Im installing an A2 “birdcage” flash hider and it needs the compensated area at 6 o’clock. When I tighten it by hand, it makes it to about 7o’clock. Will a crush washer handle a full 340 degree torque? Crush washer is DPMS.
Ive also heard its easier to “crush” if the smaller “pointed” end of the washer is facing the flash hider, but there is a chance that the hider can go crooked. How much truth to this?
Correct position has the wide end facing the FH.
It is meant to crush to proper time and while the torque range for FHs is rather wide but 340 degrees is too far a turn IMHO. What you may want to try is slowly sand the narrow/pointed end down until you get to about 45 degrees at hand tighten. That’s what I ended up doing once.
I had read somewhere that the crush washer was originally designed to have the “pointed” end facing the flash hider, but it generally isn’t done because there is more of a chance that hider can go crooked. If there is any truth to this placement (pointed towards flash), I am only looking about about 180 degrees of crush.
Croc - thanks for the post. I figured that seemed like too many degrees to accomplish with only one crush. So my options are use 2 crushes, get a peel, or try and find a decent sander (I just moved). Should have just gotten the peel washer… ( I was too lazy to peel it in hopes that the crush would work fine:( ) Biggest problem is finding parts in my area. If I want ANYTHING ar-15 related, gotta go to Midway or Brownells or pray the once-a-month gunshow has what i need. And I live in Michigan!
Straight from the current -23&P with Chg. 8…
Assemble compensator to the barrel using recessed washer (12991533) (figC-6, item 5) with the large diameter of the recessed washer forward toward the compensator and the small diameter rearward toward the barrel. Tighten the compensator hand tight and then tighten a minimum of ¼ turn but no more than 1 ¼ turns to align the center of the middle slot (4) with the front sight post (5). Tighten the compensator to complete the alignment with the front sight post. Do not over rotate. If the compensator is turned backwards, the compensator will loosen, so the procedure must be started over with a new recessed washer.
So, 90 degrees minimum, to a maximum of 450 degrees.
The Colt Mtx Manual says basically the same…
c. When using a constant torque washer, replace the compensator as follows:
(1) Install the constant torque washer on the barrel with concave face facing the
compensator;
(2) Screw the compensator on until it contacts the face of constant torque washer; and
(3) Use the combination wrench and a 1/2 inch drive ratchet to tighten the compensator
90° minimum to 460° maximum, from first contact.
ETA- To address your “crush washer placement” question:
I have yet to read anything that states the original placement of the crush washer was the reversal of what the current instructions state.
The crush washer design is what gives it a locking feature to secure the flash hider. The washer is conical in shape, and as the washer is crushed, it flares out against the flash hider applying the proper tension to hold the flash hider from rotating after installation.
If the crush washer was reversed, it would severely limit its ability to flare out, and provide the necessary tension between the shoulder of the barrel and the rear of the flash hider. The barrel will actually sit down inside the “cone” of the washer.
It may secure the flash hider if installed backwards and enough torque is applied, (The key being enough torque.) but this is not the correct installation procedure. Nor is it the way the washer was designed to function.
I figured I would ask here, because I questioned the cone facing the flash hider. Tried to relocate the article, but with no luck. To be honest, the chance that it could go crooked was enough to dissuade me from going that route. And the fact that I always heard opposite, and tend to take the word of many over the word of one.
In your honest opinion, do you think the crush could handle that many degrees (despite what manf. have said)? I’ve heard of people struggling with anything past 90degrees. Only reason I ask is I have a 3gun shoot coming up, and hand tight at 7o’clock is better than getting to 12o’clock and it not budging without being able to get more washers delivered until after the shoot. At hand tight, it breaks after about 50 rounds and just needs a little crank back on. Not optimal for combat, but fine for a few days. I actually read the AMU found a hand tightened FH to be the most accurate. More a tidbit than a plan, cuz I need to torque it to double as a defensive weapon.
Sorry to draw this out, but anyone have any luck with crush washers going almost a full 360degrees? I am not discounting your info, Quib, it actually has me tempted to give it a shot anyways, but for the above reasons i’m hesitant until after the weekend. Really appreciate the info, and there’s a good chance i’ll get ancy and torque it on regardless. If i mess it up, i’m sure I can find a Vortex or something at a gun shop locally to serve the 3gun.
here’s someone referring to the issue, just don’t feel like searching through ar15.com to find the threads…
Crush washers are designed to tighten 1/4 to 1 1/4 turns from hand tight.
The amount of torque stays pretty constant through 1 1/4 turns, by design.
My last build I had to go a little over one turn.
You could also take a flat bastard file and remove some of the metal from the washer. Lay the file on a bench and push the washer across the file and then check the position of the FH until it’s where you like it.
Yea thats a good point. I’ll try torquing it down tonight when I get a chance to throw it in the vice. If it doesn’t make the crush, I’ll try the sanding. I know I got a flat file someplace… Thanks bro.
It will make it crush and from personal experience, sanding slowly is the best way to go. I over crushed it on a vice once.
I’ve found that not all crush washers are equal. Meaning, I keep alot of them on hand and test fit them to be approx. 3/4 of a turn to clock from hand tight. It usually takes me 4 or 5 washers to find one in the 3/4 turn to lock range.
Some may find madness in my method, but at least I don’t mind and crush washers are cheap.
I was actually talkin about vice blocking the upper receiver to torque it, but you answered my next question about putting the washer in a vice to help crush it. The sanding you mentioned sounds like the way to go. I’ll try and get it past 2o’clock or so before crushing it. I really appreciate the help guys…
All I can do is refer you to the maintenance manual references quoted above. The procedures are written for a reason. And although I admit, I might not have as many FH installs as some of our Industry Professionals, or those who work full time as Armorers, I can say that the handful of FH installs I have performed IAW the MM procedures above, have all been successful.
I can’t comment on procedures deviating from the published procedures, such as sanding FH’s or “pre-crushing” crush washers. If you wish to try those alternate procedures that would be entirely up to you.
Another alternative to consider, would be a FH install using a Peel Washer.
I really appreciate all the info, Quib. I have many less FH installs than you (I am currently at zero, trying to make it to number one:D), but I have heard from many people that crush washers can be a real PITA to install if it needs too many degrees. It seems like I got an even mix of opinions. Some say it crushes fine, others say anything past 90 degrees gets rough. My current plan of action (almost completely thanks to your info) is to just try torquing the sucker on there. If it doesn’t work, I’ll go for sanding or crushing in a vice.
And yea, I’m really starting to wish I got the peel washer. I thought a crush would be easier. Never thought my FH would only get to about 7o’clock at hand tight (what are the odds on that bad luck for a first build?!). If my local shops carried peel washers, I would go buy one at this point, but I’m tryin to get the rifle set for a 3gun competition on Sunday, so I’ve only got the one crush washer to work with. Gotta make it count. I’ll try and get it installed tomorrow and will let you guys know how it worked out.
Thanks again to all. The info on this subject is a little sparse. I found a nice chart about maximum degrees and minimum degrees awhile back but couldn’t relocate it. Quib posted the same numbers though, which gives me a lot more assurance.
If you’re spinning the FH down by hand, and the center port is stopping at the 7 o’clock position, it should be no problem to turn that port the remainder of the way to TDC with a wrench and with the barrel properly supported in a vice.