Can someone explain this to me like I’m a 5 year old please - if I was to chop a standard 22” 7mm08 barrell to say 18” how would that affect bullet speed and stability ?
Thanks in advance
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Can someone explain this to me like I’m a 5 year old please - if I was to chop a standard 22” 7mm08 barrell to say 18” how would that affect bullet speed and stability ?
Thanks in advance
Stability won't change, if done correctly accuracy potential will increase, you should lose around 150 fps depending on components usedQuote:
Originally Posted by Nathan F
Minimal effect on stability, and you might lose 100 or so fps.
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The reduced length of the barrel means that the expanding gases from the ignition of the powder have less time to drive the projectile forward so therefor the projectile will be travelling slower when it exits the muzzle than it would be if the barrel was longer. A practical way to demonstrate this is by using a pea shooter (e.g. a section of bamboo). Blow a pea through the shooter as hard as you can and have someone mark where it lands. Next cut the shooter in half and repeat. The second pea will fall short of the first.
Beautiful. Thank you all for the reply’s. Exactly what I was after. Cheers
Keep in mind the reduction in velocity does not mean you'll kill fewer animals.
I got my 7mm08 cut to 16" and it's a great rifle with plenty of killing power for short - medium distance (300yd or so) and I have found a few loads that the rifle seems to like a lot.
MV for the 139g interlock in front of AR2206H was 2700 fps as measured by chrono, but I am validating that with drops this weekend, assuming the forecast stays OK.
how does this work?Quote:
Originally Posted by Kiwi Greg
Shortening the barrel can make it stiffer giving a more consistent point of exit for the projectile.Quote:
Originally Posted by bang
Greg has magic fairy shooting dust that he sprinkles on the barrel.Quote:
Originally Posted by bang
A long barrel may deflect more, but if the stimulus is the same it will react the same, so should still be as consistent. so would it be more correct to say that a shorter barrel is more forgiving for small variances in loads or heat?Quote:
Originally Posted by sdogg73
I would be interested in obtaining some of that magic dust.... my shooting is atrocious
By shortening the barrel, it 'whips' less while the bullet is travelling down the barrel, less whip of the barrel means less inconsistency when the bullet comes out the end.Quote:
Originally Posted by bang
Same principle as a big heavy barrel on a target rifle.
As a general (approximate ) rule of thumb, for centrefires it is usually about the 50fps per inch when a barrel is shortened so the estimates of about 150fps would be within reason. As mentioned, in most rifles the projectile is accelerating rght up unto it exits the muzzle at which point the pressure behind it is released and it then relies on momentum.
This can be countered by using a faster burning powder that expends all of its energy in the time it takes to move the projectile to the muzzle, but to be hones, 100-200fps difference at the muzzle will not make much "real world" difference to most hunters.
If I run a basic calc with the Hornady white tail, instead of getting 2840fps at muzzle and just dropping below 2000fps at 400yds, it would be 2640fps at the muzzle and would drop below 2000fps at a bit over 300yds. If you are shooting eggs at 300 yards this might make a difference, but anything bigger than the 3" difference in drop and it wont matter....
How much per kilo?Quote:
Originally Posted by Rushy
Duh! It’s weightless. It’s magic. Ha ha ha ha.Quote:
Originally Posted by Max Headroom
Ok your Honour, i'll rephrase the question.Quote:
Originally Posted by Rushy
How much per cubic foot?
You’d have to ask Greg. I think he sells it by the pinch.Quote:
Originally Posted by Max Headroom
No not really. Faster powder for shorter barrels is a wide spread belief but its a myth, its not how internal ballistics work. The best burn rate for max velocity is dictated by the cartridge and the projectile regardless of barrel length.Quote:
Originally Posted by timattalon
would be interested in knowing the results,as im running a similar set upQuote:
Originally Posted by Edunn
I can report 2800 fps from a 18" sporter weight barrel with 140 grn and 3000fps with 120gr and .5" groups. CFE 223 powder. You will do better @Nathan F because I doubt you have a cataract in your right eye. :)
Water is rocket science!
Yes. I have been involved with dihydrogen monoxide for almost sixty seven years now.Quote:
Originally Posted by Tentman
I cut my 7mm08 to 16inch and never looked back,deer are just as dead.
I cut my Tikka 300wsm from 24 inches to 20 inches and only lost 100 fps
I be happy if mine works out to be the same as thatQuote:
Originally Posted by Sako85
mine is 20 inches still get 178AMAX doing 2980 fpsQuote:
Originally Posted by Sako85
From my 7saum 22” barrel I got 2950 with 168vld. Cut the barrel back to 17” and now get 2725 with the same load(validated).
Cheers
I just checked my 16inch Kimber 7mm08 yesterday with Hornady Whitetail and was only getting 2430fps.....same Chrono used for 22 and 284 so it’s real for this rifle.
I didn’t think the 7mm08 would drop that much based on other data I had read.
Will need to speed up a little to get a 400yard over 1000ft pound
Factory superformance 139sst was going 2650 in my 16in 7mm08 if that helps