.300 Blackout Rifle Questions

[CTBay]

I finally got all the parts together to finish my .300 Blackout Rifle. This is the third rifle I put together and the first upper I assembled myself. The nut at the base of the handguard/ front of the upper receiver has holes that have to line up for the gas tube. Its a wee bit loose. There is no front to back play in the barrel, its in there tight. The handguard jiggles a bit. I tried to tighten real tight but I cannot get it to that next hole. Do I need to put my purse down and crank it tight, or is it supposed to be a little loose? Handguard is aluminum. Not want to crack it.

Do the holes on the muzzle break face down. I figured the space with no holes would be to keep the flash out of the sight. Am I wrong? With the washer, the blank space facing up is kinda where it landed.

Any help appreciated.

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[d.kaufman]

Shims. They make them In different thickness. Buy a variety pack.

Spike's Barrel Nut Shim Kit (Set of 8)

The Spike's Tactical Barrel Nut Shim Kit allows you to torque your barrel nut into place with perfect alignment when having to install your Spike's Tactical SAR3 or BAR2 rail. Works with most rail systems. NOTE: Our SAR3 and BAR2 include this kit.

spikestactical.com

 

[bwframe]

...Do the holes on the muzzle break face down. I figured the space with no holes would be to keep the flash out of the sight. Am I wrong? With the washer, the blank space facing up is kinda where it landed...

That's upside down. You want the holes, on what looks like a flash hider, facing up. Otherwise debris on the ground or bench can blow back on you or stir up dust clouds.

FYI - for the barrel nut, there should be a torque spec that you should be torqueing to. I grease and season my barrel nut threads, in case I ever want to get the nut back off.

 

[CTBay]

That's upside down. You want the holes, on what looks like a flash hider, facing up. Otherwise debris on the ground or bench can blow back on you or stir up dust clouds.

FYI - for the barrel nut, there should be a torque spec that you should be torqueing to. I grease and season my barrel nut threads, in case I ever want to get the nut back off.

Thanks! Its not real tight so if I pull it down on that crush washer the holes would face up so that makes sense. I am not sure how one would measure torque with this armorer’s wrench. I do have a digital torque wrench in the garage. Not sure how I would use it.

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[CTBay]

Shims. They make them In different thickness. Buy a variety pack.

Spike's Barrel Nut Shim Kit (Set of 8)

The Spike's Tactical Barrel Nut Shim Kit allows you to torque your barrel nut into place with perfect alignment when having to install your Spike's Tactical SAR3 or BAR2 rail. Works with most rail systems. NOTE: Our SAR3 and BAR2 include this kit.

spikestactical.com

Didn’t know about these. Thanks! I cranked hard trying to get to that next hole and have it be tight. I couldn’t get there. I was either go to rip the pegs off the wrench or break something.


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[gmcttr]

...I am not sure how one would measure torque with this armorer’s wrench. I do have a digital torque wrench in the garage. Not sure how I would use it

Put the torque wrench and armorer's wrench together at 90* to maintain an accurate reading. It will not be correct if you place them parallel to each other. Use a 3/8" to 1/2" drive adapter if needed.



You can get a higher quality armorer's wrench with more pins if needed. With tools as so many things, buy once cry once.

 

[CTBay]

Put the torque wrench and armorer's wrench together at 90* to maintain an accurate reading. It will not be correct if you place them parallel to each other. Use a 3/8" to 1/2" drive adapter if needed.

View attachment 160646

You can get a higher quality armorer's wrench with more pins if needed. With tools as so many things, buy once cry once.

Well DUH! I cannot believe I didn’t notice that drive hole in the wrench. I was thinking about some special crows foot wrench or something. Ill go get my torque wrench. I don’t need any more tools. Yay! Ill see what kind of torque I have on it after work. About 85ft lb is what it should be?

I just gave it some beans and got it tight and lined up. There is still a big gap between the upper and the barrel nut. The gap is is several turns away. Its physically impossible the barrel nut will sit flush against the upper. I have a similar hand guard on my 5.56 rifle and it sits pretty close to flush. Not sure thats close enough but its going to need another 360 to get as close as my other rifle and thats just physically not happening.

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[Tactically Fat]

Put the torque wrench and armorer's wrench together at 90* to maintain an accurate reading. It will not be correct if you place them parallel to each other. Use a 3/8" to 1/2" drive adapter if needed.

View attachment 160646

You can get a higher quality armorer's wrench with more pins if needed. With tools as so many things, buy once cry once.

Isn't there torque formula to follow when you do this? Like the torque reading on the wrench itself won't be the actual torque applied?

 

[gmcttr]

Minimum torque for the barrel nut is 30 foot-pounds not to exceed 60-70 (?) ft-lb. Check the handguard/barrel nut manufacturer's info for maximum spec.

 

[999cs]

I found that I will torque the barrel nut to the manufacturer's minimum spec and then go just enough past that minimum rating to where the gas hole lines up. You don't need to crank the heck out of it. I also use grease on the threads and tighten and loosen it three times and then the fourth time is the final torque. Supposedly this seasons the barrel threads to the barrel nut. I don't know if you really need to do this anymore but that is what has always been done from what I have been told.

In regards to the Flash hider, like others said, you just keep tightening the flash hider until it is properly aligned hence crushing the washer down more in front of the flash hider, hence why they call it a "crush washer". Otherwise it looks good to me. Good job.

 

[gmcttr]

Isn't there torque formula to follow when you do this? Like the torque reading on the wrench itself won't be the actual torque applied?

If the torque wrench is 90* from the crows foot the reading will be correct. If it is anything other than 90* there is a formula to use to account for the extension.

 

[CTBay]

So much help! Thanks everyone!

I busted out the torque wrench and googled the spec. Looks like more than 35 less than 80. I was one or two holes off. I had about 25 on it. My torque wrench is set to Newton Meters and I cannot figure out how to change it. 35ft lb is 47.54 nm so I put it right on that. Tube lines up without needing to give it anymore. There is still a sizeable gap between the nut and the receiver but that probably just how its gunna be. The lower, the upper, the barrel, and the hand guard are all different brands so Im not sure I can expect perfect fit.

My new flash hider came in today. Again only holes on one vertical side. I noticed on the other two I have holes are up so you guys must be right. Now I can get it right first time I put it on and not scratch it all up. $20 on ebay and I am very impressed with the quality.

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[999cs]

No problem. Looks good. There will sometimes be a small gap between the barrel nut and receiver but once you put the handguard on it will probably cover it up so I wouldn't worry about it. That is completely normal.

 

[bwframe]

My new flash hider came in today. Again only holes on one vertical side. I noticed on the other two I have holes are up so you guys must be right. Now I can get it right first time I put it on and not scratch it all up. $20 on ebay and I am very impressed with the quality.

Unless, I'm mistaken that is a muzzle brake vs the flash hider posted above in the thread? It will be noticeably louder, but help to keep the rifle level through recoil.