Adjustable Gas Block settings questions.

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2BearArms
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Adjustable Gas Block settings questions.

Post by 2BearArms » Mon May 27, 2019 12:52 pm

Adjustable Gas Block settings questions.

A couple of weeks ago I purchased a 300 Blackout Other with a 12.5” barrel, the minimum barrel length for an Other. BTW I am in CT. I got it with an SLR Precision Adjustable gas block. I also purchased a suppressor that will sit in NFA jail till the tax stamp comes in. But I have visitation rights and the store also has a range. So I can use it there and then give it back to get locked up before leaving.

I hope to go to the range and shoot this firearm for the first time tomorrow. I am wondering what to expect to have to set the gas block for for the different combinations. I am not looking for exact setting I am just wondering the basic differences. I will be trying 115 and 120 grain supers and 220 grain subsonic rounds both with and without the suppressor. The gas block is adjustable from all the way closed to 15 clicks open. I have seen the procedure of putting one round per mag and opening up the gas block one click at a time till the bolt locks back. But if I can shorten that test to starting closer then closed all the way that would be helpful and less time consuming. Range charges by the hour.

The gas block is set to 7 clicks to start from the manufacturer. And I was told this is for the supers. So in relationship to that I assume that the subs without the suppressor would need the gas block open more. Next the subs with the suppressor would probably want the gas block closed a little bit more. And I assume that with the suppressor with the supers that the gas block would need to be closed more than the 7 clicks from closed as it came from the manufacturer. I understand that there is probably a gas block setting that will cycle in all 4 combinations of ammo with and without the suppressor. But I understand that it is then likely to be over gassed in some of those combos with the usually negatives of it being over gassed.

Am I on the right track with this?

I also have a 300 Blackout upper for my AR15 but I only shoot supers thru that one.

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Flatliner
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Re: Adjustable Gas Block settings questions.

Post by Flatliner » Mon May 27, 2019 1:51 pm

Your reasoning is solid. A few notes:

1.) keep written notes
2.) It may behave a little different as the rifle breaks in or during different weather, I generally add a click or two when using 'in the field' to account for that.
3.) I suggest taking it all the way in and out after use to keep it from getting frozen.
4.) IF you have any issues (unlikely) there are plenty here who will help you troubleshoot, tuning the rifle is half the fun (for me anyway)

2BearArms
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Re: Adjustable Gas Block settings questions.

Post by 2BearArms » Mon May 27, 2019 2:08 pm

Flatliner wrote:
Mon May 27, 2019 1:51 pm
Your reasoning is solid. A few notes:

1.) keep written notes
2.) It may behave a little different as the rifle breaks in or during different weather, I generally add a click or two when using 'in the field' to account for that.
3.) I suggest taking it all the way in and out after use to keep it from getting frozen.
4.) IF you have any issues (unlikely) there are plenty here who will help you troubleshoot, tuning the rifle is half the fun (for me anyway)
Thank you for the reply. After reading your reply I just opened up a pack of little notebooks so I can take one with me to take notes. Is the recommendation to take the gas block setting all the way in and out recommend each time (trip to the range) I use the firearm?

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Re: Adjustable Gas Block settings questions.

Post by TRshootem » Mon May 27, 2019 2:28 pm

As a constant tinker type hand loader...I've begun to wise up and note the gas setting on a label attached to the ammo box. Same bullet in a box with different powders or primer can nullify any good info you hope to collect. Even if shooting factory loaded, things can get mixed up with same or similar bullets. In that case I note the mfg of the components. You'll thank your self for this little step as your stash of rounds and data accumulates. One begins to wise up after 50 yrs of hand load shooting and a pile of confusing, not very well sorted data :shock:

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Re: Adjustable Gas Block settings questions.

Post by alamo5000 » Mon May 27, 2019 3:02 pm

I have several adjustable blocks on various guns. Even with an adjustable block don't think you can (or should) tune it all the way open or closed to get functionality.

If I were me I would start with the weakest load you can get and try to get lock back just one round at a time, unsuppressed of course.

The real trick here though isn't the gas block. It's the tail end of your gun. The buffer weight and/or spring will be what you actually should concentrate more on.

My combo for my SBR's is an H2 with an extra power spring. It will work with other springs but it works good for me. You can also go a little bit heavier with the buffer instead of worrying about springs and such.

I am using a BCM H2, but buffers come in all kinds of weights. There are no standards so read the product descriptions. Have a little bit heavier buffer between an H2 and MAYBE as far as an H3 and your gun will most likely eat anything and then the gas block will just be for fine tuning.

Everyone runs around like their hair is on fire and starts wanting to blame the gas block or the port size on the barrel but they skip over the whole buffer thing.

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Re: Adjustable Gas Block settings questions.

Post by 2BearArms » Mon May 27, 2019 3:48 pm

TRshootem, Thank you for the suggestion about notes I will try and do that.

Alamo5000, Thank you. I have seen a lot mentioned about buffers and understand the issues. I am hoping the manufacturer that knew the planned usage of this firearm knows what they are doing and set it up right. I hope I am not putting too much trust in them. I meet them at the gun store that I bought this from when I ordered it. I am planning on asking them to give me a complete list of all parts used in this assembly. So If I have to make any changes I will know what I am dealing with. It has a lifetime guarantee so if it doesn’t work as I think it should, I will be working with them on getting it to work correctly. They are not too far (about 8 miles away) from me so that is helpful.

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Re: Adjustable Gas Block settings questions.

Post by Flatliner » Tue May 28, 2019 11:13 am

2BearArms wrote:
Mon May 27, 2019 2:08 pm
Flatliner wrote:
Mon May 27, 2019 1:51 pm
Your reasoning is solid. A few notes:

1.) keep written notes
2.) It may behave a little different as the rifle breaks in or during different weather, I generally add a click or two when using 'in the field' to account for that.
3.) I suggest taking it all the way in and out after use to keep it from getting frozen.
4.) IF you have any issues (unlikely) there are plenty here who will help you troubleshoot, tuning the rifle is half the fun (for me anyway)
Thank you for your reply. After reading your reply I just opened up a pack of little notebooks so I can take one with me to take notes. Is the recommendation to take the gas block setting all the way in and out recommend each time (trip to the range) I use the firearm?
Others may disagree but I run mine in and out (not out of the block, just the setting range, on each trip. I HAVE had to replace an Odin Works adj block due to it getting stuck and subsequently damaged. That was the experience that had me put more attention to that procedure moving forward.

bearcatrp
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Re: Adjustable Gas Block settings questions.

Post by bearcatrp » Wed May 29, 2019 11:19 am

Must have got lucky on my 10 inch barrel. Set adjustable gas block to shoot Hornady 190 subs which shoots great. No adjustment needed for Hornady 110 V-Max supers.

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Re: Adjustable Gas Block settings questions.

Post by Whole Bunches » Wed May 29, 2019 1:22 pm

With adjustable gas blocks and the Blackout, you just never know until you experiment with your setup (and keep notes as mentioned by others). For example:

With my PRI gas block (no "clicks", you just turn the adjustment screw in or out, so all settings mentioned are screw turns counter clockwise from all the way closed) on my 10.3" Delta Company upper on a Colt SBR lower with Spike's T2 buffer...

Gas on 3 turns out for a light 108gr frangible bullet with 13.8gr H110 w/o suppressor
Gas on 1 turn out with full power 125gr hunting loads w/o suppressor
Gas on 1/2 turn out with full power 125gr hunting loads w/suppressor
Gas on 1/2 turn out with 220gr subsonic loads w/suppressor

If I put the same upper on my KISS SBR lower (same weight Spike's buffer; same standard carbine buffer spring), I have to increase the gas setting 1/2 turn out more with all the above loads in order to properly function.

Meanwhile, my 8" PSA upper with the MicroMOA gas block with its .087" gas hole plate uses the same size gas hole for 220gr subsonic suppressed, 125gr to 150gr supersonic with and without a suppressor. Note: I started with a much smaller gas hole, slowly increasing the size and testing with all ammo and with and without a suppressor to see when the BCG would lock back on an empty mag. When I got to .087" it was like flipping a switch, immediately all combos functioned, whereas with a smaller hole, none functioned. I had expected to need different sized gas holes for the different ammo, but didn't.

One day I fired a supersonic load w/o suppressor with the PRI set to 3 turns out. I immediately felt the increased recoil and the empty flew MUCH further away. OOPS, forgot to change the gas setting. Haven't made that error since.

Another note: In talking with Delta Co (no longer in business) I was asked what loads I'd be using. Delta recommended an adjustable gas block and that he'd open the bbl gas hole to .125" so I could take advantage of my light to heavy loads using the adjustable gas block...he was right.

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Re: Adjustable Gas Block settings questions.

Post by 2BearArms » Sat Jun 15, 2019 6:48 pm

I tried to post this a while ago and it kept asking for me to log in but I was already logged in. It looked like my reply was posted but now it isn’t there. So I am trying again.

Well it worked. My results with my setup and Remington ammo. Your mileage will most definitely vary.

No suppressor –
120 supers at 10 clicks out I got repeatable ejection and bolt lock back.
220 subs at 11 clicks out I got repeatable ejection and bolt lock back.
I was surprised it was so close.

With Suppressor –
120 supers at 6 clicks out I got repeatable ejection and bolt lock back.
220 subs at 8 clicks out I got repeatable ejection and bolt lock back.

My only problem is I was hoping for more sound reduction with this suppressor.

Thank you everyone for your help.

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