Velocity, opinions please.

mudlark

Well-Known Member
I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

Regards and thanks in advance

Mike

155 sierra match king
 
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My Nosler manual shows 2645 fps with 42.5grns of n140. That is their most accurate load, but 2887 fps was achieved with 46.5grns, so you are not loading to the maximum.
 
none of my loads are close to book data

bought a diesel volkswagen lately? same deal!


IMO it only makes any difference when out past 800+ yds when the bullet MAY become unstable as it slow down past supersonic speeds

My 300WM (.30cal bullets obviously) are much slower than book data at a factory max load
My .308 loads were only up around and slightly over book data when I was running a 29" barrel compared to the powder makers 24" test barrel!!


at 600 yds it won't make a jot of difference
accuracy is what matters
 
The Viht 'book figures' are very low for ammo to be used in industry standard 0.300" bore / 0.3080" groove dia. barrels, and seem to be held down maybe over concerns over cartridges to be used in 'tight-barrel' rifles which can make a significant difference (Minus 2-3gn with most powders in a Paramount TR rifle I have with an older spec Lothar Walther 1-14" twist barrel).

Most TR and FTR shooters even at club level run N140 somewhere between 46 and 47gn with either of the 155 SMKs and other popular 155s. However, if you don't shoot beyond 600 yards and your current load performs well, don't fix something that's not broke! At 44gn, your barrel will last a long, long time especially as N140 is a reasonably cool burning propellant.

(Owners of older Enfield Number 4 TR rifles should stick to the Viht max and stay below that even if they have a heavy original Enfield match barrel still on - they had really tight internal dimensions.)
 
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It's only too slow if it doesn't suit your needs.
You should try shooting a larger sample next time. Four rounds is far too small a sample.~Muir
 
I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

Regards and thanks in advance

Mike

155 sierra match king

Also worth noting temperature during testing as its surprising just how much a rise or fall of 10 degrees Celsius can have on powder burn rate and muzzle velocity. Some powders can be affected to the tune of 3.5fps depending on cartridge and load, per every one degree change (ie a one degree rise gives a 3.5fps rise in velocity). For long range (out past 600m) shooting in colder conditions, this might have a greater effect on accuracy requiring an increase in load or a change of powder to one less susceptible to temperature changes. Some powders might be less susceptible but even those might see a 1 to 1.5fps change per degree change. It's important when looking at all of these figures then that you reference them to standard environmental data. Some manufacturers will state velocities based on an ambient 20 degrees C for example.

For your loads tested, I don't know what the temperature was on the day or where the cartridges were stored, but for argument's sake it might have been 12 degrees, then at 22 degrees, your 2580fps could well become 2600 and at 2 degrees, you might expect a drop the other way. From your measurements, your loads seem ok for your needs so I wouldn't let it bother you too much and just carry on doing what you're doing.
 
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I've only been reloading for a cpl of years so still learning. I recently bought chrono, and last week ran some 308 rounds over it last week results were 2579, 2594, 2593, 2589, 2579, fps. Accuracy was fine but my mate who's been loading for years said hmmm bit slow. Load was 44grains N140 through a Howa heavy barrel. Load is near book max and not sure I won't to go above max but how slow is it and will it matter over say 600yds.

Regards and thanks in advance

Mike

155 sierra match king

Silly boy - you were happy before in blissful ignorance. On the basis of six rounds you have pretty consistent velocity and by your own admission an accurate load. But by pursuing too much information you have let a niggling doubt which won't go away. Does the load work - of course it does.

I made the mistake of thinking I had a good load for my 7x65R - pretty accurate and deer fall over. but then I borrow ed Bushers chronograph and found that my bullets are only doing 2,500 fps and not the 2,600 fps and velocity variation of 60 fps. I am still using the same load but I need now to get out and work up a better load - why oh why did I enquire too much????
 
Heym beat me too it, your published velocities are pretty consistent which shows your reloading is consistent. Don't worry if they're down on book speeds, as these are often not realistic. If they're accurate and doing the job they're intended for, I'd leave it alone.
 
I am sending a 168 Amax down the line at 2505 fps average with a 16" Barrel. It's std ammo rather than reloaded but it's so accurate in this gun I decided not to bother to reload. As it's std ammo it's not going to be near max pressure. You don't say what your barrel length is but if it was 22" you would probably be up at around 2650fps with the same ammunition I am using. Your bullets are 13 grains lighter so you could probably expect to get around the 2700 fps mark without stretching the pressure envelope if you played a bit. If you pushed it hard perhaps 2750 fps.

However, at stalking ranges, no deer is going to notice the difference in the 150 fps you might be under max velocity by and I would take accuracy over speed every day of the week. Unless you are finding your rifle doesn't have the knock down power that you require I wouldn't worry about it. Just carry on knocking 'em over.

On a 600 yd range trajectory is irrelevant as you can accurately dial it in. You will benefit a little on the wind front with a faster bullet but your ES is so consistent you are risking upsetting a great formula.

And an ES of 15 is very good, although it would be good to get a bigger sample as Muir says.

Don't play unless you have a need to do so. It can take too many hours off your life. Better to spend them out hunting.
 
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