14.5 1/7 twist LMT upper

bluesclues

bluesclues

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Continuing with my first AR build...

To build my "as close as possible M4-gery", I am really considering the LMT 14.5 inch 1/7 twist, chromed lined upper.

Now for my question...
Is the 1/7 twist a good rate for "plinking", if you will? This rifle will be mostly for fun plinking (and the odd 3 gun match) and will probably be fed a steady diet of WWB or equivalent 'cheaper' ammo. Or, would a 1/9 twist be the better way to go?

As always, all thoughts and advice is welcome.
 
1:9 twists are better for general purpose range use. They will stabilize both the M193 and M855. Get the 1:7 only if you want to shoot 75 gr. and up. True M4's all have a 1:7 twist barrels.
 
my m-4 clone has 1:9 twist on a 14.5 inch barrel, shoots US 62 grain green tip and 55 grain blasting ammo great no problems, no hicops, I am running an RRA A3 Flat top upper wiht a RRA lower that i built'
I have no experiance with the 1/7 but the 1/9 suits me fine
 
I suppose you might think that if you have a short barreled shorty, like a 10.5 incher, where your not getting high enough velocity to promote fragmentation. You might want to go with heavier bullet to compensate for this. With that in mind maybe a 1:7 for something short might make sense. But a 14.5 I think is borderline and you still get fragmentation.

That was my take on it at least. But then again I shoot it only at the range, and use bargain basement American eagle 55gr in my 10.5 LMT wiht 1:7
 
barrel

Unless you happen to luck into one cheap I think a 1:7 barrel will probably cost you an extra $100-150 over the equivalent 1:9 barrel.
 
ShooterMcGavin said:
my m-4 clone has 1:9 twist on a 14.5 inch barrel, shoots US 62 grain green tip and 55 grain blasting ammo great no problems, no hicops, I am running an RRA A3 Flat top upper wiht a RRA lower that i built'
I have no experiance with the 1/7 but the 1/9 suits me fine
Click to expand...

RRA makes a 14.5" A4 upper?
 
koalorka said:
RRA makes a 14.5" A4 upper?
Click to expand...

I didn't see it listed on their website...
Come to think of it, I haven't seen any 14.5 inch barels with 1:9 twists.
Thanks for the replys. Just to see if I am reading the information correctly, 40 & 55 grain plinking ammo is not really recommended for the 1:7 barels?
 
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barrel twist

As a general rule, heavier bullets are better suited to fast twist barrels and vice versa but there can be considerable overlap. For example, a 1:10 barrel may shoot 69 gr. bullets quite accurately and a 1:7 barrel may shoot 55 gr. bullets the same way but the heavy bullet/fast twist analogy should still be your general guide when selecting a barrel/bullet combination.
 
bluesclues said:
I didn't see it listed on their website...
Come to think of it, I haven't seen any 14.5 inch barels with 1:9 twists.
Thanks for the replys. Just to see if I am reading the information correctly, 40 & 55 grain plinking ammo is not really recommended for the 1:7 barels?
Click to expand...
Using the lighter stuff isn't usually a 'problem'... it's just not a good 'match' between bullet weight/twist rate.
By the way just as a reminder, stay away from using the lighter weight
bullets (40, 45, etc) that typically have hollow point tips. The tip can hang up on the feed ramp, and even if it's crimped, can push the bullet into the case.It still feeds, but now you've got a potentially high pressure situation.
Stick to feeding your units ball ammo and you'll minimize this problem.
 
For me it is a problem indeed Foxbat! Shooting factory 55gr bullets produced 3~4" groups. Going to 75 gr. bullets brought that down to around .8 MOA. Twist rate is everything in a rifle, I know custom barrel makers that will ask you what load you want to shoot in your rifle before the fab one up for you. The reason for that is they want to tailor the rifling to the task you have for it.
 
Glenfilthie said:
For me it is a problem indeed Foxbat! Shooting factory 55gr bullets produced 3~4" groups. Going to 75 gr. bullets brought that down to around .8 MOA. Twist rate is everything in a rifle, I know custom barrel makers that will ask you what load you want to shoot in your rifle before the fab one up for you. The reason for that is they want to tailor the rifling to the task you have for it.
Click to expand...
Yeah...I get it. Just as stated in my post...it's not a PROBLEM...it just won't work (be as accuarate) as where you match the weight to the twist.
Read the post....
 
I've got one of these... nice if you can find one, shoots great.

HPIM0645.jpg
 
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