223 hornady tumbling

renas

had a chance to notice something very unusual today, recently bought few different manufacturers 223 ammo to test out with my tikka t3x, everything but hornady shoot without issues, once i load hornady rounds are tumbling… yes you reading this right… one of mostly expensive rounds going sideways in to the target even at 50m distance, not just sideways they hit like 5-7in apart from each other at all directions left and right from the center point of the target, anyone have simillar experiences ?

BSA International

Only time it happened to me was a 75 grain bullet in a 1 in 12 twist rifle.

renas

https://www.boards.ie/discussion/comment/117821478#Comment_117821478

its a 73gr in 1/12 so its kinda close, it works good with 64gr so far

Feisar

https://www.accurateshooter.com/cartridge-guides/223rem/

The above states a 65 grain flat base as the max in a 1:12. Note the flat base element, length is also an issue. I've read that a 1:12 is marginal for the Hornady 53 grain although my Remington 1:12 has no issues with it at all, it's like a laser with them. I tried some Sellier and Bellot 69 grain in it and while they flew straight they were all over the paper at 100 yards.

I'd say it's just a simple case of the rifle's twist not being fast enough for the bullet. Speed is also a factor so a 22-250 may stabilize a twist/bullet combo that's marginal.

Try the Hornady 53 grain Superformance, it has a savage combination of speed and high ballistic coefficiency

Cass

Nothing as bad as what you describe, but yes I've seen it in a 308. Its a stability issue most times. Other factors include "outside" influence such as clipping the baffle of a Moderator, poor crown, etc.

From a post some years back by me might help explain it a bit better:

Cass - Weight of a bullet is misleading. We all talk about twist rate and suitable weight of bullet, when if fact it's bearing surface length of the bullet that is key. Every calibre is fixed. Meaning a 40 gr bullet and 75 gr bullet in 223 have the same diameter. To make it heavier they make it longer. This is when twist rate comes into play. The longer a bullet the more bearing surface that engages the lands and grooves.

However if i were to talk to someone about suitable bullet for twist rate in terms of bearing surface i'd be talking in thousandths of an inch. For example (and excuse the numbers they are completely made up because i don't have the actual numbers) a 40 gr would not be a 40 gr but a 0.4721 bullet compared to the 0.5512 bullet (75 gr).

It's easier to talk in weights.

The reason i say weight is not ideal is because sometimes this weight to bearing surface is not always as predictable as you'd think. I'll discuss this in 308 as i know them. My rifle is 1:10 twist. It's suitable for bullets of 168 - 185 gr. They have longer bearing surfaces than 123 - 155 gr bullets so work better in the faster twist rate.

However the Lapua Scenar 155 gr is a long bullet. So long in fact that it's bearing surface length is the same as the 175 gr Sierra, and close to the 180 gr bullet. Because of this the bearing surface is longer, and the "lighter" bullet acts more like a "heavy" bullet. This means that although it's a 155 gr bullet it works, quite well, in a 1:10 twist.

It's for this reason that some rifles will shoot heavy or light bullets that seem to contradict the twist rate:bullet weight ratio.

renas

Feisar thanks i def try 53gr hornady, besides all bad luckyou had with Sellier & Bellot sure lighter 55gr i found them to be best grouping so far with few different ammo i had tested

Cass thanks sure does explain a lot ,what im going to do is im going to take apart now 64gr and 73gr as im more then just wondering to see the length difference betwean those two as the weght difference looks so minor but effect is really massive