Effects of varying powder charges?

[billmc2]

I have no formal training with any kind of ballistics. I'm learning as I go. I know that too much powder is bad but so is too little powder. Too much powder can lead to over pressure conditions and possible kabooms. What happens with too little powder?

At the moment I'm playing with 45 ACP, Accurate No 5, and a new MP mold 45-225. With Lyman #2 my bullets are coming out at around 224 grains for the solid bullet (haven't played with any hollow points). I'm powder coating the bullets. In order for me to get the assembled cartridge to fit both my gun (HK 45) and my Cartridge gauge I have an OAL of 1.180".

Yesterday I loaded and shot several different loads ranging from 6.9 gr to 7.9 gr in 0.1 grain increments. Average velocities ranged from 796 to 891 fps. Charges below 7.3 grains have widely spaced velocity spreads and large Standard Deviations. Once I get to 7.3 gr charge, these numbers tighten right up and look (to me anyway) what I'd consider to be normal ranges.

Am I correct to assume that the lessor charges are what is giving me the velocity spreads and Standard Deviations that I'm seeing? Are those large spreads and deviations signs of too little powder (which I assume means not enough pressure). What are other signs to look for when it comes to lesser charges? (I'm not considering a stuck bullet in this grouping of symptoms.)

[TD1886]

It sounds to me like that's not a good powder for your what you are loading. Have you tried another powder? The main culprit of high SD's is varying velocities, yes, there are other things, but that is the main one.

There are too many things to name of using too little of a powder. Maybe Larry Gibson will chime in here and explain that to you.

[bruce381]

you are fine there is a sweat spot for most pistol charges and too low will have more larger SD and sometime smokey residue or cases . as you go up it cleans up and you hit a good load normally. stay within powder mfg recommendations and u will be fine.

[chriskendziora]

The powder hits a sweet spot and too low can cause issues. Not sure what powder you're using too help further. Some powders have a dual pressure curve found put the hard way once with BLC2. I think too low is called detonation.

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[45_Colt]

Am I correct to assume that the lessor charges are what is giving me the velocity spreads and Standard Deviations that I'm seeing?

Yes.

Are those large spreads and deviations signs of too little powder (which I assume means not enough pressure).

In this case, yes, not enough powder. The charge isn't burning consistently as the pressure doesn't get high enough for the powder you are using (AA #5).

The 2003 AA loading guide shows a minimum of 7.7gr for a L 230gr RN. For 891 fps, using #5.

For lower velocities AA #2 is a better bet:

The 2003 AA loading guide shows a minimum of 5.0gr for a L 230gr RN. For 800 fps, using #2.

The Accurate Arms loading manuals are free on line. Best to get a recent one and check out the various powders along with the boolit weights. Then pick the powder that covers the velocities that you are desiring.

45_Colt

[gwpercle]

Too Little Powder and the boolit will not exit the barrel ... it will Stick in the bore .
Be extremely careful of this ... another shot fired behind a stuck boolit will damage something ... usually the rifle barrel but sometimes more damage occurs .
Be Very careful with Minimum Charges or the case that gets No Charge , Look and Listen for a shot that doesn't sound "right" ... Stop and check the bore for a stuck boolit !
It's Okay to get Anal and OCD about getting one charge , of the correct weight , in each case ... My loading method lets me eyeball the powder in a case 3 different times before boolit seating ... You can't be too careful when loading ... you must have the right powder and the right charge ... not two charges and not 0 charges in that case .

45_Colt's advice , see post above , is right on about powder . If the Accurate Arms loading Guide is still available , send off for one ... Most Excellent Data contained in the Guide .
Load Safe ,
Gary

[Winger Ed.]

Am I correct to assume that the lessor charges are what is giving me the velocity spreads and Standard Deviations that I'm seeing? )

As said, often loads will have a sweet spot in relation to the weight of the powder charge.

Other times, for lack of a better explanation,
you'll find that certain powders, boolits, and combinations of the two that one or more guns simply don't like.

It reminds me of a life long friend. I used to ask people questions just to see how they'd answer.
I asked various people:
If a dog likes to hang their head out the car window at 50mph, why do the get mad when you blow in their face?
Rather than admit they didn't know-
Some would go off into describing about the pressure differences on their ears & nose, or some other bs.
My buddy answered by saying- "They just don't like you blowing in their face".

I've never had the time or inclination to go off into uncharted waters with my reloading, much less start at the max. and work up.
I've found I normally get my best performance/accuracy by using the published data in the books at about 80% or their max. listings.

[charlie b]

This is a well documented conclusion about light charges with some powders. The worst culprits for me have been double base powders. Win noted that W296 should not be downloaded. Some people assumed that to mean the gun might blow up but later notes from Win explained that below a certain pressure the powder would give erratic results, not dangerous, just erratic.

That is why it is best to follow the book loads. I especially like to reference the loads recommended by the powder mfgs for this reason.

There are some powders that will do ok outside their 'normal' pressures. When you deviate from the norm you are on your own.

[Pirate69]

Based on the data given, I ran the 7.9 grain Accurate No. 5 load through both QuickLoad and Gordon. Both indicate this load is above the maximum allowed pressure. I think the 1.18" OAL is an issue with this charge. Data that I am seeing says it should be around 1.23". An OAL of 1.23" gives about 85% of the allowable max per GRT.

Just a word of caution.

[billmc2]

Hey guys, thanks for the info.

First, it was pointed out to me that I made a typo with the mold designation. I had originally posted it was 45-255, that is wrong. it is 45-225. So I edited the above post to correct that.

A couple of you mentioned that the "powder" will have a "sweet spot". I didn't know that but looking at my data I can see where that happens.

People have asked about the load data I used. I couldn't find data for a 225 gr bullet, so I used data for a 230 gr bullet. I was looking at the 2nd Edition of Lee's Modern Reloading, 4th Edition of Lyman's Cast Bullet Handbook and the 3rd Edition (which I believe is the most recent) of Western Powders Handloading Guide.

My bullet is shorter than a 230 gr Keith bullet mold I have, which is 0.622" long; uncoated it has a length of 0.582". The loading manuals call for an OAL of the 230 gr bullet to be 1.230"; as I stated mine is 1.180"; its sized this short to fit in my chamber. Knowing that my OAL is shorter than specified, I knew I'd need less powder but I didn't know how much less. I picked up a copy of Quick Load (which for me has a big learning curve; and I'm still behind the curve). I used the function in Quick Load to generate charges above and below a particular starting load, I chose 7.4 gr to start with and let Quick Load go up and down from there.

I knew that some of my loads would be to small but I didn't know what the symptoms would look like. What I'm trying to do, is understand what is happening. Rather than just following a recipe and leaving it at that; I'm trying to learn what is going on so that, at another time, I can diagnose problems when they come up. Now I'm not saying that I'm discarding the recipe, but as in this case, when there is not an exact recipe for the bullet I'm using, modifying the published recipe so I have something that works safely with the bullet I have.

Pirate69 - your response came in while I was typing this particular post. I also ran this through Quick Load and saw that 7.9 gr was above the pressure for 45 ACP but it is just below the pressure limit of 45 ACP +P. My pistol is rated for +P loads so I'm thinking it would be safe to document what is happening. As it turns out, with this particular gun, I'm finding in general, whatever loads I try, including factory loads, they all come up a little short of what is published.

Edited to add: I did fail to mention that I have checked my brass and when necessary trimmed them, so that all my brass is the specified trim to length of 0.898".

[billmc2]

The powder hits a sweet spot and too low can cause issues. Not sure what powder you're using too help further. Some powders have a dual pressure curve found put the hard way once with BLC2. I think too low is called detonation.

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I really don't have a good grasp on the idea of pressure curves and what they mean, yet; still working on that.

Could you please describe what you mean by a dual pressure curve? Looking at my data and your comment, I noticed that after a "sweet spot" (that was pointed out to me) my numbers diverge and then later come back together again. Could this be the dual curve you speak of?

[billmc2]

Yes.



In this case, yes, not enough powder. The charge isn't burning consistently as the pressure doesn't get high enough for the powder you are using (AA #5).

The 2003 AA loading guide shows a minimum of 7.7gr for a L 255gr RN. For 891 fps, using #5.

For lower velocities AA #2 is a better bet:

The 2003 AA loading guide shows a minimum of 5.0gr for a L 255gr RN. For 800 fps, using #2.

The Accurate Arms loading manuals are free on line. Best to get a recent one and check out the various powders along with the boolit weights. Then pick the powder that covers the velocities that you are desiring.

45_Colt

Thank you. You answered my questions. I did make a typo error earlier and my bullet is supposed to be 225 gr, not 255 gr.
Western Powders are now publishing the Accurate Data. I bought a copy of their book earlier this year, its the 3rd edition.

[billmc2]

The powder hits a sweet spot and too low can cause issues. Not sure what powder you're using too help further. Some powders have a dual pressure curve found put the hard way once with BLC2. I think too low is called detonation.

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After reading your post again and noticing the word detonation, it made me think of gasoline in a cylinder of a motor. Pinging. That is also called detonation; it is not a good thing. I kinda view that as a hammer whacking into the piston. Instead when the gasoline burns correctly, there is a constant push against the piston from the flame front. As the piston moves, the air/fuel mixture follows the face of the piston, pushing against it.

Now that you point that out, it sounds as if we want to see the same thing with the bullet (bullet = piston, case = cylinder).

[unique]

Probably powder variation in case is culprit.
Less powder in a case means more space. More space means powder position varies more. Take your minimum loads and raise muzzle up before firing and then slow lower before firing and measure velocity...now do that again with muzzle down before firing. what you are doing is placing powder charge on primer in first case and in second case powder is further away from primer. Makes a big difference in pressure/velocity. It is one of the tests I do when selecting powder/charge combination.

[Dusty Bannister]

Probably powder variation in case is culprit.
Less powder in a case means more space. More space means powder position varies more. Take your minimum loads and raise muzzle up before firing and then slow lower before firing and measure velocity...now do that again with muzzle down before firing. what you are doing is placing powder charge on primer in first case and in second case powder is further away from primer. Makes a big difference in pressure/velocity. It is one of the tests I do when selecting powder/charge combination.

This would likely influence a large rifle cartridge. Given the length of the interior of the 45 acp case with a bullet seated, and loading between 7 and 8 grains of a relatively slow burning pistol powder, I would question if this is such a significant factor. Has this been your actual experience with the 45 ACP?

[unique]

Yes with 45acp and bullseye. OP said No5 was being used and that is a ball powder and ball powders tend take a bit more energy to ignite so I would think powder position would be factor for sure. Only way to know is to test for it.

Believe it or not, one cartridge that I found that was NOT sensitive to powder position was 45-70 with 16 grain unique powder. If i ran 45-70 with rel7 then got to point of click-boom based upon powder position...but I digress. Of course if your powder charge is >90% of volume then variations are small or non-existent.

[Wayne Smith]

One issue is your choice of powder. Ball powders are very convenient and measure very easily, but they also have a 'sweet spot' in the amount of pressure needed for them to burn completely. Other types of powder forms have much larger range of pressure that allows them to burn completely. With a ball powder if your charge does not reach the minimum pressure needed the powder will not burn completely and thus become erratic. Bullseye and Unique do not have this characteristic, so that is the reason why unique's 45-70 unique load had no problem and his RE7 (a ball powder?) might have.

[dverna]

As said, often loads will have a sweet spot in relation to the weight of the powder charge.

I've never had the time or inclination to go off into uncharted waters with my reloading,

I am in the same boat. Putting .45 ACP loads over a chronograph seems like a waste of effort to me. In fact, I feel that way about most pistol loads. If the load groups well, chasing SD and ES seems pointless. But then I rarely shoot pistols past 50 yards anymore.

Makes sense to use loads for 230 gr for your 225 gr bullet. This is not rocket science.

[Winger Ed.]

Makes sense to use loads for 230 gr for your 225 gr bullet. This is not rocket science.

That's where I'm at. And I try not to over think this stuff.
There is a fair amount of wiggle room in the published data and still be safe.

My .45 cal. 405 mold for the .45-70 actually casts out with my alloy at 424 or 425.
I use the 405 gr data and haven't lost any sleep over it, blown up the Marlin, or shot my eye out.

[45_Colt]

Thank you. You answered my questions. I did make a typo error earlier and my bullet is supposed to be 225 gr, not 255 gr.

I did the same typo, just changed it to 230 gr (from 255). Here is the section from the 2003 AA load manual:



45_Colt