Horrible accuracy with custom SR-25. Help!

J

jamesbern

Sergeant
Banned !
Minuteman
Jan 12, 2012
202
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FL
#1
I'm about to give up! Had this built and it just doesn't seem to shoot. I had a guy who specializes in KAC guns put the upper together for me.

I'm only shooting FGMM 168gr and Remington Premier 168gr. It does it with either ammo. Same lots of ammo are tack drivers in my FN SPR (target on the right)

I've tried two different optics: Leupold Mk6 1-6 and a Vortex PST 6-24x50 FFP. Both mounted to spec, torqued properly etc. Nothing seems loose and everything seems tight.

Build consists of:

Knights Pre-ban SR-25 receiver set
Troy .750 Low-pro Gas Block
AAC 51T Blackout Muzzle Brake
DPMS BCG
Lilja 18" stainless 1/11 barrel
Knights URX 3.1 rail (very hard to find)
Knights URX 3.1 Rail Panel Kit
Knighs Receiver Sling Mount
Knights Combat Trigger Guard
Knights 45 degree offset sights
Geissele SSA-E trigger (2 stage, 1.5lbs, incredible)
BCM Mod 4 Charging Handle
DPMS Gas Tube
VLTOR RE-10 Buffer Tube
Damage Industries H3 buffer
BCM Mod 0 Pistol Grip
Armalite AR-10 Operating Spring
DPMS Bolt Catch
Armalite LPK
Magpul ACS Stock


Targets are all 100 yards.

Left Target: First shot green, second shot low, third green, next two low. SHOT IN LEAD SLED
Middle Target: First two green, third orange, fourth green, fifth yellow. SHOT OF BIPOD/REAR BAG

These are two of many groups I've shot.

Where do I go from here?




SR-7_zpsa1b9ef41.jpg
 
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#2
That lilja barrel should shoot well.. Very nice looking rifle by the way. Did you send the upper back and he said it was in spec or is that just what he told you when you called about it. Are you sure everything is tight on the upper and torqued properly, like the barrel nut? I would send the upper back to the builder and have him personally look it over himself. You may even try another grain of ammo since you are not hand loading your own..
 
#3
How tight is the mount on your receiver? Did you follow ADM's instructions mounting it? That will make a difference.

Have you shot it without the AAC brake?

Is the gas tube floating free or is it binding on the inside of the receiver?

Is this your first .308 precision semi? Have you let anyone else shoot it?
 
#4
akakb24 said:
That lilja barrel should shoot well.. Very nice looking rifle by the way. Did you send the upper back and he said it was in spec or is that just what he told you when you called about it. Are you sure everything is tight on the upper and torqued properly, like the barrel nut? I would send the upper back to the builder and have him personally look it over himself. You may even try another grain of ammo since you are not hand loading your own..
Click to expand...

Nope, when he put it together he said everything looked good and he checked the barrel for straightness. Since it isn't even grouping I can't imagine it's the ammo choice at this point. He puts together hundreds of uppers, so i'd like to think it's all torqued properly. I think my only option at this point might be to send him the upper again so he can check the torque on the barrel nut unless there are any other ideas.
 
#5
The third target with FGMM 168 looks to be about what you should expect out of a gas gun. I have found that the shorter barrel gas guns are a little pickier about ammo and you probably wont get the best performance unless you hand load. But i would also look to pick up some 168gr A-max, its some very good factory ammo that shot great in my gas gun.
 
#6
wareagle700 said:
How tight is the mount on your receiver? Did you follow ADM's instructions mounting it? That will make a difference.

Have you shot it without the AAC brake?

Is the gas tube floating free or is it binding on the inside of the receiver?

Is this your first .308 precision semi? Have you let anyone else shoot it?
Click to expand...


The mount was tight on the receiver, no play to speak of no matter how much I tried moving it. Same with the Vortex PST I mounted.

I didn't shoot it without the brake.

Gas tube is free floating...no binding I can feel.

This is my first precision semi .308, but i've shot plenty of AR's, bolt guns, and lever guns. I can't imagine it's me, especially since it's been shot from a lead sled and by another shooter with the same results.
 
#7
webvantage said:
The third target with FGMM 168 looks to be about what you should expect out of a gas gun. I have found that the shorter barrel gas guns are a little pickier about ammo and you probably wont get the best performance unless you hand load. But i would also look to pick up some 168gr A-max, its some very good factory ammo that shot great in my gas gun.
Click to expand...

That third target is my FN bolt gun to show the difference in targets shot. I wish the SR shot like that.
 
#8
Even if he's put hundreds together, he is human and can make mistakes. Wareagle is also correct, those mounts gotta be be tight or it will be inconsistent. I still don't think its your barrel, even though great barrel makers have had a few duds slip through the cracks. I would definitely start with checking the mount and barrel nut and even remove that brake, then try again...
 
#9
Those ADM's should be tighter than you think they need to be. With one hand it should take all you got to close the lever. You should not be able to open the lever with one hand. When I had mine it took a piece of paracord. I'd reinstall the adm per their instructions and see if that does anything. Also, remove the brake the next time you shoot it. That will at least eliminate one possibility.
 
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#10
Just because you can shoot a bolt gun with relatively accurate results, does not mean you can shoot a larger caliber (over 223) AR-10 type with the same results.

A gas gun will show the shooter's errors much more than a bolt gun, so it can be you, more so than anything else.

It certainly can be the ammo, or any other combination of things, but with a custom 308 gasser, look to the shooter to be the weak link in the accuracy chain. You just have to trial and error changing things to see what it is. Try a good factory 175gr load, try removing the brake, you swapped scopes around I highly doubt that is the issue, it's beyond a scope problem as you are not moving it, if you had good groups at 100 and bad at other ranges you might be able to blame the scope.

Also try single loading it to see what it does.
 
#13
These were two targets I picked. The rounds aren't all going in the same direction on my others, sometimes they are high, low, left, right. Brake looks fine, before I waste more ammo, I emailed the guy to see what he thinks. I'm sure it's fine, but i'd like to rule that out. Then i'll shoot without the brake if it's still giving me issues.

I just cleaned it again. No odd wear or anything in the chamber, bolt, or carrier. Everything looks fine.
 
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#16
Stop cleaning.

Put 100 rounds of fodder down the tube before shooting groups with match ammo.

This will yield you 2 things. First it will let you get more used to the rifle, second some gas guns like to be ran dirty.
 
#18
jamesbern said:
Duh....."Custom" :)

And besides, it isn't like my parts are crap. I used all good stuff, besides the DPMS BCG.
Click to expand...

Doesn't matter if you used parts blessed by Jesus.. It is not a KAC anything! It is a Frankengun built on a KAC receiver set. What does "Custom" mean? Mail order parts assembled by an unknown gun plumber??? Using the word custom implies that modifications were made or components fabricated to make it unique. It's a parts gun and evidently some of the parts are not getting along together!
 
#19
GH41 said:
Doesn't matter if you used parts blessed by Jesus.. It is not a KAC anything! It is a Frankengun built on a KAC receiver set. What does "Custom" mean? Mail order parts assembled by an unknown gun plumber??? Using the word custom implies that modifications were made or components fabricated to make it unique. It's a parts gun and evidently some of the parts are not getting along together!
Click to expand...

Thanks for the help.....

For anyone wondering, it's been put together by someone very familiar with KAC guns and who does many of these uppers.
 
#20
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#22
James,

There is some really good information here. As Lowlight alluded to gas guns are very difficult to drive. I thought there was something wrong with my SR-25 at as well, they will expose flaws in your technique. It took almost 200 rounds for me to adjust to shooting my gasser. I have a few points. first are you shooting off a bipod, sandbags, Rest? If shooting off a bipod there is an art to loading the bipod. Also be sure your cheek weld is being consistent on a gasser. I feel this is the culprit due to the erratic nature of the rounds. I find it difficult to maintain proper position on my Gasser and resorted to using a painted dot on my stock to ensure proper position (recoil impulse is violent on a .308 gasser). I would also implore you to try shooting the rifle without the muzzle device. There are many stated cases of a muzzle device hampering accuracy.
 
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#23
Another vote for the mount. QD mounts have to be tighter than all hell. Just because you can't feel movement doesn't mean there isn't any. I had that problem with a GDI and that's about the best QD mount on earth. I put my scope in a set of rings and punched the red out of the bullseye with the first couple rounds.

I suggest you do the same. If it doesn't shoot in a good set of rings it's probably you.
 
#24
jamesbern said:
Thanks for the help.....

For anyone wondering, it's been put together by someone very familiar with KAC guns and who does many of these uppers.
Click to expand...

I could care fucking less if he can spell KAC! He is not KAC! Don't drag KAC down to you and your gun plumber's level! It's a fucking parts gun! I don't understand why you are trying to get help here. Get your personal KAC expert to fix what he fucked up! Evidently he knows less than you think he does! How many of the many uppers he assembles don't work?
 
#25
All I can say is it really doesn't matter what parts your gun is built out of so it not being a "FULL KAC" doesn't matter I have model 1 sales uppers on Polly lowers that shoot like lasers. But it takes ALOT of practice with a gasser I've had mine for 2years and still don't always shoot perfect groups like I do with my bolt guns. Like others said more shooting less cleaning and repetition shoot the same way every time. Gas guns can make you look really bad.
 
#26
maggitas said:
James,

There is some really good information here. As Lowlight alluded to gas guns are very difficult to drive. I thought there was something wrong with my SR-25 at as well, they will expose flaws in your technique. It took almost 200 rounds for me to adjust to shooting my gasser. I have a few points. first are you shooting off a bipod, sandbags, Rest? If shooting off a bipod there is an art to loading the bipod. Also be sure your cheek weld is being consistent on a gasser. I feel this is the culprit due to the erratic nature of the rounds. I find it difficult to maintain proper position on my Gasser and resorted to using a painted dot on my stock to ensure proper position (recoil impulse is violent on a .308 gasser). I would also implore you to try shooting the rifle without the muzzle device. There are many stated cases of a muzzle device hampering accuracy.
Click to expand...

Thanks, builder suggested to removed brake and see if it changes which I plan to do this weekend. He said if it didn't get better he'd be happy to check it out. I'll be shooting off of front and rear bags to see how it goes. I've shot off a rear bag and bipod and a lead sled so far.

LawnMM said:
Another vote for the mount. QD mounts have to be tighter than all hell. Just because you can't feel movement doesn't mean there isn't any. I had that problem with a GDI and that's about the best QD mount on earth. I put my scope in a set of rings and punched the red out of the bullseye with the first couple rounds.

I suggest you do the same. If it doesn't shoot in a good set of rings it's probably you.
Click to expand...

My other scope isn't a QD mount and it's shooting the same. I'll make sure the Leupold is on there tight when I reinstall it.

GH41 said:
I could care fucking less if he can spell KAC! He is not KAC! Don't drag KAC down to you and your gun plumber's level! It's a fucking parts gun! I don't understand why you are trying to get help here. Get your personal KAC expert to fix what he fucked up! Evidently he knows less than you think he does! How many of the many uppers he assembles don't work?
Click to expand...

Wow dude, just pretend this thread doesn't exist. You're offering no help and so far you're posts in this thread are useless. No one said KAC is to blame..Most of the gun isn't KAC, i'm well aware of this. It doesn't seem to stop others with offering suggestions and positive options for me to try.
 
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#27
Maybe your gun is jacked but you should sign up for the online training. It will make you a better shooter and its cheap. There's a couple lessons that deal specifically with 308 gas guns.
 
#28
As the fan boys and hair splitters ruin yet another thread... I think I'll go shoot my DPMS AR10 stick with a 3.5x10 scope and a millidot reticule in it, with mil turrets cuz I think in metric and it spits out 168gr pills to 1k like it's cool. All fucking day at one moa bitches.

mind_blown.gif


OP, try the single feed with brake off. If that prints good groups, mag feed with brake off, single feed with brake on, back to mag feed with brake on. Groups that far apart on a lead sled indicate more than shooter error. If you can't get good groups with one of those combinations, including meeting up with a shooter experienced in big bore semis to let them give it a go, it needs to go back to the builder. Check the barrel torque, it might have settled in after being shot and it needs to be tightened back up.
 
#33
I didn't put the upper together. A certified Knights SR-25 armorer did.

Lilja contacted me and said check it without the brake. At this point, i'm going to remove the brake and test if off sandbags. If it still isn't shooting well the builder is going to recheck everything.

No big deal, it will get figured out.

Thank most of you for your helpful ideas.
 
#34
I was watching your build no real suggestions however I will second the traing suggestion. I too am shooting gas guns after a long break and shooting with just bolt guns for the last few years. Wow, big difference. Just getting this puppy dialed in tho.
 
#35
To the OP:

I recently had a .308 upper with a Krieger barrel assembled for my Armalite AR-10. Unlike my M1A, this barrel just doesn't like the 168-gr bullets. I couldn't get Sierra or Hornady to group; odd flyers with both. On the other hand, it groups consistently into 3/4-MOA (usually better) with 155- and 178-gr bullets.

I also learned that I need to hold the AR-10 very firmly; my bolt rifles do better when held loosely.

Good luck.

Richard
 
#36
With all due respect this is not a "Custom SR-25" but rather a parts gun based on an SR-25 receiver. The title implies problems with a KAC product.
 
#37
RGAmos said:
With all due respect this is not a "Custom SR-25" but rather a parts gun based on an SR-25 receiver. The title implies problems with a KAC product.
Click to expand...

attachment.php


:) But seriously, yes it's an SR-25 parts gun. I know that....but look at all the ideas i've gotten already. People see SR-25 and are curious. I didn't think about the barrel not liking the 168gr ammo. I'll pick up a box or two of some other stuff (match or otherwise) and check it out as well.

If after removing the brake, shooting off sandbags, and trying different ammo it still doesn't shoot well, i'll send the upper back to have him recheck the barrel nut and torque.

I'll almost bet it isn't the optic as i've mounted two different optics already, one QD and one not, with a torque wrench and proper settings. I've mounted many optics and never had an issue with a loose mount. Plus, they were triple checked before hitting the range.

rg1911 said:
To the OP:

I also learned that I need to hold the AR-10 very firmly; my bolt rifles do better when held loosely.

Good luck.

Richard
Click to expand...

This is a good point. I was probably holding it looser than I should.

The first day I took it out to the range I did have 4 rounds at 100 touching each other, then a 5th flier. From all this talk about it being different compared to a bolt gun or AR-15 is definitely going to make me aware of my body position and grip. Maybe it is me. :D I'd actually be fine with that as it means nothing is wrong with my build.

Hoping to get to the range on Sunday, so except an update at that point.
 
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#39
I have three AR based 308's. They shot factory ammo like crap. Worked up hand loads and life was a lot better. I chono graphed the loads. Hand loads and factory match were only 20-30 fps off of each other. But it was enough to make the guns shoot rat crap groups. You may need to hand load to get what you want the gun to do. Sometime "custom" guns need custom loads.
 
#40
Im betting on sight picture. Keep your face on that stock between shots. Dry fire, dry fire, dry fire. Concentrate on keeping those cross hairs on the same spot after you pull the trigger. Your last group looks better. I think you just need a little trigger time and thats OK. You can fix that!
 
#41
First, is this your first large caliber AR semi auto that YOU own...

Second, I'd rule out the scope... slap a nice 15x plus power scope if you have one on that bitch with a different mount and shoot at 1" perfectly round circles @ 100yards... If going for small ass groups, a 15x plus power scope is going to blow a 4x or 6x power scope out of the water in regards to small ass groups.... even at 100yards.... as for target size, aim small, miss small.. use a 1" circle @ 100yards with a 15x power scope and cut the circle into 4 perfect pcs of pie and pull the trigger... using HUGE targets doesn't help!!...use a rear sand bag where the rear buttstock doesn't fall off too much when shot. try a couple 5shot groups with the bipod loaded, and a couple 5shot groups with bipod not loaded, couple 5shot groups with sand bag front and rear.... all while keeping everything consistent from body form, trigger pull, grip, cheekweld, scope shadow, blah blah blah... Once you start taking your shots, DO NOT move your head / eye from clear scope glass with no scope shadow... if you move your head half way thru your shots = group goes to shit!!!... shooting a big caliber .308 and larger is NOT easy compared to a bolt action.. you can NOT compare the two! big caliber semi-auto's are MUCH HARDER to consistently shoot... trust me, been there, done that, told others the same that didn't believe me at first and came back later after spending THOUSANDS OF DOLLARS to say the very same thing I'm telling you now...... adding in reloads can shave off another .25 to .5moa off your group too!

Big caliber AR's .308 or larger WILL PRONOUCE ANY ERRORS IN YOUR SHOOTING FORM!! regardless if your bolt action that YOU shoot is crazy accurate...

Also, semi auto AR's are really really picky about the ammo used.. especially with factory ammo... will take some time to find what your AR likes. Until you reload that is!

If you do the above and you can't keep your groups consistently under 1.75 to 1.5moa or less, then there is something wrong with the rifle / set up.... anything close to 1moa or sub-moa is REALLY GOOD!!

My 5.56 AR's consistently blow my 7.62 AR's out of the water in terms of accuracy 400yards or less!!! I'm telling you, my $950 dollar rock river varmint is much much more accurate than my $2500 dollar LMT all the way out to 600yards. Shooting large caliber semi auto AR's is NOT easy at all... especially if you're new to the game.

If you do the above, then anything IMO with a .308 AR @ 100yards consistently 5shot groups:
- anything sub moa 5shot group = amazing
- 1moa to 1.25 = really good
- 1.25 to 1.5 = average
- 1.5 to 1.75 = so so
- 1.75 to 2moa = something is fishy
- anything over 2moa = something is jacked up with YOU or the RIFLE. Most likely the rifle or ammo used.

Not saying there isn't anything wrong with the rifle, but I've been down this road myself... and with others in this very same forum. It only takes a few thousand dollars in rifles, ammo, and time to beat it into your head sometimes.




jamesbern said:
I'm about to give up! Had this built and it just doesn't seem to shoot. I had a guy who specializes in KAC guns put the upper together for me.

I'm only shooting FGMM 168gr and Remington Premier 168gr. It does it with either ammo. Same lots of ammo are tack drivers in my FN SPR (target on the right)

I've tried two different optics: Leupold Mk6 1-6 and a Vortex PST 6-24x50 FFP. Both mounted to spec, torqued properly etc. Nothing seems loose and everything seems tight.

Build consists of:

Knights Pre-ban SR-25 receiver set
Troy .750 Low-pro Gas Block
AAC 51T Blackout Muzzle Brake
DPMS BCG
Lilja 18" stainless 1/11 barrel
Knights URX 3.1 rail (very hard to find)
Knights URX 3.1 Rail Panel Kit
Knighs Receiver Sling Mount
Knights Combat Trigger Guard
Knights 45 degree offset sights
Geissele SSA-E trigger (2 stage, 1.5lbs, incredible)
BCM Mod 4 Charging Handle
DPMS Gas Tube
VLTOR RE-10 Buffer Tube
Damage Industries H3 buffer
BCM Mod 0 Pistol Grip
Armalite AR-10 Operating Spring
DPMS Bolt Catch
Armalite LPK
Magpul ACS Stock


Targets are all 100 yards.

Left Target: First shot green, second shot low, third green, next two low. SHOT IN LEAD SLED
Middle Target: First two green, third orange, fourth green, fifth yellow. SHOT OF BIPOD/REAR BAG

These are two of many groups I've shot.

Where do I go from here?




SR-7_zpsa1b9ef41.jpg
Click to expand...
 
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#42
I went through something similar with a LMT MWS. My problem was I went from shooting MOA pretty consistently with it to a 3 MOA shotgun after cleaning the barrel. After trying everything under the sun it came down to just having to put about 90 rounds through the barrel before it would start to group again. My guess is this is not going to help you but if you havent put a few hundred down the pipe yet you may give it a go as another poster suggested. If for no other reason than to gain the experience of shooting a new set up.

Just wanted to add that I have never understood the KAC fan boy mentality of riding to the rescue of a company that demonstrably could give a shit less about any customer not on a government contract. KAC couldn't give less of a fuck what any civilian thinks about its stuff so its funny to see people getting a case of the ass over a thread title.
 
#43
JCIN said:
I went through something similar with a LMT MWS. My problem was I went from shooting MOA pretty consistently with it to a 3 MOA shotgun after cleaning the barrel. After trying everything under the sun it came down to just having to put about 90 rounds through the barrel before it would start to group again. My guess is this is not going to help you but if you havent put a few hundred down the pipe yet you may give it a go as another poster suggested. If for no other reason than to gain the experience of shooting a new set up.

Just wanted to add that I have never understood the KAC fan boy mentality of riding to the rescue of a company that demonstrably could give a shit less about any customer not on a government contract. KAC couldn't give less of a fuck what any civilian thinks about its stuff so its funny to see people getting a case of the ass over a thread title.
Click to expand...

Why don't you tell us more? How many people do you know that actually have problems with their commercial KAC guns?

If if they did, a simple phone call would get the ball rolling. Hell, you could get ahold of KevinB on here, M4 or ar15.com if you really had a problem.

Your right though, KAC does not really give a fuck what the civllian wants. They build shit for warfighters. It just so happens that what warfighers want and what the competent tactical market want are the same. How is this a problem? You get to decide how a company runs itself and how it makes a living now? Well, aren't you a special little snowflake.
 
#44
Man CC, you sure don't mince words, (although you were pretty gentle here) and more often than not I find myself agreeing with you... for what's it worth, I love my KAC guns and have never had a problem with either of them.
 
#45
This may sound a little strange but run a q-tip down the barrel to see if there are any burrs. Other than that I would try a few different ammo's. I have a 300WM that couldn't hit the broad side of a barn with match ammo. Had a box of the cheapest ammo I could find so tried that and one holed 5 rds. Guns are like people we all have different tastes.
 
#47
Cobracutter said:
Why don't you tell us more? How many people do you know that actually have problems with their commercial KAC guns?

If if they did, a simple phone call would get the ball rolling. Hell, you could get ahold of KevinB on here, M4 or ar15.com if you really had a problem.

Your right though, KAC does not really give a fuck what the civllian wants. They build shit for warfighters. It just so happens that what warfighers want and what the competent tactical market want are the same. How is this a problem? You get to decide how a company runs itself and how it makes a living now? Well, aren't you a special little snowflake.
Click to expand...

You mad bro?

Please show me exactly where I said anything about KAC guns having problems. The point of my statement was that guys like you amuse me. The dude who feels he has to stand up for a big ass firearms company like its his sister who got finger banged under the bleachers and now has to have her honor defended.

OP sorry for the derail. My bad.
 
#48
JCIN said:
You mad bro?

Please show me exactly where I said anything about KAC guns having problems. The point of my statement was that guys like you amuse me. The dude who feels he has to stand up for a big ass firearms company like its his sister who got finger banged under the bleachers and now has to have her honor defended.

OP sorry for the derail. My bad.
Click to expand...

No one is mad, you just sound like a clown.

You said: "Just wanted to add that I have never understood the KAC fan boy mentality of riding to the rescue of a company that demonstrably could give a shit less about any customer not on a government contract. KAC couldn't give less of a fuck what any civilian thinks about its stuff so its funny to see people getting a case of the ass over a thread title."

This would imply they don't care about their commercial customers and don't support them. Amazingly, people who ACTUALLY own their shit, don't seem to have this problem. Also, please tell us how designing weapons and gear for the military, gov and PMC market does not benefit the civilian customers. It's not like guys want to run the same stuff the warfighters do, you know, because maybe the warfighters use what works.

I will defend (and do if you read my posts) any company who gets unjustly blamed for stupid unsubstantiated bullshit. And at the same time, I will call out those who fuck up. It goes both ways. The only thing you can say about them is their shit is expensive and its hard to get. You going to blame them for that? Must not be too expensive if they sell every gun and most accessories before they even hit the shelves. Supply and Demand, how does it work?

You sound petty and jealous. Maybe you can't afford their gear or maybe some big mean KAC man hurt your feelings. Would you like to show us on the doll where he touched you?

Sounds like you wanted to call someone out, here is your prize.
 
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