Light bullets in fast twist


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gdcpony
September 4, 2009, 03:05 AM
I am about to start throwing loads together for a 16" 1-9 twist AR-15. I am looking for a good 300yd load capable of dropping varmints out at that range. I am not as concerned about drift in the wind at that range as I am about flat trajectory. I want as long a MPBR as possible. With just 16" to accelerate the bullet, I am thinking of going back to the lighter bullets. I know they will shed speed faster, but I don't think the heavier bullets will be faster or significantly more accurate with most of my shots being <300yds.
I have long loved 40-50gr bullets out of my .223's but my last AR (1-8) hated anything under a 55gr. I was thinking of trying some budget SP's and a box of Ballistic Tips.

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ants
September 4, 2009, 03:13 AM
Yes, load the box of 55g Nosler Ballistic Tip. You won't regret it. We use it in 3-gun USPSA matches out to 330 yards. Generally, load for about 2900fps out the muzzle, but your gun may want a little more or a little less. Mine likes more. You work up your own.

Remo-99
September 4, 2009, 03:32 AM
55gr has been a poplular performing bullet weight in .223rem for a long while now, regardless of the barrel length or twist rate.

gdcpony
September 4, 2009, 10:00 AM
I was hoping for a 40 or 45gr load. I'm using Varget behind 55gr now. In fact, I'm going out to use some factory fodder to break in and base line the new toy today.

gdcpony
September 5, 2009, 02:16 AM
Baseline 1.5" @ 100yds. I'm still hoping for a load to come by for my rig. Short barrel, fast twist, light bullet.

IndianaBoy
September 5, 2009, 02:53 AM
A good 55 gr bullet with a higher BC will likely shoot flatter than a 40 grain bullet with higher muzzle velocity.

40 grain bullets shed velocity so much faster than 55 grain pills, they aren't worth the higher MV.


I load for a 220 Swift and a 1:9 twist AR. Going to lighter bullets gains you nothing.


50 grain V-Max bullets are stellar performers. I wouldn't go any lighter. Heavier is probably better, and I would go with heavier if I had a fast twist Swift.

Bart B.
September 5, 2009, 06:16 AM
The only issue I know of when shooting lighter weight bullets from a fast twist intended for heavier ones is this.

What happens when the light bullets are spun so fast the centrifugal forces caused by their unbalance (97 bullets out of a box of 100 are to some degree) causes them to jump away from the bore axis when they exit the muzzle?

Depending on the rifling design, some bullets shed their jackets when spun too fast. The centrifugal force coupled with the weakened jacked due to rifling cuts in it is the cause.

ants
September 5, 2009, 08:04 PM
Good point, Bart B. That's probably why few reloaders use 36 or 40g bullets for the AR platform. I've tried some fast lightweight varmint bullets in a 1/8 twist AR15 (24" stainless bull barrel) and they tended to scatter a lot. Although the Barnes bullets were superior to the rest.

Anywhere from 2800 to 3100 fps MV with 55 grain bullets in a 1/9 twist AR-15is the benchmark for these rifles. You can find good accuracy. You won't lose a jacket. You have a thousand published loads to choose from. Tons of information out there.

Walkalong
September 5, 2009, 08:11 PM
Yep, Bart is right.

That is why Benchrest rifles use the slowest twist that will stabilize the bullets being used. They don't want to spin them any faster than necessary.

Beelzy
September 5, 2009, 09:04 PM
Try the Nosler 50gr BTs.

Excellent performance.

gdcpony
January 20, 2010, 10:55 PM
Ok sorry for the delay. I had some home issues and wanted to get some good data on the bullets I have right now. My wife controls the wallet, and until I get rid of the rest of the 55gr fodder, she won't let me play around with a new weight. I still plan to try out lighter pills. I just don't think I will develop the velocity to have them shred themselves with only 16 inches to do it in.

I have a 1.5-5 Konus shotgun scope on it that is excellent for the fast yet precise shooting I have in mind for this rifle. Add in a collapsible stock, and it is not a built precision rifle by any means. I am getting excellent groups with averages of about .9, 1.5, and 4 inches at 100, 200, and 300yds. Not bad considering I shoot off a bipod with a rear bag. I have no chrono available so I have no clue what they are flying at.

I am trying to decide on components right now for my mad experiment. I have a deployment coming up and will be loading them after I get back. So I have time. So far I am thinking H335 or A2230 for a powder. I have never seen a difference in group size from one primer to another, but CCI has been a standby for me for a long time so they will probably remain. The bullet is the big question. I would like to try a bullet of each of 40, 45, and 50gr variety and see if they hold up. I will be ordering new brass as mine is on its last loading probably Winchester or military (I understand the concerns with this brass, and start low on my loads) what ever I can get in bulk cheaply.

ForneyRider
January 21, 2010, 12:16 AM
I've had good luck with Sierra 40gr HP.

The 36gr Barnes VG were .75in at 100 yards with 5 shot group. My worst group in my 1:9 twist 20in DPMS AR. Tried lots of powder charges of AA2230 to no avail.

40-75gr can do around .5in in my rifle.

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