None really.  Its in between slightly.  If I was to guess what this is most like, it would probably be N140, but its "slightly" faster than N140 I think.   Take a look at this bar graph.  We can see its about 1 entire Grain SLOWER than Benchmark and N135.  How many grains slower is N140 than N135 using 77 SMK?  Answer:  about 2.2 grains to get similar pressure.  So if this was a Vihtavhouri Power, it would be called N137?  Uh oh...we know what people are thinking.  That is like XBR 8208 load data almost.  Oh boy..this is quite upsetting.  Now this *&^ damn powder will never be in stock again....sigh... 

SWPR = Shooters World Precision Rifle, which is similar to Varget.

Using 2 different match barrels, same loads in each to get better idea of performance across different platforms and twist rates, barrel lengths...

First thing we see we have 2 about 1/2 inch groups with the MP 540, which is tighter groups than any of the 8208 XBR, but not by much and its a trade off because the XBR was higher velocity and barely not as accurate.  The point is this..

8208 XBR if you look across the internet, is the holy grail of powder people say, its the best thing since air conditioning.  Owning 8208 XBR is like owning winning lottery tickets.  This is the general feeling about this powder. 

So we go ahead and buy demilitarized powder and it shoots groups very similar, slightly better (but lower velocity).  Folks... 8208 XBR is just a good option, just like MP 540, just like N135, just like N140, just like N540, just like Shooters World Precision Rifle, just like Varget, just like Reloder 15.   All good for the heavies. 

Look at the big picture, this is  A LOT of sub MOA groups across a lot of different loads.  For a cheaper powder that you can buy 32 lb lots of?  Folks.  BUY IT.

Here  is the new slogan for this powder..."MP 540...the powder that is inexpensive, but its always out of stock because everything is buying it up"  Why?  Because its burn rate and case fill is near "ideal" for heavy 223 bullets, especially 69-80 grain we can confirm. 

Ok based on this test, we think we know "around" where max charge would be, based on our experience.  But never take our word for it, and never use our loads.  Use only Manufacturer official data.  But if we had to guess, we would say max charge using a 77 SMK, would be in the ~23.0-23.1 range.  Which is very similar to in between N140 and XBR 8208, and slightly slower than N135, H4895 and Benchmark. 

We would call this (if it was a VV powder...N137 or N138 perhaps)  Maybe a hair faster than N140.

So how did it do?  We think really well.  Its competitive with really good powders.  Look how the "best" 4 shots in each group was statistically "exactly" the same as the winning lottery ticket (8208 XBR).

But MP540 was more accurate.  Best 4 shots on 2 groups was SUB .3 inches.  That is super good for an AR15 using magazine ONLY feeding, not single load.

First step since there is no load data.  FIND OUT WHAT THE HELL ITS RANGE IS THAT IS SAFE AND UNSAFE!!!

We are great at doing this, because we enjoy risking our bodies for the sake of science (That was a joke).  Here is what we say to everyone.

DO NOT LOAD ANYTHING WITHOUT MANUFACTURER RECOMMENDED LOAD DATA.  We are not a manufacturer, we cannot recommend that you load this.  We did, because we are curious.  Do not do, what we do.

Next step?  Figure out where it blows primers.

FOUND IT!!!  24.5 did not blow primers, but 25 grains blew 1 primer, and the other one did NOT blow. So with this Nammo Brass, which weighs around 97 grains and has call fill in the ~30.5-30.8 grain range, it will blow primers in the 24.6-25 grain area probably.  Note, that 1 of the shots at 25 grains was, lets see... 2,992 FPS, 77 SMK, 20" barrel.  SO yea...about ~350 FPS over max load if it had one...

Comparing RL15 and N540 to this, we noticed to get same "Compression" of the load, that MP 540 requires about .5-.7 or so LESS powder.  So in other words, if N540, 24 grain load with 77 SMK made like 80lbs of compression to load.  Then about 23.3 grains of MP 540 would make same compression, generally.  Because its more bulky.  But its LESS bulky that say, RL15.5 and RL16.  Its similar case fill to AR Comp, but grains are longer ini MP540. 

***NOTE:  This barrel delivers higher than normal FPS for 20" barrel.  Expect 50-75 FPS less in a normal 20" barrel.

We are going to test this a lot more, to see if it is accurate, and temp stable possibly. 

Using this data could be dangerous, because lots are different, brass different, barrels different.  What worked for us, may not work for you.