well im no pro at reloading.so i have a few things on my mind about my rang day this pasted weekend.i was makeing a load for my 308.it started out with 165 hornady BTSP and IMR 4895.i did 3 loads 43gr,44gr,45gr all a COL.the thing that is getting me is i had 80-100fps difference through out each load.i did weigh each round when i was rolling them too.
acceptable variation of FPS?
- Thread starter kyjelly44
- Start date
Well there are allot of variables. A few flecks out on the powder, different primers hole sizes, overall brass thickness, casing volume is different, humidity, heats, etc. All this affest how the powder sits, ignites, burns, etc.
The best I ever had was a 30 to 25 FPS difference. I was pleased. But it was allot of work.
Pete
The best I ever had was a 30 to 25 FPS difference. I was pleased. But it was allot of work.
Pete
BigUglyMan
CGN Ultra frequent flyer
- Location
- New Scotland
Lots of BPCR guys strive to get down to single digit extreme spreads. But I've seen a lot of smokeless loads that shot really well but had an ES of 100 FPS.
Lower ES are easier to get using powders with smaller kernel sizes - like the SC and SSC powders offered by IMR/Hodgdon. Big, chunky stuff can be harder to try to get uniform (I have actually shouted obscenities at my trickler and scale while loading the 300 WM with H4831 in the non-SC version) and I think the smaller kernels burn more uniformly, though I can't empirically prove it. I can prove that they meter better than the chunky stuff.
Lower ES are easier to get using powders with smaller kernel sizes - like the SC and SSC powders offered by IMR/Hodgdon. Big, chunky stuff can be harder to try to get uniform (I have actually shouted obscenities at my trickler and scale while loading the 300 WM with H4831 in the non-SC version) and I think the smaller kernels burn more uniformly, though I can't empirically prove it. I can prove that they meter better than the chunky stuff.
My reloads are all weighed to the nearest 1/10th of a grain (digi dispensers are great IMO) ES is usually under 50 fps which I am satisfied with. I get pretty picky about case prep which can't hurt.
I started last year with a lyman set and lee dies.
I've got my speed at about 2690fps, Extreme Spread to about 20fps and Extreme Deviation at about 7.5.
These are averages tracked over 50 shots firing 5 groups of 10 on different days.
I'm using 175grain Sierra HPBT, 44.5grains of Varget, Federal brass, CCI 200 Primers.
A digital scale really was the key for me.
Here are some other things I do.
Every charge weighed and trickled to spec.
Brass sorted and grouped by weight, neck runout, neck wall thickness. Flashhole uniformed.
Bullets sorted by weight.
Alot of work to avoid buying Lapua brass.
When I had a beam scale, I was in the 100fps range.
I've got my speed at about 2690fps, Extreme Spread to about 20fps and Extreme Deviation at about 7.5.
These are averages tracked over 50 shots firing 5 groups of 10 on different days.
I'm using 175grain Sierra HPBT, 44.5grains of Varget, Federal brass, CCI 200 Primers.
A digital scale really was the key for me.
Here are some other things I do.
Every charge weighed and trickled to spec.
Brass sorted and grouped by weight, neck runout, neck wall thickness. Flashhole uniformed.
Bullets sorted by weight.
Alot of work to avoid buying Lapua brass.
When I had a beam scale, I was in the 100fps range.
You should be getting better (lower) extreme spreads with the type of powder that you are using. Two possible sources of the problem, and neither have anything to do with weighing each powder charge (I have thrown 72 grains of H4831 and consistently received ES of less than 10 fps).
Your primer seating is not consistent. and or, your firing pin strike is sluggish. Both will result in inconsistent primer strikes and will contribute to variations in igniting the powder.
Your primer seating is not consistent. and or, your firing pin strike is sluggish. Both will result in inconsistent primer strikes and will contribute to variations in igniting the powder.
well looks like 80-100fps is an ok speed spread out of this kit(lee 50th anniversary).i use a rcbs rock chucker supreme master kit for my Precision Rifles.the reason i picked up the lee kit is to make a portable kit for the travel trailer.
For my match loads I look at the SD and not necessarily the ES. For match loads you want to have an SD of 10 or better.
A good number of my 6BR loads run around the 10fps over 5 rounds. I had one load that was 7fps ES over 10 rounds but the accuracy was not there.
Go for the most accurate load and worry about the extreme spread only if you are planning on shooting long range.
A good number of my 6BR loads run around the 10fps over 5 rounds. I had one load that was 7fps ES over 10 rounds but the accuracy was not there.
Go for the most accurate load and worry about the extreme spread only if you are planning on shooting long range.
- Location
- victoria bc
the 45gr load may be a little hot, what rifle are these for
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
There is a rule of thumb that in most cases SD ends up being about one-third of ES (so a load with an ES of 100fps, will have an SD in the low 30s).
An ES of 100fps for rifle ammo is not particularly unusual high for factory ammo, or typical handloads. Much better is possible, of course, but usually only with a fair bit of care and attention (and for what it's worth, if you are shooting at 600 yards or less, you can pretty much ignore the effect of velocity variations on your accuracy).
One thing that you don't often hear said is that if the load is wrong, it doesn't matter how precisely you make your ammo, it will still have poor accuracy or poor ES. "Wrong" could mean the wrong amount of powder, or the bullet not seated in the correct position.
An ES of 100 is not caused by a tenth of a grain of powder more or less. Thrown charges can easily do quite a bit better than this, if the load is right. (my thrown charges of Varget shoot a 155 Sierra at 900m almost accurately enough to win a national championship - under 2 MOA for 15 shots)
So don't bother weighing each charge, if you have a 100fps ES and want to reduce it. Try different (thrown) powder charge weights. Oftentimes mild ammo will have a pretty large ES (though it might shoot very accurately), and near-max or max loads can often produce the smallest EST (and oftentimes shoot very accurately too).
An ES of 100fps for rifle ammo is not particularly unusual high for factory ammo, or typical handloads. Much better is possible, of course, but usually only with a fair bit of care and attention (and for what it's worth, if you are shooting at 600 yards or less, you can pretty much ignore the effect of velocity variations on your accuracy).
One thing that you don't often hear said is that if the load is wrong, it doesn't matter how precisely you make your ammo, it will still have poor accuracy or poor ES. "Wrong" could mean the wrong amount of powder, or the bullet not seated in the correct position.
An ES of 100 is not caused by a tenth of a grain of powder more or less. Thrown charges can easily do quite a bit better than this, if the load is right. (my thrown charges of Varget shoot a 155 Sierra at 900m almost accurately enough to win a national championship - under 2 MOA for 15 shots)
So don't bother weighing each charge, if you have a 100fps ES and want to reduce it. Try different (thrown) powder charge weights. Oftentimes mild ammo will have a pretty large ES (though it might shoot very accurately), and near-max or max loads can often produce the smallest EST (and oftentimes shoot very accurately too).
You would be completly lost at 900 meters shooting with loads that had 50 to 80fps differances, your verticale would be all over the place. in a 223 rem
I was shooting at 900 meters on Sunday, using a load of 25.3gr with 75gr bergers, I ran out of that load and used a load with 25.5gr same bullet shot 2.5 min high, thought it might have been me so came down 1min and that where bullet hit had to go down another 1.5min to get into 5 ring.
All brass is neckturned, primer pockets uniformed lapua brass within 1/10gr each, benchrest primers, using electonic scales with .01 accuracy.
I was shooting at 900 meters on Sunday, using a load of 25.3gr with 75gr bergers, I ran out of that load and used a load with 25.5gr same bullet shot 2.5 min high, thought it might have been me so came down 1min and that where bullet hit had to go down another 1.5min to get into 5 ring.
All brass is neckturned, primer pockets uniformed lapua brass within 1/10gr each, benchrest primers, using electonic scales with .01 accuracy.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
A load with a 50fps extreme spread will usually show an SD of about 16 or so. This is decently competent ammo, better than most, but it isn't quite "top tier" long range target ammo. You should try to get SDs into the lower teens if you can (so ESs under 40fps); under 10fps SDs (so sub-30fps ES) are top-notch.
A 75 grain Berger fired at 2900fps will drop a certain amount at 900m (31.2 minutes). If the next shot is 50fps faster (2950fps), it will not drop as much since it gets to the target sooner - 30.0 minutes. So the 50fps faster bullet will print 1.2 minutes (about 12 inches) higher.
(manitou210 I'm quite surprised that a 0.2 gr powder charge difference a 2.5 minute shift; that would suggest 100fps difference between your two damn-near-the-same loads...!!!)
If a rifle and ammo is otherwise capable of producing (say) a 1.0 minute group, adding the 1.2 minutes of variation will produce a group about 1.6 minutes in size (square root of sum of squares, for anyone interested).
This could well be enough to cost you a national championship, but it could also be characterized as "not too terribly bad" either. Certainly good enough to take out at shoot at 900m.
Absolutely no harm in it. You can't hurt anything, and you might possibly help. All I was saying though is that it takes time and effort, and if you want your time and effort spent to be effective in producing good accurate ammo, you can make your charge weighing work much more useful if you first figure out *what* the charge weight is that you want, and then weigh it out precisely. If you have a mediocre load (which could be for any number of reasons), precisely weighing the powder charge is unlikely to show an improvement
A 75 grain Berger fired at 2900fps will drop a certain amount at 900m (31.2 minutes). If the next shot is 50fps faster (2950fps), it will not drop as much since it gets to the target sooner - 30.0 minutes. So the 50fps faster bullet will print 1.2 minutes (about 12 inches) higher.
(manitou210 I'm quite surprised that a 0.2 gr powder charge difference a 2.5 minute shift; that would suggest 100fps difference between your two damn-near-the-same loads...!!!)
If a rifle and ammo is otherwise capable of producing (say) a 1.0 minute group, adding the 1.2 minutes of variation will produce a group about 1.6 minutes in size (square root of sum of squares, for anyone interested).
This could well be enough to cost you a national championship, but it could also be characterized as "not too terribly bad" either. Certainly good enough to take out at shoot at 900m.
Absolutely no harm in it. You can't hurt anything, and you might possibly help. All I was saying though is that it takes time and effort, and if you want your time and effort spent to be effective in producing good accurate ammo, you can make your charge weighing work much more useful if you first figure out *what* the charge weight is that you want, and then weigh it out precisely. If you have a mediocre load (which could be for any number of reasons), precisely weighing the powder charge is unlikely to show an improvement
"Absolutely no harm in it. You can't hurt anything, and you might possibly help. All I was saying though is that it takes time and effort, and if you want your time and effort spent to be effective in producing good accurate ammo, you can make your charge weighing work much more useful if you first figure out *what* the charge weight is that you want, and then weigh it out precisely. If you have a mediocre load (which could be for any number of reasons), precisely weighing the powder charge is unlikely to show an improvement "
Ah - agreed.
Ah - agreed.
