Shooting a 270 wsm with 60.8 gr of RL 22, federal 215 primer and a 150 Nosler Partition out of a Tikka T3 SS with a 24.33 barrel. Should be getting well over 3000 or 3100. Shot it through a guys Chrony at the range today and it read 2713 and then 2775. My powder charges are exact. It was over cast and raining. 300 or 400 fps less than expected. Is this possible or??? Appreciate the input.
Bad Chronograph reading or reality check??
- Thread starter malahatmike
- Start date
blaser.306
CGN Regular
- Location
- Saskatoon , Sask
Most not all times the listed velocity is higher than you will acheive! This is due to the firearm you are shooting as opposed to a test chamber , Their equipment may have a tighter chamber longer throat etc. . There are many variables that can affect chamber pressure and velocity Brass type/lot, bullettype / lot, lot# to Lot # variations in the powder itself , Ambient temp, atmospheric pressure , altitude and others as well. If you are getting the accuracy that you want from a load with no signs of chamber pressure I personaly do not let a hundred or two FPS get me down.
Its quite possible, and happens more often than you might think. The next guy will show up with a smooth custom barrel and tight chamber and get the book speeds before reaching the max listed charge.
It puts caliber arguments in perspective.
It puts caliber arguments in perspective.
- Location
- Prince Albert, Sk
Yes, agreed, when I tried my custom barrel/chamber I was achieving almost max book velocities with below starting charges.
Tightness does make a difference.
Did you work up your loads and was there any pressure signs?
Tightness does make a difference.
Did you work up your loads and was there any pressure signs?
Its quite possible, and happens more often than you might think. The next guy will show up with a smooth custom barrel and tight chamber and get the book speeds before reaching the max listed charge.
It puts caliber arguments in perspective.
With all the reasons given of why your velocity may be lower than the book figure, none gave the most logical answers.
1) Trumped up, high figures, to sell the calibre.
2) Trumped up, high figures, to keep you happy and keep you from loading too heavy, thus lowering the chance of being sued.
Remember, a small percentage of shooters have chronographs.
1) Trumped up, high figures, to sell the calibre.
2) Trumped up, high figures, to keep you happy and keep you from loading too heavy, thus lowering the chance of being sued.
Remember, a small percentage of shooters have chronographs.
- Location
- In the middle of gopher country
Published numbers are a guide line.
In my experience if you are getting book velocities you had better start looking at pressures.
In my experience if you are getting book velocities you had better start looking at pressures.
I've checked numbers for a Sierra 0.277" 150gr GameKing in 270 WSM and the load and velocities are almost exactly what you got!
Around 2850fps, even with a full load they only got 3000fps for a Winchester 24" M70.
Nosler numbers might be the best values under the best conditions not typical real life rifles.
When it comes to velocities, you can always trust Sierra (and Lyman).
Alex
Around 2850fps, even with a full load they only got 3000fps for a Winchester 24" M70.
Nosler numbers might be the best values under the best conditions not typical real life rifles.
When it comes to velocities, you can always trust Sierra (and Lyman).
Alex
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Chinbullco
Regular
- Location
- NW Alberta
Velocity Problems
There are many things a person must do in the rain, but shooting over a chronograph in the rain seems ........ goofy. One tiny droplet of water on the window and the readings are wrong. I wouldn't worry about low velocity just yet.
There are many things a person must do in the rain, but shooting over a chronograph in the rain seems ........ goofy. One tiny droplet of water on the window and the readings are wrong. I wouldn't worry about low velocity just yet.
saskgunowner101
CGN Ultra frequent flyer
- Location
- middle of Sask
Care to expand on that one??
I've started with the nosler posted minimum and worked up to the max which was the best group. Under an inch. I backed of the max 2 tenths and got under 3 quarters of an inch with no pressure signs at all. The guys tested one of his rifles with a previously confirmed load and it was the same. This load was a 223. Could it be muzzle blast from the magnum?
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
Overcast conditions are generally very good light conditions for chrono'ing. When it's overcast you can almost always get away with not using the rods and light diffusers.
Rain isn't a problem, but if a drop of water falls on one of the sensor lenses, it could conceivably give you a false reading (it might make the sensor "look" in a slightly wrong direction).
If you're chrony is 10' or more from the muzzle, you should not get false readings due to muzzle blast. And usually when you get false readings from muzzle blast, the reported number is higher than reality (sometimes even 4000fps or 5000fps).
Rain isn't a problem, but if a drop of water falls on one of the sensor lenses, it could conceivably give you a false reading (it might make the sensor "look" in a slightly wrong direction).
If you're chrony is 10' or more from the muzzle, you should not get false readings due to muzzle blast. And usually when you get false readings from muzzle blast, the reported number is higher than reality (sometimes even 4000fps or 5000fps).
A friend was showing a .257 Weatherby to an injured workmate that was looking into some low recoil options this winter. Just happens that I was at the range at the time.
Buddy was working up loads for a Vanguard in .257, and doing the whole process over the CED. The low recoil guy got to try it out and chronograph his old standby .270 load of 55 grains of 4350 and a 130 TSX at the same time.
Long story short, ole standby was only going 2650 and no amount of rechronographing later would change that. Long story slightly longer, its now clocking 3100 with H4831 and he did buy the bee.
I don't know how these low velocities get past guys when they check the drops at extended ranges. Actually, scratch that I do know.
Buddy was working up loads for a Vanguard in .257, and doing the whole process over the CED. The low recoil guy got to try it out and chronograph his old standby .270 load of 55 grains of 4350 and a 130 TSX at the same time.
Long story short, ole standby was only going 2650 and no amount of rechronographing later would change that. Long story slightly longer, its now clocking 3100 with H4831 and he did buy the bee.
I don't know how these low velocities get past guys when they check the drops at extended ranges. Actually, scratch that I do know.
Reality Check... My dad was very surprised to find that his 308 norma load with 200 grain bullets he thought was 2700 was 2400 when I got a chrony. He did not believe it, so I shot one of my 300 win mag loads and got the velocity I should have, 2850 with 200 grain bullets, he tried one of his and got 2400. Then he went home and pulled all his noslers and worked up a load with the velocity he wanted. He had killed a few moose with the lower velocity, and the moose never missed the 300 feet. Overcast is when the chrony works best, there is more light coming down on a cloudy day.. Try a load with a known velocity. How did your friends loads work on his chrony?
Weigh a bullet or two, maybe your scale is weighing a bit light.
Actually, 150 gr bullet with 61 gr of Re22 is a pretty mild load for a WSM, so my guess is the chronographed velocities are correct.
I load both H4831 and Re22 in several 270 Winchesters, and get close to 2900 fps with the 150 Partition.
Ted
I load both H4831 and Re22 in several 270 Winchesters, and get close to 2900 fps with the 150 Partition.
Ted
I was thinking the same thing. I was using a bit more than that with a "regular" .270 Win and 130 TSX. I chrono'd at well over 3100fps out of a 22" barrel.
I can't remember my charges and loads, but the 160gr Partition was ~2800fps.
Edit - Ted, I was just looking at the Barnes Manual and they are showing 60.5gr of RL22 for the .270 Winchester with 150gr TSX for 3000fps. Man that good old .270 is still as good as it ever was - or even better!
I once had access to a Oehler chronograph, that had the screens set at 5 feet apart. Obviously, this would be more precise than the current chronos which have the screens 12 inches apart.
I'm looking at my figures and see that with my 270 Sako, 24 inch barrel, H4831 gave a 150 grain Hornady bullet a velocity at 15 feet, of 2908, average of five loads. The low to high was 22 fps apart, which I think is very good.
I was using the old WW2 surplus powder.
I have been trashed on various threads, from time to time, for asking reloaders why they are so precise, like weighing and seperating every case and weighing every powder charge, when it will be shot in an ordinary sporting rifle.
But here are my notes on that five shot group that was 22 fps apart, low to high.
The charges were not weighed, just measured with my old Lyman 55 Ideal measure. And everybody knows how inaccurate H4831 is to measure. 2/10 grain above or below is about all you can hope for.
My notes say, Cases, mixed brands.
Just one of the many examples I could give, of why I never weigh each charge.
I'm looking at my figures and see that with my 270 Sako, 24 inch barrel, H4831 gave a 150 grain Hornady bullet a velocity at 15 feet, of 2908, average of five loads. The low to high was 22 fps apart, which I think is very good.
I was using the old WW2 surplus powder.
I have been trashed on various threads, from time to time, for asking reloaders why they are so precise, like weighing and seperating every case and weighing every powder charge, when it will be shot in an ordinary sporting rifle.
But here are my notes on that five shot group that was 22 fps apart, low to high.
The charges were not weighed, just measured with my old Lyman 55 Ideal measure. And everybody knows how inaccurate H4831 is to measure. 2/10 grain above or below is about all you can hope for.
My notes say, Cases, mixed brands.
Just one of the many examples I could give, of why I never weigh each charge.
My experience with 2 rifles that had been rechambered: both Brnos.
One a ZKK-602 rebored from .375H&H to .416 caliber, rechambered to .416RM and the other a CZ-550, which was reamed from .458WM to .458Lott.
I believe the custom reaming, results in tighter dimensions, and that results in higher pressures = more velocity, as a few others have said.
Both of these rifles achieve max velocities at powder levels below listed maximums. I've never had that happen with a factory reamed chamber.
One a ZKK-602 rebored from .375H&H to .416 caliber, rechambered to .416RM and the other a CZ-550, which was reamed from .458WM to .458Lott.
I believe the custom reaming, results in tighter dimensions, and that results in higher pressures = more velocity, as a few others have said.
Both of these rifles achieve max velocities at powder levels below listed maximums. I've never had that happen with a factory reamed chamber.
