Burn Percentage

[Shaggy357]

May want to confirm primer also. Ignition source will play with the numbers also. My Varget loads in the 260 vary with Rem 9 1/2 vs WLR primers.

Just more to throw on the fire......

 

[Ned Ludd]

That's what i suspected. That 48.0 gr Varget recommendation would probably work for a much longer barrel. BTW, i was only able to get an average 0.6" group in my load testing. Best was 0.45" and worst was 1.06".

I'm going to step down to a N135 which has a burn percentage around 98% and good pressure numbers.

It doesn't really matter what powder you choose, as long as it has a burn rate more appropriate for the task at hand. Varget is one of my favorite powders for .308, but it's not well-suited for your specific use. Hopefully, you will see an improvement after the switch. Good luck!

 

[waldo1979]

May want to confirm primer also. Ignition source will play with the numbers also. My Varget loads in the 260 vary with Rem 9 1/2 vs WLR primers.

Just more to throw on the fire......

Yes this is another consideration. 48gr is a lot of powder to ignite. I'm using a Tula small rifle magnum primer and it might not be hot enough. But then again, if I go to a faster burn rate powder it will solve some of this.

 

[Webster]

Webster,
QL give you the approximate burn rate of the load spec's you feed it.

Tia,
Don

I don't give up easily. I have always found good loads quickly by shooting. I have some knowledge of how difficult the statistics and math can be from my workplace. It's difficult to correlate cause and effect with 5 variables. It doesn't seem reasonable to accurately calculate something like % burn with about 15 variables and all of the thermal dynamics going on. It would be nice to try to confirm the QL calculation by shooting a 90% & a 99% burn rate powder at a piece of paper and looking for powder burns. I have shot shotguns and rifles at night you can not believe how much flame there is. You cannot see it in the daytime. I would love to see a picture of a 90% & and a 99% burn load fired at night. It would make me a believer.

NASA uses super computers to calculate burn rates in solid fuel rockets. They are basically a tube with a hole in one end. The solid fuel can be molded into many shapes.

 

[Dusty Stevens]

It doesnt matter if you have a 42" barrel varget is not a good choice in your combo. Its like trying to use retumbo in a 223. No matter what you do its not optimal and wont be in the top 10 as far as accuracy and efficiency is concerned. Will it go off? Sure it will. If youre in an end of the world scenario you could use it to get by but thats about it

 

[Webster]

It doesnt matter if you have a 42" barrel varget is not a good choice in your combo. Its like trying to use retumbo in a 223. No matter what you do its not optimal and wont be in the top 10 as far as accuracy and efficiency is concerned. Will it go off? Sure it will. If youre in an end of the world scenario you could use it to get by but thats about it

I don't understand that if you have a 48 gr charge of Varget and 4.8 % of it doesn't burn in the barrel, how do you still get good velocity with 43.8 gr. burning in the barrel? Has anyone verified QL on % burn or do they just accept? I am not trying to say Varget is a good choice just trying to understand what's going on.

 

[Dusty Stevens]

Quickload is like a chronograph- Its all good til you start putting the bullet on the target. Its a tool to play around with and get you started in the right direction, but i assure you nobody has ever won a match because of quickload or a chronograph. It doesnt matter what quickload says varget is not a good powder for a 308 with an extremely light for caliber bullet.

 

[Dusty Stevens]

To answer your question varget is just too slow for a light bullet in that big of a case

 

[Brians356]

H335 would be likely to work very well here.
-

 

[BillPa]

I don't understand that if you have a 48 gr charge of Varget and 4.8 % of it doesn't burn in the barrel, how do you still get good velocity with 43.8 gr. burning in the barrel? Has anyone verified QL on % burn or do they just accept? I am not trying to say Varget is a good choice just trying to understand what's going on.

Web, take a few minutes and read all three pages what Rocky had to say about it.
https://www.shootersforum.com/handloading-procedures-practices/48081-reloading-short-barrel.html
Bill

 

[Webster]

Web, take a few minutes and read all three pages what Rocky had to say about it.
https://www.shootersforum.com/handloading-procedures-practices/48081-reloading-short-barrel.html
Bill

Who is Rocky? Sounds like all personal opinion. No research articles quoted by the military, DOD, powder manufacturers ect. When you give out technical info you should always quote your sources otherwise who knows it's value.

 

[waldo1979]

Looking like Primers is a bigger issue. Today i loaded some N135 and towards the upper in 1 in 3 of the primers would flatten out. The rounds with flat primers flew outside the group.

I bought some CCI #450 but may also try some Remington 7 1/2s.

 

[Dusty Stevens]

If you had the same primers and they looked different most likely it was case capacity doing that. Other factors are different neck tensions due to hardness or thickness, unreliable sizing, and unreliable seating like bullets varying in places your seater doesnt touch, or powder charge varying, or cooking the rounds in a hot chamber. Unless you shot them on different days one of those did that

 

[waldo1979]

Waldo1979

What is your bbl length?

This info will help in getting headed towards the best powder possible.

Tia,
Don

24" Benchmark barrel 1:10 twist in a REM 700 action.

 

[waldo1979]

If you had the same primers and they looked different most likely it was case capacity doing that. Other factors are different neck tensions due to hardness or thickness, unreliable sizing, and unreliable seating like bullets varying in places your seater doesnt touch, or powder charge varying, or cooking the rounds in a hot chamber. Unless you shot them on different days one of those did that

The brass is fairly consistent (Lapua Palma) but it is new. The necks were ~.304 and I resized the necks in a Lyman M-die to .3065". Seatting die is a Whidden seater and shoulders were bumped 0.002" using a Forster FL sized.

Ill measure the case volumes when I get a chance.

 

[Dusty Stevens]

Regardless youre on the edge of pressure. You may have trouble when it gets hot

 

[Webster]

im working a load with a .308WIN 116gr custom bullets (reserving the manufactures name for the time being). I don't have much data on the bullet so I'm going by best guess and the manufacture recommendation of 48gr of Varget @2.8" COAL. The closest match I can find is a 125gr or 110gr Berger, or maybe a Hornady Vmax 110gr.

Anyway, no matter how I look at it my burn percentage with Varget is going to be below 90%. I've never had such a low burn percentage before so im not sure what that means? Im guessing more carbon build up in the bore.

The best match powder for what I have on hand is VV N135 or maybe Benchmark. Both have a good burn percentage but the Benchmark pressure numbers are a little higher than I would like. I have 5 more matches in my season and I don't think I have enough N135 so it's looking like I'm going to be using Varget.

Look at the 308 charts on this website. They are using Varget with light and heavy bullets. I am not saying Varget is the best choice.
http://www.accurateshooter.com/cartridge-guides/308win/

If the powder is to slow because of below 90% burn why are they getting good velocity? If 10-15% of the powder is burning outside the barrel wouldn't you get low velocity? I believe real world results before computer generated data. Don't believe everything a computer spits out. Chrono the velocity.

My Sierra manual list these powders with the higher velocity with their 110 gr bullet:
H322 3300 fps
748 3200 fps
H335 3300 fps

The Berger manual list 10 powders for their 115 gr bullet. All above 3114 fps.
Some of the highest fps listed:
H322 3206 fps
H335 3161 fps
Ramshot Tac 3195 fps
Win 748 3241 fps
BL-C-2 3234 fps.
N135 is listed for the 125 GR bullet.

The manuals are conservative. I always assumed that the listed powders that give the highest fps for a given bullet weight are the most efficient for whatever reason. Compare these powders to others close in burn rate.

 

[Brians356]

Look at the 308 charts on this website. They are using Varget with light and heavy bullets. I am not saying Varget is the best choice.
http://www.accurateshooter.com/cartridge-guides/308win/

If the powder is to slow because of below 90% burn why are they getting good velocity? If 10-15% of the powder is burning outside the barrel wouldn't you get low velocity? I believe real world results before computer generated data. Don't believe everything a computer spits out.

Only 0% of powder ever burns outside the barrel. If only 90% actually burns, then the remaining 10% doesn't burn at all.

 

[Webster]

Only 0% of powder ever burns outside the barrel. If only 90% actually burns, then the remaining 10% doesn't burn at all.

Does it matter if powder blown out the barrel burns or doesn't burn, it isn't used.

 

[Brians356]

Does it matter if powder blown out the barrel burns or doesn't burn, it isn't used.

Not disputing that. Only disputing that some powder burns outside the barrel, a common misconception which doesn't need to be reinforced here.