Reduced Load Calculator

[Knob Creek]

I ran across this at Handloads.com. It takes your existing load and calculates how much powder to use to get a reduced load based on what fps you want. As always use this only as a guide:

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

 

[Gammon]

I divide the velocity of the current load by the powder charge expressed in tenths (5.3 grains would be 53 tenths). This gives you the velocity produced by one tenth of a grain. You can now adjust your velocity, knowing how much of a change one tenth of a grain will make. I use this system for decreasing velocity and don't recommend it for developing hotter loads.

 

[milktree]

I divide the velocity of the current load by the powder charge expressed in tenths (5.3 grains would be 53 tenths). This gives you the velocity produced by one tenth of a grain. You can now adjust your velocity, knowing how much of a change one tenth of a grain will make. I use this system for decreasing velocity and don't recommend it for developing hotter loads.

How well does that work, and for how much?

I imagine it's only close to linear very near the last measured load. e.g. 1/10 charge won't get you 1/10 velocity, it'll get you a bunch less than that.

 

[highscore]

I took a look and since they posted it, there might be something to it??? I would try very small reductions in powder charges to prove it out. Not taking different burn rates into consideration does make me wonder...

 

[Gammon]

You are right sir! This system works very well within a limited range but it works very well with the powders I have used within this limited range. I forgot to mention that I use this system with non magnum pistol ammunition only. The powders I have been using 231, WST, and Tite Group use relatively small charges and I am working within a limited range of less than 200fps.

 

[44marty]

Be VERY CAREFUL when loading reduced loads. It is counterintuitive, but reduced loads, especially with slow-burning powders, can cause hangfires and very high pressures. This is especially true for larger magnum rifle cases. See the warnings in reloading manuals for the .300 WBY Mag, for example.

Reduced loads for the .375 H&H Mag are listed but use different, faster-burning powders.

 

[milktree]

Be VERY CAREFUL when loading reduced loads. It is counterintuitive, but reduced loads, especially with slow-burning powders, can cause hangfires and very high pressures. This is especially true for larger magnum rifle cases. See the warnings in reloading manuals for the .300 WBY Mag, for example.

That's really weird. What's the mechanism?

 

[DukeInFlorida]

The mechanism is a combo of factors:

• Too much (more) distance between the primer and the powder. The ideal ignition is where the powder is right against the primer. Tilting the gun containing a short load of powder, when the rifle case is long can cause the powder to not get hit with enough of the primer fire to properly ignite it. One of the old tricks is to pack some polyester pillow stuffing in on top of the powder, to keep it near the back, where the primer is.
• Some powders need a LOT of fire to properly ignite. H110 is one of those, and you'll often see a listing in the reloading data book for the use of a magnum primer in some instances. Reducing the load even further can cause the situation to get even worse.
• It takes a certain amount of gas pressure, in a given amount of time to get the bullet started on it's way down the barrel. If you reduce the powder too much, that pressure/ time ratio is disturbed, and the bullet can sit in the case, building up excessive pressure before it finally gets pushed out. That's why the reload data shows a "starting" load. The calculations take into account a properly sized case, seated and crimped bullet, etc. Bob J recently gave me some fire lapping loads. Those were fire formed in my gun, and prepped with out resizing. They had a severely reduced load of powder, with the pillow stuffing on top of it, and a barely seated cast lead bullet. Because it was so loosey-goosey, it gave off a pop when fired, and sent the lead bullets (with the lapping compound on them) down range at about 200 fps, just enough to do it's lapping job. If the cases had been resized. Or the bullets crimped. Or the pillow stuffing left out.... It could have been disaster.

 

[44marty]

I know someone will ask, so:
Reduced loads for the .375 H&H Magnum
Reduced loads for Whitetail Deer are listed in the Hornady #7 and Sierra reloading manuals. Hornady lists SR 4759, H 4227, and AA 5744 powders. Sierra lists only SR 4759

HORNADY
Hdy #3705 Flat Point, 220gr bullet
SR 4759 powder, 34.4gr starting (2000 fps) to 39.4gr (2200 fps), with a Max of 42.0gr (2300 fps)

SIERRA
Sierra #2900 Flat Nose, 200gr bullet
SR 4759 powder, 36.5gr starting (2050 fps) to 39.8gr (2200 fps), with a Max of 41.0gr (2250 fps)

Sierra lists their best accuracy with 38.7gr (2150 fps), giving 2053 ft lbs energy

Sierra data was generated from a Win M70 with 25" bbl
Hornady used a Rem 700 (barrel length unspecified)
Both rifles have a 1 in 12" twist

NOTE that full-power loads use powders such as IMR 4064 and RL-15

NEVER SUBSTITUTE powders for those listed in the reloading tables, even if they are listed as similar on burn-rate charts.

 

[44marty]

Thanks, Duke, that was a very good explanation. I won't be trying the pillow stuffing trick, though.

As an aside, I read a post recently on another forum that could have been a total disaster. A reloader was using reduced loads to fire-form brass. He used semolina to make up the missing volume of powder. I don't know whether the cartridge got shaken and mixed the powder/semolina combo. What I do know is that he ended up with complete case separation, and a damaged rifle. Somehow no injury, though.

 

[DukeInFlorida]

Yeah, I have used the pillow stuffing trick with some extreme long distance hunting rounds for Colorado hunting. When shooting up or down some of those mountain sides, you always want the powder up against the primer, no matter what. And, since the pillow stuffing gets consumed during the burn (polyester) , you have to account for that by adjusting the load, working up carefully to your final result. It's certainly an ADVANCED reloading thing, and not for the beginner at all.

Semolina (wheat flour) is the wrong material, and that guy should have his picture on the cover of the Darwin Awards Annual book. He's lucky that people near him didn't also get damaged.

There's a science to fire forming brass. A science. And, anyone thinking of making a wildcat (which is where you need fire formed brass) round, needs to read up on the science first.

I have a book, showing all of the known wildcat cases, what they are made from, how to make them, and suggested loads. If I needed to make a wildcat, I'd still be reviewing any of that with my buddy, Mike Demers in Sanford, Maine (one of the most respected of the New England wildcat experts) before I did anything.

 

[oneswithfunes]

Yeah, I have used the pillow stuffing trick with some extreme long distance hunting rounds for Colorado hunting. When shooting up or down some of those mountain sides, you always want the powder up against the primer, no matter what. And, since the pillow stuffing gets consumed during the burn (polyester) , you have to account for that by adjusting the load, working up carefully to your final result. It's certainly an ADVANCED reloading thing, and not for the beginner at all.

Semolina (wheat flour) is the wrong material, and that guy should have his picture on the cover of the Darwin Awards Annual book. He's lucky that people near him didn't also get damaged.

There's a science to fire forming brass. A science. And, anyone thinking of making a wildcat (which is where you need fire formed brass) round, needs to read up on the science first.

I have a book, showing all of the known wildcat cases, what they are made from, how to make them, and suggested loads. If I needed to make a wildcat, I'd still be reviewing any of that with my buddy, Mike Demers in Sanford, Maine (one of the most respected of the New England wildcat experts) before I did anything.

I have now shot out 2 barrels on my 243ai. I have formed 400 rounds of brass using Unique, cream of wheat and then a little polyester fill in the neck. Care to provide a explanation for you opinion above? I am guessing that since it is a science and not voodo you have a lot of information to back that up.

 

[DukeInFlorida]

You're the obvious expert with the cream of wheat.

You tell us how it all works. Why use the wheat products?

And, tell us about the actual specifics of the process.

And, did you mean to tell us that you get 200 rounds per barrel???? 400 rounds divided by two barrels? Or, am I missing the math or the point of your two comments?

I need enlightening.

I have now shot out 2 barrels on my 243ai. I have formed 400 rounds of brass using Unique, cream of wheat and then a little polyester fill in the neck. Care to provide a explanation for you opinion above? I am guessing that since it is a science and not voodo you have a lot of information to back that up.

 

[oneswithfunes]

The math part does not matter. 400 rounds with 10-12 loads each. 12 grains Unique, fill up with cream of wheat, fill neck with poly and fire. I felt uneasy about trying to fill the case up with enough with poly to keep the powder from moving. Saves money and the throats. It also is a pretty common method. Down side is the cleaning. Like you I did some research on fire forming and came to a decision on how to best approach it for my needs. On the other hand I guess I belong on the cover of your magazine.

 

[DukeInFlorida]

You still have all your fingers and toes and eyes? How many guns have you blown up?

 

[oneswithfunes]

You still have all your fingers and toes and eyes? How many guns have you blown up?

Yes and none. A explanation as to how I could would be nice.

 

[DukeInFlorida]

If you have all your toes and fingers, and haven't blown up a gun, then you can't be on the cover of the book.

We're waiting for you to explain to others how the fire forming process goes, how to do it, what to use, in a general sort of way.
Maybe use the example of what you currently fire form.

I'm hoping it discourages some of the beginners from giving it a go (once they see how involved it is)

 

[44marty]

I can see the "average" shooter forming a standard case into an Ackley improved chamber of the same cartridge. Beyond that, I would suggest leaving it to the experts, or working with experts. I don't mean self-proclaimed experts - check references.

Good health to you.

 

[oneswithfunes]

Ok, no expert here just what I do. I form .243 brass to use in my 243ai. I could and have loaded regular loads in normal 243 brass and fire formed them that way. I decided that forming with no bullets and very reduced loads would save me money and throat life. So I searched and spoke to others who do this. What I came up with is this. Buy virgin Lapua 243 brass. I go through my normal case prep that has no bearing on fire forming ( flash holes, weight sort) Prime with cci 200's, load with 12 grains Unique. Make sure the powder in settled. I then pack the case full to the bottom of the shoulder with cream of wheat. I am careful to make sure I do not shake the case or bump it. I don't want to mix the stuff or have empty space between the powder and wheat. Or the primer and the powder. I then pack the shoulder and neck with poly fill. I used to cap with wax but have found that this is not needed. I then fire as normal. I need to clean every 5 or 10 rounds which sucks. I am of the mind that cleaning can do more damage than good a lot of the time. What I end up with is 243ai brass that matches the chamber. What is changing is the case taper and the shoulder angle. It can now be loaded as one would do normally. If that does not make sense let me know. I am tired and need to eat, so I bet I left something out or need to edit it for clarity.

 

[milktree]

I have now shot out 2 barrels on my 243ai. I have formed 400 rounds of brass using Unique, cream of wheat and then a little polyester fill in the neck.

Why cream of wheat? That sounds (you know, based on nothing other than what I just read here) like something someone would come up with while drunk, or something that someone tried 60 years ago before handloading was as well understood as it is now, but for some reason works. Kinda like Aspirin. It works, but nobody's really sure why.

Does brand matter? What about oat flour? Corn flour?

 

[milktree]

The mechanism is a combo of factors:

• Too much (more) distance between the primer and the powder. The ideal ignition is where the powder is right against the primer. Tilting the gun containing a short load of powder, when the rifle case is long can cause the powder to not get hit with enough of the primer fire to properly ignite it.

I can see how that could lead to a squib load, but not an overpressure, what part am I missing?

• Some powders need a LOT of fire to properly ignite. H110 is one of those, and you'll often see a listing in the reloading data book for the use of a magnum primer in some instances. Reducing the load even further can cause the situation to get even worse.

How can "failure to properly ignite" lead to overpressure? Wouldn't that just lead to a squib?

• It takes a certain amount of gas pressure, in a given amount of time to get the bullet started on it's way down the barrel. If you reduce the powder too much, that pressure/ time ratio is disturbed, and the bullet can sit in the case, building up excessive pressure before it finally gets pushed out.

I don't get it. What's different if the pressure builds up slowly or fast? Wouldn't the bullet just get pushed out later (and slower)?

They had a severely reduced load of powder, with the pillow stuffing on top of it, and a barely seated cast lead bullet. Because it was so loosey-goosey, it gave off a pop when fired, and sent the lead bullets (with the lapping compound on them) down range at about 200 fps, just enough to do it's lapping job. If the cases had been resized. Or the bullets crimped. Or the pillow stuffing left out.... It could have been disaster.

I'm clearly missing something. Where does the pressure come from? Squib loads, hangfires, that's obvious, but overpressure has to come from .... something that increases pressure, right? Too little volume, too tight a crimp, obstructed barrel, etc.

If you fire a case with only a primer, it'll go "pftt" and leave the bullet in the barrel. If you put a full load of powder in, it'll go "bang" and function properly. What you're suggesting (If I'm reading you right) is that there's some reduced load point between zero (primer only) and normal charge where the gun blows up. What's going on there?