Acceptable speed tolerance?

[775mud]

Hi everyone,
I am new to reloading and had a question on what the speed differences are for loads. What is the tolerance I need to look between each load? There was a 1" difference in height when we had the faster shot at 3200+FPS compared to the slower 3178FPS at 200 yards.

I reloaded .257 Weatherby Mag with RL22 using 64.5g of powder. Hornady suggested max load in the book. It's a 117g bullet at 3.170" total length. Also suggested in the Hornady book.

The max speed we got using a LabRadar was 3255 and the slowest speed was 3178. Our average after 8 shots was 3209fps.

I was pretty anal loading the bullets so I made sure I tared the scale each time I poured the powder, to make sure I had the 64.5g of powder each time.
The 8 speeds were 3189,3255,3178,3202,3239,3177,3247,3188.

Is this normal and I'm just sweating the small stuff or did I do screw up somewhere?

 

[ckleeves]

It kinda depends on the distance you’re hunting/shooting at. A ES of 77 isn’t ideal, but at 500 yards with a 117 SST (not sure what bullet your shooting so I just ran that one) it only calcs to 2.3” of vertical difference. Assuming your dope is based off the 3209 you’re only looking at 1.4” of vertical miss off your dope worst case scenario.

Your actual ES is probably bigger then 77 fps just because 8 shots over the chrono isn’t telling the whole story but at the same time it’s better then 3 shots.

Set up some paper at the max distance you plan to shoot/hunt at and see what it looks like. Chrono those also so you get a bigger sample. Trying different primers is an easy thing to try if you want to clean it up.

 

[A382DWDZQ]

Hello & welcome to reloading, enjoy!

I think by tolerance you mean the deviation in velocity from shot to shot. This is genefrally characterized as you ES, extreme spread, and SD, standard deviation. Lower is better. You have an SD of 32.8 and ES of 78. That could just be the load, and it might be normal for your set of unique variable, but…

…with your scale, I’m curious what kind of scale you’re using. You should not need to tare it each time, if you do, get rid of it and get a better scale.

The best you can do is be scientific with your process and try and keep things consistent. Don’t change a bunch of things at once. Try a different powder keeping all your other steps the same and see how it does in comparison. It might give you better or worse ES/SD. Or change your primer, or change your neck tension, or change your seating depth.

HTH

 

[Vern400]

You're measuring three things at least.
1. Your ability to support aim and fire
2. Your rifles precision capability
3. Combustion, harmonics, and flight characteristics of the bullet

An ES of 78 isn't the best. It's not the end of the world either. But work on getting more consistent combustion first. Try a primer change or a charge weight/ powder change to see if you can get es down in the 30s. I don't know anything about WBY 257 so I really don't know where you should end up.

Weatherby Magnums have a lot of free bore typically so playing with your seating depth might not have much effect. I don't know, but I know how to find out. Testing.

Welcome to reloading! If you are able to create ammunition with a good bullet at good velocity where you can put five shots in an inch at 100 yd repeatedly... On different days and conditions... That is beyond successful with a regular sporting rifle. When you get that, try to load a hundred or 200 with the same lot number of everything, and consider sealing the primers and bullets so you never have to worry about humidity changes screwing up your load. And then don't mess with it. Just shoot it. That's what I've done. Same load since 1992. Sure I play around and look for better recipes, but the old trusty box of success is always nearby.

 

[Tahoe1305]

Agree with the other posts, it depends. As a new Reloader you’re about to dive down a rabbit hole of items that “can” impact your load consistency. Some will have more of an impact than others. Some require expensive equipment while others just paying more attention.

As a general goal for hunting/shooting I aim for less than 50fps ES and 10 SD. With non-crazy expensive equipment and not too much tinkering this is usually not too difficult to achieve. When I’m really trying hard i shoot for 30fps and about 8 SD. That’s about as good as I’ve been able to achieve with a 10 shot group. I assume, but haven’t tested, that a cartridge that pushes as fast as yours 3200fps+, it will be even harder to get those ESs down. The % of speed may be the same but the ES a bit bigger because the bullet is going 10%-20% faster than most CF cartridges (if that makes sense). Someone may be able to chime in on that. Most of my reloading is below 3000fps.

50fps with slick ~.6 BC bullets allows 3-4” of error at reasonable long range hunting distance (call that 600yds or so IMO anyway).

Like the others said the external ballistics is just one piece of the miss distance though. Your ability, the guns ability, environment conditions are the other big ones that will combine with the ballistic error.

 

[WeiserBucks]

What chronograph are you using? Most of them aren't very accurate or consistent. Shooting at long range will confirm or deny any discrepancies.

 

[EdP]

Like others have said, that is not particularly good statistics. You should expect to be able to get your SD at least below 20 with some experimentation. Do you have data for factory loads in that rifle to compare with your handloads?

What you do as a shooter can affect velocities also. Ammo sitting in the sun can heat up causing a difference as can a round chambered in a hot action if making the shot is delayed. Just a couple of other things to be mindful of.

 

[775mud]

What chronograph are you using? Most of them aren't very accurate or consistent. Shooting at long range will confirm or deny any discrepancies.

I have the Lab Radar

 

[775mud]

Hello & welcome to reloading, enjoy!

I think by tolerance you mean the deviation in velocity from shot to shot. This is genefrally characterized as you ES, extreme spread, and SD, standard deviation. Lower is better. You have an SD of 32.8 and ES of 78. That could just be the load, and it might be normal for your set of unique variable, but…

…with your scale, I’m curious what kind of scale you’re using. You should not need to tare it each time, if you do, get rid of it and get a better scale.

The best you can do is be scientific with your process and try and keep things consistent. Don’t change a bunch of things at once. Try a different powder keeping all your other steps the same and see how it does in comparison. It might give you better or worse ES/SD. Or change your primer, or change your neck tension, or change your seating depth.

HTH

I am using the hornady digital scale. I am looking into a different style. Probably one that I use in our materials lab that is super accurate and I can get it calibrated. I probably didn't have to tare my scale each time. The scale was accurate with it being "Zero" each time I put a case on their. I just wanted to make sure I was at 0.0G prior to weighing out the powder.
I think I might start at the primer change, if I can find magnum primers. Seems to be a pain in the ass in NV right now. Thanks for the response

 

[775mud]

It kinda depends on the distance you’re hunting/shooting at. A ES of 77 isn’t ideal, but at 500 yards with a 117 SST (not sure what bullet your shooting so I just ran that one) it only calcs to 2.3” of vertical difference. Assuming your dope is based off the 3209 you’re only looking at 1.4” of vertical miss off your dope worst case scenario.

Your actual ES is probably bigger then 77 fps just because 8 shots over the chrono isn’t telling the whole story but at the same time it’s better then 3 shots.

Set up some paper at the max distance you plan to shoot/hunt at and see what it looks like. Chrono those also so you get a bigger sample. Trying different primers is an easy thing to try if you want to clean it up.

I did use the Hornady 117SST bullet. It grouped well. We were shooting a 1.2" group at 200 yards. That was measured with digital calipers. But with the different speeds, we are getting High and low shots in the groups shot. We are doing more testing. We are going to drop the powder by .5g to see if that helps with consistency. We are still way under factory speed that Weatherby produces. They are up to 3250 I believe.

 

[ckleeves]

The ES isn’t the root cause of vertical at that distance, it calcs at basically 1/8” of vert. It can’t hurt to try to clean it up, but a 1.2” group at 200 may or may not change by reducing es by 40 fps over a large sample size.

I used to have a HUGE amount of factory second ammo available to shoot and sometimes the ES on it was atrocious but at the end of the day If I was to shoot a box that had 200 fps and a box that had 40 fps the groups at 100 yards wouldn’t look that different.

Now at 1000 yards it absolutely matters, and I’m in no way trying to talk you out of trying to reduce it, just saying at 200 yards you may not see it on the paper.

 

[Tahoe1305]

I am using the hornady digital scale. I am looking into a different style. Probably one that I use in our materials lab that is super accurate and I can get it calibrated. I probably didn't have to tare my scale each time. The scale was accurate with it being "Zero" each time I put a case on their. I just wanted to make sure I was at 0.0G prior to weighing out the powder.
I think I might start at the primer change, if I can find magnum primers. Seems to be a pain in the ass in NV right now. Thanks for the response

I’m still a big beam scale fan. But i personally think the best bang for buck digital scale is this one. I use it, but still check on a beam…I just trust them more.

Creedmoor Sports TRX-925 Precision Reloading Scale

Creedmoor Sports TRX-925 Precision Reloading Scale When every tenth counts, this scale measures to the hundredths. Introducing the TRX-925 precision digital reloading scale by Creedmoor Sports. Our development team set out to create one of the most accurate and precise scales on the...

www.creedmoorsports.com

This is one of those more expensive pieces of equipment that has improved my reloading…..but not by a ton. This also used to be $250 and was a better deal there.

 

[775mud]

Hi everyone,
I am new to reloading and had a question on what the speed differences are for loads. What is the tolerance I need to look between each load? There was a 1" difference in height when we had the faster shot at 3200+FPS compared to the slower 3178FPS at 200 yards.

I reloaded .257 Weatherby Mag with RL22 using 64.5g of powder. Hornady suggested max load in the book. It's a 117g SST bullet at 3.170" total length. Also suggested in the Hornady book.

The max speed we got using a LabRadar was 3255 and the slowest speed was 3178. Our average after 8 shots was 3209fps.

I was pretty anal loading the bullets so I made sure I tared the scale each time I poured the powder, to make sure I had the 64.5g of powder each time.
The 8 speeds were 3189,3255,3178,3202,3239,3177,3247,3188.

Is this normal and I'm just sweating the small stuff or did I do screw up somewhere?

I’m still a big beam scale fan. But i personally think the best bang for buck digital scale is this one. I use it, but still check on a beam…I just trust them more.

Creedmoor Sports TRX-925 Precision Reloading Scale

Creedmoor Sports TRX-925 Precision Reloading Scale When every tenth counts, this scale measures to the hundredths. Introducing the TRX-925 precision digital reloading scale by Creedmoor Sports. Our development team set out to create one of the most accurate and precise scales on the...

www.creedmoorsports.com

This is one of those more expensive pieces of equipment that has improved my reloading…..but not by a ton. This also used to be $250 and was a better deal there.

Thanks foe sending that over. I will check that out.

 

[Tahoe1305]

I did use the Hornady 117SST bullet. It grouped well. We were shooting a 1.2" group at 200 yards. That was measured with digital calipers. But with the different speeds, we are getting High and low shots in the groups shot. We are doing more testing. We are going to drop the powder by .5g to see if that helps with consistency. We are still way under factory speed that Weatherby produces. They are up to 3250 I believe.

Agree with above, not sure the ES is causing 1.2”. Btw depending on #shot in group, 0.6MOA is solid. If I shot a 10 shot .6 MOA group I’d call it good. That variation can be coming from lots of other factors other than ES. More likely are the guns ability and shooter ability (especially with that cartridge…..isn’t a light kicker).

As long as you aren’t comp shooting at 1k plus yards you’ll be in good shape. If you can checking a group at 400yds would be good. If your still ~.5moa I wouldn’t change anything.

 

[Harvey_NW]

Velocity and vertical dispersion don't have a linear correlation to impacts downrange, because of random distribution. You can have a slow shot go high, or a fast shot go low, that's where guys started geeking out on positive compensation that isn't consistent either for the same principle.

Round count has been proven to be a factor in velocity consistency. If that barrel has less than 200 rounds on it, that could be a contributor. My chrono is nothing fancy, but it's not uncommon for me to see 50fps ES over a large sample size of 10 or more. I wouldn't sweat it, as mentioned above tune your calculator and judge by how it performs on target.

 

[775mud]

Agree with above, not sure the ES is causing 1.2”. Btw depending on #shot in group, 0.6MOA is solid. If I shot a 10 shot .6 MOA group I’d call it good. That variation can be coming from lots of other factors other than ES. More likely are the guns ability and shooter ability (especially with that cartridge…..isn’t a light kicker).

As long as you aren’t comp shooting at 1k plus yards you’ll be in good shape. If you can checking a group at 400yds would be good. If your still ~.5moa I wouldn’t change anything.

Thanks for all the help. Sounds like I am making a big deal out of something that is not that big of an issue as I may have thought. Our marks were on at 5,6, and 700 yards. I may have just let the numbers on the screen get to my head. I am just anal about wanting everything perfect, so there is no excuses for bad shots. We will go out and shoot paper at 400 instead of the steel plates at the range to see exactly where we are out at 400.
I am just used to building arrows and getting my archery set up all the same and hitting the same spot each time I shoot. Reloading rifle loads is a brand new world for me. Once again, thanks for all the help.

 

[TaperPin]

Thanks for all the help. Sounds like I am making a big deal out of something that is not that big of an issue as I may have thought. Our marks were on at 5,6, and 700 yards. I may have just let the numbers on the screen get to my head. I am just anal about wanting everything perfect, so there is no excuses for bad shots. We will go out and shoot paper at 400 instead of the steel plates at the range to see exactly where we are out at 400.
I am just used to building arrows and getting my archery set up all the same and hitting the same spot each time I shoot. Reloading rifle loads is a brand new world for me. Once again, thanks for all the help.

Reloading is like a lot of things - at a basic level it’s pretty easy and seems simple, but as you start to look closer at each component and how they interact it becomes more complicated. The more you do it, eventually you’ll settle into a more comfortable way of doing things and interpreting results.

When a lot of velocity variability exists my first thought is to try another powder. If multiple powders have a lot of variability I’d try another primer. If you still have more than average variability it might indicated something weird with the firing pin - maybe gunk slowing down the firing pin, or a weak spring, or even something wrong with the firing pin or bolt itself - defect, short protrusion, or burr.

If you haven’t had the bolt apart in a while it’s worth it to clean and lightly oil it. Inspect the spring, or even remove it and measure the length to compare with a new one.

If the primer and powder are functioning well, what else affects variability? Bullet friction with case neck? If you are lubing the case necks on some cases and not others that could do it. If your bullets have an inconsistent shape, some might get seated deeper than others.

 

[Elite]

What chronograph are you using? Most of them aren't very accurate or consistent. Shooting at long range will confirm or deny any discrepancies.

This is accurate. Step out to 400-600 yards and the ES issues will disappear


Sent from my iPhone using Tapatalk

 

[seand]

Thanks foe sending that over. I will check that out.

a more accurate scale isn’t going to change anything. This thread is a great example that shows when powder charge variance isn’t the major driver for ES in velocity, so getting more precise charges is not going to solve anything. You could be throwing charges straight out of a drum measure and very likely wouldn’t see a difference in ES.

That scale looks appears to be a real bargain though.