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Posted: 6/14/2003 12:17:40 PM EDT
[#1]
Devl, A friend of mine just installed the PRI on mine that has the cross bolts. He had to enlarge the old cross pin slots at the bottom of the barrel so they could lock in the old cross pin slots and thread into the other side.
I would imagine that the same would have to be done with the set screw version. I don't know about the gas tube, I didn't see him do it and he gets to keep the old stuff for installing the new parts. So, I'm not sure what tube he used, If one was supplied, I would use that one. Hopefully this helps! Mark |
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Posted: 6/14/2003 3:00:53 PM EDT
[#2]
I had the cross bolt version and sold it as it didnt fit and I would have had to modify the barrel for it to fit.
MSTN assured me this would fit unlike the older version. Has anyone installed a PRI front sight on a barrel themselves that already had a front sight installed? |
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Posted: 6/14/2003 6:23:35 PM EDT
[#3]
I have the cross bolt version, I enlarged the hole with a round file with about the same diameter as the screw. I slowly worked on the holes until the screw just made it through.
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Posted: 6/14/2003 7:06:13 PM EDT
[#4]
Well these holes with the set screws are the same size as my front sight holes just lower. MSTN no longer carries the cross bolt version and assured me this would fit no problem.
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Posted: 6/14/2003 7:17:06 PM EDT
[#5]
I'm also planning to get a PRI flip up front sight in the near future.
I recently posted asking about the pin hole specs on the "Optics and Sights" forum and I found out there were no specs! Troy replied and told me this was indeed true and that it's the same way with all the major AR manufacturers. The pin holes are drilled out as needed on each batch of barrels. This is news to me and it sounds crazy that no one has specified that pins must be x distance apart. I wonder how the we know the gas ports on the sights are in the correct place if there are no specs?[:\] This may be why you ran into trouble with fitting yout PRI sight. I called PRI and asked about this because I was concerned about getting a sight that I couldn't fit. They told me their flip sight with the clamp screws had the pin holes at 1 3/8" distance center to center. They said this was setup to match the Colt front sights they would be replacing. I measured the pin hole distance on my new CMMG/DPMS M4 upper and luckily it measures at exactly 1 3/8"! The PRI support person also told me they recommend using the clamp screw for combat rifles and set screws for match rifles. The reason being most match barrels have set screw style sights so that they can be adjusted for windage. According to the person I talked to at PRI they will be releasing a new model of the clamp screw (cross bolt)flip up sight in 3-4 weeks. It's suppose to have the screws a bit lower than the previous model so that no filing will be necessary to install them. How lowering the bolt locations will fix this is a mystery to me but that's what PRI said. It seems they often get a lot of calls about having to modify the barrel so the new model should make this a non-issue. BTW, if anyone can measure their clamp screw(cross bolt) PRI flip up sight I'd be interested to know if they are indeed 1 3/8" apart. I didn't know the PRI sight came with a gas tube. Is this tube different from the regular one? |
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Posted: 6/14/2003 10:01:17 PM EDT
[#6]
I've got the crossbolt version and it does indeed measure 1 3/8".
-Cap'n |
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Posted: 6/15/2003 3:28:46 AM EDT
[#7]
Whta is the pRI web site address. I wanted to buy a PRIO front sight and I am now a tad confused on the the two type of set-ups. Do they explain it?
Thanks |
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Posted: 6/15/2003 5:28:19 AM EDT
[#8]
Capn_Crunch,
Thanks for measuring the pin holes! WSAR15, The PRI website is here - [url]http://www.pri-mounts.com/index2.htm[/url] |
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Posted: 6/15/2003 6:07:11 AM EDT
[#9]
Thanks Yojimbo
What is the difference between "clamp screws" and "opposing set screws"? - the photos seem the same. Given a choice, which is the better set-up and why? |
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Posted: 6/15/2003 11:17:59 AM EDT
[#10]
If you will reread my post I said GAS TUBE ROLL PIN not gas tube. This is in fact because the space for the gas tube is wider than factory. Some people use two gas tube pins one from each side for certain gas blocks if they lose the longer one provided with a different front sight or gas block. I do not know this is for a FACT for the PRI front sight but I know it is the case with other aftermarket sights and gas blocks.
The problem with front sight pins is not the space apart. They (front sight pin holes) are all the same distance apart. The holes are not low enough on my barrel to mate with the set screws on the front sight. If PRI is going to make the bolt location lower it will not be touching the barrel at all, but connecting with friction only and while the shoulder the front sight rests on is more than enough to prevent the front sight from coming backward the only thing holding it from going forward will be friction. I dont know if they are infact coming out with a new version for replacement on factory barrels in a few weeks but I am a bit upset. By now one of the guys at MSTN is reading this thread. I sold the cross bolt version of the PRI front sight I had because it would not work without modification to my barrel and on the advice of MSTN bought this front sight instead. If there will be a new front sight that fits my requirements perfectly and this is a poor solution I feel that pushing a product because its on your shelf and saying something will fit when in fact its known not to is a VERY poor business practice. Its not something I expect from a company as professional as MSTN. I hope someone from MSTN can chime in and clarify all this. |
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Posted: 6/15/2003 4:53:34 PM EDT
[#11]
Devl,
Thanks fir the clarification. BTW, not all front sight pin holes are in the same place. My pre-ban Eagle Arms upper has the front sight pin holes spaced 1 7/16" apart. It's not much difference but it's enough to make it PIA to install a sight with pin holes set at 1 3/8" apart! [;)] |
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Posted: 6/16/2003 8:47:02 AM EDT
[#12]
DEVL,
BACK FROM A WEEKEND OF DOING MY REAL JOB. YOUR PROBLEM WITH THE PRI FLIP UP FRONT SIGHT IS THE FIRST OF ITS TYPE WE'VE ENCOUNTERED. I HAVE PERSONALLY INSTALLED SEVERAL OF THE NEW MODEL PRI FLIP UP FRONT SIGHTS ON BARRELS, TO INCLUDE OTHER BUSHMASTER BARRELS, WITH NO PROBLEM WHATSOEVER. WE LIKE THIS NEW VERSION OF THE PRI. THIS IS THE TYPE USED ON THE SPR MK 12 MOD 0 UPPERS, AND WE HAVE OUR SPR BARRELS BUILT WITH FOUR FLAT END MILL CUTS TO ACCOMODATE THE SIGHT, RATHER THAN THE TWO CHANNELS MILLED ACROSS THE BOTTOM AS REQUIRED WITH THE CROSSCOLT VERSION. PLUS, THIS NEW MODEL WITH THE FOUR SET SCREWS HAS WORKED PERFECTLY ON ALL M4 BARREL INSTALLATIONS WE HAVE DONE. NOT ONLY IS IT EASIER TO INSTALL. IT ALSO ALLOWS THE SHOOTER TO GO BACK TO THE FRONT SIGHT TOWER AT A LATER TIME IF DESIRED, AS THE TAPER PIN CHANNELS REMAIN INTACT. YES, THE SET SCREWS DO IN FURTHER ON ONE SIDE. AND YES, THE GAS TUBE PIN IS JUST A NICE-TO-HAVE ITEM, AS MANY GAS TUBE ROLL PINS DO NOT WITHSTAND REMOVAL VERY WELL. I DO RECALL INSTALLING THE OLDER STYLE CROSSBOLT VERSION OF THE PRI ON A SINGLE BUSHMASTER BARREL IN THE PAST THAT HAD THE HOLES DRILLED SO HIGH INTO THE BARREL THAT THEY WERE ENTIRELY WITHIN THE BARREL. THE TAPER PIN HOLES DID NOT EVEN CUT THROUGH THE BOTTOM OF THE BARREL'S RADIUS, AS THEY DO WITH A COLT. SIMPLY, PUT, THEY WERE DRILLED WRONG. THIS SOUNDS LIKE THE SAME PROBLEM YOU'RE RUNNING INTO. YOUR BARREL. NOT THE SIGHT. THE PROBLEM IS NOT, AS YOU MAINTAIN: ..."pushing a product because its on your shelf and saying something will fit when in fact its known not to is a VERY poor business practice"... OUR BUSINESS PRACTICES HAVE BEEN RECEIVED RATHER WELL, I DO BELIEVE, AND SPEAK FOR THEMSELVES. I'LL BE QUITE FRANK AND STATE THAT I VIGOROUSLY RESENT YOUR ACCUSATION THAT WE SOLD YOU SOMETHING "known not to" PROPERLY FIT. THE PRI FLIP UP FRONT SIGHT IS MADE TO WORK WITH A COLT/MILSPEC BARREL. NORMALLY, THEY WORK WITH BUSHMASTERS, ARMALITES, ETC. DESPITE WHAT BUSHMASTER MAINTAINS, THEY DO NOT ALWAYS MEET SUCH SPECS, AS I AM SURE YOU ARE AWARE. WES GRANT [URL]MSTN.BIZ[/URL] |
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Posted: 6/16/2003 10:00:54 AM EDT
[#13]
Anyone install a PRI flip-up front sight on a SR-15 Match rifle? Just curious, I might consider upgrading my KAC SR-15 to a pseudo SPR rifle...That's right I said Pseudo, not a replica or even a copy...
Any thoughts on this type of project? Thanks as always- |
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Posted: 6/16/2003 10:24:18 AM EDT
[#14]
Quoted: Thanks Yojimbo What is the difference between "clamp screws" and "opposing set screws"? - the photos seem the same. Given a choice, which is the better set-up and why? Sorry for the late reply. The clamp screw modell has a full length screw that goes through the pin holes. The set screw model has four shorter screws that do not pass all the way through the pin holes. According th PRI the set screw model is mostly for match or precision rifles so that you can adjust windage on the front sight. It sounds like a toss up as far as witch one is better. Wes seems to prefer using the the set screw model and his reasoning for it is sound. As for me I would probably get new clamp screw version as PRI recommended. |
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Posted: 6/16/2003 4:08:17 PM EDT
[#15]
Sorry I just wanted a response and was getting upset you had not chimed in so I was speaking a bit out of turn I suppose. The front hole is open on the bottom in the front hole but the rear one is just barely closed on the barrel by a 1mm piece of ultra thin barrel. If I filed out the bottom just a tiny bit would this allow propper seating?
I really should not have posted something that could have been construed as implying you were dishonest in any way but I was getting worried since you never replied. Sorry about that. |
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Posted: 6/16/2003 6:00:49 PM EDT
[#16]
IF YOU HAD A QUESTION FOR ME, I'M SURPRISED YOU JUST DIDN'T EMAIL ME DIRECTLY, AS YOU HAVE MANY TIMES BEFORE. I SURMISED THAT SINCE YOU DID NOT, YOU WERE SOLICITING OUTSIDE OPINIONS.
I WOULD NOT MOVE ANY METAL! HERE'S WHAT I WOULD DO: 1. SLIDE THE SIGHT WITH GAS TUBE ATTACHED INTO PLACE. 2. ALIGN IT VERTICALLY. I USE A LASER LEVEL AND A PLUMB LINE. MARK 1 MOD 0 EYEBALL WILL WORK. 3. TIGHTEN THE SET SCREWS EVENLY, HALF TURN EACH, UNTIL THEY EACH BEGIN TO TAKE TENSION. 4. CHECK ALIGNMENT. CORRECT AS NECESSARY. 5. CONTINUE TIGHTENING THE SET SCREWS, HALF TURN EACH, UNTIL YOU CAN'T USE THE SHORT END OF THE ALLEN WRENCH TO GO MUCH TIGHTER. 6. CHECK YOUR WORK. 7. SHOOT THE WEAPON WITH AMMO OF KNOWN RELIABILITY TO CHECK FOR PROPER SEAL. WES GRANT [URL]MSTN.BIZ[/URL] |
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Posted: 6/16/2003 6:34:03 PM EDT
[#17]
Thanks Wes. Are you saying I should only go to the tightness I can get with the short arm then do an extra half turn with the long arm of the hex key?
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Posted: 6/16/2003 6:51:34 PM EDT
[#18]
my colts are 1 3/8 ,but i have a wilson upper that measured 1 1/2 center to center.does this mean a PRI cant be installed?
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Posted: 6/16/2003 8:08:21 PM EDT
[#19]
DEVL,
STICK W/ THE SHORT ARM. NEXT BEST THING TO A 20 INCH-LB TORQUE WRENCH! GIRARD, THE NEWEST CLAMP-ON VERSION WILL WORK. IT SHOULD BE RELEASED SOON. WES GRANT [URL]MSTN.BIZ[/URL] |
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