We wrapped up (pun) a rifle yesterday for a gent down in NM with the intention of shipping it today.
Not gonna happen. . .
Prior to receiving the parts, the customer had another shop fit up a Vaise muzzle brake on his ABS barrel. He later settled on us to build the gun. The barrel is a "palma looking" 6mm chambered in 243AI. We did the threading/chambering work on this piece along with stockwork, paint, etc.
Threads on the muzzle were cut to 1/2-28. The shop that did the work included a large fillet at the back of the thread where it transitions to the shoulder. The fillet was undercut creating a virtual corner and eliminates any issues with the brake failing to suck up to the shoulder nice and tight. Not a bad thing generally, but in this case it made a mess.
The work potentially ruined the barrel. Garrett noticed a faint, barely detectable anomaly right at the tangent point of the radius where it transitions to the shoulder. To the casual eye it appeared to be a crack.
In fact it was the lead thread of the barrel nut that goes onto the barrel as a part of making the carbon process work. My understanding is its designed to compress the carbon and put the barrel liner under compression.
We contacted the cst and informed him. We also spoke with the folks at Proof Research to see what they had to say. Proof Research DID NOT manufacture this barrel. They merely bought the patent rights from ABS. Regardless, they were very professional and have offered to replace it if it is indeed defective from this machine work.
A test yesterday pretty much solidified that the barrel isn't going to work. We shot it once in our test cell and upon inspection we discovered that the inclusion extended all the way around the periphery of the radius. It appears that the barrel is indeed cracked or somehow being distressed by the machine work. It distorted and ballooned right around where the problem was first discovered. Might not be, but it sure looks like it is to us.
SO, lessons:
From our chair if your installing a brake/can on a barrel like this use the LARGEST thread you possibly can on the muzzle. This particular barrel measures close to .800" in OD yet a 1/2 thread was used with a very snorty undercut. Using a larger thread will preserve much wanted/needed wall thickness at the muzzle. Always a good thing. it also keeps you out of the barrel nut threads.
<span style="font-weight: bold"><span style="font-style: italic">
Next, give the barrel maker a call if your unsure and ask them what the best procedure is for threading their barrels as there is a difference.</span>
</span>
There's been a lot of chatter lately about these kinds of barrels so this seemed like a great opportunity to share some technical stuff related to them. Just to reiterate, this problem WAS NOT the fault of the barrel or the barrel manufacturer. It was not LongRifles, Inc's. fault either. We just discovered the problem created by another shop. Out of professional courtesy their name will stay out of this so don't ask.
Hope this helps someone down the road.
C.
Not gonna happen. . .
Prior to receiving the parts, the customer had another shop fit up a Vaise muzzle brake on his ABS barrel. He later settled on us to build the gun. The barrel is a "palma looking" 6mm chambered in 243AI. We did the threading/chambering work on this piece along with stockwork, paint, etc.
Threads on the muzzle were cut to 1/2-28. The shop that did the work included a large fillet at the back of the thread where it transitions to the shoulder. The fillet was undercut creating a virtual corner and eliminates any issues with the brake failing to suck up to the shoulder nice and tight. Not a bad thing generally, but in this case it made a mess.
The work potentially ruined the barrel. Garrett noticed a faint, barely detectable anomaly right at the tangent point of the radius where it transitions to the shoulder. To the casual eye it appeared to be a crack.
In fact it was the lead thread of the barrel nut that goes onto the barrel as a part of making the carbon process work. My understanding is its designed to compress the carbon and put the barrel liner under compression.
We contacted the cst and informed him. We also spoke with the folks at Proof Research to see what they had to say. Proof Research DID NOT manufacture this barrel. They merely bought the patent rights from ABS. Regardless, they were very professional and have offered to replace it if it is indeed defective from this machine work.
A test yesterday pretty much solidified that the barrel isn't going to work. We shot it once in our test cell and upon inspection we discovered that the inclusion extended all the way around the periphery of the radius. It appears that the barrel is indeed cracked or somehow being distressed by the machine work. It distorted and ballooned right around where the problem was first discovered. Might not be, but it sure looks like it is to us.
SO, lessons:
From our chair if your installing a brake/can on a barrel like this use the LARGEST thread you possibly can on the muzzle. This particular barrel measures close to .800" in OD yet a 1/2 thread was used with a very snorty undercut. Using a larger thread will preserve much wanted/needed wall thickness at the muzzle. Always a good thing. it also keeps you out of the barrel nut threads.
<span style="font-weight: bold"><span style="font-style: italic">
Next, give the barrel maker a call if your unsure and ask them what the best procedure is for threading their barrels as there is a difference.</span>
</span>
There's been a lot of chatter lately about these kinds of barrels so this seemed like a great opportunity to share some technical stuff related to them. Just to reiterate, this problem WAS NOT the fault of the barrel or the barrel manufacturer. It was not LongRifles, Inc's. fault either. We just discovered the problem created by another shop. Out of professional courtesy their name will stay out of this so don't ask.
Hope this helps someone down the road.
C.
