I have a Model 700 Remington in a 22-250 with 24" barrel. I've been trying to work up a load using 38.0 grains of H-380 and 53 gr TSX bullet.The best group I have been able to achive so far is 3/4"(3 shots) at 100 yards. Barnes recommends a faster twist than 1:12 with this full copper bullet. My bullet are not key holeing in the paper so I was wondering if my group would improve if I added more velocity to the bullet. The reason I ask is I read somewhere that if I speeded up the bullet the group may improve. Looking for advise or different opinions.

Thanks
Steve
www.skymountainoutfitters.com

It's possible that increased velocity will help.....but I'm not sure that you're already not at the max.....I doubt there's enough gains to be made in velocity to actually see a difference........I'd try some Nosler 55 grain BTips....

The higher the velocity that less twist rate is needed. It is a secondary effect, but it is there.

How long is a 53 gr TSX bullet?

I can stabilize 60 gr bullets with 1 in 12", but the bullets might be shorter.

The 53 TSX is .793 and I can still go two more grains before max.

The nosler 55gr blows to big of holes in coyotes.

Thanks

Steve

Velocity indeed influences rate of required twist. However, the most important thing is bullet length. I assume the need for a twist faster than yours is due to the o/a length of a pure copper bullet.

I had a Rem 722 in 222 with 1/14 twist that shot very well with flatbase 55-=grain bullets, but poorly with the military FMJBT 55-grainers.

It doesn't matter what the velocity is, the bullet will never spin faster than the twist rate of the barrel (i.e., with a 1:12 twist the bullet will never spin faster than 1 revolution per foot traveled). Increasing the velocity helps a little but not all that much. Also, a bullet can be unstable and giving less than optimal accuracy even if it's not keyholeing.

If you don't want to blow big holes on coyotes, just use a FMJ bullet; it will kill them and will be cheaper than using Barnes bullets.

Also, if you're using a rifle with a strong action and are not at a maximum load, I would increase the load until the groups start opening up or you get signs of excessive pressure. Barnes bullets seem to do better when pushed hard.

Another option would be the Speer 70 gr. Semi-Spitzer. It's accurate even in my 222 1:12 twist barrel and has killed everything I've hit with it (including a couple of deer) with one shot. It doesn't blow big holes in things either.

If I put a 1 in 16" rimfire barrel on a centerfire action and chamber it for .223, the 50 gr will stabilize at 3300 fps, but the 55 gr at 3200 fps will not.

The HNDY TAP bullets are .774" long and will stabilize in a 1 in 12" barrel. At 2600 fps muzzle vel with 13 gr Blue Dot, they are still stable way out there.

The 8mm, 308, and 270 are SAAMI registered for 35,000 psi, 60,000 psi, and 65,000 psi respectively. They are all good for 62,000 psi, and that is how I load them.

The .223 is SAAMI registered for 55,000 psi, and it is good for 72,000 psi, and that is how I load them. With H335, short brass life threshold is ~ 8 gr over max published.

What does it all mean?
.793" is a long .224" bullet.

You don't say what your twist is...........If you add powder and your groups begin to open up, go back to the last load that got 3/4 MOA (which is not bad for a hunting rifle shooting hunting bullets) or whatever your best (5 shot) group is and start playing with seating depth.

Most people think they don't need wind flags when doing load development. Most people are wrong wrong.

The twist is 1:14 for my 22-250. I took Barnes advice and seated the bullets .50 from the landings. At one time I believe I seated the bullets .20 from the landing and acually got a better group so I might try that.

Thanks

Steve

www.skymountainoutfitters.com

quote:

Originally posted by tnekkcc:
.....

What does it all mean?
.793" is a long .224" bullet.

The Greenhil formula gives a rough prediction of the barrel twist you will need to stabilize a bullet of a certain length for caliber.

It predicts that you will need a barrel twist of 11.4 (or faster) to properly stabilize a .224 bullet - 0.793" long above 2800 fps.

quote:

Posted 09 January 2009 19:26 Hide Post
It doesn't matter what the velocity is, the bullet will never spin faster than the twist rate of the barrel (i.e., with a 1:12 twist the bullet will never spin faster than 1 revolution per foot traveled). Increasing the velocity helps a little but not all that much. Also, a bullet can be unstable and giving less than optimal accuracy even if it's not keyholeing.

That is wrong. Velocity has a direct effect on rpm's. Higher velocity means more rpm's no matter what the twist.
If you have a 1 in 10" twist and shoot it at 1000 fps, the rpm's are 72,000, at 3000 fps, the rpm's are 216,000.

Here's a link to a webpage with an extensive treatment of this.

LWD

quote:

Originally posted by bfrshooter:

quote:

Posted 09 January 2009 19:26 Hide Post
It doesn't matter what the velocity is, the bullet will never spin faster than the twist rate of the barrel (i.e., with a 1:12 twist the bullet will never spin faster than 1 revolution per foot traveled). Increasing the velocity helps a little but not all that much. Also, a bullet can be unstable and giving less than optimal accuracy even if it's not keyholeing.

That is wrong. Velocity has a direct effect on rpm's. Higher velocity means more rpm's no matter what the twist.
If you have a 1 in 10" twist and shoot it at 1000 fps, the rpm's are 72,000, at 3000 fps, the rpm's are 216,000.

Sorry BFr, that data is incorrect.

A 1:12 inch barrel will only spin a bullet 1 time every 12".
Example One: In a 1:12″ twist barrel the bullet will make one complete revolution for every 12″ (or 1 foot) it travels through the bore. This makes the RPM calculation very easy. With a velocity of 3000 feet per second (FPS), in a 1:12″ twist barrel, the bullet will spin 3000 revolutions per SECOND (because it is traveling exactly one foot, and thereby making one complete revolution, in 1/3000 of a second). To convert to RPM, simply multiply by 60 since there are 60 seconds in a minute. Thus, at 3000 FPS, a bullet will be spinning at 3000 x 60, or 180,000 RPM, when it leaves the barrel.

bfr is correct in that with a given twist a higher velocity results in higher RPM. His calculations and RPM data are incorrect as 33806whelen points out.

Steve Lefforge

Up the powder charge if you are indeed 2 gr below max. If accuracy doesn't get better it could be your rifle isn't going to shoot that bullet any better. What accuracy does it shoot with other bullets? Many would be happy with consistent 3/4 moa out of a 22-250.

Larry Gibson

quote:

Originally posted by bfrshooter:
Velocity has a direct effect on rpm's. Higher velocity means more rpm's no matter what the twist.
If you have a 1 in 10" twist and shoot it at 1000 fps, the rpm's are 72,000, at 3000 fps, the rpm's are 216,000.

Nothing wrong with the math here!!!!

Higher velocity does in fact increase RPMs and it's RPMs that effect stability.....not the twist per unit of length!

The formula, which is apparent from but not explicitly stated by several posts, is

(MV in fps x 720) / Twist rate in inches = RPMs

Thus, 3000 fps with a 1:10" twist is 216,000 RPMs because 3000 x 720 / 10 = 216,000.

LWD

quote:

Originally posted by vapodog:

quote:

Originally posted by bfrshooter:
Velocity has a direct effect on rpm's. Higher velocity means more rpm's no matter what the twist.
If you have a 1 in 10" twist and shoot it at 1000 fps, the rpm's are 72,000, at 3000 fps, the rpm's are 216,000.

Nothing wrong with the math here!!!!

Higher velocity does in fact increase RPMs and it's RPMs that effect stability.....not the twist per unit of length!

So as velocity drops, do the RPMs decrease and If so, is stability also reduced?

quote:

So as velocity drops, do the RPMs decrease and If so, is stability also reduced?

If one measures RPMs at the muzzle he has then created the RPMs that the bullet will exhibit it's entire path.....well almost.....the forces acting on the bullets foreward path are enormous and the linear speed of the bullet will slow dramatically......but there is almost no forces acting to retard the bullet's RPMs so that will remain for a very long time.

for example....if a bullet exited the muzzle at "X" feet per second and at "Y" RPMs.....at five hundred yards it might have "1/2 X" feet per second but possibly ".95 Y" RPMs

If the bullet was stable at the muzzle then most likely it will also be stable 500 yards away

I picked up somewhere that muzzle velocity is not the criteria for twist rate and bullet stability. Apparently, there is a point where a given bullet might require a lower twist at a lower velocity. Not a lot, mind you. Point is, the higher the velocity the higher the spin required to stabilize the bullet. Then there is the issue of 'transition' velocity!?

IMO 3 rounds groups are not a good indicator. Try five.