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Discussion Starter · #1 ·
Does Hogdgon use calculated values and then reduce them by 30% for their load data? I am working up a load that I had trouble finding the powder for in either of my load manuals (universal)--With help from this forum somebody got me the page from Hornady's 5th ed that had the data I needed. Then I heard that Unique was a similar powder so I made a little chart and compared the Unique loads in the other two manuals to get an Idea of whether my load would be safe or not. I also searched and found some people that had a load that would be .4 grains over the max load according to Hogdgon but .4 grains less than the Hornady manual. Now I know that Lynman, lee, Hornady etc actually test what they load---Does Hogdgon?
 

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Cartridge pressures vary by bullet temp humidity barometric pressure barrel length twist rate and from gun to gun. Could be they tested there load with a different gun on a different day at a different place with a different lot of powder
 

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Were the bullets and specified COAL the same between Hodgdon and Hornady data?

Just because two bullets are described as 200gr. LSWC (for example) doesn't means that they are the same length or shape.

Almost every time I've found inconsistency with Hodgdon loads being lower, it turned out that their recommended COAL was significantly shorter too.

Look in a Lyman manual. You'll find can find 2 bullets, same weight, with different recommended COAL and powder charges.

Last but not least, please don't assume that load data published by a powder distributor is wrong. Yes, they can make mistakes but not nearly as often as hand loaders do. If two manuals show different data, try to figure out WHY.
 

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Discussion Starter · #4 ·
Cartridge pressures vary by bullet temp humidity barometric pressure barrel length twist rate and from gun to gun. Could be they tested there load with a different gun on a different day at a different place with a different lot of powder
That is true--But I compared 3 other sources and 3 other powders and it seems to hold true for all of them. Their 308 loads seem to be consistent with the manuals but their 45 acp data for 230gr bullets seems quite a bit off--ie--3 manuals same bullet same col same powder give a min load 6.5 gr MV 700fps---Hodgdon list's 6.4 min MV 762 with same physical stats. for that same powder ---Manuals max 7.6gr mV 900--Hod--7.0gr 867.
To better match up 7.0gr in the manuals list 800fps. Now I am no expert by any stretch but is velocity at the muzzle really that effected by Bar. press? temp--maybe but I would say that the elements have a greater effect on trajectory--except for temp sensitive powders.
I started my test loads at Hodgdons high end and the manuals low end (also got info from a very reliable source on this forum) If the lightest loads chrono according to the manual I will try some of the heavier ones. Going out tomorrow and will report my findings.
 

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Hodgdon definitely tests their loads that's how they get the pressure and velocity figures. If you are loading for your 45ACP I wouldn't bother hot rodding it, the factory loads are 800fps etc. Easily doable with Universal staying within the Hodgdon data.
 

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Discussion Starter · #6 ·
Hodgdon definitely tests their loads that's how they get the pressure and velocity figures. If you are loading for your 45ACP I wouldn't bother hot rodding it, the factory loads are 800fps etc. Easily doable with Universal staying within the Hodgdon data.
BULLET WEIGHT230 GR. HDY FMJ FP
ManufacturerHodgdon
PowderUniversal
Bullet Diameter.451"
C.O.L.1.200"
Starting Load
Grains5.1
Velocity (ft/s)716
Pressure11,800 CUP
Maximum Load
Grains5.6
Velocity (ft/s)844
Pressure16,800 CUP
This is Hodgdon's data
 

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Discussion Starter · #8 ·
After all of this I forgot to ask my original question--can I directly correlate MV to pressure--so if I chrono my loads and they give me X speed can I safely assume that I am producing Y pressure according to tabulated load data?
 

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Hodgdon seated the bullets deeper and could've used heavier brass than hornady those two things would explain the higher pressures/velocities. They aren't that much different honestly. Maybe 10%.

Yes you can correlate muzzle velocity to pressure if you are using all the same components, seating depth etc. When I load I chronograph and measure factory brass to develop a baseline velocity/brass growth and then start working up.

However you aren't the only person on the planet with 45ACP and universal powder. There are tons of guys loading for it. So there is a real brain trust out there that you can tap into to get an idea of what is okay and what is a bit much.
 

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Discussion Starter · #10 ·
Hodgdon seated the bullets deeper and could've used heavier brass than hornady those two things would explain the higher pressures/velocities. They aren't that much different honestly. Maybe 10%.

Yes you can correlate muzzle velocity to pressure if you are using all the same components, seating depth etc. When I load I chronograph and measure factory brass to develop a baseline velocity/brass growth and then start working up.

However you aren't the only person on the planet with 45ACP and universal powder. There are tons of guys loading for it. So there is a real brain trust out there that you can tap into to get an idea of what is okay and what is a bit much.
-If you look closely they used the same seating depth for the FP for the comparison. I actually did get very good advice from someone on this forum that had worked up loads for the projectile I am using. My main concern is not achieving a velocity but staying within presure limits and getting an accurate load.
 

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Different bullets mean different seating depths. If you are using that flat point bullet then you use that depth, if you use their round point then you use the longer seating depth. What bullets do you want to use? A typical 230gr round nose FMJ or are you using lead?

FWIW a friend of mine uses clays in lots of stuff, I sent him a text about 45ACP if he responds I'll post his data.
 

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Discussion Starter · #12 ·
Different bullets mean different seating depths. If you are using that flat point bullet then you use that depth, if you use their round point then you use the longer seating depth. What bullets do you want to use? A typical 230gr round nose FMJ or are you using lead?

FWIW a friend of mine uses clays in lots of stuff, I sent him a text about 45ACP if he responds I'll post his data.
actually I'm using the HAP which is the same as the XTP without the slices in it--same seating depth as in the manual--what I was saying is that Hodgdon seems to be off from reputable loading manuals. Also seems to be off from other peoples experience. It is just nice to have matching data in regards to reloads----Manuals match up, Hodgdon does not. And I get nervous when I see a "flier" in the group. I looked at this trend in other powders for the acp loads and it seems that Hodgdon is always light. I will accumulate my data tomorrow and post what I find on this thread--if anyone else has chrono'd 45 I would love to see the data and compare it to hodgdon.
 

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Discussion Starter · #14 ·
Hodgdon data is not 'off' it's just for a different bullet than you are using and a different seating depth than you are using.
you don't seem to understand--I know I am using a different bullet--what I said was when you compare apples to apples--same bullet---same col---same powder The Hodgdon data differs(on the low side) from the manuals. I can't compare the bullet I'm using with Hodgdon but I can compare the FMJ FP for universal--I also compared other powders, again keeping all other variables the same and Hodgdon comes out Low in the case of Universal ~15%. For example:

BULLET WEIGHT230 GR. HDY FMJ FP
ManufacturerIMR
PowderSR 4756
Bullet Diameter.451"
C.O.L.1.200"
Starting Load
Grains6.4
Velocity (ft/s)762
Pressure12,900 CUP
Maximum Load
Grains7.0
Velocity (ft/s)867
Pressure16,500 CUP
This is Hodgdon

BULLET WEIGHT230 GR. HDY FMJ FP
ManufacturerIMR
PowderSR 4756
Bullet Diameter.451"
C.O.L.1.200"
Starting Load
Grains6.5
Velocity (ft/s)700
Pressure:not listed
Maximum Load
Grains7.6
Velocity (ft/s)900
Pressure:not listed
This is Hornady
Now--if I wanted a 762 ft/s load according to Hornady I would need to use 6.8+ gr. of the same powder same bullet same COL. Now in this scenario a difference of .3 gr. is not that significant percentage wise but on several pistol powders .3gr is quite significant. I am not trying to be smart (hurts too much) all I am pointing out is that it is common to check several sources when you work up a load. When manuals like Lee, Hornady and Lynman match up, not something everybody can get too, and a neat calculator exists, which most everybody can get too, it would be nice if they were consistent with other reputable sources. "Even a seed of doubt, sows dissension"
 

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MtTom,

NO NO you can not directly calculate chamber pressure from velocity NO NO NO. you can get your self in deep do do trying to do that.

That's why there is no direct formula for this calculation the equation would simply have too many varialbes. bullet material, seating depth, bullet weight, barrel, barrel length, revolver, auto, chamber dimensions, powder composition, burn rate, fiction, lube, lube chemistry, atmospheric conditions, to name only a few.

If it was that simple you would have already seen someone take all of Lyman's old cast bullet data and use the velocity to convert the pressure over to PSI instead of copper crushing units, since the formula doesn't exist this why all the tests have to be rerun using modern piezoelectric pressure testing, yielding PSI.


I think what most of us that reload over time find is that you can extrapolate some basic load information using data from different sources but even that you need to be careful and not be dealing with maximum loads, the chronograph helps for this. This also can get you in trouble, you can look at case volumes that are similar and get an idea of possible powder choices, something like using 45 Colt loads in a .44 for target loads, the case capacity being close enough that what would be a full power load in .45 LC would "safe" target load for the .44 mag. Or 10mm with .357 data case capacity again being somewhat close. This is extrapolation and is also risky. So please be careful when making these type of assumptions, you have to be careful and watch the type of powder you are messing with and are you exceeding maximum loads. BE CAREFUL
 

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Discussion Starter · #16 ·
MtTom,

NO NO you can not directly calculate chamber pressure from velocity NO NO NO. you can get your self in deep do do trying to do that.

That's why there is no direct formula for this calculation the equation would simply have too many varialbes. bullet material, seating depth, bullet weight, barrel, barrel length, revolver, auto, chamber dimensions, powder composition, burn rate, fiction, lube, lube chemistry, atmospheric conditions, to name only a few.

If it was that simple you would have already seen someone take all of Lyman's old cast bullet data and use the velocity to convert the pressure over to PSI instead of copper crushing units, since the formula doesn't exist this why all the tests have to be rerun using modern piezoelectric pressure testing, yielding PSI.


I think what most of us that reload over time find is that you can extrapolate some basic load information using data from different sources but even that you need to be careful and not be dealing with maximum loads, the chronograph helps for this. This also can get you in trouble, you can look at case volumes that are similar and get an idea of possible powder choices, something like using 45 Colt loads in a .44 for target loads, the case capacity being close enough that what would be a full power load in .45 LC would "safe" target load for the .44 mag. Or 10mm with .357 data case capacity again being somewhat close. This is extrapolation and is also risky. So please be careful when making these type of assumptions, you have to be careful and watch the type of powder you are messing with and are you exceeding maximum loads. BE CAREFUL
Thank you, My next question is hard to word but here goes--let's say I have load data from a manual that doesn't have pressure for the exact load I am using and I get the same velocity for my load using the same specs. Now I have to make an assumption that they would not publish loads that would be dangerously high. So I look at another manual that does not have my same load but a different one that mates up with the previous one and shows pressure. Am I OK?
 

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So I look at another manual that does not have my same load but a different one that mates up with the previous one and shows pressure. Am I OK?
You can't really compare manuals side by side like that. Even with the same bullet and seating depth they still use different brass type, maybe different testing methods, different primers.

FWIW I do not think the hodgdon data is conservative at all. When I chrono'd winchester, federal, and gold dots (all 230) out of the gold cup I was messing with they were in the high 700s and low 800s. My bullseye load was maybe 730? 45ACP ain't no 44 mag...
 

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Thank you, My next question is hard to word but here goes--let's say I have load data from a manual that doesn't have pressure for the exact load I am using and I get the same velocity for my load using the same specs. Now I have to make an assumption that they would not publish loads that would be dangerously high. So I look at another manual that does not have my same load but a different one that mates up with the previous one and shows pressure. Am I OK?
Are you asking if you can assume that equivalent velocities using different powders is safe?

In regards to your original question, as was pointed out by others, Hodgdon is using different components in their cartridges. Looking at the data online vs. the data in my Hornady reloading manual, I see that Hodgdon is rating the velocities at about 60 fps faster than Hornady does and that makes sense when you look at the components used to build the cartridge. They use different cases and different primers, both of these variations will cause differences in pressures and velocities. Variations in primers can cause almost 60 fps in some situations and the case volume will also effect pressure and velocity.
 
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Discussion Starter · #19 ·
Are you asking if you can assume that equivalent velocities using different powders is safe?

In regards to your original question, as was pointed out by others, Hodgdon is using different components in their cartridges. Looking at the data online vs. the data in my Hornady reloading manual, I see that Hodgdon is rating the velocities at about 60 fps faster than Hornady does and that makes sense when you look at the components used to build the cartridge. They use different cases and different primers, both of these variations will cause differences in pressures and velocities. Variations in primers can cause almost 60 fps in some situations and the case volume will also effect pressure and velocity.
Ok, Sorry Noobs14, I understand now--so I started my loads within hodgdons limits and went up to 6gr according to hornady. Can I use the chrono'd data I gather tomorrow to judge If I am at safe pressure? Ie if my load matches up with the hornady manual then I should be safe?--lets say that a 5.9 load = 800 f/sec. since hornady does not give pressure at given velocities.
Thanks,
Tom
 

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Discussion Starter · #20 ·
quick update
Universal at 5.6gr-winchester cases-federal match primers. COL 1.233
5 shot ave 808 fps/ 16% std. dev. Shot 3 inch groups at 25yds. Felt recoil was smooth and it cycled perfectly.
There was no excess dirtiness.Nice safe target load--making up 100 right now to see how they group.
 
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