light and hot load for Ar

kylewood · July 6, 2011, 10:37 PM

I'm wanting to load some real light bullets for my 16" AR with a 1 in 9" twist. I was planning on starting with 40 grain V-max boat tail with a splash of Varget. Can anybody give some input or possibly recommend something better?

Wood

**Unclenick** · July 6, 2011, 11:13 PM

Don't use a "splash" of Varget or any other slow powder intended for heavier bullets if you value your gun. It can cause a high pressure spike or chamber or bore ringing. Hodgdon says 25 grains is minimum at your bullet weight and it is not safe to go lower. It's not a good powder choice for a light bullet anyway, as it wants more to push against as it builds pressure. If you want a truly light plinking load either use 7 grains of Trail Boss or for a little warmer, 7 grain of Unique or a bit more, 12 grains of 2400. No light load is likely to function the action, so these would be one-at-a-time loads.

If you want something that makes enough gas to function the action AR with that light bullet, you'll need a rifle load with a powder that's relatively quick, as rifle powders go. Try about 20 grains of IMR 4198 to start.

kylewood · July 6, 2011, 11:26 PM

I meant a light bullet and a hot load. like maybe 3700 fps.

Wood

LarryFlew · July 7, 2011, 03:55 PM

http://www.handloads.com/loaddata/de...Powder&Source=

has some loads in your range. At those grains all will be compressed loads so expect full cases.

kylewood · July 7, 2011, 09:02 PM

Thanks for the help. Is high velocity hard on a chrome barrel like it is on a carbon barrel?

Wood

**Unclenick** · July 8, 2011, 12:08 PM

Sure. It just resists longer. The main thing that does damage is differential heat expansion. Firing gases heat the bore surface far faster than the heat can penetrate steel. It only gets a couple thousandths into the steel by the time the bullet exits. That means the top two thousandth expand while the base metal does not, and the difference in size eventually fatigues the connection between the surface and base metal. It winds up with heat stress cracks, looking like an alligator skin, and finally the squares in the pattern start to break off.

Chrome is tough and will resist that longer than plain steel, but not forever. You just need to decide how often you want to replace the barrel. The maker may be able to tell you how its life expectancy compares as a ratio to normal steel, and I expect that ratio will hold up with the hotter loads, too.

July 6, 2011, 10:37 PM	#1
kylewood Member Join Date: August 12, 2009 Location: Kennewick, WA Posts: 48	light and hot load for Ar I'm wanting to load some real light bullets for my 16" AR with a 1 in 9" twist. I was planning on starting with 40 grain V-max boat tail with a splash of Varget. Can anybody give some input or possibly recommend something better? Wood

July 6, 2011, 11:13 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,733	Don't use a "splash" of Varget or any other slow powder intended for heavier bullets if you value your gun. It can cause a high pressure spike or chamber or bore ringing. Hodgdon says 25 grains is minimum at your bullet weight and it is not safe to go lower. It's not a good powder choice for a light bullet anyway, as it wants more to push against as it builds pressure. If you want a truly light plinking load either use 7 grains of Trail Boss or for a little warmer, 7 grain of Unique or a bit more, 12 grains of 2400. No light load is likely to function the action, so these would be one-at-a-time loads. If you want something that makes enough gas to function the action AR with that light bullet, you'll need a rifle load with a powder that's relatively quick, as rifle powders go. Try about 20 grains of IMR 4198 to start. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

July 8, 2011, 12:08 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,733	Sure. It just resists longer. The main thing that does damage is differential heat expansion. Firing gases heat the bore surface far faster than the heat can penetrate steel. It only gets a couple thousandths into the steel by the time the bullet exits. That means the top two thousandth expand while the base metal does not, and the difference in size eventually fatigues the connection between the surface and base metal. It winds up with heat stress cracks, looking like an alligator skin, and finally the squares in the pattern start to break off. Chrome is tough and will resist that longer than plain steel, but not forever. You just need to decide how often you want to replace the barrel. The maker may be able to tell you how its life expectancy compares as a ratio to normal steel, and I expect that ratio will hold up with the hotter loads, too. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

July 6, 2011, 11:26 PM	#3
kylewood Member Join Date: August 12, 2009 Location: Kennewick, WA Posts: 48	I meant a light bullet and a hot load. like maybe 3700 fps. Wood

July 7, 2011, 03:55 PM	#4
LarryFlew Senior Member Join Date: June 15, 2009 Location: Minnesota CZ fan Posts: 902	http://www.handloads.com/loaddata/de...Powder&Source= has some loads in your range. At those grains all will be compressed loads so expect full cases.

July 7, 2011, 09:02 PM	#5
kylewood Member Join Date: August 12, 2009 Location: Kennewick, WA Posts: 48	Thanks for the help. Is high velocity hard on a chrome barrel like it is on a carbon barrel? Wood