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Discussion Starter #1
With both Vihtavouri N135 and N140 readily available... which one would be better suited to the M1A gas system ?

Judging by the various burn rate charts, N135 appears to be a much better match to IMR 4895 and IMR 4064.

While VV N140 seems to be even slower than Varget.

And for what its worth...there is a fair amount of people even using N150.... (right around H4350... no thanks.)


So I did a search on the two and considerably more people are using N140 !?

Won't N135 be better ?

FYI, I am one of those M1A guys that doesn't believe in speed only, accuracy is more important to me.

The speeds between the two with a 155gr bullet are similar, but the "Max .308 bolt action load data "with a 168gr the N135 is 140 fps faster... ( I do fully understand the need for proper gas port pressures , so I would not be using the Max .308 data )

So....Given the choice which one would be the "wise" choice for my M21 ?
 

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I'd go with N140, it produces numbers that are in between IMR 4895 and 4064 and it's easier to find an accurate load that isn't compressed. Notice that the ratio of specific heats is greatest for N135 which means that it has the greatest amount of pressure per volume of powder. N135 also has the lowest bulk density so it fills a case up quicker than the other powders.

 

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Velocity & accuracy N135 for me. 1-12 twist Winchester C/L & 155 Sierra HPBT/AMX = Happy Happy Happy M1A
Thank you RAAMAC for the data. Just my rifle seems partial to N135. Just found 32 lbs after 1 & 1/2 year wait!
 

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I use N135, it is fast burning and keeps the gas system and the barrel clean and reduces muzzel Flash.
Wolf
 
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I agree that N135 looks good overall but there is a slight difference in how much case capacity is used and under some specific situations that would be a problem for me.

Keeping a 168gr SMK supersonic at 1000 yards will be easier with N140, you will have to compress the load more to get the necessary muzzle velocity with N135. On the other hand, if you are using 175gr SMKs out to 1000 yards then there is virtually no difference in pressures or velocities and it just comes down to which is available and which you like better.
 
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Who said I was afraid of a compressed load?

I'm not "afraid" of a compressed load (although it's not recommended for ball powders), I just don't like them because I don't believe that they burn as well. I like a powder that uses just under 100% of the available case volume.
 
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Discussion Starter #8
Gentlemen, Thank you for all your answers.

RAMMAC, I had not considered the "bulk" of either powder. ( I will use a drop tube with the N135.. since I ordered some of both. ) I will being using the powder at ranges up to 600 yards ( The longest at my club. ) I have had good luck with my rifle as long as I keep its barrel and gas system clean... accuracy starts to fall off after about 150 rounds. So the cleaner the burning the powder the happier I will be.

And thank you very much for the charts !! Is that a "QuickLoad" program ?

Again , I would like to thank everyone that responded... your input is always welcome.
 

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168gr supersonic to 1000 is a very tall order. You need about 2750-2800fps at the muzzle I know they did one load with 168s for service rifle that would pull it off but it was very hot.

Buying both is the smart move I would bet on N140 being the better of the two though. You should be happy with them as the vihtavouri powders are very clean burning.
 

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Main reason that I use N135 is, that we are limited to small amounts of powder in our homes over here. I needed a powder that works sufficiantly in 2 short barreled .308 + 1 long barreled .308 and 1 short barreled .223. Works fine with all of them. Same with Unique in 9mm, .45 and .44.
Wolf
 

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168gr supersonic to 1000 is a very tall order. You need about 2750-2800fps at the muzzle I know they did one load with 168s for service rifle that would pull it off but it was very hot.

Buying both is the smart move I would bet on N140 being the better of the two though. You should be happy with them as the vihtavouri powders are very clean burning.

The speed of sound is approx. 1115 fps at sea level and it's even lower as you increase in altitude but lets assume that you need 1120 fps (just to be safe) at 1000 yards to stay super sonic. With the right 168gr bullet (high enough BC) you can easily retain 1000 yard super sonic speeds. Hornady 168gr Amax and 168gr Berger VLDs will both hold super sonic speeds with muzzle velocities of around 2525 - 2550 fps. Just about any common powder will produce those kinds of muzzle velocities. But even though you can make them go fast enough it doesn't necessarily mean that they will be accurate, you can only find that out with real world testing.
 
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I've shot those in the real world @ 1000, you need a lot more than 2525fps LOL. That's whole other topic not going to derail thread.
Oh and by the way, let's not wallow in the mud and be jerks and try to belittle each other. DI5

I'm sure that you'd rather talk like an adult and discuss our disagreement...oh wait, too late.
 

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Regardless of the poor manners, I agree that I posted incorrect information, another good lesson in using software...garbage in, garbage out. I have no problem discussing my mistakes and posting corrected info, nobody is perfect, but I wont tolerate being ridiculed or laughed at, I don't do it to others and I expect the same kind of consideration.

Ballistic Coefficients are really important when estimating things at long range and the software I use automatically defaulted to the wrong value.

The wrong value resulted in greater retained velocities.


That BC value resulted in an estimated 1000 yard velocity of 1137 fps. When I corrected the BC values



the velocity dropped to 1045 fps. In order to get the 1000 yard velocity up to super sonic speed (1115 fps or higher) I needed to increase the muzzle velocity to 2710 fps. Even so, there are quite a number of powders that will push the 168gr Amax to 2710 fps.

I wouldn't recommend using N135 and N140 though, while both will push the 168gr Amax to 2710fps at the muzzle the chamber pressures are just over the max recommended by SAAMI (N140 having lower pressure than N135). If you want to use a Vihtavuori powder then you need to switch to N530 or 540, would both work. Most of the standard go-to powders will work well too (IMR 4895, H 4895, RL-15, W748, to name the more common).

I know that you didn't want to shoot at past about 600 yards but I wanted to clear up my erroneous information.
 
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