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Posted: 12/17/2003 5:20:50 PM EDT
Sorry if this is another asked and answered topic but I couldn't find anything using the search.  Can anyone give me some figures on the carry handle changes in POI when pulling them off and back on your flat-tops.  Is it consistant and repeatable, a crapshoot, or are they re-zero?  Any thoughts would be appreciated.
Link Posted: 12/17/2003 5:29:14 PM EDT
I've never really hand a re-zero problem for the  years I've swapped a contract Bushmaster(Anchor Harvey) carry handle back and forth.

Some of those cheap chinese carry handles you may  find, can have loss of zero, mounting and fitting problems. Stay away from the cheap shit and you'll be fine.
Link Posted: 12/17/2003 5:34:34 PM EDT
YOU WON'T NOTICE MUCH IF ANY DIF WITH IRONS, BUT IF YOU HAVE AN OPTIC IN THE CARRY HANDLE, YOU WILL SEE THAT REPEAT ZERO USING THUMB NUTS IS NOT AS GOOD AS YOU MIGHT LIKE.
JACK
Link Posted: 12/17/2003 5:42:29 PM EDT
Jack  How much movement are you guessing? 1 MOA, 5?  The carry handle I have came from either bushmaster or rra.  
Link Posted: 12/17/2003 10:17:44 PM EDT
It is very hard to tell since the thumb nuts are the culprit. You can run a test and it will turn out dif. everytime for a very good reason. Widage is affected by how much or little you thighten the thumb nut since the direction of force is from side to side. When you tighten them, the repeat of pressure can't be replicated accuratly by the hand. If you fixture a weapon in a vice and tighten thumb nuts and you use a red dot laser, you can see the laser wonder on a distant target as you tighten the nut. That is not practicle in the field, so you will always get a variation with any type thumb nuts due to the fact that a hand is not at the same exact strength each time, and can be wet from rain or persiration, or cold or hot, or from a dif. angle, many many variables. Ratchet knobs are a little better, but the trouble with ratchet knobs is that that ratcheting noise you hear is actually metal being worn, hence repeat is slowly lost and the side to side direction of variation in the direction of force can cause loss of zero as proven via laser aiming tests.
Jack
Link Posted: 12/18/2003 4:36:22 PM EDT
Wouldn't counting revolutions each time eliminate that problem?
Link Posted: 12/18/2003 4:55:59 PM EDT
Just the opposite. Revolutions don't measure how much wear or pressure is changed, which has been worn during the clicking sound of metal on metal. Repeat pressure is what makes or breaks repeat zero. Wear is very slight each time, but there is a point where it realy gets noticable. A laser set up as previously mentioned will demo what I mean.
Good shootin, Jack
Link Posted: 12/18/2003 4:58:04 PM EDT
[Last Edit: 12/18/2003 4:58:31 PM EDT by Lumpy196]
Mark the knobs and the handle itself.

Now granted, this may involve removing some of that show-room floor perfect finish [shock]
Link Posted: 12/18/2003 5:04:17 PM EDT
I forgot to mention that there are variables that contrubute to the wear factor. One is how how the metal has been heat treated to what RC. The othere real tough one is what type of grit has gotten in there and acted like every paper. Then add those two factors together and it becomes an averaging out of best and worst case scenerios.
Good shootin, Jack
Link Posted: 12/18/2003 5:05:31 PM EDT
ERR, emery paper
Link Posted: 12/18/2003 5:26:08 PM EDT
Wont the same microscopic wear effect ARMS throw levers too Jack? [;)]
Link Posted: 12/19/2003 2:07:48 PM EDT
Originally Posted By Lumpy196:
Wont the same microscopic wear effect ARMS throw levers too Jack? [;)]
View Quote


Of course not, they are special..... [}:)]
Link Posted: 12/19/2003 5:28:13 PM EDT
No lumpy!
The levers pull down, not across, and down is down and held there by spring tention. The levers are not a ratchet and you don't hear or feel any grinding with the spring tention or pushing in the buffer pad. Any wear top the buffer pad is ajusted to by the spring. I have never seen a buffer pad worn out, but shure have seen a lot of messed up broken or bent ratchet knobs coming in from the field.
Jack
 
Link Posted: 12/21/2003 1:15:13 PM EDT
The thumbscrews on my carry handle have a synthetic(delrin?)material on the inside that meets the metal. I understand the wear argument.  There are some repeat mounts that don't operate like the arms mounts. Iv'e had some Warne mounts and never had a problem.  When I asked the Q about the carry handle I was hoping for some numbers.  
Link Posted: 12/21/2003 4:45:29 PM EDT
Yep, Delrin is a good locking method once you stop turning. The Delrin expands and locks the threads into place after it sits for about 30 seconds depending on average temp.  That however has nothing to do with the repeat back to zero. Repeat back to zero is governed by how much the tention of the previous tention was used in the previous zero process. Unless you can actualy measure the amount of tention used in a side to side direction of force via your hand, you can't guarantee a repeat of the last setting.
Good shootin, Jack
Link Posted: 12/21/2003 4:57:54 PM EDT
In my experinces the only way to ensure RTZ is to use either a torgue wrench on a bolt/nut arrangement - like KAC/BADGER/LEUPOLD MKIV etc. rings.

OR to use a ARMS throw lever system.

I have both #22's and #35's, and KAC and BADGER rings all RTZ.

 The ARMS thumb lever is just a simpler field solution.
Link Posted: 12/21/2003 5:20:04 PM EDT
Too bad theres no market for a carry handle with throw levers...
Link Posted: 12/21/2003 5:23:53 PM EDT
I'm glad there isn't a market for carry handles accept the antique market:)
Jack
Link Posted: 12/21/2003 5:34:34 PM EDT
[Last Edit: 12/21/2003 5:35:29 PM EDT by Lumpy196]
Sometimes optics and weather dont interact well...
Link Posted: 12/21/2003 5:39:22 PM EDT
Yep, but just heat up the mount of your choice and lock it in position in the snow and ice, and then it can freeze to zero:)
Jack
Link Posted: 12/21/2003 6:02:48 PM EDT
Originally Posted By Lumpy196:
Sometimes optics and weather dont interact well...
View Quote


How about an LMT fixed BUIS with an ARMS lever mount?
Link Posted: 12/21/2003 6:19:43 PM EDT
I imagine that if a lever back there was practical that ARMS would have already done it. I think it would prob. be a knuckle buster whan charging the weapon. OWWWWWWWWWW
Give me a folder any day then nothings in the way for any optic.
Good shootin, Jack
Link Posted: 12/24/2003 5:54:37 PM EDT
Thanks for the input.  It took me a while to get back to the puter and read the posts.  Merry X-Mas and happy holidays.
Link Posted: 12/25/2003 8:41:16 AM EDT
[Last Edit: 12/25/2003 9:00:00 AM EDT by Red-Leg]
Are those ARMS throw levers available as an aftermarket item for other devices...say to replace the thumb screw on an EOTech?

Edited to add:  Or is there a recommended QR base for my EOTech on an A3 receiver?  If I add a QR base, will an ARMS #40 still co-witness?

Thanks!
Link Posted: 12/25/2003 9:32:34 AM EDT
If you are not using a scope and not shooting over 300 meters, then thumb nuts work fine.  I have had no noticeble shift in zero with my carry handle or aimpoint railgrabber mount, both of which use thumb nuts.  The level of precision with iron sights and red dots is not so high as to be affected a great deal by a change in tolerances in the range of 0.001" to 0.0001", which is what we are talking about when it comes to removable carry handles and such.  Changes is barometric pressure, wind speed and direction, and temperature will play a bigger role in shifting POI and repeatability of zero.
Link Posted: 12/25/2003 10:33:39 AM EDT
Originally Posted By Red-Leg:
Are those ARMS throw levers available as an aftermarket item for other devices...say to replace the thumb screw on an EOTech?
View Quote


Wont work with the EOTECH

Edited to add:  Or is there a recommended QR base for my EOTech on an A3 receiver?  If I add a QR base, will an ARMS #40 still co-witness?

View Quote


Nope.


I have an EOTECH 552 on my CQB gun, the thumbscrew is suffiecently fast enough if you really have to remove the Eotech (which is unlikely for you can use the irons through it.)

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