educate me

[Hersh]

Can you guys help me understand something about ballistics? Based on what I've learned here, ( I post very little, but read a lot) a 1:7 twist is needed to stabilize heavier bullets.

For arguments sake, say you had a rifle with a 1:9 twist that shot dead center on a 10" plate at 100 yards with 55 gr ammo. Now if you take the same rifle, conditions etc and shot 62 gr ammo what would be the effect on accuracy on the same plate at the same distance?

Thanks for the help.

[Shabazz]

I am not sure if you are asking about accuracy or point of impact.

And I am not sure if you are asking about steel core 62 grain bullets or lead core 62 grain bullets.

Steel core 62 gr bullets will be a little long for a 1:9 twist, so your group size will likely open up (less accuracy).

Generally, a lighter bullet will shoot higher than a heaiver bullet because generally a lighter bullet will be travelling faster than a heavier bullet. But there are other variables like barrel whip, some load their ammo hotter than others, etc. But generally you can expect the 62 gr bullets to hit lower than the 55 grain bullets. But you better shoot to find out because that is not always the case.

[Hersh]

Yeah I was asking about point of impact ... thanks.

[FeltaDorce]

In my experience, changes in ammunition can cause fairly dramatic POI shift. For example, I am setup to shoot 55 gr M193. If I shoot PMC .223, my POI shifts 4 inches at 100 yards, up and left. Same grouping size. I do not believe that there is any reliable way to anticipate a shift in POI based on different ammunition types. Shoot it, and adjust.

Your 1:9 barrel will have more trouble with "heavy" bullets, like high 60s and 70+ gr. bullets. It should shoot 55/62 gr. varieties nicely. It is my PERSONAL OPINION that the 1:9 barrel is a very nice optimization of the rifle twist for recreational shooters, as 55/62 gr. ammo is primarily what most people shoot, most of the time.

I fully expect to hear about why I am a dumbass for saying that I LIKE (note, this is not PREFER or DESIRE or RECOMMEND) the 1:9 barrel twist

Flame on!

[Shabazz]

I fully expect to hear about why I am a dumbass for saying that I LIKE (note, this is not PREFER or DESIRE or RECOMMEND) the 1:9 barrel twist

To the contrary. You can get a good deal on barrels no one else wants.

[wrinkles]

Can you guys help me understand something about ballistics? Based on what I've learned here, ( I post very little, but read a lot) a 1:7 twist is needed to stabilize heavier bullets.

For arguments sake, say you had a rifle with a 1:9 twist that shot dead center on a 10" plate at 100 yards with 55 gr ammo. Now if you take the same rifle, conditions etc and shot 62 gr ammo what would be the effect on accuracy on the same plate at the same distance?

Thanks for the help.

Don't want to sound like a jerk but one thing I would tell you is. You question is not about terminal ballistics it would be internal and exterior ballistics.

[MegademiC]

Can you guys help me understand something about ballistics? Based on what I've learned here, ( I post very little, but read a lot) a 1:7 twist is needed to stabilize heavier bullets.

For arguments sake, say you had a rifle with a 1:9 twist that shot dead center on a 10" plate at 100 yards with 55 gr ammo. Now if you take the same rifle, conditions etc and shot 62 gr ammo what would be the effect on accuracy on the same plate at the same distance?

Thanks for the help.

As noted, this is in the wrong subforum.

However, there is no one answer. The effect depends on the barrel/bullet/load combo.

Some barrels prefer different ammo than seemingly identical barrels.

1/9 is plenty fast enough twist for a 62 grain bullet.

Your particular barrel could group either round better, or both the same. The only way to know is to shoot it yourself.

Edit to add - Im pretty sure twist has nothing to due with poa/poi, just stabilization and accuracy from it.