ACR Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
103 Posts
Discussion Starter · #1 ·
Which one do you have? 1:9 is the most common by far. Most of us shot 55gr I believe both shoot it well. However which one shoots 55gr with a tighter group? And having the option to get one or the other what would you get if you had to pick?
 

·
Registered
Joined
·
75 Posts
The 1 in 9 gets the nod for 55 grain.I have the 9,thats what i wanted.
 

·
Registered
Joined
·
279 Posts
soapboxpreacher...http://www.gunblast.com/Bushmaster-ACR.htm check this link..it will give you any idea on what to expect as far as accuracy/groups shot through 1:9 barrel. Typically the faster twist will stabilize heavier pills. The guy who wrote this article.review had pretty good success with 62 gr.

55 gr's bullet flies out straighter out to 200 yds out of either 1:7 or 1:9, so the bullet drop is going to be a little less than, lets say a 75 gr.

Once I start doing my analysis of the ACR I picked up today... I will share the info
 

·
Registered
Joined
·
2,790 Posts
Which one do you have? 1:9 is the most common by far. Most of us shot 55gr I believe both shoot it well. However which one shoots 55gr with a tighter group? And having the option to get one or the other what would you get if you had to pick?
1:9 is all that availible for the ACR right now.

It works for what I do with it. I shoot mostly 55grn or 62grn stuff. With the occasional box of 69grn match stuff out to no more then 100yrds, (occasionally 200yrds) I have both twists in AR type rifles and they is no real difference. I did shoot 1 box of 77grn stuff thru my ACR and had no keyholing or extreme spread and it was no more accurate then the 69grn stuff.

The key is finding what load your rifle is most accurate. Every barrel has it's favorite.

Something that people forget, the original spec for the AR15 was a 1:14 twist using the 55grn m193. The military changed it to 1:12 because the accuracy during cold weather testing was not to spec. The 1:7 twist was specified to stabilze the ultra long bullet that the m856 tracer used, it made no difference to the general issue m855.
 

·
Forum Vassal
Joined
·
709 Posts
I mostly shoot 55gr and 62gr so it isn't a huge issue.

1/7 is the military standard, and should be the civilian standard, with 1/9 being "optional". All of the best SD and precision rounds are 72grs and up, which can be problematic in 1/9.

Also, 1/9 SBR's are prone to instability and will cause baffle strikes with suppressors.
 

·
Registered
Joined
·
1,587 Posts
I'd rather do a 1:8 and split the difference. It'll stabilize up to 80gr tips that won't even feed from a mag. Doesn't spin the bejesus out of lighter rounds and helps keep barrel life longer through less friction and heat.
 

·
Registered
Joined
·
279 Posts
I have a krieger barrel with a 1-7.7 twist and it handles 75gr and 55gr. pills just fine too
 

·
Registered
Joined
·
1,587 Posts
I have a krieger barrel with a 1-7.7 twist and it handles 75gr and 55gr. pills just fine too
My buddy has a barrel for shooting the 90gr tips in something like 1-6.5 or something. I told him it was no longer a rifling twist but a thread pitch. :)
 

·
Registered
Joined
·
2,790 Posts
My buddy has a barrel for shooting the 90gr tips in something like 1-6.5 or something. I told him it was no longer a rifling twist but a thread pitch. :)
90grns!!!! My god, those must be 2 inchs long. :) I can't even imagine that. I can't even picture what the OAL must be.
 

·
Registered
Joined
·
34 Posts
Is that a Spike's barrel? Did it come complete or did you have to provide the gas block, op rod, etc....
Yes it is, I ask for a 14.5 and I provided my gas block because I dont have the time or patience to switch it out myself.
 

·
Registered
Joined
·
226 Posts
JR Foxtrot,
Dude! That is seriously beautiful!
More details, like cost and weight change!
Thanks for the pic!
Need a range report later and some more pics!
Thanks
 

·
Registered
Joined
·
2,790 Posts
JR Foxtrot,
Dude! That is seriously beautiful!
More details, like cost and weight change!
Thanks for the pic!
Need a range report later and some more pics!
Thanks
+1

Inquiring minds want to know!!
 

·
Premium Member
Joined
·
4,707 Posts
hey thats my thread lol

500 is too much for just a barrel imo, and it takes me about 3 minutes to remove everything, and about the same to install it all properly

overall i do give him props since he beat bushmaster to the punch for their own weapon system
 

·
Registered
Joined
·
226 Posts
Bushmaster is probably ahead of FN in this regard. How long have the SCARS been out? No barrels for them either and changable barrels were one of the points FN touted in their ads.
I do not know what Bushmaster will get for their barrels and caliber change kits or what FN will get for their barrels but it will be interesting to see if $500.00 will get a new 1/7 barrel.
If a fellow had a spare gas block and access to a few simple shop tools I think he could do it himself.
Sooner or later someone will make a barrel blank with the index pin set and this will become a home job that will be more affordable.
Just my opinion...
 
1 - 20 of 25 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top