Confused about powder test results... help!

[Allen Corneau]

Quick background... I'm relatively new to loading/reloading, got started earlier this year as I added high power to my list of silhouette disciplines. Like many silhouette shooters, I'm using a 6BR and have been using the components and loads that were recommended to me by my friends that got me in this game. After initial testing I was able to get my two loads dialed in reasonably quickly and to a sufficient accuracy (about 0.5 to 0.75 MOA) and just ran with it for all the matches this year.

Now that my competition season is done until February, I started to do some more in depth ammo testing as well as checking some alternatives to bullet weight, powder, etc. I ran five different load tests yesterday on a near-perfect windless day on the 300 yard range with the range to my self. After analyzing the data, I'm struggling to understand the philosophy behind the process...

What I can't understand is how some three-shot groups can have smaller or larger extreme spread in velocities to an adjacent group and have similar or complete opposite size group on paper. For example: a group with an ES of 47 with a group size of 2.25", followed by a group with an ES of 45 and a group size of 1.6", followed by a ES of 4 with a group size of 1.85".

There are plenty of instances where a particular shot's jump/drop in velocity resulted in a high/low shot on paper, but also shots where there was a similar spread but with no flyer down range.

Another part that is making me confused about the process is some high-level high-power competitors that have YouTube channels (where I've been learning a lot) don't even look at group size during powder testing, only the chronograph data. Should I be following suit and just ignore the group sizes at this point?

Hopefully some of you fine folks can shed some light on this for me. I want to get this powder testing process figured out much better before moving on to any seating depth testing. I'm including a graph of one of my tests with the added group size indicated just to the right of each result.

Thanks.

Forum Boss: From text it appears these groups were shot at THREE HUNDRED yards (300 yds). If that's true, even 1.5" isn't bad (equivalent to 0.477 MOA).

 

[Prose]

Welcome to the rabbit hole(s).

Extreme spread doesn’t matter as much for short range shooting. At 1,000 yards extreme spread will really show up in vertical.

There are multiple methods of load development that prioritizes different things. There’s barrel dwell time, optimal charge weight, ladder testing to check for “noads.”

Stick around here and you’ll learn what you need to know.

 

[gpoldblue]

Quick background... I'm relatively new to loading/reloading, got started earlier this year as I added high power to my list of silhouette disciplines. Like many silhouette shooters, I'm using a 6BR and have been using the components and loads that were recommended to me by my friends that got me in this game. After initial testing I was able to get my two loads dialed in reasonably quickly and to a sufficient accuracy (about 0.5 to 0.75 MOA) and just ran with it for all the matches this year.

Now that my competition season is done until February, I started to do some more in depth ammo testing as well as checking some alternatives to bullet weight, powder, etc. I ran five different load tests yesterday on a near-perfect windless day on the 300 yard range with the range to my self. After analyzing the data, I'm struggling to understand the philosophy behind the process...

What I can't understand is how some three-shot groups can have smaller or larger extreme spread in velocities to an adjacent group and have similar or complete opposite size group on paper. For example: a group with an ES of 47 with a group size of 2.25", followed by a group with an ES of 45 and a group size of 1.6", followed by a ES of 4 with a group size of 1.85".

There are plenty of instances where a particular shot's jump/drop in velocity resulted in a high/low shot on paper, but also shots where there was a similar spread but with no flyer down range.

Another part that is making me confused about the process is some high-level high-power competitors that have YouTube channels (where I've been learning a lot) don't even look at group size during powder testing, only the chronograph data. Should I be following suit and just ignore the group sizes at this point?

Hopefully some of you fine folks can shed some light on this for me. I want to get this powder testing process figured out much better before moving on to any seating depth testing. I'm including a graph of one of my tests with the added group size indicated just to the right of each result.

Thanks.

View attachment 1496048

There's no such thing as windless days due to thermal dynamics....just put out some wind flags and see for yourself. I personally think 100yds would be better for testing especially if you're not using wind indicators.
Wind can/does cause all kinds of POI changes. Also,your smallest groups are going to be on the "node",so you need to find where your nodes are and where you are on that node. If you're not using wind flags,I highly suggest you get some....the going will be much easier.

P.S........You can listen to whoever you want,but remember the most accurate and the most precise shooters on this planet are Benchrest shooters........I'd listen to them if I wanted the smallest groups possible.


Good luck and stay safe.

 

[Bc'z]

26.6 is your smallest group shot at 300yards looks like a .3 moa for that target, not bad.
What powder and bullet were you using?
More details would benefit in helping you sort it out.

 

[David Christian]

I would really dig into and start measuring everything related to your brass prep and read as many articles as possible on the subject. Like someone already stated, there are many different load development rubrics out there that can be successful. However, if you are going to use the data (like myself) improved brass prep could help see the details in the results. Large ES numbers make it hard to analyze the data, especially for 3 shot groups. As an aside, your graph actually looks pretty good and is pointing at a strong are to explore further.

 

[Jeff Porter]

Three shots may tell you a bad load but it does not confirm a good load...

You are not pushing these real hard at all under 2700 fps. What are the others in your area getting for velocities? Faster is flatter with less drift all other things being equal but group size will be your true indicator.
I look for indications like the 26.6gr and work around that load 26.4-26.8gr looking for no change in POI or group size over a few 0.1gr increments and play with seating depth a bit to try and tighten the group some more. You may be real close with what you have there.

 

[J_idaho]

Looks like you’re doing it right. Getting case fill is very important and I’m guessing that 26.6 is getting closer to full and you found a good node there. Just like everyone said case prep will help you keep that load the same every time and with tight tolerances you should be able to repeat it. I know nothing about 6br but if your not getting same case capacity, shoulder bump, neck tension and seating depth your not going to see consistent groups or velocities.

 

[Webster]

Quick background... I'm relatively new to loading/reloading, got started earlier this year as I added high power to my list of silhouette disciplines. Like many silhouette shooters, I'm using a 6BR and have been using the components and loads that were recommended to me by my friends that got me in this game. After initial testing I was able to get my two loads dialed in reasonably quickly and to a sufficient accuracy (about 0.5 to 0.75 MOA) and just ran with it for all the matches this year.

Now that my competition season is done until February, I started to do some more in depth ammo testing as well as checking some alternatives to bullet weight, powder, etc. I ran five different load tests yesterday on a near-perfect windless day on the 300 yard range with the range to my self. After analyzing the data, I'm struggling to understand the philosophy behind the process...

What I can't understand is how some three-shot groups can have smaller or larger extreme spread in velocities to an adjacent group and have similar or complete opposite size group on paper. For example: a group with an ES of 47 with a group size of 2.25", followed by a group with an ES of 45 and a group size of 1.6", followed by a ES of 4 with a group size of 1.85".

There are plenty of instances where a particular shot's jump/drop in velocity resulted in a high/low shot on paper, but also shots where there was a similar spread but with no flyer down range.

Another part that is making me confused about the process is some high-level high-power competitors that have YouTube channels (where I've been learning a lot) don't even look at group size during powder testing, only the chronograph data. Should I be following suit and just ignore the group sizes at this point?

Hopefully some of you fine folks can shed some light on this for me. I want to get this powder testing process figured out much better before moving on to any seating depth testing. I'm including a graph of one of my tests with the added group size indicated just to the right of each result.

Thanks.

View attachment 1496048

Stats on 3 shot groups are meaningless. To be accurate you probably need at least ten shots in each group. If you shot 10 shot groups the ES would be much bigger. If your only shooting out to 300 yards I would forget about SD and ES, group size is the only thing that matters.

Someone else can comment on reasons you might have so much spread. 45 ES on one group .3 gr increase 4 ES ? Don't know what typical charges are for a 95 Gr bullet with VV133. When you get to 26.3 gr the data looks much better. How far are you from a max. load. Can you go higher than 26.9 gr? With my 6BR and 60 gr bullets I can shoot 34 gr of 8208. I would try Varget powder.

I'll see if I can find a load map for 95 gr. bullets.

Based on the loading data on this website VV133 isn't popular for heavier bullets.

You are being redirected...

 

[BoydAllen]

A couple of things that others have mentioned. Case fill is important, and the powder that you are using is not considered suitable for that weight bullet for that reason. Do a little research regarding medium burn rate powders that have worked well for that bullet weight. Secondly, the wind. Your at the firing line appraisal of what is happening between there and the target is not accurate enough for important work. My old friend Wilbur Harris once said that it is amazing how putting out a few wind flags will make the wind start to blow. That information is particularly important at the distance that you are testing at. You do not have to buy flags, if that is an issue. Sticks with surveyors tape hanging down to just above the grass or ground will work fine, Buy some 8' 1x2s at Home Depot, along with a roll of surveyors tape, cut the boards in half and sharpen one end. Attach teh tape to the other and put them at several distances between you and the target. At that distance a half dozen should do. The closest one will show the wind that has the most effect. I would put it out at 10-15 yards. No one puts them out right at the target. Another issue is that ES is really not the same as tune at all. You need to completely rid yourself of that idea. You can have really good ES and not be in tune. Finally you need to learn to read the shape of groups. If the shots seem to correspond to what the wind was doing at the time you fired them (this is one of many advantages of flags) then the issue may not be your load at all. I tend to pay attention to vertical and exaggerated wind effect. Good luck with your efforts. Finally, the easiest way to get the most done, with the fewest trips to the range and least components and barrel wear is to load at the range.

 

[TaperPin]

For a silhouette rifle at a max 500 meters, I don’t see the advantage to testing at anything longer than what you’ve done. Others will be better at talking you through interpreting groups, but keep in mind the resolution of groups from a 3/4 moa rifle will show more seemingly random results than a 1/4 moa gun.

Also keep in mind the effects of temperature on barrel tune - it’s good to know what load shoots best at the different temps that are common at your matches. Our range was often in the shadows and late winter morning temps were quite cold compared to later in the year.

Don’t forget to throw $.25 per shot in the piggy bank for barrel replacement down the road. I was quite surprised and disappointed the first time a 1/2 moa gun wore out and became a moa shooter. The concept of a barrel being a consumable was foreign to me coming from a small bore and hunting background.

Best of luck - sounds like your gun will be quite competitive even if it simply continues shooting like it is.

 

[Allen Corneau]

Thanks for all the replies so far. Lots of questions mixed in with the comments so I'll try my best to answer them.

1. Silhouette is shot 200m to 500m but I don't have access to anything farther than 300 yards at my club, so that's what I use for my testing.

2. Berger 95 VLD Target, Lapua brass (once fired), CCI 450 primers, VV N135 powder (not N133 as someone mentioned).

3. Reducing recoil is a major factor in Silhouette, especially when you're shooting 80 shots a day for three days. Loads are generally kept as soft as you can get away with and one of the main reasons all the top shooters use 6BR.

4. Powder: one of the tests I ran was using VV N140, 24 grains up to 28 grains in 0.5 grain steps. The three shots at 28 grains yielded an ES of 1 (2666, 2666, 2665) and a group of 0.74". I'll be doing more testing in this area.

5. I have a new barrel blank waiting in the wings, just need to get it to the gunsmith. I have about 1,300 rounds on my current barrel and folks that I talk to are getting 3,000 to 5,000+ rounds with the softer loads that we typically shoot.

 

[searcher]

Barrel life is very subjective - and depends on how accurate you want your barrel to maintain shooting. It is possible for a 6BR barrel to get dialed in with a 1/4 MOA load and be able to still shoot 1/3 MOA well into 3,000+ rounds. I have several that are still shoot 1/3 +/- after 4,000 but I've retired them to varmint duty.

Regarding the You Tubers, many people vary in how they do load development, some focus on seating depth first, some velocity (as you noted), etc. After doing load development in scores of barrels, my method is finding the powder(s) that the bullet I'm using works best with. I start with the two most likely powders I think "should" work". If I don't get any good groups on the first run, I don't hesitate to switch powders if I was shooting in good conditions. Then I re-run the ladders again with those powders, having made notes on which charge(s) shot the best on the initial run. I tend to only start my ladder at the projected minimum velocity I would deem acceptable - and up to about 1 1/2 grains above the maximum velocity I would want as my max load. Many accurate loads (particularly in PPC and BR) run at the very top. You just don't want to select an accurate load at the top without going further to see that you are not going to have excessive pressure problems - and find out on a hot day - or find your accuracy dropped off a cliff.

I then get my four best loads, then shoot a 5-shot group of each, followed by another 5-shot of each, in the same order. That way, you are getting different conditions for each of the two 5-shot groups of each load. Then I take the average of each two 5-shot groups, taking into consideration the ES's if you are to shoot these at 500, as you say. To tune your rifle based on velocity or ES alone does not necessarily translate into great groups. I have shot my 6BR and Dasher into many super-low ES groups that measured 1 1/2" MOA, in rifles capable of shooting in the ones. Respecting velocity, you will be able to get your bullets in the velocity zone you want - but a powder your barrel doesn't like with that bullet might not get you a great group, no matter how much tweaking or depth adjustment.

I'll take a 6 ES over a 2 ES any day, if it gives me a 1/4" better group. There were some great points made by BoydAllen. I'd do your initial load development closer-in, 200 yards max to find what works - then try them at distance. I can't recall the last time I shot in a "calm" day - there is always something moving out there, influencing the bullet, it seems.

Good Luck!

 

[CharlieNC]

Group size and Chrono stats from a few shots are not reproducible or reliable. On the other hand the vertical poi is useful to determine the node where it is stable and insensitive to charge weight, aka the Audette ladder test used by many successful shooters.

 

[Webster]

Quick background... I'm relatively new to loading/reloading, got started earlier this year as I added high power to my list of silhouette disciplines. Like many silhouette shooters, I'm using a 6BR and have been using the components and loads that were recommended to me by my friends that got me in this game. After initial testing I was able to get my two loads dialed in reasonably quickly and to a sufficient accuracy (about 0.5 to 0.75 MOA) and just ran with it for all the matches this year.

Now that my competition season is done until February, I started to do some more in depth ammo testing as well as checking some alternatives to bullet weight, powder, etc. I ran five different load tests yesterday on a near-perfect windless day on the 300 yard range with the range to my self. After analyzing the data, I'm struggling to understand the philosophy behind the process...

What I can't understand is how some three-shot groups can have smaller or larger extreme spread in velocities to an adjacent group and have similar or complete opposite size group on paper. For example: a group with an ES of 47 with a group size of 2.25", followed by a group with an ES of 45 and a group size of 1.6", followed by a ES of 4 with a group size of 1.85".

There are plenty of instances where a particular shot's jump/drop in velocity resulted in a high/low shot on paper, but also shots where there was a similar spread but with no flyer down range.

Another part that is making me confused about the process is some high-level high-power competitors that have YouTube channels (where I've been learning a lot) don't even look at group size during powder testing, only the chronograph data. Should I be following suit and just ignore the group sizes at this point?

Hopefully some of you fine folks can shed some light on this for me. I want to get this powder testing process figured out much better before moving on to any seating depth testing. I'm including a graph of one of my tests with the added group size indicated just to the right of each result.

Thanks.

View attachment 1496048

My Berger Manual 1st. Edition list For VIHT N135 and a 90 gr bullet:
starting load 27 gr 2624 fps
Max load 30.2 gr. 2888 fps

No data for a 95 gr bullet but for the powders Berger listed they give 9 powders above 2800 fps at max load.

Your at 26.9 gr. at your max load tried and about 2720 fps. Sounds like you could go 1-2 gr more powder or try a different powder. You want light recoil maybe one of the below powders at a lighter load would work. I shot a 7mm Mag from the bench with small groups. Probably never shot more than 10-15 shots on any day. Never shot anything much more than a 70 gr bullet with my 6BR. The rifle weighs 13 pounds. Recoil is a push rather than a sharp snap. Maybe you could add weight to the stock butt? Heavier barrel?

Berger manual: Powders listed for a 95 gr. bullet. Max load only below.
AA2495 28.9 2834 fps
H4895 29.5 gr. 2852 fps
Varget 30.3 gr. 2818 fps
IMR4895 30.4 gr. 2876 fps
RE-15 30.6 gr. 2859 fps
Norma 203B 30.7 gr 2855 fps
VIHT N150 31.8 gr 2814 fps
Ram Shot Big Game 32.7 gr 2895 fps
Win 760 34.1 gr 2897 fps

ADDED Later:
Maybe you have big ES because your shooting light powder charges and your way out of tune. I think light cgharges are known to be erratic? I would shoot one shot each increasing .3 until I see signs of pressure so you have some idea of the limits with your rifle.

 

[DLT]

Welcome to the rabbit hole(s).

Extreme spread doesn’t matter as much for short range shooting. At 1,000 yards extreme spread will really show up in vertical.

There are multiple methods of load development that prioritizes different things. There’s barrel dwell time, optimal charge weight, ladder testing to check for “noads.”

Stick around here and you’ll learn what you need to know.

Or it will drive you bat shit crazy one

 

[searcher]

Group size and Chrono stats from a few shots are not reproducible or reliable. On the other hand the vertical poi is useful to determine the node where it is stable and insensitive to charge weight, aka the Audette ladder test used by many successful shooters.

This is absolutely true! And this is also why a lot of guys (like me) will chrono and record the velocity off each case in a batch to come up with a group of cases to use in matches. The differences in cases alone will stagger your ES's and keep you chasing your tail to figure out what is going on. Even when cases have been weighed or checked for water capacity, flash holes uniformed, pockets leveled, necks turned, etc., there can still be a very slight difference between cases. Been there....

 

[Evan]

It’s easy to get overwhelmed. Here’s my process which I think is relatively simple:

My new 22BR!

Really appreciate your detailed reports. Keep up the good work!

forum.accurateshooter.com

I would put away the chronograph and read the target. I would also get wind flags. Surveyors tape tied to a stick of rebar is really easy and cheap and will give you a whole new understanding of the wind. I say use 3 to start. One about 10 feet in front of you and in your sight just to the side of the gun. One halfway down range that you see in the scope, and one about 10 or 20 yards in front of the target that you can again watch in the scope. Choose a wind condition and only shoot your group in that condition. “Windless” days are usually the least predictable for me. A steady wind has always produced smaller groups and more readable targets.

 

[Forum Boss]

If those groups are at 300, the accuracy is not bad -- under half-MOA. However, some of the ES suggests a problem with your reloading, and your velocities are low for a 6BR with 95gr bullets.

1. Try a slower powder
2. You should be able to get a 5-shot ES at 16 fps or better. Failure to do that indicates need for improvement.
The 3-shot ES of 47 and 45 indicated something is likely quite wrong (powder measurement or you may not be prepping your cases properly).
3. With a powder such as Varget, try to get around 2850 fps or better (with 26" or longer barrel).
4. Suggest you shoot from a good rest, then confirm the accuracy standing for silhouette.
5. Do your load development at 100 yards, not 300.

 

[Webster]

This is absolutely true! And this is also why a lot of guys (like me) will chrono and record the velocity off each case in a batch to come up with a group of cases to use in matches. The differences in cases alone will stagger your ES's and keep you chasing your tail to figure out what is going on. Even when cases have been weighed or checked for water capacity, flash holes uniformed, pockets leveled, necks turned, etc., there can still be a very slight difference between cases. Been there....

Did you ever sort the same cases twice to see if the results are the same? Many variables, easy to assume you know what causes it.

 

[searcher]

Did you ever sort the same cases twice to see if the results are the same? Many variables, easy to assume you know what causes it.

Believe me, I don't assume to know what an internal "defect" is with any one piece of brass when firing it. And I really don't need to know. I'm only concerned with trying to find brass that all shoots the same at least once.
You are correct that there are so many minute variables - even in primers, bullets, bore fouling - the list goes on. Every time you chrono a particular round, it will always deviate a little due to all those dynamics at play. It does, however, exclude the cases which fall so far out of the parameter that they are probably better left out of the group. And, maybe some were pushed out of the "good" array of cases undeservingly because of a weak primer, heavier bullet, etc., but that is O.K. Once I start practicing with those cherry picked lots, I always find that I get better ES's. Definitely not a perfect science. I don't re-chrono each individual round as I did the first time, though I do chrono samples of those in one lot as compared to another segregated by velocity. And the difference in overall velocities of each group were amazingly close to what they shot as a group the first time. You can get carried away with this. I think a lot of people won't do this just to spare the barrel a hundred shots. I'll do it as a one-time shot - and that is it. It has proven worthwhile for me, for sure. If I were shooting a caliber that is only good for 1,000 rounds - maybe not. I'd probably spend my time with water volume, weighing, flash hole checking, etc. Fortunately - I don't have any of those barrel burners.

I've shot so many thousands of rounds over a chrono doing this that it dispelled all doubt in my mind about how "perfect" some brands of brass supposedly are. None are. some just worse than others. Lots of ways to try and spot the weak ones