Chopping Seekins SP10 6.5CM Barrel - Help

[NHPiper]

I have one of the newer gen SP10 6.5CM with a 22” barrel and the +1” rifle gas system.

To make the system more portable, and give the fact a have long barrel (24-26”) 6.5CM bolt guns, I want to cut the barrel down to 17”-18” if I can. This will put the gas block about X back from the muzzle. Will this create a bunch of issues? The gas block is adjustable and I will be running the gun 100% suppressed with an Sig 7.62SRD can (mid-high back pressure). Ideally I would like to have a much shorter gun that is super soft shooting.

If it will create a ton of issues, I will likely pass on this and burn another 2000 rounds to cook the barrel, then buy a shorter one.

Thoughts from the Hide? More concerned with the ability to cycle vs the whole long vs. short 6.5CM performance. I am a sucker for shorty builds and just swapped my 18” ATX barrel a buddy. So want to turn this into the 17” or 18” gun. FWIW, a 17” barrel puts the crown about 2” in front of the gas block.

 

[mettee]

With it being a longer barrel the gas port will be on the "smaller" size due to extended dwell time. By smaller I mean, less than if it were 18".

If you cut it down to 17/18" its my guess it will still function fine due to you running a suppressor.

If it doesn't function you may be able to increase the gas port (since the dwell time is reduced). But I don't think this will be the case because you plan to suppress it. And it's likely you'll have to also adjust buffer and spring weights.

 

[NHPiper]

Theoretically does this mean I could end up with an even softer shooting gun?

 

[WillHugh]

Theoretically does this mean I could end up with an even softer shooting gun?

Not likely, as you've already turned your gas down so it's barely cycling. Reducing the dwell time will just mean you have to open the block to get the same amount of gas you're getting currenty.

 

[mettee]

Theoretically does this mean I could end up with an even softer shooting gun?

Like Will said, probably not. But it might happen, because you'll need to re-adjust your gas. And when you do that, the spring and buffer could also be adjusted. I say post back when you cut it down, I'd love to see what it takes to get it running.

 

[TonyTheTiger]

I want to cut the barrel down to 17”-18” if I can. This will put the gas block about X back from the muzzle. Will this create a bunch of issues? .

I probably sound like a broken record talking about my guns, but if a RLGS +1" 17" 5.56 can work unsuppressed, your idea absolutely can suppressed. You may need to enlarge the port, but I'm sure you can get it functional.

Theoretically does this mean I could end up with an even softer shooting gun?

It's been my experience (in small frame guns, but same theory of operation) that given a specific gas system length but different dwell lengths, the shorter the dwell the lower the recoil. It's not a big difference, but it's there. I've built quite a few 18" RLGS and 16" RLGS guns and the 16's are always a hair softer.

 

[Jsp556]

You may have to adjust the buffer weight. I had @unclemoak chop an 18” 308 MWS barrel down to 16”. I had to drop down to a carbine buffer to get it to reliably cycle while I have 16” 308 and 6.5Creedmoor rifle gas Criterions that run with H3’s.

 

[mettee]

You may have to adjust the buffer weight. I had @unclemoak chop an 18” 308 MWS barrel down to 16”. I had to drop down to a carbine buffer to get it to reliably cycle while I have 16” 308 and 6.5Creedmoor rifle gas Criterions that run with H3’s.

Are you running your gun suppressed?

 

[Jsp556]

Are you running your gun suppressed?

No. My first can is still in jail

 

[NHPiper]

Appreciate it. I have about 800 rounds of loaded ammo for this barrel, so I am going to burn that first and then decide.