Zeroing Colt pencil barrel

[1986s4]

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

[georgeib]

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.

[Uncas47]

Consistency has more to do with me than the weapon. I give it my best always, but I'm just a human.

[DG23]

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).



From left to right - 2lb 3.4oz, 2lb, and 1lb 12oz:



85lbs:

[1986s4]

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).



From left to right - 2lb 3.4oz, 2lb, and 1lb 12oz:



85lbs:

Good idea and an interesting experiment.

Question: your 85lb item, is that stripped also?

[ssc]

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

[georgeib]

85lbs:

[El Vaquero]

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. 😜

[DG23]

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.

[MistWolf]

…Not picking on pencil barrel…

Skinny super models need love, too!