Hello all, here is today's article posted on TheArmoryLife.com. It is titled “Best Bullet Weight for 1 in 7 Twist Rate?” and can be found at https://www.thearmorylife.com/best-bullet-weight-for-1-in-7-twist-rate/.
Best Bullet Weight for 1 in 7 Twist Rate?
- Thread starter Mike H.
- Start date
Great read and answered some of questions about why a 20" SS 1-7 twist loves to fire 55 grain BTHP over heavier rounds. I can custom load a 68 gr that will do well at 200 yards, but it doesn't like Factory 75 grain Match Rounds or others as much as the 55 grain. I actually zero with the 55 grain match because of it. Here I thought, this just ain't right and I may need to confirm the rifling and the article pretty much provided some clarification as to why...
Talyn
SAINT
A certain twist rate doesn't guarantee a certain bullet weight will run well in all barrels.
Barrels are individuals based on who makes them, how they're made, who made them, and the style and quality of the bullet.
It's always best to try different brands in the same weight if you're handloading.
Barrels are individuals based on who makes them, how they're made, who made them, and the style and quality of the bullet.
It's always best to try different brands in the same weight if you're handloading.
Back in the late 80's when I bought my Colt AR-15 HBar that is a 1:7, I read an article that talked about a police department somewhere that had bought up a bunch of 55-grain ammo for training. They had new HBar rifles with 1:7 barrels and they had cases of random shots splattering the target from shredded bullets. The article broke down the pressures/velocities and bullet rpm from various barrels (I wish I could find the article). The theory was that the lighter bullets were pushed at greater velocities that generated excessive bullet spin rpm that exceeded the bullet's capability of holding together and broke up in flight, or they were just very poorly manufactured bullets, but it was an interesting take.
HansGruber
Ronin
Pure horse feces.
I’ve run 55gr through a 20” 1:7 numerous times; never had a bullet blow up due rotational force.
It can happen…but it involves super-thin jacketed, super lightweight bullets pushed WAY too fast—usually in excess of 4kfps…
KillerFord1977
SAINT
While not an absolute guide, this reference chart has been around for quite awhile :
Top numbers are the grain weight
Top numbers are the grain weight