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Post by hacker54 on Jul 3, 2014 19:07:57 GMT -5
Whether you are buying or doing a build what for barrel are you going to get. The barrel what about the barrel? This seems to be a top question. Some would ask what difference does the barrel make. I would ask what bullet weights are you going to be putting down it 55gr or 90gr or what ever between. For your AR to be acceptable in accuracy one needs the proper twist rate for the barrel. Here is an article from "Guns and Ammo" on matching up twist rates with bullets weights. I found it informative as to what I may be limited to as I load for the son-in-law's AR. www.gunsandammo.com/2013/12/23/pair-barrel-twist-rates-ammo/ |
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Post by krwada on Jul 3, 2014 21:23:53 GMT -5
Currently, I am thinking about matching the barrel to the projectile. Or is this a fool' errand?
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Post by hacker54 on Jul 3, 2014 21:54:01 GMT -5
Not at all. If you look at Dan's post on his 30BR rig you will see that he shoots a 115gr pill and the twist rate for his rifle is 18 or 18.5 and he is averaging around 3,000+ fps for this combo. Is there a range that a twist can handle yes. I do believe the article had the ranges for each. Your over the counter rifles made will shoot a range. Like the most common twist for almost any 30 cal. rifle is 12 to 10 most 7mm's are 9 to 9.75 The load data in the manual is for the lack of a better term the general twist rates. Some manuals for the heavier pills will stae for a faster rate. Hornady does this. As for my som-in-law's AR it has a 9 twist and I know what range of weights I can load for it and have acceptable accuracy.
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SnapShot
Member
Jeep & Mocha "Remembering Patches, always"
Posts: 699 
Location: Finally free from the Republic of Kalifornia!
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Post by SnapShot on Jul 7, 2014 14:39:12 GMT -5
Very good article Gary, thanks for sharing. I am in the build process and looking for right upper.
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loafer
Member
No Loafing around
Posts: 52
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Post by loafer on Nov 4, 2014 20:22:52 GMT -5
I am on a quest for a Barrel also, I think I have found what I want..still not 100% sure yet, still doing home work....Gary thanks for the info, I did post up what I am looking AR 308 general rife BS
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dangun
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I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Nov 9, 2014 22:32:08 GMT -5
I just ordered a barrel that is 1:17 twist. I am moving to a heavier DRHG 125gr. This move will allow me to carry 2 separate loads and two separate barrels on a match day. It should push about the same velocity but the heavier bullet will buck the wind slightly better.
It is surprising the number of reloaders that don't consider or total ignore the twist rate of the barrel they are loading for. I see many reloaders at the range trying to work up loads but they can't tell you what the twist rate is for their barrel. I just have to shake my head and walk away.
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bob
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I'm too old to be nice but never too old to learn!
Posts: 1,457
Location: Northern California
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Post by bob on Nov 9, 2014 22:44:28 GMT -5
Twist? Is that that crooked splines down the barrel? I thought they were supposed to be straight and someone screwed up and twisted the barrel because the machine was still turning.
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gws
Member
Posts: 969
Location: NW New Mexico
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Post by gws on Nov 10, 2014 12:39:19 GMT -5
OK Dangun, I'll bite 1:17? You have a 35" barrel?  I thought the 1:14" barrel I found on my .22-243 wildcat was extreme! However I have discovered really tiny preemie .224" bullets and how fast they can be slung out of that barrel.......getting excited to try it!! Bob, ha ha, we know you better than that.  Reminds me of a tour I took at the Vicksburg Civil War Battlefield. Most cannons were clear bore. Some of them were more slender barreled and had those crooked "spines" in them. They were called rifles...on the little plaques near them! In fact one "rifle" was big enough to crawl into and was aimed at the Mississippi River......no doubt towards the Union ships coming south. |
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dangun
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I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Nov 10, 2014 13:05:09 GMT -5
Greg, Yes a 1:17, my current barrels for both of my .30BR rifles is 1:18.5 twist. I started out shooting 112gr pills then discovered the 115gr pills liked those barrels even better. Barrel length for my light barrel is 22" the heavy gun barrel is 26". I am wanting to try some 125gr pills. I had been swaging the 115gr in .925 J4 jackets but have discovered that the 125's will require the 1.00" J4 jackets. There are several other that have already made this switch and are seeing good results. Same powder and weight as with the 155gr except now the load will be even more compressed. Chamber pressure was tested with the heavier bullet and I was surprised that it only went upto 67599 from 66822. Well within the specs for this chamber.  |
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gws
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Posts: 969
Location: NW New Mexico
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Post by gws on Nov 10, 2014 16:51:40 GMT -5
Dangun,
What I find interesting, is that usually less twist means less bullet weight and/or length......you are going the other way!!
I'm pretty sure I can't stabilize heavy .22 bullets in 1:14.....at least according to the experts. So what makes .30 caliber bullets different? (in 30BR at least)
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Nov 11, 2014 10:49:21 GMT -5
Greg,
I'm not going less twist! I think you are looking at this backwards. 1:14 means 1 twist for every 14 inches of barrel which is slow 1:7 is 1 twist for every 7 inches of barrel which is faster, so by going from a 1:18.5 to a 1:17 I am increasing the twist and therefore need a heavier bullet.
In a .223 1:14 barrel the heaviest bullet that should be used is 55gr maybe 60. To shoot an 80gr pill you need a 1:7.
Heavier bullet need to spin faster to stabilize.
Shoot a .223 80gr pill in a 1:14 barrel at 50 yards and you more often than not you will see. Keyholes!
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gws
Member
Posts: 969
Location: NW New Mexico
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Post by gws on Nov 11, 2014 15:34:20 GMT -5
Dan,
No, I just understood what you said backward. You said:
I assumed you were talking about the 1:18.5 twist "current barrels,"when you said, the 115gr pills liked "those barrels" even better. I obviously misunderstood. Now it makes more sense.
I'm still amazed that 1:17 or 1:18.5 is enough twist to stabilize 115 or 112 gr bullets......but I'm thinking in .22 terms....I probably should compare those to the little 40 and 35 grain pills of .22 caliber. Short and light.
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Nov 11, 2014 22:12:44 GMT -5
Oh ok now I see how you came to think that. Yes a 112 or 115gr pill is very light for .30 caliber and they are being pushed up to 3200fps sometimes faster. I have seen guy swage lighter pills but couldn't keep them on paper if there was any wind at all.
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I thought the 1:14" barrel I found on my .22-243 wildcat was extreme! However I have discovered really tiny preemie .224" bullets and how fast they can be slung out of that barrel.......getting excited to try it!!
My daughter came from Missouri, my son and grand son, my wife and I had a nice dinner of grilled "porter house" pork chops, corn on the cobb, my son, G'son and I share 10/5. G'son is 4 minutes early though @ 10/4.
Pooh I hope you find to right house . 
