Suppressors Low “blowback” option for SP10 .308

[JLTX]

Good evening, after thoroughly using the search function and striking out, I would love to seek guidance from all in re to my issue. I gave this one last chance today, meticulously going through the gas block adjustments using the same ammo (FGMM 168g) over a 2hr period. No solution or setup was found to this semi usable.

-Running a Seekins 2nd gen SP10 in .308 w a TBAC Ultra 7. After ordering the tools in order to access and manipulate the adjustable gas block (Seekins low profile adjustable gas block), I am still unable to effectively use this weapon. Zero issues wo suppressor, btw! There is virtually no adjustment (I started at closed and opened at 1/4 turns w single cartridge in 10rd PMAG) that gives me anything usable, either it fails to cycle or beats the crap out of the brass with massive blowback. There is nothing in between. At this point I am considering a “low blowback” suppressor (Rugged or OSS) solely for this semi. Background, I am using FGMM 168/175, Atlas PSR, and I am not new to shooting.

Any and all help is greatly appreciated!

 

[AMGtuned]

A light buffer will let you tune the gas flow lower, but IMHO limit adjustability. Heavier buffer won't let you limit as much gas, but will delay unlock long enough to gain you some adjustability.

Is this a carbine type, or rifle type buffer tube/spring?

Edit: not too familiar with the seekins platform, but after a quick look, it appears to be rifle type. That gives you a lot of buffer to play with. You could add whatever weight you needed by replacing the steel weight with tungsten

 

[jrweston]

Double check the gas port and gas block alignment. I had a similar issue and ending up slightly enlarging the gas port on Wilson Combat 6.5 Creedmoor Barrel and i was using the Superlative adjustable Gas Block. This fixed my cycling issue.

 

[JLTX]

AMG, it is a rifle type buffer tube/spring. https://seekinsprecision.com/rifles-new/modern-sporting-rifles/sp10-1.html

 

[YammyMonkey]

On my SP10M I was able to set the lever gas block so that the constricted side works for the can & the most open setting works without. I think Seekins has two different gas blocks. One with a set screw kind of adjustment & another with the lever. I don't know if there might be a functional difference between the two other than the lever/set screw adjustment.

Might try to contact Seekins & see if they have any suggestions or if they'd take the upper, or the full gun back & give it a once over.

 

[JLTX]

Great suggestion, I know how slammed those guys are, just trying to make sure that I did not overlook anything. Btw, SP10m is a different gas block than SP10. If I can not find a solution from the brainpower here, I will send it back.

 

[YammyMonkey]

I thought it was a different block, but I don't keep up on their details. Might try the other head block.

I have an email out to them about getting a rifle for the PD sniper team. It's been about 3 weeks, but with the current environment we gotta be patient.

 

[BikePilot]

The OSS 7.62 ti can would likely be much easier to get working. Even a tbac dominus k would be a lot easier. An ultra 7 is meant for bolt guns primarily and pretty high backpressure as I understand.

 

[JLTX]

G

The OSS 7.62 ti can would likely be much easier to get working. Even a tbac dominus k would be a lot easier. An ultra 7 is meant for bolt guns primarily and pretty high backpressure as I understand.

good point, after buying the rifle I sought a rec from Seekins and they gave me U5 and U7.

 

[Zak Smith]

Do you have the Seekins double set screw gas block? I use that extensively on AR-15's and AR-10's and have no problem getting it set right for suppressed, unsuppressed, or both. Typically it gets very sensitive once you get to the operative range, like making 1/8th-turn adjustments once you get to the right range.

I am not familiar with the lever style, but with the set screw style, if you are going from too little to too much gas, then by definition there is a setting in between that has in between gas and you are turning the screw too fast.

Here is the SP10M working with most of the cans in our lineup



Low blowback is just code for "loud" BTW.

 

[2aBaC̶a̶]

Not familiar with that rifle or can so I can only suggest trying a heavier buffer and spring combo.

 

[JLTX]

Zak, thanks for chiming in! I do have the double set screw gas block. Perhaps I am over adjusting, but after taking my time on the adjustments there does not appear to be a ”correct” adjustment. I am going to try and take it out over the next several weeks and give it one more chance. Needless to say this is not a TBAC issue, I am just searching for some way to adjust this SP10 in order to fire it with a suppressor. Unsuppressed it is great!

2aBaCa, thank you, your observation is consistent with what I have been told by friends who have shot this with me.

I greatly appreciate the feedback!

 

[Zak Smith]

Feel free to give me a call tomorrow if you want to chat real quick about a method or procedure to seek out a good adjustment

 

[JLTX]

Thanks Zak, I will give you a ring tomorrow with my contact info. I understand how busy y’all are, no rush at all!

 

[shax2lex]

Following. I have a Ultra 9, Gen 2 awaiting a tax stamp and a 6.5 Sp-10. I did put a JP SCS H2 in mine.

 

[larryh128]

Good evening, after thoroughly using the search function and striking out, I would love to seek guidance from all in re to my issue. I gave this one last chance today, meticulously going through the gas block adjustments using the same ammo (FGMM 168g) over a 2hr period. No solution or setup was found to this semi usable.

-Running a Seekins 2nd gen SP10 in .308 w a TBAC Ultra 7. After ordering the tools in order to access and manipulate the adjustable gas block (Seekins low profile adjustable gas block), I am still unable to effectively use this weapon. Zero issues wo suppressor, btw! There is virtually no adjustment (I started at closed and opened at 1/4 turns w single cartridge in 10rd PMAG) that gives me anything usable, either it fails to cycle or beats the crap out of the brass with massive blowback. There is nothing in between. At this point I am considering a “low blowback” suppressor (Rugged or OSS) solely for this semi. Background, I am using FGMM 168/175, Atlas PSR, and I am not new to shooting.

Any and all help is greatly appreciated!

Whether or not it helps you, I went to a Tubb flat wire spring and a 9 oz buffer to keep it locked up longer.

 

[wade2big]

Following. I have a Ultra 9, Gen 2 awaiting a tax stamp and a 6.5 Sp-10. I did put a JP SCS H2 in mine.

You are going to be disappointed. Plan on getting a new gas block, buffer, and recoil spring to mask some of the symptoms. The 22” creedmoor is not suppressor friendly. Seekins is sending me their upgraded lever style gas block to try and remedy. Of course these are backordered so who knows when I will get it.

I can close the gas block all the way and its still overgassed. This is a huge failure on Seekins for sending these out like this. They know there are problems.

 

[larryh128]

You are going to be disappointed. Plan on getting a new gas block, buffer, and recoil spring to mask some of the symptoms. The 22” creedmoor is not suppressor friendly. Seekins is sending me their upgraded lever style gas block to try and remedy. Of course these are backordered so who knows when I will get it.

I can close the gas block all the way and its still overgassed. This is a huge failure on Seekins for sending these out like this. They know there are problems.

I guess that when you totally shut the gas off and it's still over gassed, you don't have much of a gas block. I've been using Strike Industries collar gas blocks. They can be adjusted by hand or a bullet tip etc. Not cheap at $100 retail but they work VERY well. I've had "adjustable" gas blocks that didn't do anything but frustrate me. I was doing my own before I found the Strike. I know you want the manufacturer to correct it which they should but it's a immediate alternative.

 

[shax2lex]

You are going to be disappointed. Plan on getting a new gas block, buffer, and recoil spring to mask some of the symptoms. The 22” creedmoor is not suppressor friendly. Seekins is sending me their upgraded lever style gas block to try and remedy. Of course these are backordered so who knows when I will get it.

I can close the gas block all the way and its still overgassed. This is a huge failure on Seekins for sending these out like this. They know there are problems.

I don’t think I’m going to be disappointed and I haven’t been so far. The gun has shot great and I have manipulated the gas block to adjust for different buffers and ammo.
It’s unfortunate that you have had a bad experience. Seekins Precision rifles are shot all the time in comps and by lots of other folks. They are almost a guaranteed great rifle. Keep at it and I hope you get it figured out.

 

[wade2big]

I don’t think I’m going to be disappointed and I haven’t been so far. The gun has shot great and I have manipulated the gas block to adjust for different buffers and ammo.
It’s unfortunate that you have had a bad experience. Seekins Precision rifles are shot all the time in comps and by lots of other folks. They are almost a guaranteed great rifle. Keep at it and I hope you get it figured out.

Have you shot it suppressed? There is no gas block adjustment for that.

 

[FuhQ]

I went and shot my Sandman-S at my local SOT's range yesterday (still waiting on my stamp, so they're still holding onto it), and did a few mag-dumps with my 14.5" 5.56, and shot about 30 rounds through my 16" .300 BLK, and everyone that shot through that can was impressed at how there was NO gassing in the face. It was insane. I haven't shot it on anything larger than those 2 yet, but this upcoming weekend I will be shooting it on my 6.5 Grendel and .260 Rem, as well.

 

[Jigstick]

Can you get it tuned properly without the can on? Sounds like you can’t if I’m following correctly. Completely closed gas block and it’s still ejecting hard enough to destroy the brass? The factory Seekins bolt does have dual ejectors on it but I can’t believe it’s kicking brass that hard.

since you already have an Ultra suppressor I’d definitely discuss this issue with zac. But I’m guessing it’s not an issue with the can. However I can tell you that I run both a DeadAir Sandman L and S on some of my gas guns. On my 10.5in Seekins CQB with its lever throw quick adjustable gas block I’m able to get it tuned perfectly with no discernible blow back in my face. This is a 556 though not a creedmore. I do plan on running them on my 6.5CM SP10 as soon as I get. Month past due and still waiting ...

 

[Hans7]

https://pewscience.com/sound-signature

Jay at Pew Science has all the silencer data, including back pressure metric. I’d suggest the CGS Hyperion K based on your use case and his findings.