Posted: 12/4/2025 2:01:10 AM EDT
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I was at the range one day shooting my LR308 in 6.5 Creedmoor. I had adjusted the gas block for optimum function, and it was shooting a very nice tight group with my favorite ammo. I thought I would try the gas block in bleed-off mode (using a Superlative Arms) just to see if it reduced the amount of powder residue in the BCG. After getting it adjusted to lock back the bolt, I shot a five shot group and was surprised to see the my group size had opened up to almost double what it was earlier with the gas block adjustment by restriction instead of bleed-off. I got to thinking about why my accuracy would be destroyed by the bleed-off setting. When a gas block is adjusted by restricting the flow of gas to the BCG the gas in the bore stays behind the bullet until it leaves the crown of the barrel. When a gas block is set to bleed-off, the gas in the bore drops a little after the bullet passes the gas port, thereby dropping the pressure slightly for that distance from the gas port to the crown. That is only a few microseconds in that 4"-5" travel to out of the barrel. Is that enough to mess with my accuracy? Or is my analysis of he mechanics of the operation off or wrong? Maybe the bolt has already opened, and reduced pressure by the time the bullet reaches the gas port? Any of you out there experimented with this at all? What are your thoughts on this? |
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I have that same block in bleed off configuration and no drop off in accuracy vs a standard adjustable block. Edit Guess that’s was an old post I replied to. Either way no issues with the SA gas block |
"Never argue with an idiot. They drag you down to their level, then beat you with experience."
| I've only used bleed off on my SA piston block once. I'm going to give it another go and see if it 1) impacts accuracy, and 2) further reduces gas back to the user (which is still much less than a DI gun in restriction mode). |
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