Subsonic 6 ft. impact

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Pavsuper
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Subsonic 6 ft. impact

Post by Pavsuper » Fri Dec 06, 2019 11:02 am

I have recently gotten into 300 blackout. I make my own ammo for 5.56, .308, and 300BO. This weird thing is happening. all or my other subsonic rounds impact the target as sighted except my 300BO rounds. They impact the burm 6 ft above the target. it does not matter what grain the round is. i have 125gr HP, 168gr HP, 190gr HP and store bought 150gr sub and 220gr sub.

There is not marks or damage to the front of my suppressor (Griffin SD-30) which i use for all of my rifles.

Any help would be great.

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20X11
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Re: Subsonic 6 ft. impact

Post by 20X11 » Fri Dec 06, 2019 11:54 am

Sounds like a barrel issue. Whose barrel is it? Who built it? Have you re-torqued the barrel nut?

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bangbangping
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Re: Subsonic 6 ft. impact

Post by bangbangping » Fri Dec 06, 2019 1:03 pm

Can you clarify what "as sighted" means? Are you saying that you are sighted in with supers, but subs hit 6 feet higher? At what range?

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Re: Subsonic 6 ft. impact

Post by golfindia » Fri Dec 06, 2019 3:15 pm

viewtopic.php?f=138&t=107577

You guys must have both got a batch of those anti gravity bullets.

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GregP42
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Re: Subsonic 6 ft. impact

Post by GregP42 » Sat Dec 07, 2019 12:16 am

Welcome to the W.T.F. club, I think we are the only members right now.

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Pavsuper
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Re: Subsonic 6 ft. impact

Post by Pavsuper » Sat Dec 07, 2019 1:09 am

Replying to bangbangping, what i mean is my sub rounds group 1.5 to 2.0 inches at 100 yds. without the suppressor. GregP42, thanks for the welcome. I'm going to the range tomorrow to test my suppressor mounted 180 degree from where i normally mount it. Provide feedback then.

I bought a complete upper from

BCA (Bear Creek Armory) AR-15 Complete Upper has a 16” barrel with a Heavy profile, made of 4150 Chrome Moly Vanadium Steel with a Parkerized finish, and features a 1:8 Twist Rate, a Carbine length gas system and .750 Gas Block. The Upper includes a 15” MLOK Rail, an M4 flat-top forged upper receiver with forward assist, a BCA Bolt Carrier Group, and a Charging Handle. It is chambered in 300 Blackout and machined with 300 Blackout feed ramps in the barrel extension.

16” Heavy Barrel
4150 Chrome Moly Vanadium
Parkerized Finish
1:8 Twist
15” MLOK Rail
300 Blackout Caliber
Standard BCA BCG
Carbine Length Gas System
M4 Flat-Top Forged Upper Receiver
Standard Bear Creek Arsenal Bolt Carrier Group
Charging Handle
This BCA AR-15 Complete Upper, like all BCA products, is subjected to numerous QA/QC checks which for BCA's firearms and complete upper receiver assemblies includes test firing prior to approval and shipment. This Rifle is also backed by the Bear Den Guarantee.

Pavsuper
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Re: Subsonic 6 ft. impact

Post by Pavsuper » Sun Dec 08, 2019 11:06 pm

Tested as described, not change, still impacting 6 to 8 ft. Above target.

Gas pressure causing the rounds to exit the suppressor with more velocity?

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bangbangping
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Re: Subsonic 6 ft. impact

Post by bangbangping » Mon Dec 09, 2019 11:56 am

A suppressor will add a little velocity but not 6-8 feet worth. The barrel is likely drilled/threaded off center and the bullet is clipping the suppressor on the way out.

The next step is to check alignment with an alignment rod. Or, since an alignment rod costs more than a BCA barrel, it may be more prudent to place the barrel in the circular file and put that money toward a quality barrel.

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dellet
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Re: Subsonic 6 ft. impact

Post by dellet » Mon Dec 09, 2019 12:27 pm

bangbangping wrote:
Mon Dec 09, 2019 11:56 am
A suppressor will add a little velocity but not 6-8 feet worth. The barrel is likely drilled/threaded off center and the bullet is clipping the suppressor on the way out.

The next step is to check alignment with an alignment rod. Or, since an alignment rod costs more than a BCA barrel, it may be more prudent to place the barrel in the circular file and put that money toward a quality barrel.
Might be able to pull the upper and carrier and bore sight it.
300 Blackout, not just for sub-sonics.

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John A.
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Re: Subsonic 6 ft. impact

Post by John A. » Mon Dec 09, 2019 8:22 pm

Yeah, 6-8 ft of rise is not increased pressure.

I tend to agree with the other folks. Get you a guide rod and put in the bore and through the suppressor one baffle at a time starting at the muzzle and see what you are either:

A. Hitting
B. Almost hitting and is causing bullet destabilization.

I'm not knocking your choice, but bear creek sucks ass. I don't know any other polite way to say it. And there is no possible way they test fire every upper.

The 7.62x39 upper that my son bought from classic arms included 3 empty steel case bullets sure enough.

But the chamber was incomplete and it would not even accept a 7.62x39 round, let alone the 3 empty piece of steel that they included with it. They are the biggest group of liars that existed.

FWIW, there are other better business bureau complaints about the same thing, and the replacement upper they sent to my son, had the proper 7.62x39 barrel that time, but came with a 223 caliber bolt.

I wouldn't buy accept anything of theirs if it was a free gift.

Also, there is this:
https://rantnc.com/2019/02/05/ice-agent ... ing-plant/
When those totally ignorant of firearms make laws, you end up with totally ignorant firearm laws.

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