SIG 716i Tread sticky bolt.

[Fenrisulfur]

Hi All

I have a SIG 716i Tread that I'm very happy with.
Very accurate (1 MOA with quality match ammo).
However it starts to have a sticky bolt (the internal piston becomes difficult to move) after just 50 rounds,
after 100-150 rounds I will need to mortar the rifle to get the rounds and it will not reliably feed from the magazine.

I usually shoot the rifle with a ASE UTRA Dual 762 short BL low flow suppressor.
I don't think it's creating too much back pressure and the bolt piston does not seem very dirty after firing.

I put small amounts of oil on the gas rings (keeping them dry makes the issue worse).

What do you think could be the issue?

 

[msgriff]

What specific oil are you using?

 

[Fenrisulfur]

What specific oil are you using?

I have tried both M-Pro 7 LXP and CLP.

 

[msgriff]

There are a lot of personal opinions when it comes to AR lubes. Although the CLP types aren't usually a big issue, maybe clean everything thoroughly and try a different product, one specifically for lubrication only. You don't need much on the rings, but I would go medium/heavy everywhere else.

 

[BCP]

Clean it up really well both bolt and barrel, spray a bunch of generic clp on the bolt and shoot without suppressed. If it still does it send it back for warranty, if not it’s a combo of ammo/suppressor/lube.

 

[RUTGERS95]

Hi All

I have a SIG 716i Tread that I'm very happy with.
Very accurate (1 MOA with quality match ammo).
However it starts to have a sticky bolt (the internal piston becomes difficult to move) after just 50 rounds,
after 100-150 rounds I will need to mortar the rifle to get the rounds and it will not reliably feed from the magazine.

I usually shoot the rifle with a ASE UTRA Dual 762 short BL low flow suppressor.
I don't think it's creating too much back pressure and the bolt piston does not seem very dirty after firing.

I put small amounts of oil on the gas rings (keeping them dry makes the issue worse).

What do you think could be the issue?

you are 'very happy' with your rifle when you have to mortar after 100-150 rounds? low standards huh?

 

[DirtDart]

The 716 I have. The bolt interface with the bolt carrier is extremely tight. It might be the gas rings are too tight. Put a good coat of gun grease on the bolt body, the lugs and inside the carrier. Rack it 10-15 times. Check to see if that has loosened the bolt in the carrier. Clean and repeat if necessary. Put twenty fgmm 175 clones through it and it is still stiff but have not had the same issue as the op.

 

[Fenrisulfur]

The 716 I have. The bolt interface with the bolt carrier is extremely tight. It might be the gas rings are too tight. Put a good coat of gun grease on the bolt body, the lugs and inside the carrier. Rack it 10-15 times. Check to see if that has loosened the bolt in the carrier. Clean and repeat if necessary. Put twenty fgmm 175 clones through it and it is still stiff but have not had the same issue as the op.

Could be that it's just unusually stiff. I have tried to polish the gas rings and will check if they get smoother

 

[BCP]

Mine was stiff too but it ran 100%. Wouldn't polish them either lol.

My guess is the suppressor gunks up the chamber and/or not running it with enough lube.

 

[hlee]

Mobile1 full synthetic.

 

[loveha]

Prefer grease over oils. I like this stuff, but other companies like Boretech make grease for the same application. Smells tasty.

BLACK RIFLE BALM | CherryBalmz

Our Black Rifle Balm: Our best all-around lubricant - excellent on all centerfire rifles and handguns Provides roughly 10x the shooting on one application of lube over gun oils - ARs and centerfire pistols typically get 2000-4000 rounds on one lube job. Stays put, stays wet, and stays slick and...

www.cherrybalmz.com

Then give this a read.

How to Lube an AR for Maximum Reliability

There's no voodoo here - when lubricating an AR or any gun, this is your universal rule: Learn to examine your guns in terms of "friction surfaces" - when this becomes habit, guns reveal nearly all of their operational and reliability secrets, and it tells you exactly where to lube, even on...

www.cherrybalmz.com

Only thing I oil any more is the bolt body on my bolt action rifles. My AR BCG's are cleaned, dried, and then just the grease.

 

[ansel]

How did this issue resolve??? OP....what's was the fix??

 

[BCP]

Probably gave it a good cleaning

A heavier buffer spring is another possibility

 

[Fenrisulfur]

How did this issue resolve??? OP....what's was the fix??

I haven't resolved it, hoping that once the rings wear down it will stop..
I also called SIG and according to them they do not sell ANY parts for the SIG 716i Tread.
Even the buffer spring and gas rings that are wearable components and proprietary to SIG are not sold by SIG.
The supporter from SIG was pleasant, but he could not even inform me about 3'rd party components.
Useless!

 

[mewillis]

Mobile1 full synthetic.

Yep, and I make grease by mixing the M1 with M1 grease to make a buttery smooth concoction for light grease use. The beauty is it's cheap, easy and you can mix it to whatever texture you like. IMO oil/grease doesn't need to be expensive by buying "gun" oil/grease, it's a lubricant not rocket science. It's amazing how people overthink it.....

 

[loveha]

I haven't resolved it, hoping that once the rings wear down it will stop..
I also called SIG and according to them they do not sell ANY parts for the SIG 716i Tread.
Even the buffer spring and gas rings that are wearable components and proprietary to SIG are not sold by SIG.
The supporter from SIG was pleasant, but he could not even inform me about 3'rd party components.
Useless!

This post is why my Sig 716, first gen, piston driven with quad rail. Is my first and ONLY Sig product I will ever own.

I may call my next day off from work and see what parts they DO have if any for a platform they no longer sell.

 

[Ernest 5.56]

I haven't resolved it, hoping that once the rings wear down it will stop..
I also called SIG and according to them they do not sell ANY parts for the SIG 716i Tread.
Even the buffer spring and gas rings that are wearable components and proprietary to SIG are not sold by SIG.
The supporter from SIG was pleasant, but he could not even inform me about 3'rd party components.
Useless!

Sounds like a warranty issue should be broken in by 150 rds

 

[BCP]

I haven't resolved it, hoping that once the rings wear down it will stop..
I also called SIG and according to them they do not sell ANY parts for the SIG 716i Tread.

They sell bolt carrier groups, firing pins, charging handles, the buffer spring is just a buffer spring and the buffer is a regular carbine buffer so you can get extra power springs from sprinco or a heavier buffer (or just get an armalite 308 spring). Ejectors are I think AR15 ejectors but I don't remember exactly. Extractor should be a DPMS 308 one.

Clean it up spray a bunch of lube into the action and run 3-4 mags through it unsuppressed if it binds up then I'd call sig and send it back because it's not working.

Honestly it's probably the suppressor, you might need to run a heavier buffer spring and keep it lubed to hell and back. It looks kinda dry in the pics.

 

[BCP]

This post is why my Sig 716, first gen, piston driven with quad rail. Is my first and ONLY Sig product I will ever own.

I may call my next day off from work and see what parts they DO have if any for a platform they no longer sell.

Sig P226/228 handguns are good

P320s I had were both hot garbage imho not for me at all

 

[Ernest 5.56]

They sell bolt carrier groups, firing pins, charging handles, the buffer spring is just a buffer spring and the buffer is a regular carbine buffer so you can get extra power springs from sprinco or a heavier buffer (or just get an armalite 308 spring). Ejectors are I think AR15 ejectors but I don't remember exactly. Extractor should be a DPMS 308 one.

Clean it up spray a bunch of lube into the action and run 3-4 mags through it unsuppressed if it binds up then I'd call sig and send it back because it's not working.

Honestly it's probably the suppressor, you might need to run a heavier buffer spring and keep it lubed to hell and back. It looks kinda dry in the pics.

1000% this I didn't take a good look at the pics but yeah it's way way to dry especially for a gun you are trying to break in.

Clean the bolt carrier where the bolt goes and the cam path and pin and check the barrel extension and wipe any crud out of there. After cleaning You can separate the upper and lower and remove the charging handle and slide the bolt back and forth and check for binding.


Post is for grease but its applicable for oil as well

How to Lube an AR for Maximum Reliability

There's no voodoo here - when lubricating an AR or any gun, this is your universal rule: Learn to examine your guns in terms of "friction surfaces" - when this becomes habit, guns reveal nearly all of their operational and reliability secrets, and it tells you exactly where to lube, even on...

www.cherrybalmz.com

 

[Fenrisulfur]

How did this issue resolve??? OP....what's was the fix??

Long time since the last update, but I have finally resolved the issue.

The main fix was replacing the standard SIG gas block. This gas block is basically open and with a suppressor is way to dirty in the internal piston. I replaced it with an SLR 7 0.750"gasblock.

https://slrrifleworks.com/sentry-7-clamp-on-adjustable-gas-block/

This made a huge difference, see picture below. The left case is after the gas block replacement and the right one is before.
After about 100 rounds the cases were covered in carbon fouling.

The other was replacing the standard SIG helical gas ring with 3 individual rings from Sprinco AR-10.

Sprinco USA -- Recoil Solutions

They do not fit as is, I had to reduce the thickness on waterstones to get all 3 to fit.

 

[BCP]

Surprising that an adj gas block would make it run cleaner

 

[Fenrisulfur]

Surprising that an adj gas block would make it run cleaner

Much less fouling in the receiver