I had in the past installed and used the 2 screw posts, and I liked them although they did take 15minutes to a half hour to install with a Dremel tool allen wrench and loctite.

I recently bought a 4 set screw PRI post (the ones hailed as being easier to install, and today I installed it, took me about 35 minutes, ajusting screws (there seemed to be no rhyme or reason to the process the post just wouldn't level for anything, finally I just tightened them down and walked away.) Then I decided to take another look at it and of course it is canted about 5 degrees.  So I took out the allen wrench and tried to loosen the screws to take another wack at it, and the first set screw stripped out(that does it for these, as now that single screw has it locked on in and of itself.)  I got a little upset and though about the possibility of wacking it to a closer to upright angle, couldn't find a rubber mallet and started hitting it with my hand (I think I broke a bone in my hand but the post still sits there defiantly at 5-7 degrees left.)

Now I really wish I had bought the standard one.

By the way while I'm at it, purple BM products never bothered me (they were barely purple if at all but lately I have been getting purple everything, in the last month I have collected a Bright purple PRI M84 Charging handle, a lighter purple PRI post (this one), and a purple KAC FF RAS.  well my gun looks kind of like a rap star's idea of a wet dream now.  I can see why purple really pissed you guys off. Now if I had a bright purple lower and upper at least the thing would match

If I can get it zeroed at 100yds without maxing out my KAC 600m BUIS I will be happy but if not, I'll really have a reason to regret not buying a PRI 2-screw, or better yet, if I had bought the KAC RAS mount flip up front I would have had it mounted properly in about 45seconds.

I just had to have the globe front sight : (

[booze]

[img]www.skadi.net/forum/images/smilies/skadi_forum/hm000000.gif[/img]
Yer talking about the front sight I assume?
I wish PRI could use the indents already drilled for the standard front sight tower, I don't care for the 4-screw model either.

Yep the front sight

"I wish PRI could use the indents already drilled for the standard front sight tower, I don't care for the 4-screw model "

Unfortunately it looks like that would be impossible. Those pin hole's locations aren't always exactly the same.  I wish they just used two simple set screws in the bottom just like KAC low-profile gas blocks (then I would be able to level it and tighten the screws, not level it and then tighten screws while watching it drift all over the place.)

They could also have designed their first post so the screws didn't actually index in slots in the barrel but instead simply clamped on (that was what held it in place latterally anyway, so why the huge slots in the barrel?)

This is like one of those chinese top-hinged weaver scope rings (you can tighten it a dozen times and it will never be level, unless you get lucky.

[b]I noticed there was a lot more play in these posts than my earlier ones(2-screws), instead of two locking roll pins in the moving part (the folding post hinge), there are a couple of pin-like structures simply cast into the metal, it is cheaper and the post has more play in it.[/b]

If I can't get it to sight in I guess I'll have to drill out all the set screws, weld in the holes and put a single set screw through the hole in the bottom used for the gas tube hole drilling, then it will be designed the way it should have been in the first place.

[b]Now I am beginning to think KAC engineers are geniuses, If only they put a closed round hood on their flip up front sight...[/b]

green0, the newer PRI clamp style front flip-up does not index on the taper pin slots, unlike the first one. the two cross bolts are below the barrel - no filing or dremeling is required.  the sight base slides on and you just tighten up the two clamp screws.  i installed one of these on my MRE upper a few months ago.
cheers,
MM

Just for the record I have installed and uninstalled my 4 set screw version totally straight several times with no issues.  I just held it straight and snugged diagonally opposing screws till I was sure it was straight and then did the others.  It took a little fiddling but just by eyeball it was super easy.  I cant see how you stripped a set screw either.  It just does not have to be that tight that it could strip.  Yes it took 3 or 4 tries to get it right as far as not canted but that was not a biggie for me.  Sorry about your troubles.

I installed on a BM DISSIPATOR, the barrels are contoured slightly less than .75in forward of the gas block, and thus at the position of the sight post.  

That might have caused part of the problem, I did notice that if you were to install and not touch the taper pin holes install was much easier, but I thought the design requirred contact with the taper pin holes and thus put the set screws into the taper pin holes, and noticed:

A: that the taper pin holes have give to them (meaning if you want the sight mounted solid you have to keep turning the screw till finally it doesn't turn anymore, or your post could be nocked loose).

B: That the design sucks for getting the post level, I'm talking play with it till you get lucky, not level it and tighten screws.

[b]My sight is permanently mounted onto the barrel but I went to the range today and found out that at least I can sight in the sights, the KAC 600M rear was only halfway to the left limit too.

The gun wouldn't cycle semi-automatic however, I had the PRI fatboy tube installed, meaning changing to a std tube would hopefully solve my problems, This same tube failed to function on both my M4 and this dissipator barrel, so right there I promised myself I would send a strongly worded letter to PRI. I will but I haven't sent it yet.

Those tubes should be advertised for one kind of gun A 10.5 with a .100 or bigger gas port.

Because my sight is permanently attached I had to chop the gas tube in 3 places to remove it, and now when I get a STD tube I will have to install it by sliding it under the FF RAS. So PRI screwed me twice now, I've got new rules, if it isn't an M84 CH buy it from KAC [/b]

I went with the clamp style as well.  Install took all of about 5 minutes.  In fact, it took longer to get the gas tube roll pin in than it did to install the sight.  Gun functions beautifully on semi.  

I think it is obvious that someone else should take a look and solve the problem as I don't see why there is a problem I never had one on gov't mil spec barrels. Send the upper/or all, to WES, or whom ever. Second, first hand tries never hurt.
Jack

[b]Before I post this I just want to remind people that the PRI post is mounted and I did get a chance to fire it today and the rifle did sight in somewhat close to center, so the only problem with this sight is minor, the sight is non-removeable, well I can live with that.[/b]

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"Just for the record I have installed and uninstalled my 4 set screw version totally straight several times with no issues. I just held it straight and snugged diagonally opposing screws till I was sure it was straight and then did the others. It took a little fiddling but just by eyeball it was super easy. I cant see how you stripped a set screw either. It just does not have to be that tight that it could strip. Yes it took 3 or 4 tries to get it right as far as not canted but that was not a biggie for me. Sorry about your troubles."

Tightening diagonally opposing set screws... that might be the key, why didn't they add that to the instructions that don't come with this product?


What is the proper torque spec? these screws were indexing in pin holes and if you have installed one you might have realized the metal in these areas has give- the screw contacts and then continues to screw into as if the metal is squishing or something- If I wasn't supposed to put this in the pin holes maybe that was the problem, the only reason I did was that the holes just happened to be spaced exactly the same as the pin holes, reinforceing my belief that that was the proper place to install the sight. (I guess if I had a gastube hole that would have narrowed it down as allignment with the hole would be obvious but I was mounting on a Dissipator barrel.) When I don't have a torque spec I usually overtighten things out of fear they will later loosen on their own at an in-opportune time.

A clamp on version- I wasn't aware of that or I would deffinitely have used it. I was just looking for ease of assembly not what the gov't is using on anything.

[b]my gunsmith is me, if you haven't noticed we are the red-headed stepchild of the firearms industry, my local gunsmiths will work wonders with a bolt action but won't touch the "demonic ar-15."  And even if they did work on them they see so few of these that every new project is a first time project and they are every bit as likely to screw it up as I am. I am not the kind of person who routinely ruins guns through his stupidity and incopetence, I have actually assembled 14 rifles from parts now, probably less than a weeks work for an ar-15 gunsmith but still more than limited to no experience.

oh and 3RTK.. no one in his right mind would touch this knowing what I have said up front, it is only a chance to ruin a product get frustrated, spend more time than you are paid for (these are known as the blackholes of the gunsmithing world" when something is allready so FUBAR that you know it can only be challenging and time consuming with very little chance of proper repair.) [/b]

The only way I see myself as screwed is that PRI put tiny setscrews into this design that were too weak for the task, and didn't include install instructions (if there is a trick to leveling these believe me it would have come in handy.)

Besides that [sending to someone] would take a while for sure and I need this gun running by Friday. It is my deer rifle and deer season is Saturday morning. (I would think it was allignment with the gas port that was the problem except that this is the second rifle that has had the same problem, so I can now pretty much narrow it to incompatibility of the gas tube and weapon. If I can get a std gas tube before Friday all will be well with my world and I will be able to sight in my rifle and go hunting.