Bushmaster m4 1in9 twist


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Cagedtiger
October 16, 2011, 11:50 PM
Need to know ideal bullet weights from light to heavy the 1in 9 m4 can handle safely?

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suzukisam
October 16, 2011, 11:54 PM
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
October 16, 2011, 11:59 PM
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
October 17, 2011, 12:02 AM
Thanks suzukisam

Cagedtiger
October 17, 2011, 12:04 AM
I am new to reloading and figure better safe than sorry

MtnCreek
October 17, 2011, 08:38 AM
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
October 17, 2011, 03:49 PM
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
October 17, 2011, 05:25 PM
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
October 18, 2011, 08:05 PM
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
October 18, 2011, 09:15 PM
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
October 18, 2011, 09:20 PM
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
October 18, 2011, 09:23 PM
+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
October 19, 2011, 05:31 PM
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.

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