AR-15 Pencil Profile Barrel Whip

I saw a MrGunsnGear video testing the ACSS ACOG Ta44 recently and his pencil barrel was whipping like mad. I prefer heavy barrels for a lot of reasons
 
The basic reason behind pencil barrels is weight. My HD carbine wears a DD pencil barrel along with a T2 and weigh just over 6lbs. I built it for weight to be my work carbine and not a range or target type. That DD barrel (CHF mid length chrome lined) will hold about 1 1/2 MOA for a 5 shot group with 64gr Speer Gold Dots soft points and 2-3 MOA all day if I don’t do mag dumps or such ... used for the purpose designed and chosen. If I want to make nice little clover leafs I’ll go with a 8+lbs version that will make you smile at the range but cry if you have to lug it around all day.
 
The birdcage really drives it down. The compensators are bad for pencils. Be interesting to lock it in a vice and shoot quick pairs and see how far it screws you on your second shot.

Stick with an obnoxious brakes!
 
Faxon perfected the pencil profile and calls it a 'Gunner'. Starts out with full A2 diameter and narrows down to a .625 gas block to save weight. I love mine and would buy them again for any working rifle I needed to tote around.
My 18" rifle gas barrel weighs less than 2lbs with the gas block and gas tube attached. No loss of POI after a few mags of quick shooting in my experience.
 
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So as I understand this video: just because a machine shop cuts a profile and adds a high price tag to the product, odds are, they do not know what the hell they are doing?

Is that a good understanding?

The M16A2 profile and the M4 profile is cut the way it's cut for a reason. If you remove the M203 notch from the M4 profile, the profile forward of the journal "dwell section" is the same OD profile and if you take note, the behind the journal the whip is very minor.
 
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JBoyette said:
So as I understand this video: just because a machine shop cuts a profile and adds a high price tag to the product, odds are, they do not know what the hell they are doing?

Is that a good understanding?

The M16A2 profile and the M4 profile is cut the way it's cut for a reason. If you remove the M203 notch from the M4 profile, the profile forward of the journal "dwell section" is the same OD profile and if you take note, the behind the journal the whip is very minor.
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Didn't the very first A1 have a pencil barrel?
 
Ikarus1 said:
I was always under the impression they made it thicker because when GIs in Vietnam used it to pry the barrels of agent orange open, it tended to open up group sizes :D
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That sir was the three prog flash hider. The A2 bird cage we all know so well was the design to stop using the prongs to open up ammo cases that are wired shut and damaging the FH
 
Since most of the whip occurs after the BCG bottoms out, wouldn't tuning the gas charge and buffer be the best thing for a pencil barrel?

The thicker barrels last longer under a lot fire due to their ability to absorb more heat.
 
Pink_Vapor said:
Since most of the whip occurs after the BCG bottoms out, wouldn't tuning the gas charge and buffer be the best thing for a pencil barrel?

The thicker barrels last longer under a lot fire due to their ability to absorb more heat.
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It can work. But a profile of .690 forward of the gas journal is still enough to return to its natural point of aim before a locked bolt on a 14.5"-20" barrel

See the issue with the new bread of gun building is the lack of depth in understanding of the forces involved to make a accurate rifle. Granted a 4 moa gun shooting 4 moa ammo is lethal to 200yds.

Other issues are people wanting cake, pie, cookies and eat all of them without gaining a pound of fat. This mindset does not work in guns or a diet plan.

A lightweight rifle thats accurate must be held to a set standard. Without scope, you will own a pig. We see them on this and many other sites being sold all the time.

What is accurate? 1moa, 2moa, 3moa, 4moa?
What will be the realistic maximum engagement range?
What does light weight mean?
What is the target package? Human?, Paper?, Steel?

These questions drive ammunition types, rates of fire, uses for barricade shooting, sighting systems (IR), LPVO, RDS, thermal, and so on.

As a example my match .223 AR is designed to maintain 2MOA for 30rnds in rapid fire (1 shot every 30sec's) at 600yds using 69-77grn match ammunition using a LPVO.

John
 
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Plenty of people successfully using pencils. Many many people. People who know exactly what they are doing.

Thinner barrels heat up faster but weigh less. No real mystery about it.
 
NKD said:
Plenty of people successfully using pencils. Many many people. People who know exactly what they are doing.

Thinner barrels heat up faster but weigh less. No real mystery about it.
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Never posted you can not be successful. That success is judged by the scope of intent, as i posted.
 
Some years ago, a video similar to this opened my eyes to the dyaminc energy involved in a gun discharging. It was a guy shooting a high powered bolt gun, but what shocked me was that everything moved. Of particular interest to me was watching the scope and rings flex. This has affected the way I think AR's should be built, solid.
 
Conclusion: All guns whip.

AK 47 hit you with 5th round . :)
 
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Pink_Vapor said:
You’re worsted than me for detailing a thread, because it’s funny.
I was surprised and approve of Devo’s non PC.
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Yep Devo was ahead of their time. I remember they did the soundtrack for the Neuromancer video game well before that became a 'thing' aka Reznor did Quake years later
 
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