55grn fmj in a 7 twist tube - how crappy will this be?

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JR Hartman

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Looking for a nice varmint/laminate .223 bolt rifle for some nice tight groups.

I have seen a nice one but it has a 7 twist barrel and I know it shoots really well with 75-90 grn pills, but will do most of my shooting with the cheaper stuff. 55, 62 and 69grn stuff.

I know a 9 twist will be better, but will the 7 twist be a mistake?
 
My t97 has 1:7 twist and 55gr hollow points wont even hit the target. They disintegrate in the air. Fmj might hold up better and different guns arent as picky with the same twist.
 
Shot a few coyotes with a 1:7 ranch rifle and 55gr sp/hp hornadys. They blew up a just inside the hide, would not recomend 55's for that twist.
 
My Tavor has a 1:7 twist and shoots 53-55gr lights out. I haven't found a heavier load that shoots well yet.
 
Out of a DDMK18 1:7 @ 100m prone position unsupported

Norinco 5.56 55gr


AE223


From a 16" M4 profile barrel @ 100m scoped/bipod supported


55gr will do the job, look for 62gr for better accuracy (see below)


Recently reloaded with Hornady 68gr HPBT and went sub-moa with 3 groups while doing load development and most loads stayed MOA ish @ 100m out of an M4 profile 16" AR 1:7 twist

You should be doing better with a bolt gun anyday.
 
I guess you'll have to try and see what works. If they don't work you'll just have to switch to the heavies
 
If your using cheap stuff, 1-12 will suit you too.

I push a 50gr vmax out to 550yards no issue.
600yards i get occasional tumbles.

53gr vmax and 55gr bulk for my ar all work good too.
Developed the 50gr load at nerely 4000fps for a flatter shot and kept with it.
 
aheppner said:
1 in 7 is too fast. Most likely accuracy will be poor.

that has been my experience anyway.
Click to expand...

My experience is the opposite. Even with lighter bullets accuracy was excellent (custom 1:7 .224 match barrel) but thin jacketed bullets intended to upset at Hornet velocities sometimes would disintegrate in flight. Varmint bullets will be more explosive from a 1:7 than from a 1:12, so if a coyote, rather than a prairie dog was your target, a game bullet with a thicker jacket would be in order. IMHO, a 1:7 is the ideal twist for a high velocity .22 centerfire
 
My 1:7 T97 loves 69-77gr for accuracy but stabilizes 55gr just fine.

The twist won't inherently make anything more accurate, as long as it stabilizes and doesn't keyhole.
 
Rifles with a fast twist barrel, i.e. 1 in 7, will over stabilize 55gr bullets, but accuracy will be just fine depending on the quality of the bullet. Just don't use bullets with a thin jacket. The bullet's rotation speed will make the jackets disintegrate. These bullets are usually less than 50 grains though. Buy a box and just try them, that will be the definitive proof anyway in YOUR rifle. I my AR15 with 1 in 7 twist barrel, 55gr bullets are just as accurate as the heavier bullets.
 
55 grain FMJ bullets shoot just fine out of a 1:7 barrel in my experience. That said, they aren't really the best choice if your objective is to shoot groups off the bench as an end in itself.

Other than with a few very lightly constructed bullets, you can't go too far wrong picking a faster rifling twist than necessary.
 
I find that barrel length plays a part in this. In my experience the shorter the barrel the tighter the twist you need to stabilize lighter bullets. Put a 16" on my Savage 11, thinking it would need heavier bullets. Groups were okay, but nothing great with 69 gr. Tried some 55 gr and I can cover a 5 round group with a nickle at a 100. Started looking into it, and it makes sense. A longer barrel gives the lands/grooves longer to act on the bullet, so a tight twist may cause issues in a 22" barrel shooting light bullets. That same bullet coming out of a 10" AR barrel with the same twist, may be very accurate.

Don't just look at twist and bullet weight, consider barrel length as well.
 
ShawnC6 said:
My 1:7 T97 loves 69-77gr for accuracy but stabilizes 55gr just fine.

The twist won't inherently make anything more accurate, as long as it stabilizes and doesn't keyhole.
Click to expand...

I agree with the colliery, that at extended ranges, where transonic velocities are encountered, higher than normal rotational velocities can prevent a bullet from becoming unstable, but then that is hardly the typical venue for 55 gr bullets.
 
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