Twist vs Ammo Question

[Chefcook]

I shot a few really awesome targets with my rifle this week. My twist rate is 1:9 I was shooting 62gn hollow points. I then switched to 55gn FMJ and could not duplicate the results. My other AR is an LMT with 1:7 twist will it do better with the lighter Bullets?? Am I now in a position where I will have to keep 2 different weight bullets on hand one for each of my AR's? Both rifles are 16"...

 

[Bigum1969]

I'm sure I could be wrong, but I thought that a 1:7 twist would actually perform better with heavier bullets. My SIG 556 is 1:7 twist and does well with heavier bullets.

Again, I'm fairly new to this stuff. I think I have read somewhere that the 62 grain round performs best in a 1:9 twist.

 

[IndyBeerman]

Lighter bullets slower twist, heavier bullets faster twist.
A faster twist can do a couple of things to lighter rounds, first it can make the nose stay up as it goes it downward path, sorta like a plane landing tail first, second it can actually make a light round over spin and break apart due to rpm's over 30,000.

I used to have a old Remington 244 (now the 6mm rem) that could not fire anything over 90gr because of the twist rate being to slow.

 

[Chefcook]

Lighter bullets slower twist, heavier bullets faster twist.
A faster twist can do a couple of things to lighter rounds, first it can make the nose stay up as it goes it downward path, sorta like a plane landing tail first, second it can actually make a light round over spin and break apart due to rpm's over 30,000.

I used to have a old Remington 244 (now the 6mm rem) that could not fire anything over 90gr because of the twist rate being to fast.

Wait this doesn't make since you say heavy bullet faster twist but then you say you couldn't fire anything heavier because the twist rate was too fast that's backwards...

 

[mike8170]

If I remember correctly, 1:12 with a 20" barrel was the best twist for 55 grain bullets. I haven't seen one for a long time, but I am sure there are a few guys on the forum that have them in that twist.

 

[Chefcook]

If I remember correctly, 1:12 with a 20" barrel was the best twist for 55 grain bullets. I haven't seen one for a long time, but I am sure there are a few guys on the forum that have them in that twist.

So then the twist rate on both my rifles is too fast for 55gn bullets....

 

[Richard]

Chef,

Your twist rates are fine, it could be nothing more than just that sometimes a firearm will just "like or dislike" a peticular cartridge or load for some reason or another.

 

[IndyBeerman]

I used to have a old Remington 244 (now the 6mm rem) that could not fire anything over 90gr because of the twist rate being to slow.

Wait this doesn't make since you say heavy bullet faster twist but then you say you couldn't fire anything heavier because the twist rate was too fast that's backwards...

My bad, in my hast I did not proof read!!. Corrected to read SLOW!!

 

[IndyBeerman]

So then the twist rate on both my rifles is too fast for 55gn bullets....

Chef, here's a link to help ya out, really informative.

The AR15.com Ammo Oracle

It will bring you right to the twist rate and different ammo, but take a look at the whole page, very good stuff.

 

[Chefcook]

Chef, here's a link to help ya out, really informative.

The AR15.com Ammo Oracle

It will bring you right to the twist rate and different ammo, but take a look at the whole page, very good stuff.

That was way too much to read at this time of the morning...

 

[IndyBeerman]

That was way too much to read at this time of the morning...

Well it should have put ya to

since it's so long!

 

[Chefcook]

Well it should have put ya to

since it's so long!

Very informative thanks...

 

[IndyBeerman]

Very informative thanks...

I found it that way also, hope others take a look at it.