Unique - Differences between two Lots

Nick_C_S · March 19, 2018, 05:05 PM

Going back to when I first started loading (1984) I have used Unique now and then. But I'm not a fan of the stuff. I'll start there. However, during the shortage, I grabbed a couple pounds out of desperation - I had no intermediate speed propellant at the time, and that's all that was available. (To be used mostly for full-throttle 45 ACP.)

In March '14, I did a work up for 357 Magnum, 125 JHP (Speer's UCHP #4013, specifically), using Unique. Speer #14 has it from 8.6 grains min to 9.6 grains max. In the workup, I ran it all the way up the pole to 9.6 grains, just started getting pressure signs, and stopped. 1378 f/s through a 4" bbl (Model 686). I then backed down to 9.2 grains - for safety margin - as my "set" round and it ran a comfortable 1359 f/s (4"). Good ammo. Very good ammo. Made/shot lots of it. Handled great in a 3" 686 (1315 f/s).

Meanwhile, with the shortage still on, I grabbed another two pounds. Late last year, I exhausted my first two pounds and started in on the next lot.

For those keeping score at home:
The first lot was 633X103013 (Oct 30, 2013; I assume)
The second lot was 637Z040314 (Apr 3, 2014; I assume)

Since I had backed down the charge weight by 0.4 grains in my original work up (from 9.6 to 9.2), I saw no need to do a new work up with the new lot of propellant - that's among the reasons why I "set" my loadings with some wiggle room built in. I was wrong. My first batch of 50 with the new lot resulted in very flat primers and very difficult case extraction. They were clearly high pressure - way high. I didn't have a chronograph at the time, as I was just out for a fun shoot. But I resolved to back the charge down to 8.8 grains and (re)chronograph.

I did that today. 1373 f/s (4" bbl; 20 round sample) with some minor difficult extraction. So that's still 14 f/s faster than the 9.2 grains of the previous lot; and with slight pressure signs. All evidence suggests that the new lot has a considerably faster burn rate than the old lot. I really should back the recipe down to 8.6 grains - the Speer #14 minimum.

I have never experienced that big of a difference from one lot of propellant to the next. Worthy of a post

Here I am . . . into my 4th decade of handloading ammunition; and still got caught off guard and used up a bunch of margin of error. It's a little unnerving.

Moral of the story: New work ups with new lots of propellant.

Rifletom · March 19, 2018, 05:28 PM

Nick, I found the same thing in two different bottles of Unique with different lot #'s also. The highest I ever loaded my .45Auto with a 230gr LRN, was 6.0gr Unique. With the newer lot[black colored label], I needed to drop down to 5.8gr to get same velocity. Kind of an eye opener for sure.

243winxb · March 19, 2018, 06:39 PM

I compare old vs new lots of powder by a set volume. If there is a big difference in weight between the two, i work up a new loading.

In 357 mag, nickel plated brass may stop springing back after firing , as the brass ages. Sticking in the chamber with same lot/amount of powder. Load was reduced and brass was still sticking. Comparing fired brass to nickel brass with a micrometer , showed the difference in spring back.

zplinker · March 19, 2018, 07:04 PM

After seeing wide performance swings with Unique, I talked to the folks at Hornady, and they basically said...as powders change, and they do...its a crap shoot. Work up with what you have, but never rely on data that is published. A little scary for the new or casual reloader.

NWPilgrim · March 19, 2018, 08:47 PM

Most powder mfgrs state up to 10% variance in burn rate of any powder. I've never seen that much change between lots and very surprised it was with Unique. W231 seems rock steady to me.

Nick_C_S · April 19, 2018, 01:00 PM

So today I tested a 20 round sample at 8.6 grains and it yielded 1343 f/s through the 686 4".

That is the Speer #14 minimum charge weight and extraction was still just a touch sticky. I've decided to just find other uses for the remainder of my Unique.

I'm concurrently running other chronograph tests with Unique in 38 Special+P and 45 ACP. The results seem more nominal in these lower pressure applications; and will likely be where my supply of Unique gets exhausted.

Salmoneye · April 19, 2018, 04:45 PM

For what it's worth...

I have never seen a powder company admit to 10% variance, but I have seen a few state that powder lots are 'in spec' if they vary +/- 3% from the 'ideal' burn rate...

That means that you may have one lot that is -3% from 'ideal', and one lot that is +3% from 'ideal' for a total spread of 6% between those specific lots...

This was all long ago pre-internet, so where I read these numbers is not filed in my memory banks for a corroborating link...

Any time I change a component (lot of powder/primers, bullet, or brass brand), I drop back a minimum of 5% charge weight, and go from there...

243winxb · April 19, 2018, 06:42 PM

Measure at same setting. Old 2400-13.0 grs.
New 2400- 13.6 grs. By volume.

**Unclenick** · April 19, 2018, 07:18 PM

The printed Hodgdon manual I have (early 2000's) said they keep their Australian powder burn rates to +/-3%, and IMR powders to +/-5%. +/-10% is closer to what bulk grade powders often have, though historically they occasionaly been off by twice that.

One thing mentioned in the Norma manual is that a powder going from 80% RH to near 0% (desiccated) see's a burn rate increase of about 12%. So if your old powder was kept in significantly more humid conditions than the new lot is, that could be a contributing factor.

Nick_C_S · April 20, 2018, 09:10 AM

Quote:

Measure at same setting. Old 2400-13.0 grs.
New 2400- 13.6 grs. By volume.

I have run this same test many times. The freshly opened canister of propellant - even if the same lot # - is always more dense than the old.

Quote:

So if your old powder was kept in significantly more humid conditions than the new lot is, that could be a contributing factor.

They're kept in the same location /environment. I'm in the northern California central valley. It's a pretty dry climate here. Especially with the air conditioner running in the summer.

BTW, these charge weights were done on an RCBS 10-10 balance scale; using checking weights; and hand trickling to the exact amount.

AhChi WaWa · April 20, 2018, 11:12 AM

Very interesting...
I've also done several old vs new powder comparisons over the years -mainly from buying old powder at gun shows. Some of the stuff dated from the 60's and 70's was compared to fresh production in 2011 & 2015. Off hand I found date for Unique, Herco, AA-5 and AA-2230. Comparisons were for a same-same bullet-case-primer-charge shot over a CED chrono from multiple barrel lengths.

60's Herco in a 38 Spl only showed 20fps slower but in the 44 mag load it was 40fps.
AA-5 in 38 Spl was only 12fps between 80's powder and new (and they seem to change country & manuf. plants every few years)
Old paper can Unique in a 44 Mag was 50fps difference

The real surprise was AA-2230 - new 2016 stuff was between 100 & 200fps slower than my 2010 production lot... closer to the newer AA-2460 I have.

buying in small lots, guess I'll have to check more often

April 19, 2018, 01:00 PM	#6
Nick_C_S Senior Member Join Date: March 21, 2013 Location: Idaho Posts: 5,522	New chrono data So today I tested a 20 round sample at 8.6 grains and it yielded 1343 f/s through the 686 4". That is the Speer #14 minimum charge weight and extraction was still just a touch sticky. I've decided to just find other uses for the remainder of my Unique. I'm concurrently running other chronograph tests with Unique in 38 Special+P and 45 ACP. The results seem more nominal in these lower pressure applications; and will likely be where my supply of Unique gets exhausted. __________________ Gun control laws benefit only criminals and politicians - but then, I repeat myself. Life Member, National Rifle Association

April 19, 2018, 07:18 PM	#9
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,060	The printed Hodgdon manual I have (early 2000's) said they keep their Australian powder burn rates to +/-3%, and IMR powders to +/-5%. +/-10% is closer to what bulk grade powders often have, though historically they occasionaly been off by twice that. One thing mentioned in the Norma manual is that a powder going from 80% RH to near 0% (desiccated) see's a burn rate increase of about 12%. So if your old powder was kept in significantly more humid conditions than the new lot is, that could be a contributing factor. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

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March 19, 2018, 05:05 PM	#1
Nick_C_S Senior Member Join Date: March 21, 2013 Location: Idaho Posts: 5,522	Unique - Differences between two Lots Going back to when I first started loading (1984) I have used Unique now and then. But I'm not a fan of the stuff. I'll start there. However, during the shortage, I grabbed a couple pounds out of desperation - I had no intermediate speed propellant at the time, and that's all that was available. (To be used mostly for full-throttle 45 ACP.) In March '14, I did a work up for 357 Magnum, 125 JHP (Speer's UCHP #4013, specifically), using Unique. Speer #14 has it from 8.6 grains min to 9.6 grains max. In the workup, I ran it all the way up the pole to 9.6 grains, just started getting pressure signs, and stopped. 1378 f/s through a 4" bbl (Model 686). I then backed down to 9.2 grains - for safety margin - as my "set" round and it ran a comfortable 1359 f/s (4"). Good ammo. Very good ammo. Made/shot lots of it. Handled great in a 3" 686 (1315 f/s). Meanwhile, with the shortage still on, I grabbed another two pounds. Late last year, I exhausted my first two pounds and started in on the next lot. For those keeping score at home: The first lot was 633X103013 (Oct 30, 2013; I assume) The second lot was 637Z040314 (Apr 3, 2014; I assume) Since I had backed down the charge weight by 0.4 grains in my original work up (from 9.6 to 9.2), I saw no need to do a new work up with the new lot of propellant - that's among the reasons why I "set" my loadings with some wiggle room built in. I was wrong. My first batch of 50 with the new lot resulted in very flat primers and very difficult case extraction. They were clearly high pressure - way high. I didn't have a chronograph at the time, as I was just out for a fun shoot. But I resolved to back the charge down to 8.8 grains and (re)chronograph. I did that today. 1373 f/s (4" bbl; 20 round sample) with some minor difficult extraction. So that's still 14 f/s faster than the 9.2 grains of the previous lot; and with slight pressure signs. All evidence suggests that the new lot has a considerably faster burn rate than the old lot. I really should back the recipe down to 8.6 grains - the Speer #14 minimum. I have never experienced that big of a difference from one lot of propellant to the next. Worthy of a post Here I am . . . into my 4th decade of handloading ammunition; and still got caught off guard and used up a bunch of margin of error. It's a little unnerving. Moral of the story: New work ups with new lots of propellant. __________________ Gun control laws benefit only criminals and politicians - but then, I repeat myself. Life Member, National Rifle Association

March 19, 2018, 05:28 PM	#2
Rifletom Senior Member Join Date: February 11, 2011 Location: So-Cal Posts: 786	Nick, I found the same thing in two different bottles of Unique with different lot #'s also. The highest I ever loaded my .45Auto with a 230gr LRN, was 6.0gr Unique. With the newer lot[black colored label], I needed to drop down to 5.8gr to get same velocity. Kind of an eye opener for sure.

March 19, 2018, 06:39 PM	#3
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	I compare old vs new lots of powder by a set volume. If there is a big difference in weight between the two, i work up a new loading. In 357 mag, nickel plated brass may stop springing back after firing , as the brass ages. Sticking in the chamber with same lot/amount of powder. Load was reduced and brass was still sticking. Comparing fired brass to nickel brass with a micrometer , showed the difference in spring back.

March 19, 2018, 07:04 PM	#4
zplinker Senior Member Join Date: February 21, 2011 Location: way out here Posts: 262	After seeing wide performance swings with Unique, I talked to the folks at Hornady, and they basically said...as powders change, and they do...its a crap shoot. Work up with what you have, but never rely on data that is published. A little scary for the new or casual reloader.

March 19, 2018, 08:47 PM	#5
NWPilgrim Senior Member Join Date: September 29, 2008 Location: Oregon Posts: 2,346	Most powder mfgrs state up to 10% variance in burn rate of any powder. I've never seen that much change between lots and very surprised it was with Unique. W231 seems rock steady to me.

April 19, 2018, 04:45 PM	#7
Salmoneye Senior Member Join Date: December 31, 2011 Location: Vermont Posts: 2,076	For what it's worth... I have never seen a powder company admit to 10% variance, but I have seen a few state that powder lots are 'in spec' if they vary +/- 3% from the 'ideal' burn rate... That means that you may have one lot that is -3% from 'ideal', and one lot that is +3% from 'ideal' for a total spread of 6% between those specific lots... This was all long ago pre-internet, so where I read these numbers is not filed in my memory banks for a corroborating link... Any time I change a component (lot of powder/primers, bullet, or brass brand), I drop back a minimum of 5% charge weight, and go from there...

April 19, 2018, 06:42 PM	#8
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	Measure at same setting. Old 2400-13.0 grs. New 2400- 13.6 grs. By volume.

April 20, 2018, 11:12 AM	#11
AhChi WaWa Member Join Date: July 20, 2012 Posts: 19	Very interesting... I've also done several old vs new powder comparisons over the years -mainly from buying old powder at gun shows. Some of the stuff dated from the 60's and 70's was compared to fresh production in 2011 & 2015. Off hand I found date for Unique, Herco, AA-5 and AA-2230. Comparisons were for a same-same bullet-case-primer-charge shot over a CED chrono from multiple barrel lengths. 60's Herco in a 38 Spl only showed 20fps slower but in the 44 mag load it was 40fps. AA-5 in 38 Spl was only 12fps between 80's powder and new (and they seem to change country & manuf. plants every few years) Old paper can Unique in a 44 Mag was 50fps difference The real surprise was AA-2230 - new 2016 stuff was between 100 & 200fps slower than my 2010 production lot... closer to the newer AA-2460 I have. buying in small lots, guess I'll have to check more often