What Size Inner Diameter for A Muzzle Device on an AR308

[Sharrie*1 1]

Ok, so I purchased a muzzle brake from Primary arms. It is a Seekins ATC. The text on Primary Arms says "No special gunsmithing required." So I pick one up and install it. Today I am oiling the gun in preparation for the first shooting and I notice the patch is tight going thru the brake. So, I do some looking and see on the Seekins site and it says "Seekins Precision's gunsmith ATC is designed to be installed by a gunsmith depending on caliber and install preference ...The center bore is shipped undersized and may need to be enlarged depending on caliber"

 

So, here I am with a muzzle device that it pinned on to a barrel with a gas block and barrel nut already installed.

 

My question at this point is what are my options? Can I drill it out with a drill? What size do I drill it in order to work on my AR308? Can the inner diameter of this brake be cut in a lathe now that it is fixed on the barrel?

 

Honestly, I am just glad I cleaned this gun prior to shooting it, it could have been disastrous!!  Currently the inner bore is .305."

[bignic83 0]

Wow, agree you are lucky you cleaned it. Probably can be drilled, but I would let a gunsmith do it. Don't want to accidentally damage the rifle lands.

[Sharrie*1 1]

I am cool with bringing it to a gunsmith...have over $550 invested in the barrel, nut, gas block and muzzle device. I just hope they can do it now that the device is pinned on which means the gas block and nut are also permanently installed.

[JT Custom Guns 956]

PM Sent.................

[PK90 3,570]

Will the bullet fit in the exit hole? How much clearance does it have?

 

Sent from an undisclosed location.

 

 

[Sharrie*1 1]

Measuring the last port in the brake I get .305 with a dial caliper. I am not thinking the bullet will make it thru.

[Old School 611]

This is not a big deal.  Listen to Paul.  Any Machinist / gunsmith should be able to straighten it out for you at a minimum charge.

 

After a little research here you go...

 

Midway

Product #: 499359 PTG #: 499359

 

Cuts the brake .015" larger than groove diameter.

 

If you want one give me a shout.

Edited March 31, 2014 by Old School

[Sharrie*1 1]

Old School, thanks!

I guess .015" larger than the barrel is about right.

 

Man they have a tool for everything :-)

[Old School 611]

Precision shooters that shoot a rifle with a brake always have the brake reamed for alignment.

[Sharrie*1 1]

So here is an update of my ordeal.

 

Jack at JT Custom Guns sent me a PM that he thought he could fix my problem. Being in the position I was in, I took him up on it. So, I talked to his machinist with the options open to me. He recommended that I remove the pinned muzzle device, drill it and reinstall. Mike (the machinist) also explained that it may be possible that he would need to pin the brake on the top if the holes did not align when he reinstalled the muzzle device. I asked him to remove it and let me know how it looked. Literally a couple of hours later, Jack called me back and informed me that the device was off and that the person who originally pinned the brake (a shop in Rahway) really didn't pin it too deeply. Usually, this is bad. For me it worked to my benefit. So anyhow, the device was removed and resized (so that a 308win projectile would pass). The brake was reinstalled, pinned and I must confess, it looks great.

 

So, I dropped of the barrel on wed. night and it was complete and ready to go on thurs. night.

 

I must confess that I am a newby at building AR type guns even though I have a couple AR15s under my belt. This is my first AR308. That being said, here is a valuable lesson that I learned. Check the muzzle device prior to having it installed. Also, be careful where you have your muzzle device pinned.

 

Old School - I did look at the tool you suggested at Midway. As it turns out, my cost was only slightly more than the cost of the tool plus shipping. And, now my pin is flush and blends much better than the original pin. I do truly thank you for your suggestions though!

 

Thanks to all that helped me. I hope this helps a newby out there that may have been in a similar situation if they did not read this thread.

[mikka1 2]

Sorry for stealing the thread, but didn't really want to start a new one on a similar topic.

 

So, trying to finalize my super-budget AR build (PTAC parts & upper etc) and make it NJ legal I have been looking for a *cheap* muzzle break. Finally I ran into this one

 

http://www.buyzillion.com/1117186048097106/ar15-223-1-2x28-competition-muzzle-device-brake

MZ-1008B NoName :-)

 

I ordered one off Amazon for ~$15, it comes, looks especially nice on a PTAC barrel (very similar color tone) and I was about to pin it... but two things caught my attention:

1) Some people on Amazon were reporting this brake "considerably reducing muzzle flip *as well as flash*"

2) An exit hole looks a little bit bigger than I would imagine for a muzzle brake (but still significantly smaller than on A2 flash hider)

 

To put it in a perspective, here is the picture.

On the left it is the unthreaded 223/5.56 barrel of my M&P15

In the middle - A2-type flash hider not very legal in NJ

On the right hand side - PTAC barrel with a mentioned muzzle brake installed.

I don't have a caliper, but it roughly measures ~0.400" at the exit hole.

 

Some people also reported that the company might have sent them a wrong compensator for .308 instead of .223

 

So, what should I do?

Should I return this muzzle brake?

Is it a brake at all?

If I still keep it and permanently attach it to the barrel, will it work as it should or is it too big to work properly?

 

[Sharrie*1 1]

Mikka, I cannot comment on legality or brake vs comp vs flash hider as I still have a lot of learning to do. But, I do know that an ar15 barrel is 1/2" thread and an ar308 barrel is usually 5/8" thread. So, it would be hard to get the .308 comp on a ar15 barrel.

[Sharrie*1 1]

Another update on my ordeal...Last night I sent Primary Arms an email explaining that their site was not correct and that they were selling a dangerous product. So first thing this morning I got an email that the site was fixed and a heartfelt thank you for letting them know. The email said that the individual was going to escalate the issue to see what they could do. Before lunch is was contacted by Primary Arms (I believe it was the manager). He told me that they wanted to make it right, and that they were going to refund all the money that I paid getting this job straightened out. I was also thanked several times for bringing this to their attention.

 

In the end, this was a great lesson for me (and others that read this on the forum); and, I found out that Primary Arms is a reputable business. One that I now intend on dealing with again in the future.

[raz-0 1,259]

Sorry for stealing the thread, but didn't really want to start a new one on a similar topic.

 

So, trying to finalize my super-budget AR build (PTAC parts & upper etc) and make it NJ legal I have been looking for a *cheap* muzzle break. Finally I ran into this one

 

http://www.buyzillion.com/1117186048097106/ar15-223-1-2x28-competition-muzzle-device-brake

MZ-1008B NoName :-)

 

I ordered one off Amazon for ~$15, it comes, looks especially nice on a PTAC barrel (very similar color tone) and I was about to pin it... but two things caught my attention:

1) Some people on Amazon were reporting this brake "considerably reducing muzzle flip *as well as flash*"

2) An exit hole looks a little bit bigger than I would imagine for a muzzle brake (but still significantly smaller than on A2 flash hider)

 

To put it in a perspective, here is the picture.

On the left it is the unthreaded 223/5.56 barrel of my M&P15

In the middle - A2-type flash hider not very legal in NJ

On the right hand side - PTAC barrel with a mentioned muzzle brake installed.

I don't have a caliper, but it roughly measures ~0.400" at the exit hole.

 

Some people also reported that the company might have sent them a wrong compensator for .308 instead of .223

 

So, what should I do?

Should I return this muzzle brake?

Is it a brake at all?

If I still keep it and permanently attach it to the barrel, will it work as it should or is it too big to work properly?

 

 

No, you shout brought a cheaply made brake. They made the end opening rather large so that they can not worry that much about keeping the threads concentric with the bore. 

[mikka1 2]

No, you shout brought a cheaply made brake. They made the end opening rather large so that they can not worry that much about keeping the threads concentric with the bore. 

OK, thanks, then I'll just live with that I'd say this whole build shouts "cheeeeap" all over it, so should not be an issue, LOL

Thanks again!

[raz-0 1,259]

No, you shout brought a cheaply made brake. They made the end opening rather large so that they can not worry that much about keeping the threads concentric with the bore. 

 

I'm really trying to figure out what typo got auto corrected to shout. IT was supposed to be just. 

[monmouth 19]

Precision shooters that shoot a rifle with a brake always have the brake reamed for alignment.

Nope.