I sprung for one of these.  Works great for a bill.  Helped to me to determine rate changes while I was trying different combos of 3 buffers and 2 springs with my 3 uppers and lower.  (Numerous combinations to try so I was out most of the day.)

Still fairly new to full auto so I couldn't tell the diff between 600 and 700 rpm without it.

Not sure why the blue one is cheaper than the grey one.
Shot Timer

ps. The hardest part for me was resisting the impulse to fire off a few more rounds after the first burst.  The urge to pull the trigger again is strong.

Below is a link to the youtube vid of one of the SMG matches I did with the Guard.
https://www.youtube.com/watch?v=M1xytZoYemk


I was running suppressed with the MK9K, 556 Tubb spring, 9mm Kynshot, A5 tube, 3.5 oz Colt carrier weight and Guard Glock lower.
Ran problem free till the last few bays when I was getting failures to eject which I believe were due to the use of the 556 ejector spring. You can see in other threads where I removed the ejector spring and it definitely needed replacement.  
This was before I found out that CMMG was then recommending the use of their proprietary 45 Guard ejector spring for use in the 9mm as well.

Same config as above (again suppressed) but switching to the Endomags has been fine.

Then switching to my dynamic LIGHTER 2.1 oz Tungsten weight results in malfunctions every 3 rounds or so....(again talking suppressed ONLY - Unsuppressed is GREAT!!!).
Likewise, using the dynamic tungsten weight and the Tubb 300 BLK weak spring results in a jam like EVERY round. (again talking suppressed ONLY - Unsuppressed is GREAT!!!)
I think the weak spring jams more since doesn't have the power to resist the increase in BCG velocity when suppressed as much as the stronger 556 Tubb spring can.

Sooo.....the static 3.5 Oz weight and NO weight works...and for that matter when I tested a static CMMG 2.0 oz steel weight it worked as well.

I think there is a considerable increase in the BCG velocity when adding the suppressor and the dynamic weight is going forward so fast that it is putting the brakes on the BCG so much so that it is causing it to jam.

I already have the strongest conical spring from McMaster Carr...so may try going back to the 20 lb multiwave disc spring.

I have also mentioned before that the standard Kynshot RB5000 buffer is very stiff...seems identical to the old Enidine carbine buffer and I don't like either one.
The RB5000L is the light version and the easiest to compress.
The 9mm RB5007 is in the middle.

I think maybe going to the RB5000 may help in this scenario for suppressed usage.
I know HDSledge as the RB5005 which I have ordered and want to test as well....I don't know where it fits in the compression strength with the other Kynshot models I have.

Of course going to any of these other Kynshot 3.25" offerings is going to require usage of the spacer in the A5 tube or going back to the carbine tube...which I don't think I'm gonna do since everything else is working great for me.

does that one have RoF built in so you don't have to do the math?
My PACT MKIV keeps crapping out.
Also make sure you count how many rounds you load your mag and that your timer counts the right amount or you could be getting BS data.
The PACT has an 'echo' factor that you can adjust when it counts wrong.  
I typically load 10 rounds and do 10 round mag dumps.  I never just run a few rounds and trust the timer counted right.

Or you can just record the string & let the bumpfire guys figure out your rate of fire - they're good @ it.

Yes it has the rpm feature.  Set it on rpm, hit the button for the beep, fire away.  I kept it down to 3 round bursts and repeated a couple times to get an average.  If I recall I set the sensitivity to somewhere mid range.  It worked like a charm and helped me discern what felt like subtle differences in rate that were actually pretty big.

This part is off topic but what surprised me the most was the difference in RoF and feel between subsonic .300 BLK and supers with the same spring/buffer combo in my lower.  Subs were at around 700 or so and soft, supers were over 950 and hella recoil impulse.  Impossible for me to stay on target.  Not sure what buffer/spring I need to keep that under control so I am just sticking to subs.

I personally don't think 3 is enough.  5 rounds at least for documenting RoF.  Like I mentioned before I do 10 round min.

Last visit was my first time to measure RoF.  What you suggest makes sense since I suppose the rifle settles into a more stable rhythm after a few rounds?  Next time out I will measure longer strings.  Curious to see if the rate varies much.

Hdllo,

I read your c3 junkie blog.  Very nice of you to share all this info!  I will subscribe to this thread, I am still catching up on it. You preferred me here from another thread.

I see tou are putting a weight in the tail of the carrier w a conical spring.  Is the spring in front or behind the weight??

Have tou seen the LARB (IIRC) buffer which has sprung weights but opposite of how the weights of an A5 buffer are sprung?  It also has an anti tilt dome on its head.

So after posting about my setup, I went back and took a closer look with the link right up against the bottom of the rear takedown lug.  With the cut-down paddle, there's enough space to clear an unmodified carrier weight.  So this means I can use a solid piece of tungsten; with no top grove or bottom profiling.  I can even make it a little longer now that the springs have compressed, say, 1.25".  A quick run through a weight calculator spits out 4.28oz.  Much better!

It is just as depicted in my picture....
Pin in the carrier, then a thick SS washer, then spring, then weight.

I have seen the LARB before but forgot about it till you mentioned it.  Looks similar to what I'm doing but I'm doing it in the carrier + with the Kynshot get some hydraulic dampening.
I was thinking about doing something similar to the LARB with a spring inside an A5 buffer using heavybuffer.com's A5 kit that I have with a various assortment of weights and getting my own springs to put inside.

I have also mentioned that I was impressed with the Griffin SOB buffer until mine fell apart but I rebuilt it as discussed here: https://www.ar15.com/forums/armory/charging-handle-on-suppressed-5-56-AR/20-494855/&page=2
It worked well unsuppressed but didn't like it suppressed.(with the Guard)

If you read the old data on my tuning page, I initially started testing the Guard with a custom 5.1 oz static tungsten weight and it was too heavy to be reliable for me and was bouncy.
Never did test that much weight in a dynamic setup.
I also found my Colt 3.5 oz static weight to be bouncy.  
Will be interesting to see what your results are with a dynamic weight beyond the 2.2 oz that I've tested with.

Too bad tuning is so subjective.  It would be cool if there was a set of formulas with variables to quantify a mathematically ideal end result for whatever system is being tuned.  Not a math whiz myself but it seems doable.

Some of the variables would be recoil force, carrier/bolt mass, dynamic carrier insert mass, carrier insert spring(s) force, buffer mass (hydraulic adds factors), buffer spring force, buffer travel distance, carrier insert travel distance, event time and duration, friction allowance (fudge).  Have no idea how recoil force on the bolt/carrier can be calculated but that would probably be the starting point.

Sound like a fun project for a genius, meaning I am not the one who can figure it out.

I mentioned on another thread that a friend of mine was working on an accelerometer that communicated over bluetooth to your smartphone to give you quantitative numbers on the recoil.  So you can change one thing at a time and know how well it was working.  He got busy with his real job and dropped it but my partner met a vendor at last years Shot Show working on the same thing so maybe we can get something like that soon.

BTW, I updated my website for some technical details on all the hydraulic buffers I have.  I document the weight and amount of compressive force required on the different hydraulic buffers.
http://c3junkie.com/?page_id=430

Pictured below is just the 9mm version.  Go to my link above to see the data on the other 4 buffers.

Did he plan to mount it on the barrel or farther back somewhere?  Check out this site where you can input variables and get an estimated recoil energy in ft.lbs. from ammo as well as other helpful data.
Recoil Calculator

Yes, the sensor was mounted to the rail.  So anywhere you wanted to put it where you had a rail.  In order to rule out the human factor, we would put the rifle in a lead sled and shoot it.  
Way more advanced than the link you referenced.  Doing things that are hard to quantify like what I am trying to do....blowing a lot of ammo and going by feel vs using something like that.  Being able to quantitatively know how much each change you make in regards to the felt recoil would be awesome.  We did a bunch of testing on various muzzle breaks as well.  It could tell you where the energy was going straight in-line, X, Y, Z axis etc..

Trying to get a handle on what the goal would be.  You need enough motion and energy transferred along the part path so things don't just stop moving.  But you want to cancel out as much terminal (left over) felt energy to your shoulder as possible.  Cancel out too much and you get failures like you did when you popped on the can.

Fire, eject, feed a round into the chamber and go back into battery for the next shot with little or no felt recoil in a lightweight weapon.  Impossible?

Would love to see it happen now that I am hooked on full auto.

Pretty much....Yes, in a perfect world, it would shoot like a water pistol but obviously not possible.  A lot comes down to the human factor.  Many people don't shoot full auto and when they do can't really tell a difference with all the tuning I'm doing unless it is very drastic like going from a blowback 9mm to delayed blowback.
Shooting unsuppressed, I'm at the point where I need to bring the MP5 out to run it side by side to know how I'm doing.  
For suppressed, I don't need even to bring the MP5 out as I know by feel I'm not close enough yet in regards to FA smoothness.
However, as stated before, I already have the MP5 beat with the Guard suppressed when it comes to cyclic rate.  It is flatness/smoothness of firing bursts that needs work.

I'm still amazed that all my uppers feel good with the same buffer and spring.  Except for supersonic .300 BLK.  Not good.  Subs make it purr like a cat though.

My favorite is the 9 mm Banshee upper by far.  I may have mentioned this before but I hope my can doesn't screw up the tune.

I know you are using the Kynshot RB5005 but I can't recall what you are using for your buffer spring and tube.  Rather than get off track, start another thread here in the M16 forum to discuss details of your setup and possible options.

The Guard/Banshee is my go to config with the RB5005, a standard carbine spring, and the Magpul CTR stock, which has a shorter tube than the A5.  Not as short as the LWRC UCIW which I gave up on.  It was too short to give me any options on the buffer and spring.

I'll post a thread as you suggested for the full setup with other uppers.  Funny thing though the CMMG Guard/Banshee stole the show (love it) and I think the other uppers won't get much use for a while.

Yep I'm cataloging different configurations I've come across (mostly yours) to get a good baseline to start from.  I'm thinking the 2.5-3.0oz range might be about right.  Also, not sure if I will keep the dual springs; may try a single like yours (would also allow more mass if needed)

I'm wanting to use this config for double duty in both 9mm and 45 but will prob start tuning the 45 first.  It's given me less problems than the 9mm thus far.

Tungsten hopefully delivers tomorrow so I can start tinkering....  

When i forst saw the LARB i was skeptical b/c it does ilthe opposite of the A5...but upon further consideration I realized that the benefit of the A5 is not necessary how the mass is secured foreward particularly, but that from shot to shot the initial mass of a sustem is consistent.  The LARB would do this, but instead of the weight stack being a static mass it would compress the buffer stack spring at unlocking like w your set up in the carrier tail.  What is not clear to me is when in the action cycle the buffer spring would extend again?  Sometime before the action bottoms out or at that point? ...i suppose that the spring whould begin to expand again after the acceleration ends, when the carrier has reached its max velocity and then begins to be slowed by the resistance of the action spring, so maybe this keeps you from gettingthe deadblowbefffect in your shoulder at the end if the cycle?  But on the other hand, the dead blowbeffect at the rear of the cycle helps the action have some “hang time” allowing the case to eject fully and the magazine to present the next cartridge, tho that may not really matter as that firing port weapon runs at over 1000rpm w/o a buffer iirc...

As the action begins to accelerate forward the weight stack would be to the rear for two reasons, then as it goes back into battery the weight stack would compress the spring and add some force to the chamvering...

Michael Bell youtube channel did some tests on a RR w an LARB and other buffers of the same weight and detrtmibed that it slightly reduced ROF compared to an other buffer.

I believe the weight stack should be sprung one way or another, but i cannot say which is better really...

Looks like the SOB is basically like the original telescoping M16 buffer, tho im not sure if that one had the internal sliding weights as well

Are you able to record the force as a function of stroke distance for compression of the hydraulic buffer?  I think this would be critical information to allow you to integrate under that curve and determine the total work required to compress the buffer.  I'm not sure why Kynshot chose the stroke lengths that they did.  I would think that a longer stroke with maybe a little less max force would make for an even softer shooting gun.

Esox

^the stroke legnth is chosen because it is basically the max distance the bcg can trave from the rrar of the bolt catch till the action bottoms out.  That way there is less chancebthe buffer can induce a shirt stroke w weaker ammo or when the gun is held loosely etc

I think the benefit of the A5 is just the use of the rifle length spring and don't think the buffer has anything to do with the benefits of the A5....however note that the default A5 configuration comes with a 5.3 oz buffer.  The regular carbine H3 buffer is also 5.3 oz.

I think by just using the Tubb 556 spring which works in all 3 buffer tube lengths, carbine, A5 and rifle, you can see basically the same results as the A5.
556 Tubb flatwire spring + carbine H3 buffer = basically same results as the A5.  I tested all of this here: http://c3junkie.com/?page_id=654

The LARB and my carrier configuration are both trying to minimize that initial recoil impulse...in order to do that you need to have the spring towards the muzzle and the weight towards your shoulder.

There are just so many variables...I wouldn't get any shooting done if all I did was record all of them
I document a lot of this stuff for my own reference and share with everyone to get different perspectives as well.

I think the reason I never liked the Enidine or standard Kynshot RB5000 buffer is that with it requiring 9 lbs to compress and a carbine buffer spring having around 9 lbs of force with the BCG forward, I don't think the hydraulic action was really doing anything unless you have an overgassed gun or high recoiling straight blowback pistol caliber where it is slamming into your shoulder.

I am not discrediting the initial recoil impulse though....I'm guessing even at 9 lbs to compress the buffer and 9lbs from the buffer spring it probably does absorb some shock as soon as the BCG/bolt begins to move, I just think that it is so stiff that the energy just ends up transferring into the buffer spring.  While the 5 lb hydraulics are absorbing/compressing more at that initial impulse.

I could certainly be wrong as I don't have anything to back that up other than what I perceive from my testing.

I'm not saying there is no place for the 9lb hydraulic versions either.  There are some scenarios where you need this like when you can't control the gas and have an overgassed gun, straight blowback or delayed blowback where there is no gas to control etc..

On that note, I've gotten better results using my weight suppressed with the Guard, 308 Tubb spring and the stiff RB5000 buffer but it is not 100% reliable.  I think there still is just too much BCG velocity when you add a suppressor to the Guard for my spring loaded weight.

I spoke to a friend of mine about the situation and he mentioned trying a 45 cal suppressor to reduce the back pressure.  Pretty sure it crossed my mind before but had thought I could get it resolved with various buffer spring, buffers etc....I tried many combinations yesterday and it just either too fast or unreliable with any weight in the carrier suppressed.

Right now, the best for me suppressed is what I posted back on the previous page.....A5 tube + 556 Tubb and no weight in the carrier.  Little too fast than I'd like at 686 RPM and not as flat as I want either.

Fascinating.  You're saying  the buffer begins to compress with the initial stroke much like the dynamic weight in the carrier?  Which is why a 5lb vs 9lb compression weight makes a difference in recoil impulse?  It makes perfect sense.

I always thought the magic of Kynshots took place at the end of the stoke, acting like normal buffers up until then.  At that point the hydraulic dampening comes into play as they compress to smooth out the bottoming in the buffer tube, much like a shock absorber.

I'd love it if Kynshot had a slo-mo video with a cutaway buffer tube showing how the magic happens

They could easily have a longer stroke length.  The important part is that the compressed length is still short enough to allow the bolt catch to engage AND the total energy absorbed by the hydraulic buffer + spring combination is less (ideally just a bit less) than the recoil energy...otherwise it would short stroke.

Is it possible that the initial recoil impulse might be the limiting factor with the RDB Guard system?  For the first fraction of a second, the recoil impulse should be similar to a bolt action 9mm as all of the energy within that timeframe is transferred directly to your shoulder while the bolt is rotating.  After that, the energy is stored in the spring and eventually the hydraulic buffer and redistributed to your shoulder over a longer period of time, making the felt recoil less (longer softer push vs. shorter harder push...but each with the same total energy).  Maybe the roller lock system design doesn't have this initial fraction of second with 'direct' recoil?

One other thing I have seemed to notice (my opinion) is that the slight amount of advanced primer ignition (API) in an open bolt fixed firing pin SMG like the M11/9mm helps to tame recoil in a blowback gun.

Once again, thanks for the incredible work you have done on this.  I really enjoy reading about it and hope to experiment with it something this spring.

Esox

A lot of the info is new to me and I am learning quite a bit.  The whole idea of the RDB is to not only to slow down the bolt so pressures can equalize a bit but to expend recoil energy as it is forced from rest into rotation.  Correct?  In practice it must have a softer recoil than a bolt action 9.

I personally do not think that is the case.  I think the Guard has a significantly softer recoil than a blowback 9mm.  If it didn't I wouldn't be putting in all this effort.

I've commented about that many times.  If you take two UZI's one open bolt and one closed bolt and shoot them side by side even in semi, the open bolt is way smoother.

Open bolt gun bolts can afford to be lighter as the bolt still settling into battery retards the action opening up.  On closed bolts you have no forward momentum at discharge so it has to be heavier.

Really strange the guard speeds up that much from the can...

Seems strange to me that you dont think a sprung weight stack, about 5 oz worth, would cause irregularities in the action if it sometimes does not impede the initial rearward motion of the action.

I think you got that backwards, most open bolt SMG's are heavier since they almost all have a heavy bolt.  UZI, Sterling, Beretta PM12 etc.  All have nice RoF's in the 600 RPM range and all have heavy bolts.
What CLOSED bolt SMG has RoF in the 600 RPM range and still smooth?  I don't think anything exists that doesn't have some kind of delay mechanism.  Full size MP5, has a light bolt since it is roller delayed but still a high RoF, I clocked the full size MP5 at 789 RPM.
You can do that with the Colt SMG by throwing more mass to the carrier and using a weak spring.  
I documented that here in my old blowback setup: http://www.c3junkie.com/m16/9mm/5inch.html
Running all the way down to 488 RPM but very bouncy.
It isn't a matter of what I 'think'....it is what I've actually tested.  
I think I tried at least 20 different variations last weekend.  All testing suppressed with spring loaded weight in the carrier failed.
I also did try an A5 buffer with a spring inside and 1 tungsten weight and 1 steel weight which weighed in at 6.2 oz total and that was rough shooting and not reliable.
Every other configuration I tried that was reliable was either too fast or too rough shooting for my liking.

There is definitely a great increase in BCG velocity when adding a suppressor to the Guard.  The malfunctions look like failures to eject.  I have mentioned several times, that Guard uses a proprietary ejector spring and that I think the Guard kills standard 556 ejector springs pretty quickly.  I took pictures of this in the other Guard thread.  The Guard ejector spring is shorter but stronger than a 556 Ejector spring as I think it is thicker gauge wire.  When I would run into malfunctions I would swap out my whole BCG and see if my second one would have issues as well as I wasn't shooting the second BCG as much.

I just checked my Guard ejector springs in both of my BCG's and they both feel weak to me....

They are currently strong enough for non-suppressed fire but I think going suppressed has killed them both.  I'm thinking if I replace them now, many of the tests I did last weekend will work now.
I've stated before that I think this is a weak point of the Guard system.  A fixed ejector would have been better but would require way more work and possibly a proprietary upper with an ejector in the upper like the Sig MPX.

All that said, if nothing else comes on the market, may just have to stock up on extra ejector springs and plan on replacing them regularly with the Guard especially suppressed.

I'm going to swap both ejector springs but still try using 40 SW and 45 suppressors to see if that drops the cyclic rate which should also in turn help extend the ejector spring life.

This is disappointing to hear, as suppression is the main reason I want a Guard/9mm PDW type gun.  Then again, mine will be mostly for "hobby".  It's unlikely to see as many rounds as yours, and I'm likely to be less critical of the operation.

It is unfortunate but it is what it is...
I just posted this up for my own reference to pay attention to the ejector spring strengths:
http://c3junkie.com/?page_id=882

Yup.  Likely still better than Colt style blowback.  It's unlikely I'll get an MP5, leaving the Scorpion Evo as the next contender.  The AR would be nice for parts commonality and adjustability (one reason you prefer it to the MP5).

When you think about the MP5, I use the #28 locking piece for my MP5K which is what HK recommends for when using 147 Gr bullets and suppressed.

CMMG had mentioned before that the operating window on the 9mm Guard was big and they could adjust the angles on the bolt lugs for a slower RoF, I would hope they would do that which I think would help for suppressed usage...like offer a bolt that is optimized for suppressed usage.  I know they recommend adding weight to the carrier for suppressed usage.  Maybe just offering a different suppressed bolt w/ different angles on the bolt would be an option.  
I think this is more probable than offering a 'full auto' optimized bolt since most people aren't running FA.

Do they recommend a particular weight from the tuning kit?

OP, you can adjust the angles on the lugs.  

You could also add angles on the bbl extension lugs...

I recall the tuning kit saying 2oz for suppressed use or +P ammo, 3oz for suppressed AND +P.

Thanks.  I've got the Banshee with the 5" barrel do you think the 3 inch shorter barrel than the Guard will make for a noticeable difference?

I only shot my 9mm Guard a little before chopping the barrel down to ~6.5" and that was with no weight in the carrier.  After I cut it, I bought the CMMG tuning kit and settled on the 2oz static weight (before experimenting with dynamic weight).  I did notice a little difference but hard to say if it was from a shorter barrel, added weight, or a combo of the two.

Already thinking about doing something similar but not messing with the original Guard bolt.
I need to add material to the current angle....
I want it to unlock slower....which would also mean I would rather leave the extension lugs alone as well.

I had mentioned before that I had worked with another manufacturer several years ago on a 9mm piston upper and we used a 5.45x39 bolt which has a .40" bolt face which worked perfectly for 9mm.
It ran well and ironically we gave up when we realized the built in ejector in the bolt was going to be a problem (occasional failures to eject) and at the time we didn't want to deal with getting a custom bolt/carrier made w/ a slot for a fixed ejector in the upper...
I knew this going into the Guard design.  However with a piston, the oprod smacks the impact lug on the carrier and the bolt is PULLED from the round vs a standard AR or in this case the Guard, the round PUSHES on the bolt.  
I thought that this would be why the ejector may not be an issue in the Guard but was always skeptical on the ejector in the back of my mind as I was already tainted from previous experience.

All that said, I have an extra 5.45x39 bolt laying around and thinking about getting it modified to fit in the Guard carrier and then cutting the angles on the lugs w/ a Dremel cut off tool.

So I got this done...
On the left is the Guard 9mm bolt, the two in the middle are 5.45 bolts that I had my buddy turn down on his lathe so they match the Guard and fit in the Guard carrier and the spring goes over the tail of the bolt.  On the right is a 556 bolt for comparison showing the radius that needed to be removed.


I used a Dremel to grind a less aggressive angle on the lugs.  It is amazingly smooth and a super slow RoF suppressed...In this case my Gemtech MK9K.
This is with NO weight in the carrier, 9mm Kynshot, 300 BLK Tubb flat spring and A5 buffer tube.


I think this is the slowest and smoothest closed bolt 9mm SMG I've ever fired.....downside is that I think with the Guard system, the more you try to delay it, the faster it kills the ejector spring.
My modified 5.45 bolt and the ejector spring that was new after about only 100 rounds.  (3) 30 round mags and a few singles that I fired to figure out the right angle to use.
The ejector spring was beat up so bad that there was no tension on the ejector...it was flopping around in the bolt.


If only the Guard had a fixed ejector.....I'm eyeballing my Sig MPX to see what kind of surgery could be done on the Guard to get a fixed ejector on it like the MPX....

This is a pretty awesome development!

Is there any type of spring that would not fatigue as fast?  The Tubbs ones for example?

Now that is all kinds of awesome, well done!!

-Do you know the approx angle you cut?

-Type of end tool...Sanding drum?  Cut off wheel?

-Are the gas rings left on the bolt for stability in the carrier?

-How smooth compared to the MP5?

-Did you try it with the dynamic weight?

Before I left the range, I put a Tubbs in there and ran another 30 round Endomag.  Felt it and it had already weakened considerably.  I took it apart when I got home and it was deformed like all the other ones I've worn out before.  Every ejector spring I've tried have all suffered the same fate and none seem any stronger in the Guard.  I've tried, no name ones, Sig, Wilson Combat, Tubb, Sprinco....none seem to be able to last that long in the Guard when tuned to run this slow.

Nah...just eyeballed it.
Cut off wheel
No particular reason.  didn't seam to cause an issue so just left it on there.
Smoother.  Like I mentioned, it is the smoothest closed bolt SMG I've ever fired...and I've fired a lot.
No, if you see the pics, it was raining out at the range and getting cold so didn't spend much time out there.  I wanted to try the dynamic weight with the standard Guard bolt w/ a 40SW and 45 can but didn't bother.  I was so impressed with the modified 5.45 bolt that I figured that I should really focus on this path.  
The whole point of putting the weight in the carrier was that I don't think the Guard was delaying enough.  Changing the angle fixed that and with no additional reciprocating mass.

I know I had mentioned before that if you put a rod down the bore and push on the bolt it would rotate right away which I know did before...well I did this again before cutting the lugs to get a feel for how much to do.  I first did it again with the factory Guard bolt and it locked up and didn't move...like the MP5 does.  I had to give it a light tap with a hammer to unlock the bolt.  This was with both of my Guard uppers.  I also felt the bolt move about a mm or so before the lugs of the bolt would hit the extension lugs.  I think with this gap that when the round is fired that it launches the ejector inside the bolt...which kills the spring.  I also noticed the ejector retaining pin was notched pretty hard...may get sheared off if shot more.

Anyways, the 5.45 bolt had about the same amount of gap as the factory Guard bolt.
I started out with very little angle and would tap the rod with a hammer to where it would unlock.....If I didn't cut any angle, it wouldn't unlock at all...obviously...
When I tried it at the range w/ live ammo, it was a single shot and it was stupid quiet.  It was comical how quiet it was.  
I had to pull out the MP5 to hear it side by side and it was quieter than the MP5 because there was no action noise while the MP5 would cycle and click the brass out.
I gradually increased the angle till it would cycle.  Didn't take long..but it ended up looking like the factory Guard angle.  Of course I'm doing this by hand and its probably not consistent.

At this point, I'm thinking to maybe try opening up the ejector spring hole to take a 308 ejector and spring and modify both to fit.   The 308 ejector spring is way beefier but who knows how long it will last.  A fixed ejector is really the way to go and still considering doing that.