How Linear Is Loading Data

[MichiganShootist]

I use Titegroup powder for reloading 45 ACP..... and have done so for 5 years.

The Hodgdon data for 230 Grain FMJs is

4.4 grains yields 744 fps = PF of 171 (171,120)

4.8 grains yields 818 fps = PF of 188 (188,140)

Can it be taken that changing the grains will produce a linear change in speed?????

If they supplied one more set of numbers it would be a basic algebra problem to calculate how many grains you would use to produce a 150 PF load for example.... But with only 2 sets of data I can't tell.

Linear or not??????????

[larry cazes]

Are you asking about the linearity of the loading DATA or the powder burn rate characteristics? Assuming powder burn rate, I would assume it is not and of course it will vary by powder.

[Hi-Power Jack]

I use Titegroup powder for reloading 45 ACP..... and have done so for 5 years.

The Hodgdon data for 230 Grain FMJs is

4.4 grains yields 744 fps = PF of 171 (171,120)

4.8 grains yields 818 fps = PF of 188 (188,140)

Can it be taken that changing the grains will produce a linear change in speed?????

If they supplied one more set of numbers it would be a basic algebra problem to calculate how many grains you would use to produce a 150 PF load for example.... But with only 2 sets of data I can't tell.

Linear or not??????????

I'll take a quick stab based on 50 years of reloading experience,

until the many experts give you a precise answer.

NO - there's a minimum and maximum. And powders tend to

max out - add .2 grain and get no more velocity; Go too low

and that can present a problem as well.

I guess there is a certain amount of linearity to a degree,

within certain limits for each powder / caliber combo -

but Your answer is NO. Don't try it at home without trying

small increments, a reloading guide for that powder, and a

chronograph.

If you post what velocity you want to achieve with what bullet,

there's someone here who can tell you how much powder to use -

might even find it on a search of old postings.

[MichiganShootist]

I don't want to switch powders or compare powders...... I'm just trying to determine how linear the relationship between powder charge and speed is....

So that I could pretty accurately calculate the charge which would yield a given speed..when the bullet type and weight is a constant.

[twodownzero]

It's fairly linear within the range between min and max in the book. Get anywhere outside that range and you're in completely uncharted territory.

If you want your bullets to go slower, use a faster burning powder. Downloading a slower powder than necessary is going to be dirty, unreliable, and result in unpredictable swings of velocity/large ES and SD.

A 230 grain .45 at 650 fps is going to be a mouse fart and drop like a rock as well.

It'd seem that what you actually want is a 9mm.

[Joe4d]

From what I have observed it is pretty linear between a minimum and maximum. Go lower and your charge density gets too low and you end up inconsistent, on the upper end you get pressure spikes and again inconsitencies, If you take your TG load and load really light, then work up .2 grs at a time, and graph it you'll see what I mean, you end up with a zig zaggy line, going to a sloped fairly even raise then the line kinda plateaus off for a bit. I have found TG to be not to good at low charge density, Something that takes up alot of space might give better results, Clays for instance,

[MichiganShootist]

Thanks... I have more than a couple 9 mms.....

I have arthritus in my thumbs... and and carpel tunnel syndrome.....and was just looking to down load some ammo for close range practice. I load my IDPA/USPSA loads at 171 PF and thought something a little softer for practice (especially indoors) would make sense as long as it was still accurate enough for that kind of "work".

I just don't want to grind out a bunch of practice loads only to find that there is little if any reduction in felt recoil. The "starting load" for Titegroup is over 171 PF.

[Joe4d]

When I first started shooting all I had was a 40 and there was zero data out there for anything but full power loads, I did try TG and 155 bullets and found my groups to open up quite a bit when I got below 140 pf, I know a few older guys with hand problems that shoot Para wide body .45's in IDPA, ESP, they like Clays or WST because of the higher volume to grain, and 200 grain bullets, loaded to about 130pf I have SO'd them and I swear I can see the bullets going down range. The guns dont move either, they kinda go cachunk, ca chunk.

[MichiganShootist]

"cachunk, ca chunk"

That's what I'm talking about Joe...... the problem is I own over 8 pounds of Titegroup and 10K+ 230 Zeros..... and plenty of single stacks:)

Edited February 25, 2011 by MichiganShootist

[CocoBolo]

Thanks... I have more than a couple 9 mms.....

I have arthritus in my thumbs... and and carpel tunnel syndrome.....and was just looking to down load some ammo for close range practice. I load my IDPA/USPSA loads at 171 PF and thought something a little softer for practice (especially indoors) would make sense as long as it was still accurate enough for that kind of "work".

I just don't want to grind out a bunch of practice loads only to find that there is little if any reduction in felt recoil. The "starting load" for Titegroup is over 171 PF.

The softest shooting 45 Load I have tried is Clays about 3.8 w/230gr or 4.3w/200gr puts you at 168-170pf. But the powder that makes the best mouse farts is WST you can drop it way down and it still goes bang reliably. With a 200gr 45 about 4.0gr of WST will wag your slide a bit and send the bullet thru card board at moderate distances.

[MichiganShootist]

You guys aren't reading my posts.

The only issue here is a solution based around my current inventory of Titegroup, 230 grain Zeros, and a single stack platform.

Bottom line how far down can I "push" this formula and still have a viable practice round????

Edited February 25, 2011 by MichiganShootist

[wmspdi]

Try this... I have used it in the past to reduce Major to Minor power factor loads and it was close to what the loads read over the chrono. If you know the velocity of the load you are using now, and the velocity you want to reach, this calculator will tell you the approximate weight load to try. The question is will the light load cycle the gun? For safety sake you can only go down in FPS from your baseline charge, not up.

http://www.handloads.com/calc/reduced.asp

Edited February 25, 2011 by wmspdi

[Joe4d]

Cowboy shooters use cornmeal to take up room in the case,dunno what kinda mess it would make, but most cowboy shooters feel like lots of smoke and mess is a good thing. How short of an OAL can you load ? Try a few dummy loads with short OALs and see how they feed. Less case volume may keep your groups together. I see published data of 3.9 grs under a 230 fmj giving 700 fps at 1.260, I'd be surprised if your 1911's wont run at OAL's around 1.180 as long as the bullet ogive allows a crimp that short. Just swagging it I'd be inclined to try 3.5 grs titegroup at 1.180-1.120 oal and see if your groups hold together.

[superdude]

on the issue of linearity: probably. take a look at a Hornady or Sierra reloading manual where they show charge weights and incremental changes in velocity - i have the 7th edition Hornady in front of me. The Hornady manual lists for the 45 ACP 230 grain bullets and titegroup; charge weights of 4.3, 4.6, 4.9, 5.2, produce velocities of 700, 750, 800, 850, respectively. so, a change of 0.3 grains produces a change in 50 fps. the linearity thing appears to hold true for the other powders listed also. in fact, everywhere i look in the Hornady and Sierra books linearity seems to be common. there might be limits on conditions when a powder behaves linear, such as when compressed or really light loads or whatever, but that remains to be illustrated.

as others noted, whether a light load will cycle the gun or not is a consideration, but changing springs can help you there.

there is also the often referred to "too light a charge will dramatically increase pressure" warning. i don't know how valid that is, and would always suggest to people that they error on the side of caution, but would welcome someone to direct me to controlled studies with data.

[MichiganShootist]

Thanks for all the great feedback. The reason I'm going through this exercise is that I have lots of time on my hand to work up a load....and to crank out some reloads.... but the snow is still piled high "up here" and I won't have access to a chrono until the thaw.

I just found a note from a trusted friend that says he uses 3 grains of Titegroup under a 230 grain FMJ as a PPC load... it requires a 10# recoil spring to work... but he says it kicks like a B B gun... and is plenty accurate enough for that "game"

So I'm going to crank out 1,000 rounds with 4 grains of TG which should generate a PF of about 150.... Not minor but softer than what I've been using.... then when the snow melts I can go at it again to refine this down to something like a 140 PF.

Thanks again for the thoughtful posts.

Mark

[Patrick Sweeney]

I'd be careful trying to "lean out" a load using fmjs. You may have a linear response to loading density down to zero, but when you reach the balance point between bore friction and pressure, you'll stick a bullet.

Lead bullets have a lower coefficient of friction, and they can be run slower without sticking. They will, however, stick if run too slow.

A 230 at 150PF means around 650 fps, which is about as slow as I'd want to go.

And, you can extrapolate from only two data sets. You just won't have a very high statistical confidence is all.

[MichiganShootist]

Thanks to all.

I settled on a load of 4.1 TG. Based on all the numbers that should be a 154 -159 PF at about 670 - 680 fps. That's hardly a powder puff load .... but it should allow me a decent practice round without swapping out springs etc.

Titegroup is such a "hot" powder----That's only 16% below the published maximum load for a 230 gr FMJ.

Again that's the posts.

Mark

Edited March 1, 2011 by MichiganShootist