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Quarter bore site gone?

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Hey guys, I just got my approval for my RDIAS and am trying to figure out timing/shims.  I remeber looking at quarterbore.com a while back but now it looks like the site is gone.  Anybody know a source for all that knowledge?  Wish I'd printed it all off now....

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50 minutes ago, STEPPONE said:

Thanks, I'll check these out

I just found this as well, I ripped it from his site long time ago



The hammer should be released from the auto sear with about a .083 gap between the face of the carrier and the back of the barrel extension (drill bits through the front of the ejection port work well as the gauge).

To adjust the hammer release, options are to either tune the auto sear, or to just adjust the carrier bottom trip edge back to time correctly.


Before you do anything, step back and take an overall look at the problem To start off, there is very little barrel after the gas port on the 10.5-barrel. This means that that once the bullet passes the port, there is very little time for the barrel to pressurize the gas tube before the bullet leaves the barrel and is lost out the muzzle. Because of this, the barrel gas port is enlarged to allow more pressure to flow into the gas tube and unlock the bolt. The problem is that the enlarged port produces very high action working pressure that has a high/quick spike and when the bolt unlocks, it does so very violently. Since now the bolt is unlocking while the barrel is still under high pressure, the spent case is still under pressure and the case is still pressure bonded to the chamber wall. This is the reason that the extractor slips off the case rim on the unlock cycle, and the use of an extra strong extractor spring or D-fender is used. Now that you have the bolt unlocking, getting the case out of the chamber, and the bolt/carrier full stroking on a A-2 butt stock rifle you are set. But if the rifle is a CAR, you have just run into the next problem, which is the bolt carriers speed is way faster than normal and the standard Car buffer is having a hard time controlling the stroke. Instead of the buffer stalling at the rear of the receiver extension tube, it is deflected and the return stroke is faster than normal. This leads to the bolt bouncing open on lock, due to the buffer not working as a dead blow device, and the rifle will not run in full auto mode due to the hammer striking the firing pin with the bolt partially open. The way that a larger volume gas tube works is that is softens the gas spike and since the pressure wave is away from the gas port, the tube will stay pressurized after the bullet leaves the barrel, and not fully drain back out the port. The stronger extractor force, applied by the stronger spring or D-fender, allows the extractor to pull the pressure bounded case out out/off the chamber walls. The heaver buffer allows the faster carrier speed to be controlled and lessens bolt bounce at lock. But still keep in mind that due to the lack of barrel past the gas port, there is very little operating/pressure margin error. What is needed is the added barrel length after the gas port, or a device that will create the backpressure needed, hence a suppressor or moderator. Bottom line is that unless you want the brain damage that comes with tuning the rifle to the 10.5” barrel and the cost of parts, just have him get a longer barrel and be done with it. P.S. If the 10.5 barrel is a commercial type, the chamber will need to be enlarged. The standard Nato chamber will not work, due to being too tight in the cross section of the chamber walls.

Timing a DIAS:

The DIAS must be timed with each change of upper or lower.  To check the timing is easy, to adjust the timing is hard. With a M16 or AR15 with M16 parts and the DIAS in place...

  1. Remove any magazine and ammo from the gun.

  2. Set the selector on the full auto position.

  3. Drop the hammer with the trigger (you did check to see the chamber was empty right?)

  4. Now you need your timing gages ( The cheapest is drill shanks at the required dimensions. I use three, one early timing gage .12 dia, one correctly timed gage .10 dia, and one late timed gage .08 dia.)

  5. Secure the trigger in the fired condition (rearward) with wire. Using the charging handle pull the bolt carrier all the way to the rear but do not let it go, slowly lower the carrier towards the front until you have a 1/2" gap left between the carrier and barrel extension.

  6. Insert the early timed gage in between the colt carrier and the barrel extension (not the bolt head) and slowly lower the bolt carrier with the charging handle. If the auto sear releases then your gun is out of time (early) and will most likely give you light primer hits. If not go to step 7.

  7. Slightly retract the charging handle and remove the early gage and insert the late gage. Slowly lower the carrier until the carrier rest on the gage that is between the bolt carrier and the barrel extension. The hammer should have dropped, if it did not the gun is out of time (late) and will most likely either not release the hammer or act sluggish and have a slow cyclic rate. If it dropped go to step 8.

  8. Pull back on the charging handle and recock the gun while removing the late gage. slowly lower the bolt carrier with the "go" or correctly timed gage until the bolt carrier rest on the gage that is against the barrel extension. The hammer might release or might not.

This same system could be used to check the timing of a M-16 or RR AR-15 using a traditional auto sear as well.  The key is to set the timing so the hammer falls with the 0.10 diameter gage but not the early gage.  Assuming that the hammer was released on this gage but not the early gage the gun is timed.

Now that you have determined the timing of the gun you must adjust it. the DIAS should NOT be loose in the gun since it can shift and effect your timing. The easiest way to secure it in the gun is to A) drill a hole and tap it in the auto sear body so you
can clamp it to the upper lug and adjust the timing with shims on the front side or 2) You can glue plastic shims to the upper lug with JB weld so the DIAS is timed to each upper by the shims on that lug. Moving the sear forward in the gun makes the timing later (therefore correcting an early timed sear) and rearward makes the timing earlier (correcting a late timed sear).



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59 minutes ago, biminimike said:



See attached photos for RLL. Let me know what else you guys would like from quarter bore. I can also make a new website if needed with all this information. 

A new site would be great!  There was able to take the time to cruise the site so I'm not sure what all info was on there but I'm sure it's all of great value to the community!

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