Today i went out to do some new years day shooting and chrono some 308 loads in my c308 g3 clone. One thing i discovered is that mp530 is significantly different from cfe223.

On my dillon 550 I loaded 47.0gr cfe223 with a 147gr m80 ball in mixed military 308 cases.
This gave around 2350 fps out of my 18" g3 clone.

The same setting on my dillon powder measure throws 47.2 gr of mp530. This loads shoots 2670 fps out of the same gun. Thats a bit fast.

Keep in mind the hodgdon start load for CFE223 is 49.0grs.

Also note surplus 147gr military ammo should shoot 2500fps out of this gun according to my research. Tulammo 150gr shoots 2400 fps.

Mp530 seems significantly faster then cfe223.

So load with less powder after adjusting your powder measure.  I'm not seeing the problem.  I check and adjust my powder measure every time I reload, and whenever changing powder..even if it is just a different lot of the same powder.  Don't most people take these precautions?

I had the same issue with the MP580 I purchased thinking it was similar to IMR 4451.

Almost blew up the gun.

Did you shoot on the same day? Temp?

Brass same? Use the same primers?

Back to back. Same everything. To the poster that is not seeing the issue, in other threads, people are claiming that these powders are the same. Lot to lot varience does not explain a difference of 200-300 fps.
I am not compaining about the powder. Now that i know, i will load it lighter. I am posting because not everyone has a chronograph to do these comparisons. Blindly using cfe223 data with this powder will result and bad things since cfe223 requires significanly more powder to acheive average performance.

I don't understand.

Did you not use manufacturer's published load data for the EXACT powder you were using???  Were you using CFE223 data for the MP530 powder?  Were you using internet scuttlebutt to establish your load recipe?

If so, in what way was that the right thing to do?  That seems to violate one of the most fundamental safety rules of reloading.

Mp 530 is a powder that American reloading was selling for $15 a pound. Label and vendor advised to use CFE223 data and reportably told some customers that mp 530 was the same powder as cfe223.

I bought some of this powder and tried loading some as a comparison to cfe223. My conclusion is that these powders are not the same and you should no use cfe223 data for mp530 powder. My lot of cfe223 performs significantly slower then my lot of mp530.

I am sharing my results to save other people who bought this powder some trouble.

Okay, I get it -  a warning.

I just looked on American Reloading's website.

It says use CFE223 Data Minus 10%

If the usual rule of thumb of 0.1gr = 10fps applies, there's 250fps.

Why you would assume you were going to have another low pressure load with a strange powder that's supposed to be like CFE223 was your lesson.

Maybe good you passed it on, but I don't think people would just go diving in to a different powder and expect the same results. I wouldn't.

So Hodgdon's start load + another 10% less.

Edit- And that start load OP has is for a lead free bullet.

For A lead bullet they list 48. 4 or some such for start load, and another 10% off that.

Like I posted above, it is good to see I am not the only one who thought this was bulk versions of canister grade powders.

In my mind, "Use CFE223 data minus 10%" means CFE223 max minus 10% for the cartridge you are shooting.

In the eyes of many on here, it means "Take CFE223 max data minus 10% and then minus 10% more".

My experience as, as I said, was with MP580 which says "Use IMR 4451 data minus 10%". Using the 10% minus an extra 10% puts this powder in the burn rate of RE15 or H380. No where near the burn rate of 4451.

Full disclosure, I should have reduced my start load more than I did and that is what got me in trouble. But even then, I would have been "Shaking hands with danger" at the starting load.

I believe the retailer is mistaken in their information on the powders they are selling.

Basic reloading practice is to use manufacture published data for power at hand.

This mystery powder does state its similar to CFE223 but clearly not the same in burn rate or load weight.

It clearly states the powder is similar to CFE223 and Work up all loads using CFE-223 minus 10% Minimum Load.

So I see your results as no suprise unless you did drop the 10%.

Wow, some of you guys seem to be really worked up over the OP providing insight and a warning to others who may have jumped on this deal.

The site does say to drop 10% which tells you either they’re placating their attorneys or MP530 is a little hotter than CFE223. Either way, I would like to thank the OP for sharing his results as more info is always a plus for the community.

To me, "Use CFE223 data minus 10%" means exactly what it says. I would expect a starting load to be a CFE223 starting load minus 10%.

Thanks for the post and it's always good to share such experiences.  FWIW, I'm finding the opposite.

For example, from Hornady's website for 5.56 load data (20" BBL assumed for this)
https://press.hornady.com/assets/site/hornady/files/load-data/5-56-nato-60-62gr.pdf

62 gr: 27.7 gr CFE = 3150 FPS

Lazy's load development with MP530:
62 gr: 27.6 gr MP530 = 2945 fps
62 gr: 27.9 gr MP530 = 3012 fps

I also tried it with Hornady 68 bullets.  with those it was fairly close to parity to published CFE data Again:

68 gr: 26.3 gr CFE 223 = 2900 fps
Lazy load development with MP530:
68 gr: 26.5 gr MP530 = 2910 fps  there was strong P sign, but nothing that really exceeded full NATO load P sign.


I'm also running MP530 with light 90 gr bullets for a 20" PSA 6.5 Creedmoor.  Again, I'm finding my charge density is such that it's taking me quite a bit more MP530, than if I were using published CFE223.  Even after accounting for the 4" shorter BBL.

Don't know what to say, but I'm finding the opposite; that my jug is similar to and maybe even slightly milder than CFE-223.

How are people thinking this powder label means it's actually 10% stronger than CFE223, and then implying the OP is some kind of a fool for believing it should be just like CFE223?  OP is not a fool, he absolutely should expect behavior to be within reason much like CFE223.

A retailer isn't going to mean "it's just like CFE233, but 10% stronger" as that's just absurd; as there are plenty of other powders you should call it similar to, if it's really that much stronger than CFE223.  It's not.  That's not what the 10% statement means.  The 10% statement, is the standard rule of thumb statement of decrease by 10% that everybody everywhere says when working up loads.  It doesn't mean it's actually supposed to be 10% stronger than CFE223.

I've actually called and talked to the guys at American Reloading multiple times.  Their powders are factory run drums that they get, and repackage themselves.  For trademark/whatever reasons, the can't SAY and label it as CFE-223, but they CAN say it's similar to CFE223.  In general, what that actually means, as it IS CFE223, that they repackage.  It could be another manufacturers powder that's similar, as their business model is one of getting things on sale or salvage as it becomes available - and package and price accordingly.  But if they say it's similar to CFE223, then for all practical purposes, you should expect to be basically be CFE223.

And in my experience, that's about right.  I'm finding my load data with MP530 to be within the nominal variability of published to my-own data, and to be close enough, that my jug at least - is CFE223 for all practical purposes and load development.  I'm not sure why OP's jug is stronger.  Maybe since they get this from drums and repack, he got a higher count of fines or something from the bottom of the drum, in his jug.  Or maybe there's something else going on, who knows.

I will say, while cheap, and the CFE behavior does work, this really isn't my favorite powder.  The size distribution uniformity is... OK.  And the accuracy and standard deviation really isn't that great.  Just like everyone says about CFE, you have to run MP530 hot, to get the standard deviations down.  At lighter loads, my standard deviations with this powder can run up to 50 fps (that's not extreme spread, that's standard deviation).  I can get it down into the teens, but have to run it hot to do it, above book-max for CFE223 loads.  And again, with my jug at least, it runs fine like that - pressure and power behaving just like I would expect based on my experiences with other powders.

Here's some more load development data I worked up with this powder (in my guns - ahem, be sure to reduce your loads by 10% and work your way up )
https://www.ar15.com/forums/industry/PSA-PA65-field-report-and-a-thanks/301-290731/

OK, I understand that according to the seller, the two powders are supposed to be "similar" (but not exactly the same).  10% stronger isn't "just like" to my way of thinking.  I'm not suggesting that OP is an idiot, I think he didn't get accurate information from the seller of the powder.  I guess I'm just over cautious, because when I get batches of the same powder, but from different lots, I still start low again and work up to the velocity I'm looking for over my chrono.   Without a chrono, it would be difficult to try and duplicate a previous loading.

Working up a load is a pain in the butt, and I am one of those who doesn't like working up loads, I prefer shooting.  However I do want to shoot safely, and I don't trust manufacturers to not have things change between lots, so I work up the load.

OP's warning about the two powders not being as "similar" as the seller claims is appreciated..it may help keep someone from blowing up a firearm.

I'll say this - after working up some MP580 loads - you're right, this lot apparently is indeed way hotter than IMR 4451.  To the point that I"m not sure you can really call it that.

What cartridge did you load and what charge did you end up with? I still haven't tested mine out after reducing again.

Nothing 580 related I'm willing to publish yet.  Working on some 6.5CM loads, and right now I'm not so satisfied with how it's going, with way excessive pressure behavior.  It's so bad, I'm thinking of treating it like 4895 (or even faster), and dropping down to .223 with some damned mild 4895 spec 223 loads, and slowly work up from there once I figure out how this stuff behaves.  I don't know what this stuff is, but that MP580 sure as Hell isn't 4451. To be honest, if I didn't have over 16# of the stuff, I'd probably just bail - but if I can make it work; that's about $500 retail worth of powder I have in this stuff, so it's worth a little time still trying to figure it out.

My 530 has been fine, but this 580 stuff... is odd.

I'm working 6.5 CM. I'll post my results if I ever get around to shooting them...

I read everything lazyengineer puts on here, as well as several others' stuff but unless I see it in print that info doesn't make it out to the loading closet.

Its true I only have a few powders in my cabinet but they are tried & true and worked up from the start by me, for my guns, and generally run on the tamer side. mostly since my g29 explosion!

Did some testing during lunch hour today.  I've got a pretty good theory from some additional tests, on what's going on with MP580, and will update tomorrow or the next day.

Based on my testing, my MP580 jug is behaving more like IMR4166, than IMR4451, and I would advise tuning initial loads with that in mind, until you work up how your particular jug behaves.

Regarding MP530, I ran some AR loads with it today, and found it behaved pretty much just like CFE again; if not even milder.  I have more than one jug, so can't comment on variability between jugs, but the one jug I have opened, appears to be basically CFE223.

That is a much faster powder than I thought it would be.

I fired 3 rounds at 39.3gr under a 140g RDF bullet with this MP580 powder, it was way over pressure but it did not blow up the gun. I think my lot may be a bit slower than that.

I hope to test them up to 39 gr this weekend under the same bullet. I feel like I will only make it to about 38 gr before I stop, but I will shoot until I see pressure.

So, tested the rounds today in my 6.5 CM with the 140gr Nosler RDF at 2.920" OAL using the MP580.

I got to 36.2g before I saw pressure signs that made me stop. The velocity at 36.2g was 2618 FPS.

Accuracy at 35.8 was really good. and I will be testing that node some more.

I believe, like lazyengineer said, that MP580 is similar to IMR 4166.

It is safe to say the the MP line of powders is far faster than the recommended "similar powders" they list. With my testing and lazyengineer's experience as well as the OP's results with the MP530 powder, this is a dangerous situation for new reloaders for sure.

Sounds about right.  I didn't think you'd make it to the 39's.

I'm curious what your velocity curve looked like.  FWIW, max load for IMR4166 is 35.2 gr for 2,576 fps.   When I ran the MP580 it in .223, my velocity curve of the rounds I tested, matched up pretty close to IMR4166.  Your data looks like it very well might also.

4166 does have 6.5 CM load data, but it's a fast powder for the heavy 140's that apparently are now the 6.5CM standard weight.  So velocity is going to be low.  Curious about your accuracy results.

#1 is 35.4gr MP580
Attached File


#2 is 35.8gr MP580
Attached File


Groups opened up on the #3 which is when I got pressure signs.

boman, is that with the 140 RDF?

Yes, loaded to about .006" off the lands.

Sorry for the hijack, have done seating test? I am about to begin with this one.

Lazy's test data.  Beware, there could be more variability between these repack jugs, than retail jugs, so work up your own loads with caution (that's not just a CYI disclaimer; I mean it).
MP530:
6.5 Creedmoor; 24" test BBL, H brass, S&B primers
-Speer 90; 44.4 gr; 3133 fps; 0.69 MOA (0.28 MR) - my current spec load for these components.

MP580
6.5 Creedmoor; 24" test BBL, H brass, S&B primers
-Speer 140; 32.0 gr; 2435 fps; 1.3 MOA (some primer cratering / primer extrusion) current spec load
-Speer 140; 33.3 gr; 2504 fps; 1.0 MOA (heavy primer cratering / primer extrusion)
-Speer 140; 34.5 gr; 2578 fps; 1.5 MOA (heavy primer cratering / primer extrusion)
Stopped here.   The Speer 140 gr bullet doesn't like to sing with this powder (or any other I've tested to be honest).  Just going to make AR10 gong-banger ammo with the ones I have left.
I'll say it again. My jugs at least of MP580 do NOT behave like 4451; and this is yet one more caution to NOT treat it like it does.  My jug behavior cross-references much more closely with IMR 4166; which gives similar velocity and pressure-max data on their website to what I'm seeing above

223; 20" NM BBL, LC brass, CCI41 (MP580)
-62 gr MK318 Mod 1 SOST: 23.6; 2830 fps; 2.1 MOA   (eh.. not that exciting; could try to bump up, but already seeing some P sign in the brass still going that slow; these bullets seem to do best with ARComp or 8208)

PM sent so as to not derail the thread further.