SLR rifleworks rail and adjustable gas block - possible issue(s)?

[voodoo_man]

two issues:

http://i.imgur.com/7lmU4zt.jpg

As I've posted before, I have a 9.25" ultralight SLR rail with a 15-position adjustable gas block. It looks like its touching, and while I don't have shims to test it, Id id try with a dollar bill and it didn't make it past both.

At 25yards I am not getting anything remotely close to the groups I should be getting, I'd say 2-3 inches, benched. I assume they are touching and the harmonics are throwing off the accuracy.

Second issue is that with a G5t on the end, every single gas setting blows gas in my face, I started at 1 and worked all the way back, each one is horribly over-gassed and I found setting 8 to be the most functional for the setup I am running (works suppressed and unsuppressed without issue) but I get a lot of gas in my face either way.

Anyone have similar experiences, maybe shed some light on one of my issues?

Also, before anyone says "you dun installed it wrong!" Seeing as it functions without a single hiccup yet other than the gas in my face when suppressed, I don't see how that's possible.

[UWone77]

Have you tested the barrel with a standard gas block?

I would personally lean towards you got a crap barrel vs. harmonics.

[schambers]

Have you tested the barrel with a standard gas block?

I would personally lean towards you got a crap barrel vs. harmonics.

I would also lean towards the barrel over Harmonics. Harmonics alone shouldn't be causing 2-3 inch groups at 25 yards.

Is it a brand new barrel? Maybe it has not been broken in yet? Barrel brand?

[alamo5000]

My SLR rail and gas block also touch. It has not caused any accuracy issues. Not that I have really noticed. Then again I haven't tried to shoot groups for a while.

[Slippers]

The majority of the gas which hits you in the face comes from the chamber, not from the gas tube. Reducing the amount of gas through the gas block slows the action back down so it's not beating itself to death. Your suppressor is still generating a ton of back pressure that is going to flow back into the receiver from the chamber.

[alamo5000]

A quick test on the harmonics will be to slightly rotate the rail and test it. The slr barrel nut will allow a slight rotation. I doubt that it's throwing the groups off though. Could be junk or mismatched ammo or as others say a bad barrel.

[voodoo_man]

Barrel was run with the gas block it came with, 3ish inch at 100y with same 55gr IMI I used today. so its not the barrel.

@slippers, yeah I know how it works, ive had the g5t on other guns and have had no such issue (11.5 bcm, 16inch kac) even my 7.75 inch piston mk107 didnt suck this bad.

[Slippers]

Wonder if there's a chamber defect causing excessive pressure?

Edit: What do the case heads look like?

[SwissyJim]

hmmm... I have 3 rifles, all with SLR blocks - 223, 300BLK and 458Socom- and I don't see what you are describing, at least in amounts. The normal bit, like slippers says, but nothing worse. But when I put my suppressor on my Colt 9620 with OEM front sight block, I get mouthfuls of gas which is highly annoying.

[Slippers]

Maybe Voodoo is trying out some canola oil instead of fireclean. :)

[schambers]

Have the bolts changed from now to what you previously used? Mis-matched head spacing may explain the gas and accuracy issues.

If everything has stayed more or less the same, 3MOA may be the average grouping you can expect with your particular barrel/ammo combination.

[voodoo_man]

It was dipped in canola oil, yes. ;)

Nothing has changed other than the gas block and rail. Barrel and upper are the same.

It may be a 3moa gun, but not at 25y.

Ill have to check the casings next time. I wasnt really paying attention to them.

[alamo5000]

If everything else remained the same just for kicks and giggles try running a different type of ammo. 10 rounds should tell you all you need to know. It is possible that you got a bad batch. Before you do that though run a brush down your barrel 2 or 3 times.

[voodoo_man]

If everything else remained the same just for kicks and giggles try running a different type of ammo. 10 rounds should tell you all you need to know. It is possible that you got a bad batch. Before you do that though run a brush down your barrel 2 or 3 times.

Yeah ill do that.

I also just remembered I mounted another optic (accupowet) in a bobro and I dont remember if I used loctite or not, haha, if thats it i owe you guys beers.

[alamo5000]

Yeah ill do that.

I also just remembered I mounted another optic (accupowet) in a bobro and I dont remember if I used loctite or not, haha, if thats it i owe you guys beers.

$5 bucks says its the mount. LOL! That same thing happened to me ;) Even a little loose makes a huge difference.

I would still try different ammo.

[SwissyJim]

Yeah ill do that.

I also just remembered I mounted another optic (accupowet) in a bobro and I dont remember if I used loctite or not, haha, if thats it i owe you guys beers.

I like IPA...

And Lord, don't get me started. I was testing some new reloads in my Glock34, trying to find a cheaper alternative subsonic bullet. My groups were all WAY low and all over side to side. I was about to hang up the test an djust buy the more expensive bullets when I checked - my front sight had worked loose and was all over the place. Duh! Tightened it, locktited it, and I'm good to go now with cheaper loads. [:D]

[voodoo_man]

Still have the gas in face issue....need to fix that

[Slippers]

Maybe I'm weird but I never loctite scope rings/one piece mounts. Loctite acts like a lube on the threads and changes the actual tension generated for a specific torque value.

[alamo5000]

Still have the gas in face issue....need to fix that

I assume that means the accuracy problem was due to the scope mount?

[voodoo_man]

I assume that means the accuracy problem was due to the scope mount?

I gata get back out to the range.

Imma stick the MRO I got on it and see if it shoots more accurately.

[GH41]

Am I missing something? If the block is touching the hand guard it could affect accuracy. If it the clearance is tight enough that barrel whip causes the GB and hand guard to collide it could also degrade accuracy. How much trouble would it be to remove the HG , rest off of the magazine and see what happens??

[voodoo_man]

Am I missing something? If the block is touching the hand guard it could affect accuracy. If it the clearance is tight enough that barrel whip causes the GB and hand guard to collide it could also degrade accuracy. How much trouble would it be to remove the HG , rest off of the magazine and see what happens??

Wouldn't be too much trouble.

Im just concerned this is an issue in the first place

[Slippers]

Having the gas block touch the inside of the rail is no different than using non-free floated plastic handguards. As long as you're not slinging up you can still expect pretty darn good accuracy out to several hundred meters. I used to shoot high power as a teenager without a freefloated barrel, and as long as I dialed windage for the prone stages to account for the sling tension, I didn't have too many problems.

There's no way a 3" group at 25 yards is caused by the lack of a free floated barrel.

[voodoo_man]

Having the gas block touch the inside of the rail is no different than using non-free floated plastic handguards. As long as you're not slinging up you can still expect pretty darn good accuracy out to several hundred meters. I used to shoot high power as a teenager without a freefloated barrel, and as long as I dialed windage for the prone stages to account for the sling tension, I didn't have too many problems.

There's no way a 3" group at 25 yards is caused by the lack of a free floated barrel.

This gun was slung at the time, used the sling for tension.

I'm still going to check the optic when I get a chance, havn't been able to do anything due to work being hectic.

[Slippers]

This gun was slung at the time, used the sling for tension.

I'm still going to check the optic when I get a chance, havn't been able to do anything due to work being hectic.

In that case, if you weren't consistent in your sling tension from shot to shot, you could certainly have caused the spread. :)

[voodoo_man]

In that case, if you weren't consistent in your sling tension from shot to shot, you could certainly have caused the spread. :)

You pissin on my tactical-ness ?

;)

[voodoo_man]

http://i.imgur.com/F5Qd1On.jpg

http://i.imgur.com/MoAD2ND.jpg

Soooo....swapped to the MRO with a samson 3.5x Shot touching 10round shots (smaller than a dime) at 25y with the can on.

Also messed with the settings, no gas in my face.

woot woot

Trijicon accupower goes on my pws mk107 after I re-locltite it.

[voodoo_man]

Sooooo

Update, I removed the rail and gas block to install an mk8 and geissele spg. You can totally see the strike marks on the rail and the gas block, I took photos which ill post later.

Emailed slr rifleworks, Todd responded saying if I am unhappy I can send it back, but no other information. Also said my site was confusing and that unless the barrel is perfectly straighy this may occur...?

Anyway, going to see what they are going to offer in terms of getting this issue worked out.

Ill keep yall updated.

[mtdawg169]

Sooooo

Update, I removed the rail and gas block to install an mk8 and geissele spg. You can totally see the strike marks on the rail and the gas block, I took photos which ill post later.

Emailed slr rifleworks, Todd responded saying if I am unhappy I can send it back, but no other information. Also said my site was confusing and that unless the barrel is perfectly straighy this may occur...?

Anyway, going to see what they are going to offer in terms of getting this issue worked out.

Ill keep yall updated.
Glad you got the accuracy issue worked out. But I'm sort of surprised that a gas block won't clear a rail from the same manufacturer.

[alamo5000]

You can totally see the strike marks on the rail and the gas block, I took photos which ill post later.

I would be interested to see the pics.

What did you have attached to the rail? What was striking?

[voodoo_man]

Glad you got the accuracy issue worked out. But I'm sort of surprised that a gas block won't clear a rail from the same manufacturer.

I had a DD low pro gas block and it didn't even remotely clear it so I decided to purchase a gas block directly from to make sure it had no such issues, unfortunately that wasnt the case.


I would be interested to see the pics.

What did you have attached to the rail? What was striking?

I have photos that I may post later. I will do a whole review of the gas block and rail together before I ship them out.

[mtdawg169]

I had a DD low pro gas block and it didn't even remotely clear it so I decided to purchase a gas block directly from to make sure it had no such issues, unfortunately that wasnt the case.



I have photos that I may post later. I will do a whole review of the gas block and rail together before I ship them out.
Yeah, the DD blocks are on the large side. Still surprises me that the Sentry won't clear an SLR rail. I wonder if any block clears without touching? I built up an 18" Noveske for a friend last year with a pinned Noveske block and an SLR Rifleworks rail. I don't recall that one having any issues.

[voodoo_man]

Yeah, the DD blocks are on the large side. Still surprises me that the Sentry won't clear an SLR rail. I wonder if any block clears without touching? I built up an 18" Noveske for a friend last year with a pinned Noveske block and an SLR Rifleworks rail. I don't recall that one having any issues.

The Geissele SGB doesnt clear either...

[Joelski]

What receiver? Could thr barrel nut threads not be perpendicular with the face of it? Could it have been previously damaged? Sounds like an issue with the mounting point...

[mtdawg169]

The Geissele SGB doesnt clear either...
That one actually doesn't surprise me. It's a beefy GB.

[Joelski]

That one actually doesn't surprise me.e. It's a beefy GB.

But he said it's under a Geissele rail, so it should fit just fine. I use a SGB under a Mk 4 and if has plenty of clearance.

[mtdawg169]

But he said it's under a Geissele rail, so it should fit just fine. I use a SGB under a Mk 4 and if has plenty of clearance.
It is now. I assumed he meant that it didn't clear the SLR rail.

[voodoo_man]

Cmt upper

[mtdawg169]

What receiver? Could thr barrel nut threads not be perpendicular with the face of it? Could it have been previously damaged? Sounds like an issue with the mounting point...
I've seen that before with URX rails. You can see the rail misalignment, if it exists, by eyeballing it from the muzzle. But it honestly just sounds like the internal diameter of the rail is small. I've run into the same issue with a Centurion CMR before. Skinny rail, skinny internal dims, needs a really slim GB to free float.

[Slippers]

Yes, the ID on the SLR rails is very small, just like an original CMR. Newer CMRs are opened up a bit. You almost have to use a gas block for a .625 journal (that isn't the same OD as a .750 gas block), or a shaved FSB. Badger also makes a very, very low profile gas block, smaller on the bottom than anything else I've seen.

[mtdawg169]

Yes, the ID on the SLR rails is very small, just like an original CMR. Newer CMRs are opened up a bit. You almost have to use a gas block for a .625 journal (that isn't the same OD as a .750 gas block), or a shaved FSB. Badger also makes a very, very low profile gas block, smaller on the bottom than anything else I've seen.
I had one of the original CMRs. Thanks for the info on the newer ones. Glad to know they opened it up a bit. I've always liked the CMR rails and the new mlok & keymod versions should be a big hit for them.

[SINNER]

Just a FYI, the CMMG micro's are the smallest gas blocks I have ever found. PRI makes a very compact one also but they are often very hard to find.

[Stone]

Ballistic advantage makes a real low profile gas block as well. http://ballisticadvantage.com/750-lo-pro-gas-block.html

[voodoo_man]

I'm not going to be putting it back together, and I'll be selling the slr rail and the gas block with a disclaimer attached. I'll actually be doing a write-up on the whole thing on my site before I do so - Now that I know of an issue I would consider myself at fault if others experience it when they could have been educated.

[SINNER]

How much you asking for the gas block?

[voodoo_man]

How much you asking for the gas block?

PM me an offer.

[Slippers]

I had one of the original CMRs. Thanks for the info on the newer ones. Glad to know they opened it up a bit. I've always liked the CMR rails and the new mlok & keymod versions should be a big hit for them.

Sorry to derail Voodoo's thread slightly, but if you get a CMR m-lok be wary of trying to mount something directly under the gas block. The m-lok nut + protruding screw may come in contact, depending on the gas block and screw length. This applies to any m-lok rail, really.

[SINNER]

PM me an offer.

PM sent.

[BoilerUp]

Any chance the upper receiver face isn't perfectly square? It would be interesting to know if lapping the upper had any effect. On skinny rails it probably doesn't take much misalignment to make a difference.

I have a Geissele Super Gas Block on my 18" upper that I just swapped from an EMR to KMR-A. I had to dremel off the corners of the "ears" for the cross pin and will probably Dremel down the bottom over the set screws just a little. The SGB is not a good choice for super skinny rails like the KMR.

[alamo5000]

Sorry to derail Voodoo's thread slightly, but if you get a CMR m-lok be wary of trying to mount something directly under the gas block. The m-lok nut + protruding screw may come in contact, depending on the gas block and screw length. This applies to any m-lok rail, really.

This has been my experience as well. The reason why the SLR rails and and gas blocks work for me is because the overall length of the gas block is shorter than other gas blocks. The way they are set up for SLR is the positioning of the slots vs the gas block leaves your screws either slightly fore or slightly aft of the gas block...

That said it is a very tight fit on a number of levels not just accessories.

One of my rails and gas blocks has a paper thin margin between the screw that holds the wing on the gas block in and the rail.

It leaves almost no room for error when dimpling the barrel. If the jig is off even a little bit there could be contact.

One of my guns I had SLR dimple the barrel for me and it's a perfect fit. My other barrel is a Rainier barrel and the gas block has a minor tilt... like maybe 1 or 2mm and it causes contact. I would have to rotate my rail out of alignment some to correct for it. It causes minor contact under shooting conditions.

https://c2.staticflickr.com/2/1612/24560982220_881b146822_b.jpg

[voodoo_man]

When I get a chance tomorrow morning (getting on shift in an hour) I'll post up photos.

[mtdawg169]

Sorry to derail Voodoo's thread slightly, but if you get a CMR m-lok be wary of trying to mount something directly under the gas block. The m-lok nut + protruding screw may come in contact, depending on the gas block and screw length. This applies to any m-lok rail, really.
True, I've also run into the same thing on the MI mlok rails. That's part of the reason I'm still running keymod.

[mtdawg169]

Any chance the upper receiver face isn't perfectly square? It would be interesting to know if lapping the upper had any effect. On skinny rails it probably doesn't take much misalignment to make a difference.

I have a Geissele Super Gas Block on my 18" upper that I just swapped from an EMR to KMR-A. I had to dremel off the corners of the "ears" for the cross pin and will probably Dremel down the bottom over the set screws just a little. The SGB is not a good choice for super skinny rails like the KMR.
I'm sure this is blasphemy to some, but the to me, the Geissele block is only suited for use with a G rail and even then, I think there are better options. It's just too big for my tastes.

This has been my experience as well. The reason why the SLR rails and and gas blocks work for me is because the overall length of the gas block is shorter than other gas blocks. The way they are set up for SLR is the positioning of the slots vs the gas block leaves your screws either slightly fore or slightly aft of the gas block...

That said it is a very tight fit on a number of levels not just accessories.

One of my rails and gas blocks has a paper thin margin between the screw that holds the wing on the gas block in and the rail.

It leaves almost no room for error when dimpling the barrel. If the jig is off even a little bit there could be contact.

One of my guns I had SLR dimple the barrel for me and it's a perfect fit. My other barrel is a Rainier barrel and the gas block has a minor tilt... like maybe 1 or 2mm and it causes contact. I would have to rotate my rail out of alignment some to correct for it. It causes minor contact under shooting conditions.

https://c2.staticflickr.com/2/1612/24560982220_881b146822_b.jpg
Dumb question time, what is the purpose of the plate on the side of the SLR gas blocks?

[alamo5000]

Dumb question time, what is the purpose of the plate on the side of the SLR gas blocks?

That is where the gas gets released from. On the front it has a set screw that you screw in and out to open or close the gas flow. Around that wing is where it bleeds off the excess gas.

From what I've heard this design is so that you can 1. Take apart the gas block (which I haven't done yet) 2. to help manage carbon build up (if it was just a hole it would eventually clog up or whatever...at least so I've heard)

All around the edges of that 'plate' gas exits and you can see carbon build up after you've shot a while.

From what I've seen it's supposed to be able to be user maintained. Again though, I've never taken mine apart yet but I did have to spray one down with some CLP to break the front adjustment screw free but that's all the maintenance I have ever had to do on mine so far. I might take it apart just to see how it works.

[alamo5000]

Dumb question time, what is the purpose of the plate on the side of the SLR gas blocks?

http://slrrifleworks.com/image/data/slr/SA6/SentryINS.jpg

[voodoo_man]

Gas block gone....rail is still available, who wants it pm me with offer.