DIY Suppressor alignment gauges

England

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I'd found a thread on Reddit about using O-1 tool steel rods to make your own suppressor alignment gauges. I have the Geissele .22 and .308 rods, but needed one for 6.5 barrels. I'd been making do with using my .22 rod and rotating the rifle 90 degrees four times to check alignment.

The rods are available from McMaster-Carr and quite reasonable: https://www.mcmaster.com/catalog/126/3946/

The Geissele rods look like they may well be made from the same material, and are 17" long. A friend is diving into precision shooting and planning to get a suppressor. McMaster sells these in 3' and 6' lengths, so I figured I would try the 36" rods and if it worked, I could give him a set of gauges.

When you order these, be sure to consider the barrel's bore diameter, not the groove-to-groove diameter! For a .22 centerfire, that would be 0.219". For my 6.5 barrels, 0.256" (so the 0.257" rod would lead to impolite language). For our .308 Win, .30-06, .300 BO, .300 WSM, and such, 0.300".

I ordered four rods: (Tight-Tolerance Oil-Hardening O1 Tool Steel Rod)

1 8893K204 0.250" Diameter, 3 Feet Long $4.53

2 8893K191 0.2120" Diameter, 3 Feet Long $5.66 (figured this for .22 centerfires and most rimfire)

3 8893K187 0.2031" Diameter, 3 Feet Long $5.13 (figured this for .22 rimfire with a tight "match" barrel)

4 8893K217 0.2950" Diameter, 3 Feet Long $7.00

Merchandise 22.32
Sales Tax 1.34
Shipping 9.72
Total $33.38

They showed up today. Now, someone like with skills, pride, and a good shop would neatly and precisely cut these for a perfect cylindrical shape, like the Geissele rods. But that's not me. So I marked 18" with a Sharpie, clamped the rod in the vice, and went to work with the SawZall and a metal blade. Then I fired up the bench grinder and cleaned up and chamfered the ends. No, you wouldn't pay $70 each for these rods, but that was kind of the point.

I have a 6"x18" granite plate with "flatness certificate" I got on a deal from Woodcraft for sharpening chisels and planes. I put each rod on the plate, rolled it, and backlit with a handy tactical flashlight. They appear quite straight; certainly straight enough for my intended purpose!

I washed each rod and then coated them with Boeshield T9. More importantly, I put a 6.5 CM rifle in my vice, screwed on the suppressor, and slipped in the 0.250" rod. Happily, the rod inserted into the barrel snugly but cleanly and unsurprisingly, the suppressor appears to be nearly perfectly aligned. Which is probably why I haven't shot it to pieces already.

I'm planning to get some PVC end caps and will make a couple 18+" tubes to hold each set of four rods. But at $17 for a set of four, they are marvelously cheaper than commercial rods and even a hack like me can turn one out.
 

phantasm

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I've been thinking of doing the same thing but wasn't too sure which rods to go with. I assume the .2950" diameter rod is for 30 cal? I've looked at the Geissele and Griffin rods and while they look nice, holy hell on that price tag.
 

England

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That 0.295" rod works fine for .308 Win/.30-06/.300 BO and the like. It is a snug but safe fit.
 

gconnoyer

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Go to a local archery store and find some carbon arrows the size you need.
Runout is typically .001-.005 (highest quality to lowest)
Suppressor overbore is typically .060 over

I've got a .259 dia shaft that would work more than good enough for 6.5creed (I'm not archer so I'm not sure on available sizes and how they match up to bullet bore size
 

England

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That’s hotdog down a hallway undersized if you ask me. Not even close to bore diameter.
Bore diameter is 0.300". The rod is 0.295", so 0.005" clearance. Are you really suggesting that an additional 0.004" is necessary as a no-go suppressor gauge? You're much braver than me or don't mind launching the occasional can downrange.
 

Supersubes

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Bore diameter is 0.300". The rod is 0.295", so 0.005" clearance. Are you really suggesting that an additional 0.004" is necessary as a no-go suppressor gauge? You're much braver than me or don't mind launching the occasional can downrange.
Why would a more precise rod put you at risk of launching a suppressor? And yes I’m suggesting that .295 is way too small for what Im doing.
 

EnXCess

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Uh, I hate to tell you but I can mount a suppressor and then simply look through it and the bore and tell you whether it is on straight or not. That's easy with a bolt gun, a little harder with an a/r.

Also, I would be concerned about damaging my rifling if I put in a steel rod that fit tight enough to do any good.
 

Supersubes

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Uh, I hate to tell you but I can mount a suppressor and then simply look through it and the bore and tell you whether it is on straight or not. That's easy with a bolt gun, a little harder with an a/r.

Also, I would be concerned about damaging my rifling if I put in a steel rod that fit tight enough to do any good.
You mean like the steel range rods most gunsmiths put down the bore to dial it in to the lathe, which have .0002-.0004 clearance? How bout a rod with .001 clearance, not .005, and with a high degree of straightness?
 

EnXCess

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You mean like the steel range rods most gunsmiths put down the bore to dial it in to the lathe, which have .0002-.0004 clearance? How bout a rod with .001 clearance, not .005, and with a high degree of straightness?
Correct. I would not do that either unless there were some good reason to, like threading a barrel.