My SLR, some thoughts...

[cr5]

I just watched a u tube video featuring that! Huh, now I'm worried cus I didn't even tighten the nut with a torque wrench! He has a free float fore end on it that I believe bolts to the barrel nut, so I guess I shouldn't have to worry about it backing off without him noticing his fore end it crooked!

I never use a torque wrench. Tighten, loosen, tighten, loosen, tighten, you'll feel it when it doesn't want to go any tighter then you just give it enough to line up the barrel nut to allow the gas tube to pass through into the receiver.

Plus I doubt that most on here that do use a torque wrench are doing the calculations needed to adjust the torque setting on their wrench correctly to compensate for the extra leverage given by attaching to the armourers wrench 2 inches from the nut center. Increasing the leverage given to the wrench changes what it's actually delivering to the nut for torque so they're probably not tightening to the correct spec anyway (they would be over tightening with the increased leverage).

Assembling an AR or ARish rifle is quite easy and doesn't require magical skills but you should use the right tools which includes properly holding the receiver or barrel while tightening the barrel nut. Without the right tools you risk not only scratching it but breaking the thin aluminum receiver that was not designed to absorb torque stresses or be crushed in a vise.
I like the reaction rod because no torque is transmitted to the receiver body, it all goes through the barrel extension.
I've also got a tool that can be clamped into a vise that has a side to hold a pic rail and the other side can grab an upper by the takedown pin holes but I use that to hold the receiver during small parts assembly not barrel nut torquing.

If you don't have the right tools and can't borrow them then at minimum don't put the receiver in a vise but instead use a couple blocks of wood to make a barrel clamp and put the barrel in the vise when you tighten the barrel nut. At least this way you won't risk damaging the delicate receiver.

Good luck everyone and if anyone in the Edmonton area need access to the right tools PM me and I can help you out.

It functions beautifully, and I learned in the process! Isn't that what doing it yourself is all about?As expected, I can see I incurred the typical forum wrath of the high horsed knowitalls, I am only sharing my experiences. Hopefully all the other newbies will learn from my mistakes, and take away some build ideas in the process. Time to put out my flame-retardant suit!

No flames from me, just trying to educate and help the inexperienced.

 

[mileageman]

I always recommend people watch the ‘How to build a AR15 lower reciever presenter by Larry Potterfield of Midway USA’, then watch the how to build a upper video./ Best 50min a newbie can spend. While you don’t need all the tools he uses, it certainly helps. He even does things like check hole sizes (something Mac Def didn’t do), chase threads and check headspace.

 

[GaryF]

That Midway guy is great...shows every tool you might want or need

 

[BattleRife]

I like the reaction rod because no torque is transmitted to the receiver body, it all goes through the barrel extension.
.

I have to dispute this very common perception.

With the AR-15 type design, the barrel nut is torqued onto the upper receiver. The flange of the barrel nut is simply sandwiched in between those two parts, with its position indexed by a single pin that engages the upper receiver.

The key is that first statement, the nut is torqued onto the upper. The upper must experience torque. The nut must experience torque. Any attempt to support the assembly via the barrel extension means that all that torque is transmitted through the index pin. Reaction rods and barrel clamps fall into this category. Do it if you must, but do not purport it to be a preferred arrangement.

The best arrangement is to support the upper directly, and torque the nut directly, and then no torque will go through anything else.

 

[NaughtyPilot]

wrong

 

[cr5]

I have to dispute this very common perception.

With the AR-15 type design, the barrel nut is torqued onto the upper receiver. The flange of the barrel nut is simply sandwiched in between those two parts, with its position indexed by a single pin that engages the upper receiver.

The key is that first statement, the nut is torqued onto the upper. The upper must experience torque. The nut must experience torque. Any attempt to support the assembly via the barrel extension means that all that torque is transmitted through the index pin. Reaction rods and barrel clamps fall into this category. Do it if you must, but do not purport it to be a preferred arrangement.

The best arrangement is to support the upper directly, and torque the nut directly, and then no torque will go through anything else.

Pretty sure I've read that the standard military practice is to use a barrel clamp. I could be wrong though, I'm not a trained armourer.

 

[JaredP]

Yeah. reaction rod torqueing presses 80 ft-lb of torque through the 1mm diameter barrel index pin into the pin recess in your barrel nut threads:

I would much rather use simple upper blocks, or an upper clamp in a vice, the force of torqueing is spread over a much larger surface area.

Reaction rods indeed the right tool to secure a barrel to a barrel extension, or to install muzzle devices. But very few people buy AR barrels and barrel extensions separately.

 

[Dr. Hunter]

I have both of the above. For the slr used the reaction rod for the bcl used the vice block.

 

[mileageman]

I have to dispute this very common perception.

With the AR-15 type design, the barrel nut is torqued onto the upper receiver. The flange of the barrel nut is simply sandwiched in between those two parts, with its position indexed by a single pin that engages the upper receiver.

The key is that first statement, the nut is torqued onto the upper. The upper must experience torque. The nut must experience torque. Any attempt to support the assembly via the barrel extension means that all that torque is transmitted through the index pin. Reaction rods and barrel clamps fall into this category. Do it if you must, but do not purport it to be a preferred arrangement.

The best arrangement is to support the upper directly, and torque the nut directly, and then no torque will go through anything else.

This is 100% correct. The clam shell style upper receiver action block is about th best way for uppers that conform the milspec shape. Unfortunately billet uppers usually don’t fit. The two CF armours I know both use Giessele reaction rods, so while not 100% the correct way to do it, it seems to be a much more convenient way with a extremely small potential for damaging the upper.

 

[JaredP]

This is 100% correct. The clam shell style upper receiver action block is about th best way for uppers that conform the milspec shape. Unfortunately billet uppers usually don’t fit. The two CF armours I know both use Giessele reaction rods, so while not 100% the correct way to do it, it seems to be a much more convenient way with a extremely small potential for damaging the upper.

You're also likely to shear the index pin off your barrel using a reaction rod to torque a barrel nut.

The reaction rod is just not the right tool to torque a barrel nut.

 

[Armedsask]

Pay no attention to AB Blaster, he is our little MacDef White Knight.

He made a good point regardless of what you think of him.

 

[scourge18a]

Mine went together fine even with a really tight bolt catch pin. I wrote a bit about the Assembly here:

https://www.canadiangunnutz.com/forum/showthread.php/1760791-SLR-tips-tricks-and-observations

Finally shot it last night just to dial the gas in. I am using a low mass carrier, taccom lightweight buffer and spring and Odin gas block. So far so good, no issues. The PST gen 2 in a QD mount that I had on my DAR 22 for a rimfire PRS match was bang on at 100 yards so that was a nice bonus.
I had also asked Mac Def if they were going to sell trigger boxes on their own...I hate a mil spec trigger and they said "soon but not yet"
Think I guy could be in trouble for modding the box to fit a trigger pack or Hiperfire?
So far I am happy besides the crap DPMS trigger. I have others but not a Geissele. I built mine more for long range as I'll be loading 77 grain Sierras to see how consistently I can hit gongs at 1k.
Time will tell but so far so good, she goes bang every time. I'll just have to build a load and see what kind of accuracy I can get.

 

[Robmcleod82]

Mine went together fine even with a really tight bolt catch pin. I wrote a bit about the Assembly here:

https://www.canadiangunnutz.com/forum/showthread.php/1760791-SLR-tips-tricks-and-observations

Finally shot it last night just to dial the gas in. I am using a low mass carrier, taccom lightweight buffer and spring and Odin gas block. So far so good, no issues. The PST gen 2 in a QD mount that I had on my DAR 22 for a rimfire PRS match was bang on at 100 yards so that was a nice bonus.
I had also asked Mac Def if they were going to sell trigger boxes on their own...I hate a mil spec trigger and they said "soon but not yet"
Think I guy could be in trouble for modding the box to fit a trigger pack or Hiperfire?
So far I am happy besides the crap DPMS trigger. I have others but not a Geissele. I built mine more for long range as I'll be loading 77 grain Sierras to see how consistently I can hit gongs at 1k.
Time will tell but so far so good, she goes bang every time. I'll just have to build a load and see what kind of accuracy I can get.

The Trigger tech trigger fits perfectly.

 

[Betty-Lou]

^^^^^^^ Did you install one? I thought these were a no go.

 

[scourge18a]

The Trigger tech trigger fits perfectly.

Same question, did you put one in and try it?
My velocity was a no go...

 

[Dr. Hunter]

I think the steel index pin will more likely damage the aluminum receiver. My factory bcl 102 has a little extra space where the index pin sits not sure if that's bcl workmanship or it got damaged taking off the ridiculously tight bcl barrel nut when using a reaction rod

 

[Shooting Centre]

It is a common misconception that modular trigger systems will not work. The main issue is the width of the hammer and or sear. It must be able to clear the slot in the trigger box. Also any system that uses adjustment screws on the trigger won’t be adjustable.

 

[scourge18a]

It is a common misconception that modular trigger systems will not work. The main issue is the width of the hammer and or sear. It must be able to clear the slot in the trigger box. Also any system that uses adjustment screws on the trigger won’t be adjustable.

What about the safety?

 

[Uisge]

Y’all wild, I thought it was min 35ft/lb and do not exceed 80ft/lb, pffft! I R mechanic I could do 35 pounds by hand! We’re not torque turning heads bolts here fellas! It’s not rocket appliances! Just dont forget the lube!

 

[Robmcleod82]

^^^^^^^ Did you install one? I thought these were a no go.

You bet and it works fine. I just set the two set screws that push down to the bottom of the receiver out slightly and its all good to go. Wouldnt be a big deal to take a file to the edges of the triggerbox if you need to clearance a hammer or to get access to adjustment screws.