View Full Version : Zeroing Colt pencil barrel
SO there are several variables here but the end result was I got my pencil barrel successfully zeroed on my 2nd outing.
New built upper using 16" Colt pencil barrel cut to 14.5 with a P&W A2, Centurion C7 carbine cutout freefloat handguard and BCM upper reciever.
1st outing I would shoot 2-3 shot groups before adjustment. I was getting inconsistent groups with fliers going high despite raising the front sight post. Additionally I was shooting with my sunglasses on instead of my clear shooting glasses and I know I shoot better with clear lenses, I just forgot to change glasses. I also used a different rear sight than my usual Daniel Defense A1a rear. It's a twist on rear that mounts to a Aimpoint twist off/on magnifier mount.
Then I read about pencil barrels heating up and changing POI.
2nd outing I shot 1 round before adjustment with longer intervals of cooling. I used my clear lenses and changed back to my DD A1 rear. I dialed in the rear and confirmed with several more shots of the same and different ammo, all 55gr. This went much better! Aside from my clear lenses what do you think the biggest difference was? Or maybe a combination? It's my first pencil barrel, my other two are SOCOM style, one Colt and one HF Centurion.
Thanks
I noticed much more consistency in grouping, a few years ago, when I used some stainless shim stock to fit a barrel to an upper. I was getting some inconsistency, and remembered that I had a slightly loose barrel to upper fit when assembling.
I disassembled the upper and measured the difference between the outside of the barrel extension and the inside of the receiver to be 0.003". I used some 0.001 thick hardened stainless shim stock and wrapped 1.5 times around the extension with the thicker part on the bottom, and then froze the barrel and heated the upper in order to insert the barrel. I won't say that I necessarily noticed the groups tightening up, but there was less stringing when hot, and overall consistency certainly improved.
The better way to do it would have been to use 0.0015 shim stock. I didn't have any laying around, and at the time didn't feel like waiting a few days for Amazon to deliver it.
Consistency has more to do with me than the weapon. I give it my best always, but I'm just a human.
Then I read about pencil barrels heating up and changing POI.
2nd outing I shot 1 round before adjustment with longer intervals of cooling. I used my clear lenses and changed back to my DD A1 rear. I dialed in the rear and confirmed with several more shots of the same and different ammo, all 55gr. This went much better! Aside from my clear lenses what do you think the biggest difference was? Or maybe a combination? It's my first pencil barrel, my other two are SOCOM style, one Colt and one HF Centurion.
Thanks
Next time out you should do your own experiment and prove it to yourself one way or the other.
Use the same lot / can of ammo and compare your Colt SOCOM to your Colt pencil after shooting them both under the same firing schedule. (same number of rounds / time before shooting for groups)
Forget what you read on the internet and test for yourself! :)
Since you have both kinds, take both to the range and shoot them side by side under the same conditions.
I do not own any pencil barrels (and won't) but have done exactly as I describe comparing my gov profile Colt stuff to HBAR Colt barrels and Match type BULL barrels. (all 16" in my testing / comparisons)
For reference:
14.5 Colt SOCOM barrel weight (stripped) is 1lb 14oz,
14.5" Colt 6920 Gov profile barrel (stripped) is 1lb 9oz,
16" Colt 6520 'pencil' barrel (stripped) is 1lb 6oz,
16" Colt 6920 Gov profile barrel (stripped) is 1lb 12oz,
16" Colt 6721 HBAR barrel (stripped) is 2lbs 3.4oz,
16" SS, BULL type barrels clock in right at 3lbs (stripped / no fluting).
https://i.imgur.com/CNPJAnT.jpg
From left to right - 2lb 3.4oz, 2lb, and 1lb 12oz:
https://i.imgur.com/9oLeYfR.jpg
85lbs:
https://i.imgur.com/jihaQLe.jpg
Next time out you should do your own experiment and prove it to yourself one way or the other.
Use the same lot / can of ammo and compare your Colt SOCOM to your Colt pencil after shooting them both under the same firing schedule. (same number of rounds / time before shooting for groups)
Forget what you read on the internet and test for yourself! :)
Since you have both kinds, take both to the range and shoot them side by side under the same conditions.
I do not own any pencil barrels (and won't) but have done exactly as I describe comparing my gov profile Colt stuff to HBAR Colt barrels and Match type BULL barrels. (all 16" in my testing / comparisons)
For reference:
14.5 Colt SOCOM barrel weight (stripped) is 1lb 14oz,
14.5" Colt 6920 Gov profile barrel (stripped) is 1lb 9oz,
16" Colt 6520 'pencil' barrel (stripped) is 1lb 6oz,
16" Colt 6920 Gov profile barrel (stripped) is 1lb 12oz,
16" Colt 6721 HBAR barrel (stripped) is 2lbs 3.4oz,
16" SS, BULL type barrels clock in right at 3lbs (stripped / no fluting).
https://i.imgur.com/CNPJAnT.jpg
From left to right - 2lb 3.4oz, 2lb, and 1lb 12oz:
https://i.imgur.com/9oLeYfR.jpg
85lbs:
https://i.imgur.com/jihaQLe.jpg
Good idea and an interesting experiment.
Question: your 85lb item, is that stripped also?
Next time out you should do your own experiment and prove it to yourself one way or the other.
What were your results?
Cheers, Steve
85lbs:
https://i.imgur.com/jihaQLe.jpg
:lol:
El Vaquero
10-03-21, 16:34
Hearing all this talk about how finicky pencil barrels are (“ooh, after 10 consecutive rounds I need to rest and cool down, my POI is off now.”)
It makes me think of them like skinny super models throwing tantrums on a photo shoot. “It’s too cold out here!! I can’t work in these conditions!!”
And just like barrels, if they had some meat on their bones there wouldn’t be no problems. Not picking on pencil barrels, variety is the spice of life. Just cracking a joke at their expense. 😜
Good idea and an interesting experiment.
Question: your 85lb item, is that stripped also?
Yup.
As a side note - The hotter it gets the less she moves. :)
…Not picking on pencil barrel…
Skinny super models need love, too!
Skinny super models need love, too!
Yeah but the chunky ones appreciate it more.
What were your results?
Cheers, Steve
Steve,
I haven't had a chance to run the experiment yet. Maybe later this week.
Hearing all this talk about how finicky pencil barrels are (“ooh, after 10 consecutive rounds I need to rest and cool down, my POI is off now.”)
It makes me think of them like skinny super models throwing tantrums on a photo shoot. “It’s too cold out here!! I can’t work in these conditions!!”
And just like barrels, if they had some meat on their bones there wouldn’t be no problems. Not picking on pencil barrels, variety is the spice of life. Just cracking a joke at their expense. 😜
Yes, well like the skinny models the pencil barrels have pleasing slender lines and don't weigh that much....
Steve,
I haven't had a chance to run the experiment yet. Maybe later this week.
When I tested mine I used the same lower for each different upper. Told myself that if I used the same exact lower everywhere that I could rule out any differences caused by this one or that one having a nicer trigger or whatever.
I know it shouldn't but still...
Already said I do not own any pencil barrels but if I had to venture a guess your results (a SOCOM compared to a pencil) are going to be about the same as mine comparing an HBAR to a Gov Profile. After you heat them up a few mags worth you will notice a difference.
Wish you luck and hope you have fun with your experimenting sir. :)
El Vaquero
10-05-21, 04:29
Yeah but the chunky ones appreciate it more.
They sure try harder. Lol
When I tested mine I used the same lower for each different upper. Told myself that if I used the same exact lower everywhere that I could rule out any differences caused by this one or that one having a nicer trigger or whatever.
I know it shouldn't but still...
Already said I do not own any pencil barrels but if I had to venture a guess your results (a SOCOM compared to a pencil) are going to be about the same as mine comparing an HBAR to a Gov Profile. After you heat them up a few mags worth you will notice a difference.
Wish you luck and hope you have fun with your experimenting sir. :)
I will use the same lower [one of many great things about the AR15..], both will utilize iron sights, and both have a standard front sight tower.
Regards.
I will use the same lower [one of many great things about the AR15..], both will utilize iron sights, and both have a standard front sight tower.
Regards.
Nothing at all wrong with iron sights friend.
:)
Nothing at all wrong with iron sights friend.
:)
My opinion too. When I first got into 2 gun matches I shot irons because I didn't know what kind of optic I wanted. I learned a lot using them and I like the clean light look of irons. A good optic is better of course so I ended up with an Aimpoint Comp M4 w/ Aimpoint 3x magnifier.
I always sight in with irons first.
Ballistic Advantage and Faxon barrel test. No noticeable zero shift after a mag dump with either.
https://youtu.be/b9gWWrVe1QA
Same test.
Faxon(not much if any shift due to heat) vs. Colt SP1(fair amount of zero shift due to heat).
https://youtu.be/QTovPt4weIs
Small/single samples and all that good stuff.
Curious what your newer(I assume) Colt barrel does when hot.
Same test.
Faxon(not much if any shift due to heat) vs. Colt SP1(fair amount of zero shift due to heat).
https://youtu.be/QTovPt4weIs
Small/single samples and all that good stuff.
Curious what your newer(I assume) Colt barrel does when hot.
Stress relief makes a difference heat related zero shift, as does barrel length.
Stress relief makes a difference heat related zero shift, as does barrel length.
Curious what Faxon means when they say 'stress relief' because their groups looked like crap hot or cold.
Curious what Faxon means when they say 'stress relief' because their groups looked like crap hot or cold.
:lol: Well, at least they were consistent. :lol:
:lol: Well, at least they were consistent. :lol:
Funny as it may be - you are correct sir. They were 'consistent' groups. :)
I watched a bunch of the Faxon Q&A videos and from those guys and the stress relief thing came up frequently but never any details about what kind of stress relieving they were doing and if they were doing it 'in-house' or sending stuff out or what. Very vague on any details.
Funny as it may be - you are correct sir. They were 'consistent' groups. :)
I watched a bunch of the Faxon Q&A videos and from those guys and the stress relief thing came up frequently but never any details about what kind of stress relieving they were doing and if they were doing it 'in-house' or sending stuff out or what. Very vague on any details.From what I read, the process is relatively straightforward. The barrels are heated to 1000 degrees in a vacuum and then allowed to cool slowly.
From what I read, the process is relatively straightforward. The barrels are heated to 1000 degrees in a vacuum and then allowed to cool slowly.
Pertaining to Faxon or 'in general' sort of terms?
Pertaining to Faxon or 'in general' sort of terms?In general. I have no information on their process, but I assume based on the straightforward nature of the process, that they probably have their own vacuum oven.
In general. I have no information on their process, but I assume based on the straightforward nature of the process, that they probably have their own vacuum oven.
https://i.imgur.com/WVBhnLR.jpg
The Colt barrel on top was done by the nice lady at Cryo Plus. The bottom one was done by Diversified Cryogenics.
Sometimes you can slip a barrel in with some tools / cutters and the receipt will look like it was all for business stuff.
https://i.imgur.com/DXM1XBL.jpg
Goofy test protocol.
Two different rifles, two different sighting systems, two different barrel lengths (free-floated), with two different shooters. No telling if the triggers were different, either.
Add in a completely new and different SP-1, probably with a GI trigger, non-free floated, over a shit front rest.
... and I'm supposed to consider the results a close, valid test.
Zeroing is the same with any barrel. It's either center of mass or center of mess depending on the quality of barrel and ammunition.
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