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Posted: 10/4/2009 9:54:55 PM EDT
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A friend of mine is installing a RDIAS and got some questions regarding timing. Btw, it's registered and got all the paper work so don't worry.
Now, the RDIAS is installed and he started adjusting the timing but it seems like it's running out of adjustment and the timing is still too early according to some instruction, but he think it will work this way. Can he try to fire it full auto to see if it will work? Is it safe? Timing is to early mean he will have light primer hits, correct? not gonna go kaboom or it might? Can anybody suggest what other adjustments he could do to retard it? Thanks! |
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From Quarterbore's website. http://www.quarterbore.com/nfa/dias.html 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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We already did that. That is how we determine the timing was early.
The hammer is dropping around .12 now it was dropping .5-.8 when we started. We can't really determine the exact drop because toward the end where bolt is closing into barrel extension it gets stuck a little there with a little tap with finger it will go in, but then u can't really tell if it was .12 or .08. We think it's ready to go. Now it might be still early or late. Will I damage anything from firing it? According to quarterbore early i get light strike and late i get slow rate of fire. Is that correct? Thanks! |
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Quoted:
Will I damage anything from firing it? According to quarterbore early i get light strike and late i get slow rate of fire. Is that correct? Probably won't damage anything. Late timing can also lead to the dreaded bolt bounce - which can look a lot like the light strike problem. Both are symptomatic of the hammer hitting/riding the carrier instead of impacting squarely on the firing pin. |
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Spend a little get A LOT....
Send you RDIAS and lower to M60JOE (Insure it but he'll explain it all in an e-mail) and he'll get it running PERFECTLY. He did w/my RDIAS and LWRC M6A2...its incredible. I wouldn't 'drop in' a RDIAS without M60JOE setting it up for me after the work he did on my LWRC. And his prices are ridiculously reasonable, especially considering the price of the components involved... 
I looked at that same 'drill bit' thing and could barely understand it all. So I sent that lower off and it was returned in less then two weeks as a perfectly functioning super gun! |
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Well as long as it doesn't hurt anything we could try it and do some more adjustment. Right now the sear is sitting perfectly in lower and dry cycling it feels like how it should be.
yeah that drill bit was a bit confusing. Gonna try some more if not then we'll give it to Joe and let him do the magic. But we do want to try to do it our self and learn how it works. In case we want to throw it in a different lower or something. So any help and info would be appreciated. |
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Quoted:
Quoted:
Will I damage anything from firing it? According to quarterbore early i get light strike and late i get slow rate of fire. Is that correct? Probably won't damage anything. Late timing can also lead to the dreaded bolt bounce - which can look a lot like the light strike problem. Both are symptomatic of the hammer hitting/riding the carrier instead of impacting squarely on the firing pin. how is late timing lead to bolt bounce? wouldn't late timing just slow the cycle down? also what if i put selector on auto without the sear in it? would it fire full auto? sorry for the stupid question Thanks |
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Quoted:
Quoted:
Quoted:
Will I damage anything from firing it? According to quarterbore early i get light strike and late i get slow rate of fire. Is that correct? Probably won't damage anything. Late timing can also lead to the dreaded bolt bounce - which can look a lot like the light strike problem. Both are symptomatic of the hammer hitting/riding the carrier instead of impacting squarely on the firing pin. how is late timing lead to bolt bounce? wouldn't late timing just slow the cycle down? also what if i put selector on auto without the sear in it? would it fire full auto? sorry for the stupid question Thanks If you put the selector on auto without the sear, the hammer would just follow the bolt. You might get some double fires, mostly just malfunctions. Due to the design of the bolt/firing pin, I don't think you'd have an out of battery discharge, but this isn't a good idea. |
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Quoted:
Quoted:
Quoted:
Will I damage anything from firing it? According to quarterbore early i get light strike and late i get slow rate of fire. Is that correct? Probably won't damage anything. Late timing can also lead to the dreaded bolt bounce - which can look a lot like the light strike problem. Both are symptomatic of the hammer hitting/riding the carrier instead of impacting squarely on the firing pin. how is late timing lead to bolt bounce? wouldn't late timing just slow the cycle down? also what if i put selector on auto without the sear in it? would it fire full auto? sorry for the stupid question Thanks If your rifle is going to have bolt bounce, it will do so regardless of sear timing. In addition, "late" sear timing would make the rifle MORE resistant to misfires caused by bolt bounce. This is because the later the sear trips the hammer, the more time there is for a bouncing bolt to "recover" to the fully-closed position, prior to the hammer's fall. As was mentioned, the rifle will not reliably function full auto without the RDIAS installed. However, it "MIGHT" function full auto well enough to meet the ATF definition of full auto. Therefore, you MUST keep the RDIAS with the rifle whenever a full auto fire control group is installed, in order to avoid running afoul of the law. |
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Stahlgewehr762,
Thanks for the explanation, now i'm understanding better. Now what about early timing? How will the rifle act if it was let say .05 too early??? So instead of sear tripping at .08 it's actually tripping early at .13-.15. misfire? light strike? or something worst? earlier than that i think it would just act like as if there was no DIAS install, Correct? |
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Quoted:
how is late timing lead to bolt bounce? In most systems, the sear is timed to drop the hammer so that it arrives pretty much exactly when the carrier is fully seated forward. If the bolt (really, carrier) is going to bounce, slightly late timing can cause the hammer to arrive just in time to be met by a bouncing carrier, blunting it's force and producing a light strike. Stahlgewehr: guess we'll have to agree to disagree... |
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Quoted:
Stahlgewehr762, Thanks for the explanation, now i'm understanding better. Now what about early timing? How will the rifle act if it was let say .05 too early??? So instead of sear tripping at .08 it's actually tripping early at .13-.15. misfire? light strike? or something worst? earlier than that i think it would just act like as if there was no DIAS install, Correct? Circuits: I wasn't trying to come off as a know-it-all in my post, although looking at it now, it does kind of read that way. I meant no disrespect, and I've been on this board long enough to realize you know your stuff. Based on my experience, I view bolt bounce as a separate issue to sear timing. Therefore, I run the heaviest "H-series" buffer that allows reliable functioning to minimize the likelihood of bolt bounce. With the M-16 series, if bolt bounce is going to happen, it seems to do so regardless of sear timing, early, correct, or late. Factory Colt RR's can experience it, and they have "correct" sear timing. The "fix" for bolt bounce seems to relate to buffer weight, rather than sear timing. blkdawg: The above paragraph might have answered part of your question. "Too-early" sear timing will either cause the rifle to fire an interrupted burst, OR sometimes only a single round if it's really out of time. Either way, the burst stops before you let off the trigger. The rifle will cease firing with a live round in the chamber and the hammer forward. This would equate to a "light strike", as you mentioned, and is functionally the same as not having the RDIAS installed. The symptoms of this malfunction are also identical to those of bolt bounce, so be aware of the difference! The rifle should not "blow up", since the design of the AR-15/M-16 does not allow the firing pin to reach the cartridge's primer until the bolt has been locked for some duration of bolt carrier travel. The best way to know for certain if your sear is acceptably-timed is to fire a 20 or 30 round burst. If you make it through the entire magazine uninterrupted, your sear timing is good. This of course assumes no bolt-bounce issues are present. Bolt bounce has been covered here before in-depth...
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