Remove the muzzle device, then retest, then swap the scope and mount out and retest, if the results are the same send barrel back for warranty. And or replace barrel.

Trying not flog a deceased equine, but when discussing ammunition and precision/accuracy, knowing the specifics matters a lot. As I mentioned, my experience with True Velocity ammunition was bad for several reasons, including the precision I got. It wasn’t horrible, but certainly not as good as something like Federal 168 grain Gold Medal Match. And that is usually true of many other common ammunition.

I have very good and consistent results with 308 Federal GMM in 168 and 175 grain as well as Hornady ELD Match in 155 and 168 grain loads. But other loads from the same manufacturers don’t perform nearly as well. I would still expect better than 5 MOA precision from something like an inexpensive hunting round, but the details of what we’re discussing are still important.

Also keep in mind that we, I, anyway, don’t know anything about your shooting experience and general skill level. I have seen many people shooting from a bench who would have been very proud of 5 MOA groups. There are so many variables that affect the sort of precision we can get from a rifle that it’s important to know all the details to help determine the cause(s) of an apparent problem.

Based on what you have told us, including that you evidently built the rifle yourself from parts, you’re no novice, but that’s an assumption and even if correct there are things we don’t know. If I were reporting a problem like yours I would say something like this (and be prepared to provide additional information if requested):

“The ammunition I’ve been shooting includes Federal 168 grain Gold Medal Match, and it produces no better groups than Winchester 180 grain Power Max. I have Daniel Defense AR-10 that consistently puts the GMM into 1.5 or less groups at 100 yards. I have other precision rifles that produce even smaller groups. I test my loads in the morning when there’s no wind and I shoot from a solid bench using a front mechanical rest and a heavy rear bag. I have been shooting for 30 years and never experienced anything as bad as this, but I asked a PRS shooter friend to try my AP and he can’t get any better groups than 5 MOA either.”

If we had information like that, it would eliminate a lot of unknown possible variables and allow focusing on the rifle itself that you’re asking about.

I get the impression that you probably have a lot of other things to worry about rather than this discussion, but when someone asks for help here it’s expected that they will be responsive to the requests from people who are trying to help. When that doesn’t happen, people express their frustration or just stop paying attention to the thread. The latter is what I usually do, and have done many times in the past.

To be honest, I think it is the rifle for a few reasons. I used very high quality ammo, I am a fairly accomplished rifle shooter. and none of the aforementioned ammo grouped worth a crap.
The real intent of the thread was to ask is there any merit to the notion that one can increase accuracy by increasing or decreasing the ejection impulse via the gas block?
I will gather the exact ammo data tonight when I get home, but I do not have the TV boxes as they asked that I send them back--it was two different variants though and they both performed the same and had splitting issues. TV said they would get back to me if they determined anything but never did.

quote:

is there any merit to the notion that one can increase accuracy by increasing or decreasing the ejection impulse via the gas block?

That I don't know. Seems to me that an all-Aero build shouldn't need an adjustable block to run right. Certainly not a bad thing to have on there either way, I reckon. Especially if a silencer might be in play later.

I got this from Microsoft Copilot in response to “do gas block adjustments affect rifle accuracy?”

“Adjusting the gas block on a rifle can indeed affect its accuracy. Here are some key points to consider:

Recoil Management: Properly tuning the gas block can optimize the rifle's cycling and reduce recoil, which can lead to improved accuracy 1 .

Bolt Velocity: Adjusting the gas block can fine-tune the bolt velocity, resulting in smoother shooting and potentially more consistent accuracy 2 .

Point of Impact: Changes in the gas block settings can alter the recoil impulse, which might shift the point of impact, especially noticeable at longer distances 3
Overall, while the primary purpose of an adjustable gas block is to manage the gas flow for reliable operation, it can also contribute to better accuracy by ensuring smoother and more consistent performance.”

The reference links:
1. https://thegunzone.com/how-to-...djustable-gas-block/
2. https://www.snipershide.com/sh...g-gas-block.6939215/
3. https://www.snipershide.com/sh...lock-tuning.6963951/

None of that specifically addresses your question and I didn’t make any attempt to research the question further, but I’ve found MS Copilot to be surprisingly useful for some queries. Like any resource, though, it is necessary to evaluate its answers in light of what else we know, and I have had to modify requests to get the information I was looking for. And yes, it’s probably keeping track of all the gun-related questions I ask, but considering my involvement with this forum and other activities, I believe that is very little to worry about.

So, I looked further. This is from Google's AI with the query "rifle gas blocks affect accuracy," and seems more relevant:

Yes, rifle gas blocks can affect accuracy, primarily by influencing gas pressure and how the bolt unlocks. While some types of gas blocks can potentially cause issues with accuracy if installed improperly or if they exert localized stress on the barrel, the biggest impact comes from gas pressure exceeding optimal levels, which can disrupt the bullet's trajectory.
Elaboration:

Gas Pressure and Bolt Unlocking:
Too much gas pressure can cause the bolt carrier group (BCG) to start the unlocking process before the bullet is clear of the barrel, potentially affecting accuracy.

Gas Block Design:
Certain gas block designs, like those that pin or use set screws that contact the barrel directly, can potentially deform the bore and negatively impact accuracy if installed improperly. Clamp-on gas blocks are generally preferred as they distribute pressure evenly around the barrel.

Gas Block Location:
The location of the gas block on the barrel, particularly on longer barrels, might also play a role in accuracy, with some arguing that more distance between the gas port and muzzle could lead to more consistent accuracy.

Other Factors:
Other factors, such as barrel manufacturing tolerances, bullet design, powder type, and even the shooter's skill, will also significantly impact overall accuracy.

[/QUOTE]That I don't know. Seems to me that an all-Aero build shouldn't need an adjustable block to run right. Certainly not a bad thing to have on there either way, I reckon. Especially if a silencer might be in play later.[/QUOTE]

I have a can for it, so I went with the adjustable block.

Sigfreund,
Very interesting, and I guess it's worth a go at the range.
Thanks much.