KAC SR25 ER Problem (under-gassed?)

O

oubeta

Sergeant
Full Member
Minuteman
Nov 2, 2003
535
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Edmond, Oklahoma
#1
I recently purchased a new SR25 ER and it won't shoot unsuppressed. It won't pick up a fresh round in the magazine. The bolt isn't coming far enough back it appears.
I sent it back to KAC and they said it was slightly under gassed. They said they tested it and it was running fine. I just got the gun back the other day and I took it to the range and had the exact issues I was having before I sent it back to KAC. Does anyone have any idea on how to address this issue myself? KAC basically told me I wasn't putting enough oil on it or I was putting too much. I tried 5 different brands of factory ammo and 4 different magazines. It cycles fine with the Mk11 suppressor on it, so it's not the magazines. it has to be gas related I would think. Below is the email I sent to KAC today along with some video links you can cut & past into your browser. I'm hoping I can fix it myself as KAC sure couldn't or wouldn't. As much money as I spent on the gun it should shoot.

KAC,

I just received my SR-25 back from KAC and I’m still having issues with it.
The gun was returned to KAC because it wasn’t cycling properly suppressed or unsuppressed. When I received the gun back, I slapped the scope on and took it to the range without doing anything to it, and the very first round I had issues. I proceeded to test several different factory loads and video taped a few of them to send to you guys. The gun will cycle suppressed now, but it will not cycle unsuppressed. After I tested several different brands of ammo, I pulled the bolt out and put a thin film of lube on it and started over. I had the same results. It will only fire 1 round and will not pick a fresh round up from the magazine unsuppressed.
I used 4 different types of factory ammo and 2 custom loads. I chronographed them all and tested all the ammo in another 308 gasser as well. I used 3 different KAC magazines and 1 Pmag.

I’ve been a loyal KAC customer for a long time and own almost a dozen KAC rifles and suppressors and I’ve never had an issue like this. Getting the gun back not functioning after going through all the trouble to ship it was a huge disappointment. I had planned on using this gun in a .308 only match, but had to make other plans
I’m not sure what work was done on the gun to address the issues, but I would like to speak with someone who worked on it. When I explained the issues I was having before i sent the gun in, it seemed that everyone suspected it was something I was doing (not putting enough oil on the bolt, etc). When I received the gun back, I put the scope on and went right to the range. I didn’t touch it except the install the scope. The bolt was not taken down or anything. It was shot as i received it back from KAC. After several attempts to get it to run, I lubed the BCG and repeated with no luck. I then took the BCG down and cleaned and applied fresh oil and repeated. Same results. Please review the videos and give me a call at 405-***-****.
These videos are just a few of the tests I ran, but you should be able to see what’s happening. If you slow it down you can see that the bolt doesn’t appear to travel far enough to pick up a fresh round. The brass kept hitting my iPhone and the video quality isn’t the best, but it’s all I had with me. The last video shows the gun functioning fine suppressed. It ran fine suppressed with all ammo and all magazines. I was able to get .72moa with Southwest 175’s. Not to shabby for a gas gun.

Thanks

Zach Meadows

VIDEOS: (brass keeps hitting my phone and knocking it over. Sorry for the shitty video, but you can see it's not cycling properly.)
KAC BH 168 - YouTube Blackhills 168gr
IMG 8128 - YouTube Blackhills 175gr
KACSR25 - YouTube AB M118LR 2598fps avg
KACSR25 - YouTube Blackhills 168gr Pmag (different lot)
KACSR25 SW175 - YouTube Southwest Ammo 175gr
KACSR25 - YouTube LC M118LR Suppressed and Unsuppressed
 
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#3
I'd be cranky too if I was being reasonable and it took a dump on me.

First - what is the story on the buttstock (since that isn't standard) - what buffer / spring / tube are you using? Did you put any lube in there?

How many rounds though the gun in total? How many suppressed?

When you you say it did not function suppressed but now it does - what did it do exactly? Where does it eject brass now when running supressed?

Ejection - looks like your phone was @ 3:30 - is that right?

What lube are you using? I see you used a 'thin layer' - ever just run it dripping? Ever used a hint of grease and run it dripping?

My ER will eat anything but seems over gassed when shot suppressed. It keeps on chugging along as long as it is wet. I use a combo of break free and tetra grease. Shooting suppressed really blows a lot of crap back and fries off lube as well.
 
#6
Coincidental that it is shooting with the suppressor on. Port pressure has much to do with extraction issues. When you screw the can on, the amount of time the port is pressurized is significantly increased because the can increases the distance the bullet travels after it passes the port then leaves the barrel. As a result, the port is now having to intake a larger segment of gas, thereby increasing pressure, which is probably punching your BCG far back enough to allow the rifle to cycle.

Will the bolt hold open on the last shot without the can?

Did KAC tell you what ammo they were running?

I guess if you want to try something yourself, slap an aftermarket block on and try it out. I have an odd feeling that would help.

I know KAC had issues with some of their SR-15's a few years ago because they designed the gas port too small, which would cause this issue. Not that this is the case with this line of rifles, but it could just be your particular block is not opened up enough?
 
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#7
Drill out the gas port and put an adjustable gas block on it and gas it to where it needs to be for the conditions at the time. Arsenal democracy and slr make the best adjustable in my opinion. Bottom line, if you keep sending it back for an "under gassed" condition, they're just going to open the port up themselves. It will save you the money of buying springs, buffers, shipping, and whatever else everyone says you should do. The gun gun will run, I guarantee it. With an appropriate amount of lube at that.
 
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#9
I just bought the gun. It's brand new. The first time I took it to the range it wouldn't cycle unsuppressed. I sent it back to Knights to be fixed. I just got it back from Knights and it still won't cycle un-suppressed. They said it was a little under gassed and they fixed it. They quoted me 10 days, and it took much longer. What I don't get is the gun comes with a test target. If the gun wasn't cycling, how did they shoot the test target?
Just to be clear, the gun HAS been sent to KAC once to be fixed. I just got it back and it still won't cycle.
I asked KAC what was done to fix it and they said it was basically a 'trade secret' and they couldn't tell me. I asked to personally spread with a tech that was working on and they said I couldn't talk with them. My emails had to be passed through a customer service rep to the techs.

I've shot all kinds of ammo through it. Black Hills, Rem, SW 175, Copper Creek, M118LR x3 lots, etc. I've used multiple mags, etc. The gun is under gassed and will not cycle without the Mk11 suppressor on it. It runs like a champ with the MK11 suppressor on it as seen in the last video.

The stock is a factory KAC M110 stock that was on it when I sent it to KAC for repair. The gun was doing the same thing with the factory A2 stock it came with.
I'm using Slip2000 oil and have run it with a thin film of oil to wet. Again the gun runs great suppressed.

I typically wouldn't be that upset, but I just got the gun back from KAC. I've spent a ton of money and just want the gun to work. KAC should have fixed it right the first time I sent it in and not let it leave unless it was running 100%.
 
#10
Zack,

Very strange. If KAC is getting it to cycle I would suspect it needs more lube. You really need to talk to them and work out the issue. If they cannot solve your problem then I would change either the recoil spring or buffer.
 
#11
Rstrick0352 said:
Drill out the gas port and put an adjustable gas block on it and gas it to where it needs to be for the conditions at the time. Arsenal democracy and slr make the best adjustable in my opinion. Bottom line, if you keep sending it back for an "under gassed" condition, they're just going to open the port up themselves. It will save you the money of buying springs, buffers, shipping, and whatever else everyone says you should do. The gun gun will run, I guarantee it. With an appropriate amount of lube at that.
Click to expand...

My uninformed and ill thought out opinion is, Rstrick0352 has provided solid advice. The manufacture seems unable or unwilling to do the final tuning this rifle needs. Besides, an adjustable gas block is a good thing, enables greater flexibility and there by greater reliability. I'm thinking there is a problem with the hole they drilled in the barrel and when you send it in for enlarging you will hear back about the defect they found.

Well there it is, uninformed, ill conceived, but the best I can offer.
 
#12
Well it sounds like you can nail your problem down to short stroking / not enough gas. KAC should have made it right the first time. I'd let them take another look at it before I asked for my money back.

Some things to consider:

Lube: New AR's need oil and plenty of it. I have found this to be especially true with .308's during their break in period as things smooth out.
Buffer Weight: A lighter buffer may help the BCG completely travel to the rear to pick up the next round or lock the bolt back. I'm not sure what your options are if you are already using the standard weight rifle buffer. Maybe a JP SCS with a lightweight spring could help.
Gas Port Size: KAC may have drilled the gas port too small. This would surprise me for a $4K+ rifle but could be the case and wouldn't be the first.
Gas Block Alignment: It's also possible the gas port in the barrel and gas port on the gas block aren't perfectly aligned, thus restricting gas flow. This is an easy fix for clamp on gas blocks but if it has been pinned or dimpled, that's a fix that needs to be done by the factory.
 
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#13
Please DON'T go drilling on your barrel. You'll void any warranty KAC may have. You may end up with a $$$ bolt gun that you can't sell if you do that.. I've had a problem with another well know AR manufacturer on a 308 platform. It took several trips back to get it to work right (and it had a adjustable gas system from the factory).
 
#14
I asked KAC what they did to fix it and they wouldn't tell me because it was some secret trade shit or something. (see below)
I cleaned the gun before I sent it back for repair and I figured they didn't want to get their hands all dirty, so i didn't put much lube on it.
They said they reworked the gas system.



"Good Morning, Z:

We cannot provide all of the notes details due to the proprietary technical information that is not open source knowledge with KAC products, we cannot divulge any more detailed information that what has been provided.

Here are the final notes that do not contain proprietary technical information:

Weapon inspected nothing to note other than weapon carrier group not lubed well for a new weapon however this could be due to several things and does not mean that it wasn’t lubed well when customer was shooting it on the range.
Weapon shot for Carrier velocity. Gun is running on the weak side of the standard curve. Gas system will be reworked to fix this" KAC


I might end up putting an adjustable gas block on it. My intent was to build a M110 clone, but I guess I might have to live with an adjustable gas block.
Still a $4000+ should run like a champ from the factory. I shouldn't have to pay extra to make it work. You would think Knights would test shoot the gun before it shipped out. I'm wanting KAC to replace the entire gun, but I they haven't answered their phone for 2 days now so I haven't discussed this with them.
I wonder how they shot the test target the first time with it not cycling? Did they even shoot it when it left the factory the section time when I sent it in for repair?
There was no way the gun shot .7moa with it not cycling. It wasn't getting close to that when I tested it with match ammo. I'm really wondering if my 'test target' actually came from my rifle.

I've lubed the shit out of it with Slip2000 and it doesn't help anything. It runs fine suppressed so it's not the magazine. it has to be gas related I'd think.
 
#16
Did you ask what ammo they are using for test fire? Be interesting to compare versus what you are running.

If the gun is running on the low end of the power curve, that would be my number one thing to see. Also, did you check your gas rings? I would think they would check that when they worked on it, but that is an easy check.

Wes
 
#17
oubeta said:
I might end up putting an adjustable gas block on it. My intent was to build a M110 clone, but I guess I might have to live with an adjustable gas block.
Click to expand...

Doing just the gas block won't help. Normal non adjustable gas blocks are running wide open already. The problem sounds for all the world like the gas port size being too small. Drilling it out is very easy. Take it out to just smaller than the port in the adjustable GB you go with to allow for future port erosion and then go to town. The warranty naysayers have a point to an extent but what good is that warranty if they're not fixing it and you're without the gun for weeks and paying all these shipping and insuring costs. Plus, having the gas tuned just right makes recoil management that much nicer. EVERY AR I have and will ever have will be adjustable. It's worth it.
 
#18
Gas Port Size: There aren't 10 different sized drill bits on the assembly bench with the smith standing there dowsing rod in hand guessing which custom port size each barrel gets - all ERs get the same port. The only way the port could be undersized is if the block is sitting slightly askew. Ask KAC if they confirmed the block was in the proper position when they inspected the rifle. Additionally ask them if there is a means by which you can demonstrate this to yourself now.

Take a close look at the carrier and confirm that the carrier key is tight.

Take a close look at the bolt itself - extractor OK? How about the ejector?

When you changed buttstocks - did you change the buffer tube / spring / buffer? Did you lube the buffer tube?

Separate upper from lower and use a dowel - slowly depress the buffer until the spring is completely coiled - does it bind in any way?

Look carefully at your mags - any thing funny?

Using the same load - where is the gun ejecting brass both suppressed and unsuppressed? (both on a clock face and distance from the rifle).




I had one of the board favorites put an AR10 together for me years ago - same deal. Lots of checking little things, lots of lube, a little patience and it settled in after a @ 150 rounds.
 
#19
Mike_Honcho said:
Gas Port Size: There aren't 10 different sized drill bits on the assembly bench with the smith standing there dowsing rod in hand guessing which custom port size each barrel gets - all ERs get the same port. The only way the port could be undersized is if the block is sitting slightly askew. Ask KAC if they confirmed the block was in the proper position when they inspected the rifle. Additionally ask them if there is a means by which you can demonstrate this to yourself now.

Take a close look at the carrier and confirm that the carrier key is tight.

Take a close look at the bolt itself - extractor OK? How about the ejector?

When you changed buttstocks - did you change the buffer tube / spring / buffer? Did you lube the buffer tube?

Separate upper from lower and use a dowel - slowly depress the buffer until the spring is completely coiled - does it bind in any way?

Look carefully at your mags - any thing funny?

Using the same load - where is the gun ejecting brass both suppressed and unsuppressed? (both on a clock face and distance from the rifle).




I had one of the board favorites put an AR10 together for me years ago - same deal. Lots of checking little things, lots of lube, a little patience and it settled in after a @ 150 rounds.
Click to expand...


Regardless of what size drill bit the assembler had the time the gun was put together, quality barrels have made it to the public with an undersized gas port. It's happened to me and it has happened to others. Most likely that barrel came from some contracted company that KAC May or may not have complete oversight over. You're spot on with checking those other components and as long as they check out, which something tells me they will, the issue lies in the gas port. Also, brass ejection direction is not really a good indicator of gas condition. Adjusting the gas condition to where the rifle can cycle and giving it a couple extra clicks for safe measure is the right way to do it. You may not even see a difference in ejection direction through the whole process. Extractor spring tension and ejectors determine that. Hell, just adding a crane o-ring changes it pretty dramatically on its own.
 
#20
Rstrick0352 said:
Most likely that barrel came from some contracted company that KAC May or may not have complete oversight over..
Click to expand...


While I understand the reason for your comments (most any other AR vendor out there is simply an assembler of other manufacturers parts) my understanding is that every thing (including barrels post Obys) except forgings are done in house.
 
#21
The rifle is being shipped back to me after being sent back a second time.
I asked what was wrong with it and they won't tell me. They said "The information regarding the repairs is proprietary."
Why would that be a secret? It was tough to get them to tell me if they had to put a new barrel on it.

I don't see how the gun left KAC with a 'test target' with it not cycling.
I just wonder how they shot it? Then when I sent a brand new gun back to them the first time, they say they fixed it and it shot fine and send it back in the exact same condition, not cycling.
Now they say they have really fixed it this time and it's working fine. They won't let me talk with any of the techs who worked on it or tell me what the issue was.
I can't believe I had to send a $4500 gun back a 2nd time. I asked them to just replace the gun since they can't seem to fix it, but that wasn't going to happen. Hopefully they really fixed it this time and it will cycle. I would expect more from KAC.
 
#22
It's a gas issue if you're using ample lube and cleaning regularly. Drill it, or get an adjustable if that's something you're willing to deal with. You can always sell it.
 
#25
oubeta,
I now see why you suggested I get anything but a Knight's SR25 in another thread I started. I am wondering how your SR@% worked after being returned for a second time?
 
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