Daniel Defense Barrel Quagmire.....

AR/M4 AR Technical Discussion
1

I purchased a Geissele Automatics Suppressor Alignment Rod (SAR), for 5.56 mm to checked all 5.56 AR 15 uppers for proper suppressor alignment. My current 5.56 mm Suppressor is a Gemtech G5-T, with the G5 Flash hider.

The procedure is to attach suppressor remove BCG and Charging handle from Upper Receiver and slide the SAR from breach to muzzle to the end of the suppressor and check the alignment. If the SAR is even on all sides the suppressor has proper alignment, if uneven it’s a partial fail and corrective action needs to be taken to mitigate a baffle strike.

Upon checking them, I found the Colt, Knights, and LWRC barrels allowed the Suppressor Alignment Rod too freely and easily slide through the barrel from breech to muzzle to the end of the suppressor with no friction and each passed with proper alignment. However, my Daniel Defense 12.5 inch barrel didn’t allow the gauge rod to freely pass through the barrel. The SAR stops about half way through the barrel and nudging was needed to push the gauge rod through the barrel. It also showed a partial fail for suppressor alignment. I believe there is something wrong with the barrel, I don’t know if it’s two different issues or one.
I am wondering why the SAR pass through freely on my other 5.56mm barrels and not on the Daniel Defense. I’m making the assumption all 5.56mm barrel manufactures have the same bore diameter? The Daniel Defense rifle shoots accurate with no malfunctions. There is about 650 rounds through this barrel. The other rifles mentioned that checked all have 14.5 and 14.7 inch barrels respectively.

Looking for some input if anyone can explain this quagmire.

2

How does it shoot?

Anything weird when you first sighted it in?

3

The Firearm shoots fine. Less than 1 inch groups at 100 meters. I didn’t notice anything weird when I first shoot the firearm or when sighting it in.

4

This gadget is nonsense. If you look through the barrel/can you can get a good enough idea. Perhaps the barrel isn’t straight. This isn’t unheard of. I mean… at FN, they have a big boingy machine that straightens out barrels that don’t pass straightness gauging.

5

Is that it’s technical name?

:slight_smile:

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6

If you saw it in action, you’d say… yeah… that’s a barrel boinger! :wink:

7

I have seen it in action & you’re right. I just had to giggle when read that. :slight_smile:

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8

Are you certain the rod isn’t hanging up near the gas port. Sometimes there’s a burr at the port inside the barrel.

9

Have you contacted Daniel Defense? Start there. They will certainly take care of it if there is a defect in the barrel.

10

I contacted Daniel Defense. I have not heard back as of yet. I’m assuming they can answer the question. Though I would throw it up on the forum to see if anyone else has heard of this before.

11

Listen to what Robb’s trying to tell you. He’s pretty good at these thing.

12

My thought is that a problem, that isn’t a problem isn’t a problem. Assuming you have actually fired it and you are not seeing issues I would probably say it’s safe.

13

I contacted Daniel Defense and there representative indicated that their barrels have a taper from Breech to Muzzle. This would account for the Suppressor Alignment Rod (SAR) not freely traveling through the barrel.
Regarding the partial fail while using the SAR, there could be some slight discrepancy in the end of the barrel. A competent gunsmith should be able to take care of this issue.

14

???:confused::stop:

I believe the taper they are referring to is on the OUTSIDE of the barrel referred to as barrel contour. I would read what Jensen said.

15

Tapered bores do exist. It seems to be common among Cold Hammer forged barrels as the bore on Centurion uppers are, or at least were, tapered.

16

I asked the representative at Daniel Defense to confirm again if the bores are tapered.

But I have also heard of tapered bores. So the explanation sounded logical…

I believe HK MR556 barrel has a tapered bore also.

17

I was just double checking to make sure you didn’t Misunderstand or something. It doesn’t taper past the actual caliber diameter though I don’t believe or you would wind up with a obstructed bore I would think. I would think the rod should slide through even if the bore was a tapered bore

18

I just dropped the Suppressor Alignment Rod into the barrel again to check and it getting hung up round the gas port. I think Rob Jensen is correct. Thanks appreciate the help. Now to rectify the problem…

19

I think you are correct thanks for the help… now to correct the problem…

20

You ca squash a bullet a surprising amount without trouble. P.O. Ackley conducted experiments to see how much rise in pressure there would be from firing .323" bullets in a .308 barrel. Turns out there was surprisingly little rise in pressure so long as the neck of the chamber was opened up to the proper diameter