Anyone in Canada doing M14 FS reaming?
- Thread starter Claven2
- Start date
TacticalTeacher
CGN Ultra frequent flyer
- Location
- Georgian Bay, ON
I’ve got yer back. Number 7 tapered pin reamer with Spiral Flutes , baby....
All great fun!!
Cheers, Barney
All great fun!!
Cheers, Barney
Ok, here is the oft-cited, sometimes over-rated, and decidedly cool National Match modification to the USGI M14 flash suppressor.
Step 1: Locate a friend with the tool you somehow don't have in your well equipped machine shop (like... WTF - how do I not own a No.7 spiral cut taper pin reamer!?! I have lots of reamers, but somehow not this one - but it pays to have friends).
Step 2: Jig up the flash suppressor in the lathe. It helps to have an old piece of barrel stub and a sacrificial castle nut, then you can do the whole (high torque) cut in the lathe which gives a smoother more consistent result that will make no difference in shooting performance, but will make you the envy of M14 smiths everywhere. I got impatient, so I only started the cut in the lathe on VERY slow speed using a live centre to apply pressure and the T-bar to prevent the reamer from turning so I could feel the resistance of the cut. You are only trying to get the first 1cm or so of the cut done straight so the reamer will remain well centered through the rest of the cut. You can have up to 10 thou or so of runout without affecting anything, more than that and you've scrapped a nice USGI flash suppressor, so be careful (!).
Once your cut is well started, if you don't have a nice mandrel jig (AKA a stub off an old shot-out M14 barrel), you'll want to clamp the FS in a vise to hold it well and use a T-bar to cut most of the taper by hand. As the reamer contacts more of the inner diameter of the FS, cutting gets harder as there is more friction. This is why you would need a slave mandrel for a lathe cut, the chuck can't grip the OD of the flash suppressor hard enough to prevent it from turning in the chuck without deforming the flash suppressor itself. So not having a mandrel jig means you'll do some of the reaming by hand. Oh well.
Important tip: buy a good bottle of High Speed Steel cutting oil and use lots of it. Clean off the chips every 2 or 3 full turns and re-oil the reamer.
You keep cutting until the opening in the front of the FS is 0.406". Stop there. You are at the Army TM spec for NM reaming. The FS is not reamed all the way down to the muzzle, there will be 1 to 2 cm of un-reamed materiel just forward of the muzzle, depending on the tolerance of the original factory bore in your flash suppressor. Before I forget, you take the diameter measurement BEFORE any chamfering.
The last step, but an important one, is to put a small 60 degree chamfer on the flash suppressor mouth so the sharp edge doesn't catch on cleaning jags and such. It's not that important how much chamfer you apply, you just need to break the edge sufficiently. I do this step in the lathe, it's easier that way. I also take a small needle file and de-bur the edges of the flutes for the same reason. I'm using a chamfering bit in this picture, but you could also cut it with a regular tool bit if you have the FS on a mandrel. Did I mention I need to get around to making another mandrel now that I can't locate the one I had years ago???
And.... done. Ready for media blasting and re-park.
Hope that helped explain the process
Step 1: Locate a friend with the tool you somehow don't have in your well equipped machine shop (like... WTF - how do I not own a No.7 spiral cut taper pin reamer!?! I have lots of reamers, but somehow not this one - but it pays to have friends).
Step 2: Jig up the flash suppressor in the lathe. It helps to have an old piece of barrel stub and a sacrificial castle nut, then you can do the whole (high torque) cut in the lathe which gives a smoother more consistent result that will make no difference in shooting performance, but will make you the envy of M14 smiths everywhere. I got impatient, so I only started the cut in the lathe on VERY slow speed using a live centre to apply pressure and the T-bar to prevent the reamer from turning so I could feel the resistance of the cut. You are only trying to get the first 1cm or so of the cut done straight so the reamer will remain well centered through the rest of the cut. You can have up to 10 thou or so of runout without affecting anything, more than that and you've scrapped a nice USGI flash suppressor, so be careful (!).
Once your cut is well started, if you don't have a nice mandrel jig (AKA a stub off an old shot-out M14 barrel), you'll want to clamp the FS in a vise to hold it well and use a T-bar to cut most of the taper by hand. As the reamer contacts more of the inner diameter of the FS, cutting gets harder as there is more friction. This is why you would need a slave mandrel for a lathe cut, the chuck can't grip the OD of the flash suppressor hard enough to prevent it from turning in the chuck without deforming the flash suppressor itself. So not having a mandrel jig means you'll do some of the reaming by hand. Oh well.
Important tip: buy a good bottle of High Speed Steel cutting oil and use lots of it. Clean off the chips every 2 or 3 full turns and re-oil the reamer.
You keep cutting until the opening in the front of the FS is 0.406". Stop there. You are at the Army TM spec for NM reaming. The FS is not reamed all the way down to the muzzle, there will be 1 to 2 cm of un-reamed materiel just forward of the muzzle, depending on the tolerance of the original factory bore in your flash suppressor. Before I forget, you take the diameter measurement BEFORE any chamfering.
The last step, but an important one, is to put a small 60 degree chamfer on the flash suppressor mouth so the sharp edge doesn't catch on cleaning jags and such. It's not that important how much chamfer you apply, you just need to break the edge sufficiently. I do this step in the lathe, it's easier that way. I also take a small needle file and de-bur the edges of the flutes for the same reason. I'm using a chamfering bit in this picture, but you could also cut it with a regular tool bit if you have the FS on a mandrel. Did I mention I need to get around to making another mandrel now that I can't locate the one I had years ago???
And.... done. Ready for media blasting and re-park.
Hope that helped explain the process
