back against the flash hole has resulted in the ringing of numerous chambers, especially those of straight walled cases such as the 45-70. Ringing is a radial enlargement of the chamber, usually occurring at the base of the bullet in a cylindrical portion of the chamber, i.e., in the body of the chamber or in the neck of the chamber but, as far as I know, not in the transition of the two. It can happen either suddenly (one shot) or gradually over a series of shots.

This phenomena was first recognized (to my knowledge) in the early seventies by serious cast bullet shooters. The word has been long getting out but, although infrequent, the ringing has ruined many a chamber. The NRA and the Cast Bullet Association have for quite some time recommended that no fillers or wads be used in any loads where they are positioned against the powder so as to leave an air space between the wad/filler and the bullet base.

The reason for ringing has not been established, but some hold that the wad or filler is propelled forward and when it strikes the base of the bullet, the bullet acts as a secondary projectile and rings the chamber (in the same manner that a bulged barrel is likely to occur if a bullet is lodged in the barrel and another is fired behind it).

Two methods are commonly used to avoid the above discussed problems of powder position sensitivity and chamber ringing.

1) Select powders that fill the case enough to avoid a powder positioning problem so that no filler is needed.

2) Position the powder by raising or lowering the rifle muzzle before each shot - again no filler required."

So, it's back to the drawing board. :<

Thanks, Bob. I had actually typed my reply to Ray Atkinson's posting, and happened to overlap your response. I hadn't seen yours when I typed mine, in other words. So no offense intended.

The problem with these dang expensive rifles is you can't afford to screw one of them up. So, while I believe the lighter bullet probably does make a difference, I'll see what else I can do in place of taking a chance on ruining the rifle. Something will work out, I'm sure.

HT and others.

I have shot over 1000 [one thousand] loads with filler in my 450 No2. That case is so large that with modern powders a filler is necessary with all the powders I have used which include IMR 4198 [nitro for black loads] IMR 3031, IMR 4831 and RL-15. I did extensive research on the chamber ringing problem. I can not find a single occurance where a chamber was damaged IF the filler was compressed between the bullet and the powder. I have used Dacron and two different types of foam that I cut out with a chamfered 50 BMG case. I have had no problems. When I use RL-15 in my 450/400 3 1/4" I use the foam filler also.

The "secret" is to be sure the filler is COMPRESSED.

HT, for an even lighter load try this Nitro For Black load with your 350 grain Hawks, start with 50grains of IMR 4198 [I use 15 grains of poly, just be sure it is COMPRESSED] and work your way up until you hit to the sights at 50 yards, looking for standard pressure signs of course. Your velocity should be around 1800 fps.

This load is also powerful enough for deer and wild pigs.

A 500grain bullet at @2100fps and a 350grain bullet at @2300fps will have the same trajectory all the way to 300 yards. This is true for the 458 bore and the 470 bore. In the 400 bore it works with 400 grain bullets at 2150 and 300 grain bullets at 2300fps. [Look in the Hornady trajectory book and check my math if you want there might be an inch or two difference, but who can hold an inch or two at 100/200/or300 with iron sights?]. The 350 grain at 1800fps will hit lower at 100, but if you can find a load that hits with the sights at 50 it is easy to hold a little high for a 100 yard shot.

N E 450 No2,

Thanks for your input!

-Bob F.

You are most welcome. I edited my post to make it more clear.
My standard 350grain load for my 450 No2 is 81grains of IMR 3031 with the filler. I now use 88grains of RL-15 with all the 480 and 500grain bullets, soft and solid, with the foam filler. They all hit close enough together at 100 yards so I do not have to cannge my aiming point.
RL-15 will work for the 350grain bullets too, it is just that I have a lot of 3031 on hand.