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Posted: 9/14/2012 5:50:51 PM EDT
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Simple question that someone may have experience with.
I got an upper 16" with 12" rail. I understand that I should be using barrel blocks but can I do this with the rail installed? Seems like there isn't enough barrel exposed to clamp to. Thanks for any ideas here. |
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Quoted:
The torque can sheer the index pin off the barrel or crack the upper. MAHA While in theory this is true, the torque setting for most muzzle devices is in the 20-25 ft. lbs. range. This is not near enough to shear off an index pin that has a barrel nut properly torqued down. |
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Quoted:
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The torque can sheer the index pin off the barrel or crack the upper. MAHA While in theory this is true, the torque setting for most muzzle devices is in the 20-25 ft. lbs. range. This is not near enough to shear off an index pin that has a barrel nut properly torqued down. Yet it still happens... MAHA |
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I used a strap wrench on the barrel (definately remove handguard). Unfortunately, I had baffle strikes and the front of the brake is already blown off after my 1st trip to the range. I'll be getting the next one installed by the smith.  Wow! What barrel do you have, which muzzle device did you install and how did you install it? Did you use a crush washer? You said you had "baffle strikes" so I assume you attached a suppressor. I'm very curious because I'm considering getting 1 suppressor to swap between all of my ARs and was going to install the QD muzzle device to all of them. What you said makes me kinda nervous, but I've installed many muzzle devices with crush washers and it was a piece of cake. That makes me wonder what a smith could do to ensure that this cannot happen? |
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If installing a suppressor mount I would suggest using a peel washer or spacers. That sounds reasonable. Do peel washer or spacers allow the muzzle device to seat more concentric with the bore in comparison to a using a crush washer? That's kinda how I interpreted it. I've read that SureFire recommends a little Rocksett on the threads. It supposedly has the breaking strength of blue loktite, but has a very high heat tolerance. |
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I used a strap wrench on the barrel (definately remove handguard). Unfortunately, I had baffle strikes and the front of the brake is already blown off after my 1st trip to the range. I'll be getting the next one installed by the smith. Wow! What barrel do you have, which muzzle device did you install and how did you install it? Did you use a crush washer? You said you had "baffle strikes" so I assume you attached a suppressor. I'm very curious because I'm considering getting 1 suppressor to swap between all of my ARs and was going to install the QD muzzle device to all of them. What you said makes me kinda nervous, but I've installed many muzzle devices with crush washers and it was a piece of cake. That makes me wonder what a smith could do to ensure that this cannot happen? I used a crush washer followed by a few layers from a peel washer to get it to index. The brake I use has 1 baffle at the very end...at least I think it's called a baffle if its a perpendicular to muzzle piece that goes all the way around. I just had the muzzle threaded, but before I go pointing fingers, I want to get a professional to take a look to tell if my installation, the threading, or the ammo is the cause. If a smith determines it's not my installation or the threading, I will contact the ammo maker to ask for reimbursement as 62 grains in a 1:8 twist shouldn't cause problems. As I see it, the threads should be precise enough to force the brake into proper alignment without allowing any wobble, ruling out improper installation. I assume a QD supressor may have more free space around the trajectory. |
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I used a strap wrench on the barrel (definately remove handguard). Unfortunately, I had baffle strikes and the front of the brake is already blown off after my 1st trip to the range. I'll be getting the next one installed by the smith. Wow! What barrel do you have, which muzzle device did you install and how did you install it? Did you use a crush washer? You said you had "baffle strikes" so I assume you attached a suppressor. I'm very curious because I'm considering getting 1 suppressor to swap between all of my ARs and was going to install the QD muzzle device to all of them. What you said makes me kinda nervous, but I've installed many muzzle devices with crush washers and it was a piece of cake. That makes me wonder what a smith could do to ensure that this cannot happen? I used a crush washer followed by a few layers from a peel washer to get it to index. The brake I use has 1 baffle at the very end...at least I think it's called a baffle if its a perpendicular to muzzle piece that goes all the way around. I just had the muzzle threaded, but before I go pointing fingers, I want to get a professional to take a look to tell if my installation, the threading, or the ammo is the cause. If not the threading, I will contact the ammo maker to ask for reimbursement as 62 grains in a 1:8 twist shouldn't cause problems. As I see it, the threads should be precise enough to force the brake into proper alignment without allowing any wobble, ruling out improper installation. I assume a QD supressor may have more free space around the trajectory. I would look at just having the barrel threaded, and why did you use 2 different types of washer. A crush washer will crush to index. Also a 22.cal cleaning rod helps to make sure things are in aligment, not as good as a true tool. |
| I used two washer types because a 2nd crush washer would have added another 1/4" to the length of my rifle. They were very difficult for me to crush at all, the brake was about 5 or 10 degrees past alignment when tightened by hand, so I would have needed to crush the washer for another 350 degrees, which just wouldn't happen. These things are only supposed to need a little force (about as much as the crown nut) to tighten. I was having trouble getting it to turn 10 degrees using what I guess is aroung 30 ft*lbs and the peelings were indexing in 20 degree increments! I looked for other crush washers at the local building supply shop, but they don't have any! I have a hard time wanting to believe the type of washer could cause much of a difference. |
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crush washer can crush 1.5 turns and still supply the right amount of force to keep things tight. If you shop went off the OD of the barrel instead of the ID. I can easily see bullet strikes be a problem. None should even assume that just because you have two circles (OD, ID) that they are dead nuts concentric.
I am guessing you did not have a vice to lock down the barrel for installing the FH. |
I don't have a barrel vice and know enough not to use a receiver vice for muzzle work. I think these crush washers may be a bit on the thick side (requiring more torque to crush than what's recommended), but that's not really the point as I don't see how that would effect the alignment unless the threads were so loose the thing could cant to an angle or come untightened. The brake has not moved from the position it was in before shooting (other than the part that went downrange), so my strap wrench method works fine. Also, for you to say how many turns my crush washer can go, you'd have to know the pitch of my threads, which I haven't mentioned, so I'm not sure where you got that number...but again, that's probably extraneous information. 
They guaranteed it would be concentric to the "muzzle" within .001" and I assumed that meant in reference to the bore, but I see how that could be an easily made mistake for some people. |
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I used a strap wrench on the barrel (definately remove handguard). Unfortunately, I had baffle strikes and the front of the brake is already blown off after my 1st trip to the range. I'll be getting the next one installed by the smith. Wow! What barrel do you have, which muzzle device did you install and how did you install it? Did you use a crush washer? You said you had "baffle strikes" so I assume you attached a suppressor. I'm very curious because I'm considering getting 1 suppressor to swap between all of my ARs and was going to install the QD muzzle device to all of them. What you said makes me kinda nervous, but I've installed many muzzle devices with crush washers and it was a piece of cake. That makes me wonder what a smith could do to ensure that this cannot happen? I used a crush washer followed by a few layers from a peel washer to get it to index. The brake I use has 1 baffle at the very end...at least I think it's called a baffle if its a perpendicular to muzzle piece that goes all the way around. I just had the muzzle threaded, but before I go pointing fingers, I want to get a professional to take a look to tell if my installation, the threading, or the ammo is the cause. If a smith determines it's not my installation or the threading, I will contact the ammo maker to ask for reimbursement as 62 grains in a 1:8 twist shouldn't cause problems. As I see it, the threads should be precise enough to force the brake into proper alignment without allowing any wobble, ruling out improper installation. I assume a QD supressor may have more free space around the trajectory. I would get this to a competent black rifle smith and have him thoroughly inspect and properly prepare the barrel for. This threading job is suspect. Your methods and theory are those of someone unfamiliar with the platform. One of the best is here |
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Quoted: Quoted: The torque can sheer the index pin off the barrel or crack the upper. MAHA While in theory this is true, the torque setting for most muzzle devices is in the 20-25 ft. lbs. range. This is not near enough to shear off an index pin that has a barrel nut properly torqued down. I have gone over 120 ft lbs without a barrel block. No sheared pin, no cracking. I have done it several times. Sometimes people worry too much. The only barrel nut I have ever stripped, some butt head had already helped along the way. |
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Quoted:
Quoted:
Quoted:
The torque can sheer the index pin off the barrel or crack the upper. MAHA While in theory this is true, the torque setting for most muzzle devices is in the 20-25 ft. lbs. range. This is not near enough to shear off an index pin that has a barrel nut properly torqued down. I have gone over 120 ft lbs without a barrel block. No sheared pin, no cracking. I have done it several times. Sometimes people worry too much. The only barrel nut I have ever stripped, some butt head had already helped along the way. 120 ft. lbs!!!  Well at least you know it 's not going to fall off.
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