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JMoto

Tubb CWS (carrier weight system) review

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TUBB CWS (carrier weight system)

Reason for my purchase: I own a DPMS SASS and was having issues with timing/extraction. I was getting an aggressive extractor mark on all cases. I ran 400 rounds of factory match ammunition through the rifle, all of which displayed this mark. 32 rounds later (load development) I was getting pulled rims and eventually the extractor broke on round 432. In the process of handloading I was also getting some casehead swipe at what I felt was a relatively low load of 43 grains of varget.

Now on to the review itself

The product itself comes in and looks simple enough, but after looking at it I see something that can be a no-go for certain users. I will go over that later.

Here is all of the stuff that comes in the packaging. Woo Hoo INSTRUCTIONS

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The installation is easy enough, it fits into the bolt carrier and whichever weight you use slips into the back. No screws and no clips to break, lose or fall off. I like this!

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Here is the part i do not like. If you look you can see there is something sticking out .08 inches. That is the flange that holds the weight. This is needed so the weight holder is not flopping around and doing things it is not supposed to do.

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At the range: I did not take any pictures at the range because I truly hate those guys who take pictures of their own guns at the range. It has benches and target stands and rangemasters, move along, nothing to see here.

I did not notice any change in recoil with the CWS and there were no changes to the function of the rifle. I put 50 rounds downrange and experienced no failures related to the CWS. I tried out a C-products mag and had a failure to feed on round three with factory match ammunition. I single loaded during my testing of the handloads. So in my case there was no adverse effects as far as reliability was concerned.

After the range

The case on the left is a factory piece of gold medal match 168gr. Take note of the heavy extractor mark. The case on the right is a handload of 44.3 gr of varget with a 168 SMK. Notice that the extractor mark is there, but much less pronounced. You can also see there is a "swipe" on this same case. I am not sure where this came from, I pulled the extractor assuming there would be a burr on it but there was not.

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On the left you have a piece of FGMM brass, 43gr varget 168 SMK. Look next to the FC headstamp and you will notice a "smear" this is casehead swipe caused by the case being forced up against the bolt face/ejector while the bolt is rotating to eject the case. This was fired prior to my initial extractor failure and was prior to the CWS installation. The case on the right is post CWS install and was 44.3 gr of varget. So here we had more pressure and a smaller amount of casehead swipe. I feel this is indicative of the CWS allowing chamber pressure to decrease IE increasing lock time. This is one of the things it was designed to do.

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Here is another photo of the "smear" on the outer edge of the rim that did not occur until the new extractor and CWS install. It really stands out on the dirty brass but it if very hard to feel, but it is there. I was baking in 90+ degrees of sun for a few hours and did not have enough sense to pull the CWS out and see if it changed that "smear" at all.

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CLIFF'S NOTES

CWS does increase lock time, allowing chamber pressure to drop and allow the case to be released from the chamber without causing undo wear on the case/extractor

CWS does not (in my case) cause any ill effect on the physical function of the rifle

If I had it all to do over again, I would probably have put an adjustable gas block on the rifle... oh wait, I have a DPMS SASS and no infinitely adjustable gas block on the market will fit it.  This will do, but it is not ideal for me personally. I have a feeling that with a rifle length gas system the CWS would make the recoil impulse more linear and make the recoil feel lighter. If the 308 AR platform is anything like the smaller platform with midlength or carbine gas systems 90% of the gas could be blocked and the rifle would still cycle with full loads.

NOTES FROM THE AUTHOR:

The one thing I do not like is that you can no longer pull the rear pin ALONE to service the rifle. If this is your duty gun or your fightin' gun do not use this product! You will need to pull both pins and finagle the upper off. I tried it on several AR rifles and all of them had to do this. I could force it ON a couple but it is not ideal, and you certainly could not manhandle it off as it would put unwanted force on the front part of the receiver that holds the cross pin. On some AR lowers this are is very thin and we would not you to die because you had to fiddle with a rifle that failed.

I am a firm believer that your duty gun/service rifle should be easy to service and you should train for failures. This part WILL INCREASE the time it takes to do an emergency bolt swap or clear a blown primer from your rifle.

My extractor: After looking at my brass i thought there was a burr or rough edge on the extractor that was disfiguring the rim, but after pulling it off of the bolt I see no such burr. This extractor is actually much nicer than my factory unit which had several sharp edges.

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here is what extractor failure does to your cases

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I'm not sure if I missed a previous post from you on this, but from what I've read about this in the forum, I understand the delayed unlocking of the bolt caused by the extra weight  is supposed to be especially useful with hot loaded ammo. Are you going to be shooting handloads? if so, I'd be interested on load data to go along with the photo's if possible, so I can better judge the effectiveness of the device for reducing pressure problems caused by the bolt unlocking too soon with the hot loads.

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So you can't shot gun the upper & lower ,to clean & inspect.

Like you said for a bench rifle ,that's not a problem . Service rifle ,well maybe & maybe not . I can see your point though .

Is this what they were talking about that would help the guy who had the buffer stop getting beat up, because the BCG was too deep into the upper or what ever ?

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I'm not sure if I missed a previous post from you on this, but from what I've read about this in the forum, I understand the delayed unlocking of the bolt caused by the extra weight  is supposed to be especially useful with hot loaded ammo. Are you going to be shooting handloads? if so, I'd be interested on load data to go along with the photo's if possible, so I can better judge the effectiveness of the device for reducing pressure problems caused by the bolt unlocking too soon with the hot loads.

The problem I am getting is with factory loaded FGMM and others. The rim is getting beat up, I am actually in the process of getting photos of my brass before the installation, tanks for reminding me. This also caused premature extractor failure. I was just starting load development when the failure occurred, but looking back at brass from factory loads showed me that I had gotten lazy during my inspection process with factory loads as well. I will share my load data in this thread as well.

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So you can't shot gun the upper & lower ,to clean & inspect.

Like you said for a bench rifle ,that's not a problem . Service rifle ,well maybe & maybe not . I can see your point though .

Is this what they were talking about that would help the guy who had the buffer stop getting beat up, because the BCG was too deep into the upper or what ever ?

Correct, you CANNOT shotgun/break the action by simply pulling the the rear pin. The front pin MUST be removed so you can slightly pull the upper forward in order for the CWS to clear. It is only .08 in but it is enough to prohibit standard breakdown. I used a poor term when I said "service rifle" I meant a rifle used my members of the armed services and the like. I should probably have said "combat rifle"

I think this would help with the buffer being beaten up as that is generally caused by excess gas in the system forcing the buffer to get torn up by the carrier striking it with excessive force. The system staying "locked" longer may give the gas more time to dissipate. Over thinking it, this extended lock time may also allow for a more linear movement of the carrier because the bolt and carrier are not fighting to extract the brass before it has contracted from the walls of the chamber.

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Is this what they were talking about that would help the guy who had the buffer stop getting beat up, because the BCG was too deep into the upper or what ever ?

Yes, completely.  I'm heading out in a few minutes to shoot two rifles with this in them - one is starting to get beat up around the edges of the buffer.  Only long-term testing/shooting will confirm, but I have very slight "problems" with one particular rifle.  A small amount of contact, one machining process "not quite right," and my buffer does contact the stop when the rifle if closed/pinned. 

This part will eliminate that problem.

Function check on the rifle (both, actually, with the .308 AR) shows that I can still lock the bolt back manually, and with an empty mag in place, so the extra 0.080" that this piece adds to the length of the BCG doesn't affect rifle function in any negative way.  <thumbsup>

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Function check on the rifle (both, actually, with the .308 AR) shows that I can still lock the bolt back manually, and with an empty mag in place, so the extra 0.080" that this piece adds to the length of the BCG doesn't affect rifle function in any negative way.  <thumbsup>

Yeah, I had to trim a bit off of the buffer so that there was a bit of a gap for the bolt stop. There was a hair of clearance but I wanted a bit more. I am still a bit shy of the gap the instructions recommended but i the part does not do what I wanted then I still have an "almost spec" buffer.

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Well, back from the range, and the results are...  WOW!!!  ;D

BIIIIIG difference in the .308 AR recoil - HUGE!  I went straight to the heavy insert, and that was not a mistake at all.  Felt recoil is radically different.  In 100-yard shots before, the recoil was heavy enough that I couldn't even keep the scope on target to see impact or round placement - not now.  I'm not saying it "eliminates" recoil, but it sure does cut it down.  What an improvement.  <thumbsup>

Now, for the 16" 5.56 gun.  This is a 16" midlength with a Spike's T2 buffer in it already.  It's a soft shooter.  I used the carrier and lighter steel weight in this one, and shot it.  Immense difference.  I was shooting 55gr UMC bulk ammo, so this stuff isn't super high powered or anything.  I decided to try the heavy insert in there just to see if it would function - YES!  With the heavy insert, it barely has felt recoil at all.  I can actually fire, and the scope hardly even "wiggles" on the target.  I was joking about thinking it would recoil like a .22LR, but that's exactly what it does.  I'll try to get video tomorrow in the riverbed shoot-fest we've got happening.  ;D

This product is worth every single penny, even if it was double the price. 

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I'll be more interested in what effects it has on his brass & extractor .

Timing or premature extraction can cause the problems he's having . Braking an extractor is on the extreme side of it .

I would look into a tight or rough chamber also.

Whats the round count through this rifle ?

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I'll be more interested in what effects it has on his brass & extractor .

Timing or premature extraction can cause the problems he's having . Braking an extractor is on the extreme side of it .

I would look into a tight or rough chamber also.

Whats the round count through this rifle ?

432 rounds at time of failure. I am off to the range and we shall see what happens.

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I am absolutely beat, my review will be pushed off until tomorrow night after work. It handled the handloads better, but my new extractor has a burr on it which was sort of eating the rim on extraction. It was not too bad, the brass is still usable.

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if all reports come  back positive, and long term testing provides no ill affects, can we get a grooup buy? <munch> i think this would be an item we could generate enough interest among members if it continues to work

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Review is up, I think I have sun stroke so please forgive me if it is scattered about a tad. There is a possibility some of it is in German, Japanese, Spanish, and Gibberish. If so I will correct it later.

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ahhh, not used to folks working like that  ;D

Oh, sorry. I figured it would be easier than having folks dig through multiple pages to find it.  If it needs to be in a new section or something, feel free.

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