Cartridge Velocity

[henry931]

Got some 32gm No 6 Fibre Hull High Pheasant Extreme for general game shooting.

 

I was testing them and getting good patterns at 30 yards but the thing is they are only averaging 1150 fps over a chronograph.

 

I know they will still kill if the barrels are in the right place but it's a little disappointing considering they're advertised as a 1450 fps cartridge.

 

Does anyone know why the speed is down? Should I be worrying about it and try something else?

 

All the best

[robbiep]

Velocity can vary quite a bit with barrel length. What length barrels are on the gun they are being tested on ?

[sitsinhedges]

I've chrono'ed quite a few cartridges due to my interest in reloading and subsonics in particular and have found that none of the factory cartridges produce what is printed on the box. Maybe they test them like car manufacturers test the fuel efficiency that we never seem to achieve.

[henry931]

30" Barrels. According to the proof certificate they are bored 0.736"

 

I tried Lyalvale Express Max Game 50gm BB Plastic Wad and they were running 1250fps which seems good considering the payload.

 

Perhaps they use very tight test chambers/bores to get their speeds?

 

Will try some clay loads tomorrow.

[Guest cookoff013]

no, they have an extrapolated MV. thats a fancy way of saying they guess at the MV from a reading at 2.5M.

 

they just chuck on ~100fps.

 

some italian loads they add 50fps and that is more realistic.

[Guest stevo]

what sort of chrono are you using ?

 

also what distance are you from chronograph ?

steve

Edited August 30, 2013 by stevo

[remmyman]

Got some 32gm No 6 Fibre Hull High Pheasant Extreme for general game shooting.

 

I was testing them and getting good patterns at 30 yards but the thing is they are only averaging 1150 fps over a chronograph.

 

I know they will still kill if the barrels are in the right place but it's a little disappointing considering they're advertised as a 1450 fps cartridge.

 

Does anyone know why the speed is down? Should I be worrying about it and try something else?

 

All the best

I think you may be confusing m/v with observed velocity. Trust me when I say that slower is better than faster when it comes to shotgun cartridges. Superior patterns, less recoil and consistency are more important than say 1500 ft/sec at the muzzle, due to the law of 'ballistic coefficiency' at 30yds or more the diff between the fastest/slowest ammo is not worth mentioning, as to diff in lead, you're literally talking about inches(and thats in single figures)

Regards Remmyman

Edited August 30, 2013 by remmyman

[sitsinhedges]

I have found thru experimenting with subsonics that a huge speed isn't necessarily required but a slightly larger shotsize does make all the difference. My 30gram 5's going at under 1100fps will match pretty much anything with awesome long range kills. If I changed them to 7's for example the picture would be completely different. Smaller pellets rely on speed far more but also lose that energy far more quickly.

[Guest cookoff013]

I think you may be confusing m/v with observed velocity. Trust me when I say that slower is better than faster when it comes to shotgun cartridges. Superior patterns, less recoil and consistency are more important than say 1500 ft/sec at the muzzle, due to the law of 'ballistic coefficiency' at 30yds or more the diff between the fastest/slowest ammo is not worth mentioning, as to diff in lead, you're literally talking about inches(and thats in single figures)

Regards Remmyman

 

I have found thru experimenting with subsonics that a huge speed isn't necessarily required but a slightly larger shotsize does make all the difference. My 30gram 5's going at under 1100fps will match pretty much anything with awesome long range kills. If I changed them to 7's for example the picture would be completely different. Smaller pellets rely on speed far more but also lose that energy far more quickly.

 

me too. seing #4s on a pattern plate did it for me. i still cant believe it !

[henry931]

what sort of chrono are you using ?

 

also what distance are you from chronograph ?

steve

 

It's just a chrony at 10 feet. It might be slighlty off but has always given reasonable results for rifle rounds.

 

I have found thru experimenting with subsonics that a huge speed isn't necessarily required but a slightly larger shotsize does make all the difference. My 30gram 5's going at under 1100fps will match pretty much anything with awesome long range kills. If I changed them to 7's for example the picture would be completely different. Smaller pellets rely on speed far more but also lose that energy far more quickly.

 

Alright that gives me confidence. I'll give the 6s a go on rabbits around the beans then. Will pick up some 5s too.

 

 

 

me too. seing #4s on a pattern plate did it for me. i still cant believe it !

 

I had a wooden pallet set up to pin the targets too and those BB smashed straight through it! Good thing I had a steep bank behind it as a backstop.

 

I tried some clay loads as well:

 

Fiocchi Golden Trap 28gm 7.5 Plas Wad 1278fps

Very Smooth and patterns very well especially with tight chokes

 

Hull Pro Fibre 28gm 7.5 Fibre Wad 1202fps

Slightly punchier I guess due to the fibre wad. Reasonable patterns.

The primer got pierced on one of these carts and you can see a hole through it. Is this bad?

 

Thanks for the advice I'll just get on with it then!

 

ATB

[wymberley]

Just to prove the point already made, taking No 6s at 1500 and 1200 ft/sec, the theoretical difference in velocity is just 54 at 30 yards and 40 at 50. The energy at 50 yards for the 1200 MV pellet, given a satisfactory pellet strike, is still (just) at a level which is/was traditionally deemed sufficient to kill a cock pheasant.