Twist Rate ?

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ExAgoradzo

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I have a 1:7" Mini 14. Will it shoot the 55 gr well or is it only the heavier bullets that will shoot well, based on TR alone.

Thanks,
Greg
 
I've always been under the impression that the lower the better. 1:7 being the lowest great for heavier, longer bullets; 1:9 middle of the road; 1:12 only really being good for up to 55 gr.

Some folks talk about over stabilizing a lightweight round, say 40gr. I personally have no experience with this. However, I have experienced poor performance with a 62gr SMK from a 24" 1:12 twist Rem 700 that shoots one hole groups with 52gr A-Max. The same 62gr SMK works perfectly from a 16.5" 1:9 Ruger M77 Compact. YMMV
 
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It is not optimal but won't make a difference with the kind of accuracy you can expect from your (or my) mini-14.

Here is a good primer on overstabilization: http://www.youtube.com/watch?v=GH-Md1lTa4g

It is not nearly as bad as understabilization and generally only important at long range (>>400yd).

Mike
 
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I generally look at 5.56 twist rates like this:
1:9- Light loads
1:8- Mostly common loads that I will be shooting more
1:7- Heavier loads

Although 1:7 is fine for most anything. I like 1:7 and 1:8 for my general purposes.
 
I have to ask - how did you get a 1-7" Mini14? AFAIK, all factory barrels were 1:9" (or 1:12" for the early units)...
 
There is a website that I don't have at hand right now that say for 10 years or so that is how Ruger made them.
Google 'mini14 twist rates'.
Greg
 
Longer bullets require faster twists for stability, but shorter-bullet accuracy isn't harmed by faster twists.

Not exactly. Very short, very light bullets spun too fast will shoot very poorly, even to the point where they can come apart in the air.

In this case bullets 60 gr or heavier will probably be the most accurate with a 7 twist, but 55's should do fine. I wouldn't recommend going much below 50 gr though. Get into the 35-45 gr. bullets and you could have problems.
 
when given a choice I go with faster twist (so I can load longer pills) but once I DID have a problem with light bullets/fast twist...

The jackets were failing, and the rifling was a copper mine. My buddy shot the same pills with a slower twist and did not experience the problem. just MHO
 
The best twist also depends on distance. A lot of 6.5 Grendel types will tell your that 1:7.5" will give you the best groups within 300 yards but 1:9 or slower will be better between 600 and 1000 yards but not as good closer. The right tradeoff point is different. At shorter distances, "overstabilized" can be good.

Mike

PS. Based on my own calculations, I am of the opinion that for 5.56/223 1:8" is the best all around twist if you don't need to shoot tracers (1:7" if you need to shoot tracers). The Seal Recon Rifle is 1:8", the Army SDM-R is 1:8", and the Marine SAM-R is 1:7.7" so the guys who shoot on 2-way ranges for a living seem to agree.
 
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