I have finished chambering a 338x284 Improved chamber for a 98 Mexican Mauser with the crush fit at the neck. I have chambered Improved rounds before...fireformed them with standard ammo and then reloaded from there.Not a problem.
Problem is this is not a factory round and it's also Improved. I have a lot of Vihtavuori N150 that I use in my 338/06 and want to use this powder to fireform my brass. Can't find any load data for the 338/284 Improved using this powder.
This is my first wildcat cartridge and wondering what would be the right load for this round? Can I use the same 55 grains in this round that I used in the 338/06 SAFELY? I want to use a good load and not use the cream of wheat method. Anybody have any experience with this round or something similar that has messed with wildcats... I need to know what a safe load would be, would you please chime in?
Thank You!

quote:

Can I use the same 55 grains in this round that I used in the 338/06 SAFELY?

How does the case capacity compare? What bullet?

Just how much did you "improve" the 284 case...??...the 284 case is just about as improved as you can get already...unless you reduced the wall taper to a bare minimum...you said you had a crush fit on the shoulder so the neck is the same length...about all you could gain is 0.015" or so on the shoulder OD...sounds like.

Even then you probably only gained 4-8 gr more volume...

Doesn't really matter as the case volume between the two are very close...just drop your 338-06 load 10% and work up your load as you fireform. As long as you have a crush fit on the shoulder you won't have to worry about headspace problems.

It should be a good'un...

Luck

quote:

How does the case capacity compare?

Good Question? (dont know)! 180 gr. bullet.
Norma 6.5x284 resized to standard 338x284 useing Redding die. Chamber is Improved with 38* shoulder and less taper.
Have not had a chance to check between the two, yet.

Found this reamer at about a fourth of the cost to have a standard reamer cut, thanks to an AR member here!

Thanks Foobar!

Thats kind of what I was thinking, just didnt want to screw up many hours of riflebuilding...

I'm not a gunsmith or a machinist but I've been doing this thing for over half a century and EVERY rifle I build gives me the "wonders" for the first round...I always wonder if I cut the chamber too close and will have to muck about with the sizing die or shell holder to get a good resize or if I slipped at the last moment and cut it too deep...or one of a hundred other questions that turns a rifle project into a jack handle.

It doesn't matter that most of the things we worry about initially are insignificant compared to all the rest of the system and what needs to be done to make it all turn into a thing of beauty and a joy forever.

EVERY rifle I build is a new baby and I want it to be perfect and grow up to be leader of the world. ...it never is or does, but that's because I'M imperfect and so it the rest of the world.

Luck

FYI QL calls a 180gr nosler in front of 55gr on N150 in a 338-06 as 44500psi even cutting the volume y 10% you are still at 59,000.

WEre you using the 55grs a a forming load? If so were you getting a sharp shoulder?

44500-4450(10%) = 40050...where does 59,000 come in? ...maybe 39000 is closer.

Whoops. Hahahahahaha

Luck

quote:

44500-4450(10%) = 40050...where does 59,000 come in?

Maybe I did a poor job of explaining. I don't have the volume of a 338-284 case much less a 338-284Imp. But a 30-284 is about 2% smaller than a 30-06.

Running his 55gr load in a straight 338-06 with a 180 the pressure is 44,500. If the 338-284Imp is larger in capacity than the 338-06 then the pressure should be lower. Since he didn't know the volume I just took a radical case and said if the case capcity of the 338-284Imp was 10% less than the 338-06(VERY unlikely)the 55gr load would generate a calculated pressure of only 59,000 while high should still be safe.

I was reducing volume not pressure by 10%.

A 338-284 case volume, standard 284 case necked up without any other changes, is ~72.3 gr H2O according to my sources...BUT...the only way to know for certain is to do the weighing.

The additional amount of H2O in a 38° shoulder angle, ~0.015" shoulder expansion is ~2.4 gr H2O running it through a custom case design program. You can get that amount and more between different case brands or lots, and is really not enough to be concerned about...UNLESS...you happen to be running loads at the ragged edge of destruction.

As you said, if the previous 55 gr load of N-150 is safe in his 338-06, then dropping it to 50 gr would still be safe...

My long throated 338-06 case volume is 71 gr using a 225 gr Hornady SP and IMR4320 powder a tad over ~2700fs is ~53-55KCUP load in a R-P 35 Whelen case.

MORE data, srtrax....we need more data...give us the H2O volume weight so we can play more.

Luck

O>K> I done this rather quick, to many arms in the fire!

Unfired/but sized to 338/284...with water filled to very top of case, 81.9 grains of water.

338/06 fired case= 90.1 grains of water filled to the very top of case also.

Both case are Norma brass.

I dont question the chamber, I question the load I should use to get a nice fireformed cartridge the first go around without blowing up my work or myself.
I usally have published data to go by and use it as I check every chamber before I start the finishing of the rifle, mine or a customers. I'll take the barreled reciever to the range and fire a couple rounds into the ground. I get a kick from thoes that dont know what I am doing...I get to tell them "well the first shot hit what it was aiming at". I usally hold on to it but could tie it down and with a string to trip the trigger.
Guns not finished but I can see light at the end of the tunnel.

Hummmmmm....those numbers are way beyond any 30-06 or 284 cases I've come across, Norma included. I've seen some belted mag 338 wildcats with weights in the 85-95 gr range, but not any '06 cases.

Forget what I've said...I'm backing out...not saying you're wrong, but barring my actually seeing and weighing one of those cases, my numbers will be way wrong.

Luck

quote:

O>K> I done this rather quick, to many arms in the fire!

I'm sorry, miss read the scale, done this and posted a few minutes before I had to be somewhere's.
Corrections are.....
338/284 = 61.9 grs. h2o
338/06 = 70.1 grs. h2o

The 338-284 weight seems a tad low...my 6mm-284 is 65gr, just the 6.5 case necked down with no other changes, so the larger 338 neck would bring it up a bit...roughly 4 gr H2O difference between the two cases in the volumes.

I used the 338-284 Canadian KCG case volume of ~72 gr for a comparison which is a 284 case necked up without any other changes...~65 gr for my 6mm-284 plus ~4 difference gives ~69-70 gr...that's close enough for initial work...water is heavy and it doesn't take much to mess up the measurements.

Post the base to shoulder length - should be close to 1.775", base to the bottom of the neck length - should be close to 1.885" and the OD at the shoulder/case wall junction - should be ~0.485" - 0.490" for your improved version...I can come up with what should be a close approximation of the case volume.

Easiest way to find case volumes is to use a digital scale...put the case on the scale THEN turn it on or tare it out after turning on...fill the case with water to the top then use a paper towel to pull off the "bubble" that ususally forms at the top of the case - using a eye dropper, small squirt bottle, or I've used syringes you can buy from any feed store for large animal injections...if you don't look like a druggy you'll have no problems. I mostly use a 30 year old saline water squirt bottle about 2" hi by 1.5" wide...it works down to 22 cal, but for 20 and 17 cals I use a syringe.

Taring the case weight out first will give you a direct reading to use...no adding or subtracting and with a digital scale you can see the weight coming up as you fill the case.

I only do one or two cases just to get a rough number to use to start load development...in the bad old days when I was benchresting and competing I did it to EVERY case after shooting them and picking the cases that always hit the same point of aim...just to see if the case volumes were identical. They weren't identical but they WERE always very close.

A lot of things have changed in those 30 odd years and makes things so much easier...less time working on brass and more time banging away.

Luck

1.772 = base to shoulder
1.881 = base to bottom of neck length
.471 shoulder case junction, its unfired and not in its improved state.

I dont play with the reloading like I use to. Accurate loads have seem to come easy for some reason. I havent even had the conagraph (sp) out in years. No digital scales, but does sound like something to put on a santa clause list!

Those numbers are basically a standard 284 case...doesn't help much...I need the fired case dimensions.

No need for a digital scale...I used a Ohaus 1010 for many years and the old oil dampened beam scale before that.

You can get a 0.001g resolution digital scale, good for 0.015gr accuracy for $60-70...literaly TONS of ChiCom stuff all over the net. China is gonna bury us unless we get out heads out of out butts...you better start learning to speak and read Chinese, because Americans have NO CLUE what's coming down the Pike.

Luck.

Fireformed and fired first round in my project rifle today. All worked out well!
1st cartridge...6.5x284
2nd cartridge...resized to 338x284 (66.6 grains of H2o)
3rd cartridge is 338x284 improved (69.9 grains of H2o)
I fireformed it with 180gr. bullet and 50 grs. of Viv. N150.
My 338x06 holds 71.1 grains of H2o, so this will be pretty much the same gun but in a nicer package. The reamer I got on the cheap...new but at a special price. Didnt matter if it was standard or improved...but I've played with some improved cartridges in the past and the 3 or4 grains dont mean a whole lot. I do like the fact there is less bolt thrust and less case streching! Got it done, now all I have left to do is finish work.

As the original shoulder angle of the 284 case is already 35 deg and I would guess you are only improving the angle to 40deg or so I would [personally] use 10-12 grs of Bullseye and a el-cheapo bullet to fireform to the new chamber. Reason is this! Slow burning powder will do the trick. Lord knows Rocky Gibbs used full loads of 4831 to do his thing and it worked. BUT! It also stressed the hell out of the brass. Thus less case life. The fast burning powder "pops" the shoulder forward to the imp design without the high pressures of the slow powders. This is what I was told by the likes of Ken Waters and P.O. Ackley himself. I tried it back in the early 70s and it worked then and now. As long as you have a "crush" fit on the brass in the new chamber you will be ok as the case has nowhere to go except to alter itself into the new design. If HOWEVER it is loose the outcome could be very different. I have been necking cases up and down for over 35 years and have always used the same methods. Necking up to 338? I neck up to 35 or 375 and then neck back down to 338 creating the "artificial shoulder" necessary to hold the case against the bolt for proper headspace. I am sure you will enjoy the 338/284 IMP as I did. I did have a few feeding issues but finally got them solved. I sold mine a few years ago to a guy who uses it for elk on the eastern side of Oregon. It is a killing machine and does as well as a magnum without the weight and recoil.

Thank you for the information, I know you have played with this round a bunch from some of your other posts!