Are these powders close to interchangeable? I am not asking identical, I am asking will I blow up the gun if I use the same charge of the H powder as I would of the IMR?
Thanks, Peter.

They are not interchangeable. IMR burnes faster than H4831. The Max load for IMR is usually a couple grains less. If you used H instead of a load for IMR it shouldn't be a problem.

quote:

Originally posted by Peter:
Are these powders close to interchangeable? I am not asking identical, I am asking will I blow up the gun if I use the same charge of the H powder as I would of the IMR?
Thanks, Peter.

You won't blow up your gun but you might stick the bolt.

These two powders are only similar.....use the correst data for the powder you're using.

The bottle of H4831 I have is a lot slower than my IMR4831. Seems to be almost as slow as RL22.

For me, the IMR4831 has worked a lot better for velocity and accuracy in my 270 and 30-06.

What round are you loading Peter??

I was afraid you'd ask! The Double Rifle quotes a load of 95grains of IMR 4831 for my 450 x 3 1/4. I don't have any of the IMR, but have close to a bottle of the H4831. Hence my question.
Peter.

quote:

Originally posted by Peter:
I was afraid you'd ask! The Double Rifle quotes a load of 95grains of IMR 4831 for my 450 x 3 1/4. I don't have any of the IMR, but have close to a bottle of the H4831. Hence my question.
Peter.

Bolt actions are far more forgiving to reloaders. They typically hold a lot more pressure than the books show.....and the case is the fuse with most bolts. With the double I'd not even think of loading anything except the exact published load.

IMO with double rifles the rules change and it's not a game I understand. I've never loaded for one and likely never will. If I ever do it'll be exact loads only....no screwing around.

I made that mistake once---never again!
My first reloading book 30 years ago didn't indicate any difference. So I accidently used IMR instead of H-4831 and blew so many primers out of the back of the cartridges that it's scary. In those days I was younger and didn't the difference. Even had to take the rifle to a gunsmith once to have him open the bolt after firing one of these rounds.
After that I pulled apart all the remaining loaded rounds that I hadn't shot, over 50, and
burnt the powder.

quote:

Originally posted by Peter:
...The Double Rifle quotes a load of 95grains of IMR 4831 for my 450 x 3 1/4. ...

Hey Peter, I'd "guess" you also need to use the exact same Bullet quoted in that Load. Otherwise, the rifle's barrels might not be regulated to hit properly.

Some of the guys on "Big Bores" that use Doubles can probably say if my "guess" about the Bullet is full of beans or not.

Hot Core, yes the bullet is the same - Woodleigh Soft Point, 480 grains.
Peter.

Hey Peter, I've never had a rifle like yours, so the majority of my thoughs below are just "speculation".

I do know how difficult it is to get "Accurate" Loads in the rifles I've used over the years that have just "one barrel".

In your situation with the two barrels, the entire Accuracy situation is different. Not only must the left barrel have to shoot the bullet to a specific spot, but the right one must be relatively close to that exact same spot. And it needs to do that at a specific distance for the Double to be considered properly Regulated(I think ).

On the other hand, you might Develop a Load from below with the H4831 that is even more Accurate, have less Pressure and similar Velocity. I would "guess" the cost of doing that Load Development would be fairly high with those bullets, but again, I don't know and the cost might not matter at all to you.

I would highly recommend you use both CHE and PRE to compare your Pressure to some Factory Ammo. Simply going by Velocity from a chronograph might mislead you into thinking the Pressure is OK when it really isn't.

And be sure to talk to the guys on Big Bores.

Best of luck to you.

I was loading the 264 mag with Barnes X's and the manual didn't state the difference. Actually the shop suggested that powder and loading manual. Well with the X bullet and a few extra grains of powder... WOW... Stuck the bolt and had smoke coming out of the vent. I wasn't even at maximum.....................

Well, I was at the range yesterday and the range shop had some IMR 4831, so, speculation over! I will use it.
Hot Core you are correct. Just because someone in Australia has some really good loads for IMR 4831, doesn't mean that you can't get the same or better with H4831. However, at $1 per bullet, the cost of load development gets rather high!
Peter.

quote:

Originally posted by Hot Core:

In your situation with the two barrels, the entire Accuracy situation is different. Not only must the left barrel have to shoot the bullet to a specific spot, but the right one must be relatively close to that exact same spot. And it needs to do that at a specific distance for the Double to be considered properly Regulated(I think ).

On the other hand, you might Develop a Load from below with the H4831 that is even more Accurate, have less Pressure and similar Velocity. I would "guess" the cost of doing that Load Development would be fairly high with those bullets, but again, I don't know and the cost might not matter at all to you.

I would highly recommend you use both CHE and PRE to compare your Pressure to some Factory Ammo. Simply going by Velocity from a chronograph might mislead you into thinking the Pressure is OK when it really isn't.

And be sure to talk to the guys on Big Bores.

Best of luck to you.

HOT CORE, you are pritty close in you take on this type of loading. I'd say much closer than most who do not load for double rifles I've read. However there are some things that are not worries, about the use of H-4831 instead of a reccomended IMR-4831 load. Since the H-4831 is slower that the IMR version, you can safely start with the IMR reccomended load without worry, in a cartridge like the 450NE 3 1/4", and work up very carefully! As you suggest, the H load may actually shoot to regulation better than the reccomended load of IMR.

As to the cost of bullets in working up loads for this round, the .458 dia is one of the easiest loads ot work with in a double rifle. You can order some HAWK 480 gr bullets with the .35" jackets, and work up to a proper load, then switch to the Woodliegh bullets to fine tune. In the case of many NE rounds, any bullet you use will be expensive.

PETER , the IMR load when useing H-4831 will be the same as backing off the IMR load by about 1.5 grs. With this load useing the H-4831, if it is close, I wouldn't go higher on the powder till I tried the same load with enough Dacron fiber fill to be slightly compressed by seating the bullet, without crimping. If that is closer yet, then I would use the same load/filler, and crimp. That should do it.

The formula for useing IMR-4831 is:

Factory Cordite load X 1.33 = IMR-4831 load

In this case the 450NE/480 gr bullet:

70 grs Cordite X 1.33 = 93.1 grs of IMR 4831

This formula is for a low starting load, and if your rifle has been shooting 95 grs of IMR-4831 with a 480 gr woodliegh, then the 95 grs of H-4831 will be low and give you 2.9 grns to move up. However, I'd be sure that was a proper load, and find out where it came from!

The regulation, when properly loaded will print two barrel groups, with the center of each group equal distances on each side of point of aim, so that the extreme left hole from the RIGHT barrel,will be no wider than the center of the left barrel group, and vice-versa.
Example: If each barrel is shooting a 2" group with the right barrel printing it's group center 1"on the right of point of aim, and the left group center 1" on the left of point of aim, the your composite group will be a 2" COMP- GROUP, and will shoot side by side, no matter the range. The comp-group will just get bigger as it goes farther, but do not, contrary to popular belief, cross! The last thing you want in a double rifle is all bullets makeing one ragged hole, if it does that, it is crossing at that point, and will continue to get cross more as it travels.

You probably already know this, but I'll say it for those who don't! When benching a double rifle the rifle should not touch anything other than your hands, shoulder, and face. A double rifle absolutely must be allowed to recoil as it would when shooting off hand, and fired in a rt,lft,rt,lft scquince, shooting no more than four shots in a string, starting from cool barrels. Barrels should be alowed to cool back to ambiant temprature before the next four shot group. Doubles are designed to be fired from cool barrels as in hunting conditions.

You need to visit, African hunting, Bigbore, forums on AR, and double rifle, and Bigbore on NitroExpress website. There is a wealth of information on the care and feeding of double rifles there!

Hey Mac, You were one of the guys I was thinking about when I tried to head Peter over to Big Bores.

As I read what you posted, the information about the Bullets "not crossing sides" makes a lot of sense.

Anyway, real glad you showed up to head Peter in the right direction without all "my" speculating.

I have found they are not the same powder, and can't use the same data....

I find IMRs version more accurate and more consistent....

I have found Hodgdons, to allow faster velocity and to be more forgiving in getting close to max pressures than IMR...

so let your conscience be your guide on what is the most important to you, in your loading techniques and what you want out of your rifle...

cheers
seafire