Is powder scalable? IMR 4198. Can you estimate bullet loads?

[PendletonCowboy]

I have came across several occasions where the load data is missing for the bullet grain that I need. It seems there is more data for the heavier loads than the light ones. So I ask you, can you scale the load data down or up for that particular powder to the bullet you are trying to load for? To me it seems logical and doable. Below are the bullets I would like to scale to given the data I have for the 80,90 and 100 grain bullets for a .243.

Speer IMR 4198

50 grain - 13.0 - 15.0?
55 grain - 13.5 - 15.5?
60 grain - 14.0 - 16.0?
70 grain - 15.0 - 17.0?
80 grain - 16.0 - 18.0 (Data from Speer)
90 grain - 17.0 - 19.0 (Data from Speer)
100 grain - 18.0 - 20.0 (Data from Speer)

Thanks for the feedback!

 

[PendletonCowboy]

Thanks for the post.
Yes those are the low and high grains charge range for the grain of bullets according to Speer manual #14 that was sent to me by Speer.

Example (from Speer)
Using IMR4198 Start: 16.0 w/velocity of 1801. Max load 18.0 w/velocity of 2037.

Is it plausible to use the 16.0 grains on a 55 grain bullet w/o worry?

 

[cliffy]

First, I'd not use H4198 in a .243 Winchester, but, yes, in a .223 Remington fast, light load. Second, with 100 grain .243 bullets, I'd use IMR 4350 or slower-burning powder, preferably slower. Third, I'd recommend Alliant RL-22 for 100 grain .243 Bullets. I have some Hodgdon H4350 loads developed for 100 grain .243 loads, but they are quite HOT & FAST. If you are using .243 85 grain Barnes TSX, to be politically correct lead-freewise within our "green" environment, I find 45 grains of Hodgdon H414 powder hitting 3300+ fps at 70 degrees at 700 feet of altitude, quite politically correct as a proper deer blaster. We all want to be politically correct, so long as we don't merely wound our quarry. Cliffy

 

[jerrschmitt]

First, I'd not use H4198 in a .243 Winchester, but, yes, in a .223 Remington fast, light load. Second, with 100 grain .243 bullets, I'd use IMR 4350 or slower-burning powder, preferably slower. Third, I'd recommend Alliant RL-22 for 100 grain .243 Bullets. I have some Hodgdon H4350 loads developed for 100 grain .243 loads, but they are quite HOT & FAST. If you are using .243 85 grain Barnes TSX, to be politically correct lead-freewise within our "green" environment, I find 45 grains of Hodgdon H414 powder hitting 3300+ fps at 70 degrees at 700 feet of altitude, quite politically correct as a proper deer blaster. We all want to be politically correct, so long as we don't merely wound our quarry. Cliffy

No, not all of us.

 

[LHSmith]

NO, I would not guess at safe charge rates. There are web-sites like Hodgedon's that provide you with safe load data.

 

[Rust]

No, powder charges are not scalable across a wide bullet weight range. If you cannot find data for a particular powder and bullet weight from the several loading manuals available on line, there is probably a good reason for it.

 

[KevinThomas]

Hey Pendleton,

I haven't seen anyone else mention this in the thread so far, but I assume that you're using 4198 to develop reduced loads? In that case, it's a good choice, but data is likely to be hard to find. Speer is one of the few sources that has traditionally listed reduced loads, and this is one of the powders that is normally used for this application. With that said, there is some flexibility in this, but I'd be very cautious about scaling loading data like this. The short answer is, no, you can't do it . . . not safely, anyway. The upside is, this powder is a lot more flexible where reduced loads are concerned, and you're not going to see the sort of pressure excursions that you may/will with more traditional 243 powders (H414, 4350, 4831, etc.). Still, try to ferret out lab tested data for this if at all possible. Speer has usually been a good source for this, as has Lyman. IMR used to offer several powder that were specifically intended for reduced loads in rifles, and this data should now be available through Hodgdon. Look up SR-4759 and there may well be some data for this combination. Another one that sees this sort of use is Accurate Arms 5744, so you might check the Accurate website as well. What exactly are you working up here, and what's the intended purpose?

Kevin Thomas
Lapua USA

 

[PendletonCowboy]

Thanks guys for the info. The intent here is to get my 2 children familiar and comfortable with the rifles as I work the load rates higher as the hunting season approaches. This reduced load adventure seems to be a task if you want to use a lighter weight bullet with no load data!!

 

[GSPV]

You're extrapolating linearly. You really, really don't want to do that.

 

[Rust]

Here's the problem with scaling charges, at some point going towards either very heavy charges or very light charges the powder burn rate can become either non-linear fast (think detonation in an engine) or slow (think sort of hang fire like), and at the very least inconsistant (think hanging a bullet up halfway down the barrel and then pulling the trigger on the next round).

P.O. Ackley succeeded in blowing up rifles with light powder charges and low case fill, although he never really determined the exact process that caused it, just proved it did happen.

And while IMR 4198 is a fast powder which lends itself to reduced loads, it doesn't give a lot of case fill for weight which is to be avoided. I believe IMR and others used to list light charge loads using IMR 4227, if I remember correctly. I don't have my references with me. This may be a more suitable powder for light loads.

 

[js223]

Another vote for using tested data here. No good reason to extrapolate. That Speer 80@1801 load you listed would be only about 2 ft/lb of recoil in a 7 lb rifle. That should be fine for teaching the children how to shoot it. Lyman's Cast Bullet Handbook has some mild loads too, meant for cast bullets of course. Check the other sources suggested by Mr Thomas as well.