AR Sponsor
Posted: 6/13/2009 11:27:49 AM EDT
|
I started to install a Geissele Match trigger in a SunDevil receiver and the first thing they say to do is make sure their pins are a light tap fit into the receiver, especially for the hammer. The fit with the SunDevil receiver is very loose. The Geissele instructions says if the fit is loose, to use the provided slightly oversize hammer pin for the hammer hole. The pin falls right through the hole! This receiver has never been used, so it is not worn. The oversize pin is .0005" bigger than the standard pin of .1558", which means it is .1563". That is verified since a 5/32" drill is .15625" and that falls right through the hole with no resistance at all.
It looks like the SunDevil receiver is nowhere close to spec. I can't tell how big the hole actually is. What now? I ordered this receiver in November 2008 got it something like 3-1/2 months later. Never assembled it until now, since it is only now that I have all the parts. Yeah, I should have tested parts out as I got them, but never expected this. Anyone else had experience with Geissele trigger installs and/or SunDevil pin hole fit? I can't use KNS pins or JP Rifles oversize pins, as those are all smaller than the Geissele oversize pin. - Phil |
| If you haven't done so already, contact Sun Devil. Tell them about your situation, I'm sure they will want to help you fix it. |
|
just dont be like this guy
http://www.ar15.com/forums/topic.html?b=2&f=282&t=171075&page=1 |
|
No, won't chop it up, but feel like it. How in the hell can you sell a part that does not function properly with pieces that go in it? - Phil |
|
That's awesome. 
|
Yes, as a last resort you could make new pins. If they don't fit the trigger you could ream them out. If you don't want to ream the trigger, you could make the pin have smaller a diameter on both ends where it goes into the receiver, and make some press fit bushings to hold them center. Sounds crazy I know, but that's just how I think
Like I said though, I would defiantly try and get the receiver replaced first. One more thing, do those anti-walk pins that bolt on the outside work with this trigger? |
|
Update: Don't know why I didn't think of it before, but I have a Noveske N6 308 lower receiver sitting here waiting on parts. Why not see how the Rock River Arms lower parts kit, Geissele standard, and Geissele oversize pins all fit vs the fit in the SunDevil receiver.
I was surprised. All the above pins go right through the Noveske pin holes with no resistance. The amount of wiggle you can get out of a pin when it sits in one hole (not through to the other side) is less on the Noveske, vs the SunDevil, indicating the SunDevil does have bigger holes. But, even with the largish standard (.1558) and oversize (.1563) pins from Geissele, the pin fit is still loose in two brands of receivers. My visit to the dealer yesterday showed another brand receiver accepting all pins as well, without interference, except the Geissele oversize pin. Of the three receivers, the SunDevil is the loosest. - Phil |
|
Update:
I contacted Geissele. Bill Geissele thinks I will be OK. He says he has installed triggers in absolutely “whipped” holes and they worked out OK. I inquired further, and Bill said it helps to have tight receiver holes for a precision trigger, but it is not always necessary. He has seen guns run very well either way. When he first started with triggers, he thought tight holes were 100% necessary, but after 5 years of building triggers, he sees it is not that way. I contacted SunDevil. They would like to see the receiver, and have offered to replace it if out of spec. I measured the SunDevil holes using a Starrett pin hole tool. Using a mic tightened to the same drag the Starrett tool presented when moved the through the SunDevil holes, the holes measure .1580”. If I tighten down the mic until the built in torque limiter takes over, the holes measure .1570”. The oversize Geissele pin which Geissele says is .1563, measured .1558”. It would appear that at the absolute minimum, there is at least .0012 clearance between the oversize Geissele pin and the SunDevil hole. This is arrived at by subtracting the oversize pin size of .1558” from the smallest hole measurement taken (.157”). This pin does fall right through with zero resistance. A machinist measured the SunDevil holes at .1584 to .1589”, depending on the holes. He measured the Geissele oversize pin at .1558”, as I did. His hole measurement differs from mine, probably because he is more experienced. In this instance, the minimum clearance between the holes and the Geissele oversize pin is .0026”. The machinist offered up an idea I had not thought of to eliminate the looseness. Lay the receiver on its side, with the hole being worked on, well supported. Place a ball bearing ball roughly twice the hole size diameter, on top of the hole, from the inside. Insert a flat tipped punch through the opposite pin hole on the other side of the receiver and rest it on top of the ball bearing. Hit the punch with a hammer (w/appropriate force!), and the ball will swell the inside of the hole a bit, shrinking hole diameter slightly. - Phil I am not sure yet I will do this or send the receiver to SunDevil for inspection and hopefully replacement. Another forum indicated SunDevil had been boring larger holes but has now made them a bit smaller. This post was from yesterday on www.calguns.net. - Phil |
|
Someone else had a problem with Geissle pins in a LaRue Billet Lower. I believe the answer and common denominator is that the Geissle pins don't measure up. Do you have to use Geissle pins, or can you use Milspec pins?
I have a RRA/Hollinger tuned trigger, and I never used the oversized pins, and it is one sweet trigger. |
|
Quoted:
Someone else had a problem with Geissle pins in a LaRue Billet Lower. I believe the answer and common denominator is that the Geissle pins don't measure up. Do you have to use Geissle pins, or can you use Milspec pins? I have a RRA/Hollinger tuned trigger, and I never used the oversized pins, and it is one sweet trigger. I measured the Rock River Arms pins that came in their lower parts kit. These are even smaller than the Geissele pins. The Geissle oversize pin is .1558" according to my mic. The RRA pins are .1538" - .1540", decidely smaller than the Geissele by about .002". That is a lot. I have no access to any other pins except to order some. A dealer tried some unbranded pins in the receiver and they fit just as loosely as the RRA pins. The Geissele pins have grooves in different locations, mandating their use. - Phil |
|
They want the receiver back to inspect it. I am sending it off this weekend, with a partially installed lower parts kit. They will call me with the results. If in spec, I expect they will return it, unless, perhaps their newer receivers have tighter holes and we agree I should have version with holes closer to the tighter end of the tolerance range. If out of spec, or otherwise not returned (exchanged for a replacement), they will remove my lower parts kit, destroy the old receiver, and send me a replacement receiver with the same serial number as the old, along with my lower parts kit pieces.
- Phil |
|
Quoted:
That's awesome. Yes that satisfied my "Holy Shit" factor for the day....thanks. |
|
I just returned a lower from a different company last week. It was not fully machined before anodizing. I had it for several months waiting for parts to complete it. I assume they will destroy and replace.
If you have lowers waiting for build up a thorough inspection would be wise. Wished I had. I wonder how long it will be until I receive my replacement. |
|
Quoted:
I contacted Geissele. Bill Geissele thinks I will be OK. He says he has installed triggers in absolutely “whipped” holes and they worked out OK. I inquired further, and Bill said it helps to have tight receiver holes for a precision trigger, but it is not always necessary. He has seen guns run very well either way. When he first started with triggers, he thought tight holes were 100% necessary, but after 5 years of building triggers, he sees it is not that way. - Phil Hmmm. I tried to set up a Geissele trigger in an MGI lower that had oversize holes. I tried and tried, and that trigger refused to have a consistent pull. I checked it with a Lyman digital trigger pull gauge and verified the inconsistency. I finally gave up and installed the trigger in a RRA lower that had tighter holes. The trigger set up properly the first try. |
|
Update:
SunDevil wanted the receiver back, with pins I am using. Per a phone conversation with SunDevil, I sent them the receiver with two pins from my Rock River Arms LPK, one Geissele trigger standard sized pin, and one Geissele oversize pin. The receiver already had the trigger guard, and bolt catch installed, and sent the receiver to them this way. I included a letter telling them to call me with the results of their findings (holes oversize or what?). I said I would take a replacement receiver with smaller holes and same serial number. SunDevil said on the phone they could produce another receiver with the same serial number if they decided to provide a replacement. Receiver was sent to SunDevil via UPS with an expected arrival date of 6/24. Hearing nothing for a week, I called them on 7/1. I was told it was to be looked at that night. I've called SunDevil since then with no response. I even tried a cell phone of a SunDevil employee I talked to before. No answer, just vociemail. They have had my receiver, with part of my lower parts kit, and trigger group pins for 15 days (10 working days), and have not called me at all during this period. I am quickly running out of patience. Next steps? - Phil |
|
My patience with SunDevil is running out. SunDevil received my original lower receiver and stated on the phone that the trigger and hammer holes were oversize. They sent me a replacement receiver. Unfortunately, the holes in the new receiver are no tighter than the old holes. Pins, including a Geissele oversize .1563" pin fall right through the holes under their own weight, if you hold the receiver on its side. This of course, with no trigger and hammer in the receiver. On top of that, this receiver has some minor marks on it that the original did not. Delayed for over a month and I end up with a receiver that is no better, and even slightly worse in appearance than the original!
At this point, I feel like throwing the thing out the window and buying another brand. I am not sure what. The Noveske N6 308 lower receiver I have has only slightly tighter holes, but are still loose. Is there ANY receiver out there that has snug or tight pin and hammer holes, or are they all this loose. My Rock River Arms kower parts kit pins are hopelessly too small at .154". This are dwarfed by the still loose fitting .1563" Geissele oversize pin. - Phil |
|
You obviously have an extenuated problem with the size of holes you are describing. That said, having built dozens of rifles using perhaps 10 different manufacturers receivers, I have never seen one with any thing close to a press fit for the hammer and trigger pins when using standard pins. I have never built a Sun Devil. In fact many of the receivers that I've worked with will alloow the pins rotate. I have seen situations where a .155 will fit snugly into a a .154 hole. I've only used a Geissele trigger on one occasion and in that situation I used a set of KNS non-rotating pins. It worked very nicely. I use KNS pins on all of my rifles with trigger jobs be it an after market trigger or one that I've worked myself. It sounds like your receivers holes may be too large for this solution but it might be worthy of consideration. They also come in .155 oversize, I've only used the .154's. I know you said you can't use the KNS pins but I'm thinking that what Geissele wants with their trigger is one that rotates on the pin as opposed to the pins rotating in the receiver. You're talking about dimensions in the 1000th's & 10,000th's of an inch. I'll bet using the oversize KNS would work with your trigger and receiver with no ill effects. Even a very good trigger doesn't know the difference of .0005". If your frustration is beyond this point. Send it back and try a different brand receiver you may minimize the problem to some degree with changing brands. |
|
Quoted:
You obviously have an extenuated problem with the size of holes you are describing. That said, having built dozens of rifles using perhaps 10 different manufacturers receivers, I have never seen one with any thing close to a press fit for the hammer and trigger pins. I have never built a Sun Devil. In fact many that I've worked with will let the pins rotate. I have seen situations where a .155 will fit snugly into a a .154 hole. I've only used a Geissele trigger on one occasion and in that situation I used a set of KNS non-rotating pins. It worked very nicely. I use KNS pins on all of my rifles with trigger jobs be it an after market trigger or one that I've worked myself. It sounds like your receivers holes may be too large for this solution but it might be worthy of consideration. They also come in .155 oversize, I've only used the .154's. I'm thinking that what Geissele wants with their trigger is one that rotates on the pin as opposed the pins rotating in the receiver. You're talking about specs in the 1000th's & 10,000th's of an inch. I'll bet using the oversize KNS would work with your trigger and receiver with no ill effects. Even a very good trigger doesn't know the difference of .0005". I just visited a dealer and tried the Geissele oversize .1563" pin in a CMMG and Seekins Precision lower receiver. I could not get the pin in the hole using finger pressure. Standard Rock River Arms LPK pins fell through the holes. Clearly, SunDevil is on the looser side. I am not sure why Geissele does not recommend KNS pins, but may have something to do with the fact that the Geissele pins have grooves in different places vs standard AR15 or KNS pins. Besides, the KNS oversize pins are smaller than both the standard and oversize Geissele pins. The holes in the SunDevil measured out at about .1584". We measured the oversize Geissele pin at .1558" (they claim .1563"). That results in a clearance of .0026", an amount which you can visibly see by moving the pin sideways in the hole. I wish the clearance was in the .0005" range, but it is actually about 5x that. - Phil |
AR Sponsor