Reloading Data Disparity

[marlin35]

I use AA5 a lot for my .45 colt. When I first started using the powder, I used western powder’s handloading guide available online which gave the following for AA5.

I developed my load to slightly higher than max as I am shooting a Blackhawk and settled on 10grains for my load. They list 9.6 grains as being 936fps.
I recently purchased the Lyman 50th edition reloading handbook. They list the following for AA5.

I highlighted the loads I am speaking of. They are more than 100fps slower with nearly a grain more as a max load.
This does reassure me that my 10grain load is safe, especially in my Blackhawk, but being that I don’t own a chronograph I’m not sure what to think about the velocities or pressure I get with it. How do I navigate the discrepancies of different reloading manuals?

[lar4570]

That is a very good question.
The difference in recorded velocities could just be the difference in which gun they used or the barrel lengths of the two different guns??
It could also be that they used different bullets with different loaded lengths...
I would guess that your 10 gn load is safe in a Blackhawk.

[Odin]

To add to the above, were both test platforms revolvers? Sometimes a Contender type setup is used and there's no barrel/cylinder gap. It'll make a difference in velocity.

Pressure can be differences in bullet design and seating depth. Alloy used. Primer choice. It all makes a difference.

[marlin35]

Feb 1, 2024 12:48:38 GMT -5 Odin said:

To add to the above, were both test platforms revolvers? Sometimes a Contender type setup is used and there's no barrel/cylinder gap. It'll make a difference in velocity.

Pressure can be differences in bullet design and seating depth. Alloy used. Primer choice. It all makes a difference.

Both show to be tested in a 7.5” barrel with a 1/16” twist. It sounds like a revolver setup.

[marlin35]

Notice also that the Lyman does not give any pressure data on the AA5. That doesn’t help at all.

[sharps4590]

You buy a chronograph and eliminate all doubt.  Those are their numbers on that day, at that time, with that lot of powder with that particular firearm or universal receiver with their equipment, not yours.

[bradshaw]

[/quote]Both show to be tested in a 7.5” barrel with a 1/16” twist. It sounds like a revolver setup. [/quote]

*****

I assume nothing. In respect to arms and ammunition, to seek specific answers to incomplete data indicates one of three challenges: 1) don’t know, 2) presumptuous, or 3) lazy.

Specifications “7-1/2” bbl with 1:16” twist” (I’m sure you don’t mean one-sixteenth inch twist), may refer to a closed breech test barrel, 7-1/2” long, which may be vented----or not----to approximate velocity from a revolver. In my view, these barrels can show optimistic velocities. I suppose an open-top revolver could be made which would allow attachment of a piezo transducer to the cylinder. In fact, anyone with a revolver and a hack saw could make an open-top .454 Casull, and glue the pressure sensor over a chamber.

Whether stated or not, some load data is published using a different firearm for velocity and pressure. Almost certainly the case when a revolver is used for velocity.

I would appreciate firearm details with all published load data.
David Bradshaw

[45MAN]

AS PRIMARILY A REVOLVERIST, SEEMS LIKE MOST PUBLISHED MV #'s FOR FACTORY AMMO ARE "FAIRY TALES" COMING FROM THE USE OF LONG BARRELS AND/OR NO CYLINDER GAP BARRELS. I APPRECIATE BUFFALO BORE's MV DATA FOR THEIR LOADS BECAUSE THEY TELL YOU WHAT GUN IT WAS SHOT IN. EVEN IF YOU ARE A RIFLE GUY, MOST DATA SEEMS TO BE OUT OF A 26" BARREL SO THE MV WILL BE HIGHER. IIRC, IN LOADDATA.COM THEY USUALLY ADVISE LENGTH OF BARREL/AND VENTED OR NON-VENTED.

[gnappi]

They're using different bullets.

[sharps4590]

I dearly love and will never forget what a German firearm authority, who resides in Saxony, Germany, told me some years ago. We were discussing velocities of old, pre-war German rifle cartridges. He said, "Vic, you do know a lot of those velocities were taken when fired over a typewriter."

[bigbore5]

Some load data really seems screwy and it's hard to tell what's right. For example:

Accurate data:

357 mag. OAL 1.660" 8" barrel:
13.5gr #9 1480fps. 42,700psi

Lyman data:

357mag OAL 1.553" 4" barrel:
13.5gr #9 1172fps. 38,000psi

So how does a shorter oal make less pressure? The velocity is right there for the longer load from my 4" barrels, but seated to crimp over the band like the Lyman data I get higher (1218fps) velocities. Velocity=pressure all else being the same.

[marlin35]

Feb 1, 2024 16:36:00 GMT -5 bigbore5 said:

Some load data really seems screwy and it's hard to tell what's right. For example:

Accurate data:

357 mag. OAL 1.660" 8" barrel:
13.5gr #9 1480fps. 42,700psi

Lyman data:

357mag OAL 1.553" 4" barrel:
13.5gr #9 1172fps. 38,000psi

So how does a shorter oal make less pressure? The velocity is right there for the longer load from my 4" barrels, but seated to crimp over the band like the Lyman data I get higher (1218fps) velocities. Velocity=pressure all else being the same.

This was more along the lines of why I started the discussion. Screwy seeming load data throws me off. I don’t try to make assumptions and I’m certainly not lazy, I just want to load safely and have a ballpark idea of velocity and pressure.

[ideal]

This is a rare case of my choice not being Lymans data simply because the AA data has been pressure tested in a 7.5 in. barrel, and Lymans load appears to have been fired in a Blackhawk. I have both manufacturers manuals, and AA shows their max load at 13,400 PSI, so it has been pressure tested while Lymans has not. There's no telling where Lyman sourced their data from since it doesn't match AAs data.

[marlin35]

Feb 1, 2024 21:28:01 GMT -5 ideal said:

This is a rare case of my choice not being Lymans data simply because the AA data has been pressure tested in a 7.5 in. barrel, and Lymans load appears to have been fired in a Blackhawk. I have both manufacturers manuals, and AA shows their max load at 13,400 PSI, so it has been pressure tested while Lymans has not. There's no telling where Lyman sourced their data from since it doesn't match AAs data.

I know it’s not a factor of fancy or high dollar equipment but I feel it counts for something..but the recoil and report as well as thump down range feels more akin to my HS-6 load than a cowboy load. This would back up what you are saying about AA’s data.

[Cholla]

Feb 1, 2024 12:33:57 GMT -5 marlin35 said:

I use AA5 a lot for my .45 colt. When I first started using the powder, I used western powder’s handloading guide available online which gave the following for AA5.

I developed my load to slightly higher than max as I am shooting a Blackhawk and settled on 10grains for my load. They list 9.6 grains as being 936fps.
I recently purchased the Lyman 50th edition reloading handbook. They list the following for AA5.

I highlighted the loads I am speaking of. They are more than 100fps slower with nearly a grain more as a max load.
This does reassure me that my 10grain load is safe, especially in my Blackhawk, but being that I don’t own a chronograph I’m not sure what to think about the velocities or pressure I get with it. How do I navigate the discrepancies of different reloading manuals?

You might consider a subscription to Loaddata.com. I filtered 45 Colt loads for AA#5 and got over 200 loads for that powder alone. Just glancing through the data and extrapolating data from several sources, including the powder manufacturer, Handloader magazine et al., I think it's safe to say your load is well within the 14,000 psi SAAMI recommendation.