Muzzle velocity for this bullet?

[andym79]

Hi guys, you may have seen me go on a bit about a single shot martini cadet cartridge and seem to be getting nowhere. I think I have been looking at it a bit wrong, assuming that I have to pick something that starts off subsonic.

I will ask all of this from another viewpoint!

If I wanted to shoot a bullet like this:
177397

and have it reach a target a 200 yards without going through the sound barrier and going subsonic what muzzle velocity would I need to start out at. In other words how slow could I shoot it and still ensure that it reaches 200 yards still supersonic?

The bullet does not have to be 32 cal I am still thinking 28, 30, 32 or 33 but that sort of bullet, what velocity, would 1400fps be enough?

[str8wal]

Do you know the BC of this bullet?

[fecmech]

Find the BC for that bullet or one very similar and plug it in here http://handloads.com/calc/index.html

[17nut]

A WAG sets BC to .25 and that means you have to go @1500fps'ish to start.

http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Til%20andre/BC_zpswzi6knxk.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Til%20andre/BC_zpswzi6knxk.jpg.html)

[str8wal]

That's why my calc said as well with a .250 BC. 1,500 +

[Bad Ass Wallace]

Have a read about transonic disturbance of a bullet in flight. For a design as you have shown, the pressure centre is amplified by the blunt nose and would affect stability of flight. According the the authoritive 1912 works by Mann "The bullets Flight" (as endorsed by Harry Pope) this 'transonic disturbance' occurs at 1400fps (Mach 1.2), so your bullet would incur two peaks, one on the 'up' as it achieves 1500fps, and another as it loses velocity in flight on the way to the target.

https://thearmsguide.com/5348/long-range-shooting-external-ballistics-transonic-region/

[andym79]

So are you saying that a spire point cast bullet would transaction better through the transonic?

Transonic disturbance is the main reason I have been considering a subsonic load and a wildcat designed to achieve a subsonic loading with a near full case of powder; only thing is I am not 100% confident in how well a subsonic load will do at 200 yards or beyond I know they do well in the 25-150 yard range.

What I am really trying to establish is at 200 yards can better accuracy be attained by a bullet leaving the muzzle at 1300-1500fps or at 1050fps?

I know that a subsonic bullet drops further over the same distance due to its low velocity, but it sheds speed much less slowly than a bullet going through the transonic zone.

At this stage I am trying to determine what would be best out of a martini cadet for bench rest lever action single shot rifle competition:

1. a small J bullet 22 calibre going fast i.e mashburn bee or 222R
2. a medium sized bullets, say 200 grain starting out at about 1450fps a 357 mag or a wildcat (like a shortened 32-40).

[country gent]

Equally impoertant as the cartridge is getting the right twist rate for the length of bullet being used. I tend to heavy for caliber bullets in most rifles and the faster twists. Getting to 200 yds or even farther isnt hard its learning the trajectory curve to adjust for the ranges. A 45-70 load with a 500 grn bullet and at 1150-1200 fps will make it 2 1000yds accuratly if you have the correct sight settings

[andym79]

Equally impoertant as the cartridge is getting the right twist rate for the length of bullet being used. I tend to heavy for caliber bullets in most rifles and the faster twists. Getting to 200 yds or even farther isnt hard its learning the trajectory curve to adjust for the ranges. A 45-70 load with a 500 grn bullet and at 1150-1200 fps will make it 2 1000yds accuratly if you have the correct sight settings

Couldn't agree more twist rate is very important, too fast and it make higher velocities hard with cast, too slow and you are limited in projectile range.

I know that the transonic issue is only one of many things that will effect groups, and is far from being the most important, but its another facet that I am trying to understand.

A lot of the shooting I have done with cast has been with medium size bullets and moderate velocities from subsonic to 1800fps. I haven't really had too much success with subsonic speeds out at 200 or beyond apart from with the 38-55 (don't own a 45-70) I guess the 270-300 grainer stand up to the wind better than 115-180 grainers.

[Chill Wills]

So are you saying that a spire point cast bullet would transaction better through the transonic?

Transonic disturbance is the main reason I have been considering a subsonic load and a wildcat designed to achieve a subsonic loading with a near full case of powder; only thing is I am not 100% confident in how well a subsonic load will do at 200 yards or beyond I know they do well in the 25-150 yard range.

What I am really trying to establish is at 200 yards can better accuracy be attained by a bullet leaving the muzzle at 1300-1500fps or at 1050fps?

I know that a subsonic bullet drops further over the same distance due to its low velocity, but it sheds speed much less slowly than a bullet going through the transonic zone.


You will find a lot of info on just this problem by searching "Schuetzen" shooting.
BTW - in this (transonic) velocity range the spitzer or spire point is NOT your friend.

[andym79]

That is why in an other post for a proposed wildcat, I didn't proposed a spire point. So what is a better choice rn or fn?
Bore rider or loverin style?
I assume flat base over bevel?