Bushmaster m4 1in9 twist

[Cagedtiger]

Need to know ideal bullet weights from light to heavy the 1in 9 m4 can handle safely?

 

[suzukisam]

with a 1:9 you'll be limited to a 62gr and some 69gr anything 69gr and up youll have to test individually in your rifle and see if they will work.. you can shoot 55's perfectly, and probably a little lighter but not sure why you would go any lighter than a 55 in an m4... 26.0 gr varget behind a 55 gr pill is excellent...

 

[TonyAngel]

What do you mean by ideal? The most accurate? Only your rifle can tell you that. I've shot as light as 45s out of 1:7 twist barrels and as heavy as 77s in 1:9 twist barrels.

If you want to stay in the super safe zone, stick to the 55 to 69gr range.

 

[Cagedtiger]

Thanks suzukisam

 

[Cagedtiger]

I am new to reloading and figure better safe than sorry

 

[MtnCreek]

IME, a 77gr SMK would stabilize in a 1:9 and a 75gr A-Max would not. Anything smaller should stabilize fine. If you’re looking for range fodder, Hornady 55gr FMJ is a fairly good, inexpensive bullet; it should shoot </= 2” @ the 100 yd line.

 

[Cherokee]

My 1/9 twist AR's shoot 45 to 69 gr bullets just fine. Never tried anything heavier, I don't shoot LR competition. I have found the 55 Hornady JSP to be great in my guns, their FMJ version is also better than any other brand FMJ that I have tired.

 

[agd1953]

I have a bushmaster Varminter with a 1:9 twist and it shoots 55 grain v- maxes very, very well. 3 shots at 100 yds that can be covered with a dime. My undestanding is you can shoot 50-65 grn bullets with the 1:9 twist.

 

[Eb1]

55 grain will probably be your most accurate. When I wasn't reloading Black Hills soft points is what I had the best luck with. Even the blue box Black Hills is good stuff in 55 grain Soft Points

 

[KansasPaul]

First, +1 for Varget - excellent powder for .223 with most bullets.

In my experience, 55 grain bullets, especially Sierra, have shot really well. The issue with 1/9 twist barrels and heavy bullets really has more to do with the length of the bullet rather than the weight - if you plan to shoot heavy bullets, pay close attention to the length/shape of the bullet. The availability and selection of bullets in this caliber is nearly staggering. Have fun - find one that works, then try another, and another, and......

 

[Hondo 60]

26.0 gr varget behind a 55 gr pill is excellent...

+1 - that's my favorite load.

I also have a 1 in 9 & have found that 55 gr is dead nuts on.
I've tried factory 55, 60 & 62.
I wasn't happy with any of them, so I started reloading with plain ol 55 gr fmj.
I haven't had any reason to change since.

Good luck & as always, stay safe!

 

[Eb1]

+1 re: length of the bullet. Hornady 68 gr hp shot well in my 1:9 twist HBAR

RL15
Varget
H335 (great with 55 grain bullets)

 

[AMG04]

DPMS 16" 1/9 twist

I have found that my rifle stabilizes 68-70gr bullest just fine. Some Loads that produced good results:

Load #1: (Picture of 5 shot group attached)
Bullet: 69 gr SMK
Powder: 26.2 gr of W748
Brass: Lapua
Primer: CCI .41
OAL: 2.260"

Load #2:
Bullet: 70 gr VLD (Berger)
Powder: 25.4 grs of RE-15
Brass: WCC '09
Primer: CCI .41
OAL: 2.260"

As always work the loads up slowly.

One thing I have experienced is that heavier bullets will stabilize in a 1/9 as long as velocity is adequate because as velocity increases so do the "RPMS." With the 70 gr load, as I increased powder charge the groups tightened up (I assume this is due to better/more adequate stabilization)... Barrel length plays a key role is this formula because longer barrels tend to produce higher velocities, thus better stabilization of heavier bullets.