Do I Need This For My New Suppressor?

[Thy.Will.Be.Done]

I've got a Geissele Super Duty Carbine, with the as built OEM Surefire 3 Prong Flash Hider. Can't help but wonder if I'd be good to go having a quality build without having to test alignment but would hate to be proved wrong on that one. Does every build truly need this for suppressors?

https://assets.surefire.com/uploads/2019/07/sf-rod-all__35801.1562870305.1280.1280-1000x1000.jpg

https://www.surefire.com/products/suppressors-division/suppressor-accessories/bore-alignment-rods/

[S Jenks]

With that setup you’ll probably be fine without one.

My story: I bought both 9mm and 5.56 rods after having a minor end-cap strike when shooting either a PTR-9C or Uzi Pro with my Rugged Obsidian 9 and tri-lug adapter. Being a suppressor noob I didn’t realize you shouldn’t brace off a barricade when using tri-lug (or ever, really).

I bought the rods mainly to see how much flex was happening with my various mounts. Quite a bit with tri-lug, not so much with direct thread or or YHM’s mounts of the Turbo T2.

[Casual Friday]

I would not take the risk, but it's your can.

Don't pay 80 bucks for a Surefire or Geissele. Buy the appropriate size drill rod from McMaster Carr, cut it to length and chamfer the ends. They run about 20 bucks last time I checked.

[4gallonbucket]

Yes McMaster Carr drill rods -- but make sure you get the one that has a straightness specification.
I first ordered without and they came loose packed in a cardboard box. There was a little bit of wobble in the .217" rod.

[whomever]

Yes McMaster Carr drill rods -- but make sure you get the one that has a straightness specification.
I first ordered without and they came loose packed in a cardboard box. There was a little bit of wobble in the .217" rod.

Can you share which ones have a straightness spec? I just spot checked a few and they have precision ground ones that have a diameter tolerance, but I didn't see any that had a straightness spec. Maybe I'm not looking in the right place.

I ask because the precision ground was the first thing I thought of, but when I checked several pieces on a surface plate, none of them were particularly straight.

I ended up springing for the Geissele ones.

[mtnbkr]

Slightly different question:
If you have a gun/can combo that is demonstrably safe, and do not intend to put the can on a different firearm, do you need one of these rods for periodic checks?

Due to ignorance on my part, I've never checked this under the assumption that using quality guns and cans to begin with mitigated the risk, but I don't know if there's an ongoing need as well.

Chris

[4gallonbucket]

Can you share which ones have a straightness spec? I just spot checked a few and they have precision ground ones that have a diameter tolerance, but I didn't see any that had a straightness spec. Maybe I'm not looking in the right place.

I ask because the precision ground was the first thing I thought of, but when I checked several pieces on a surface plate, none of them were particularly straight.

I ended up springing for the Geissele ones.

for 5.56 bore-
0.212": Tight-Tolerance W1 Tool Steel Rod https://www.mcmaster.com/8890K189/

for 30 cal bore-
0.295": Tight-Tolerance W1 Tool Steel Rod
https://www.mcmaster.com/8890K227/

I first ordered the "Tight-Tolerance Multipurpose Oil-Hardening O1 Tool Steel Rods" -- then I noticed there was no straightness spec and there is some visible wobble when rolled on glass. I noticed the "W1 tool steel" rods have a straightness spec of 0.005" per foot.
I have not ordered these yet, but I plan to do so soon.

[whomever]

I noticed the "W1 tool steel" rods have a straightness spec of 0.005" per foot.
I have not ordered these yet, but I plan to do so soon.

Thanks!

Note that .005/ft is .007 or so over the length of the rod. IMHO, that's quite a bit relative to what you are trying to measure (the Geissele spec is .001 over the length of the rod).

I just measured the end hole on a 30 cal suppressor and got .370 or so; (370-308)/2 = .031, so a collision ought to show up. If it were me, I'd mark a line on the end of the rod and rotate it to check at a few orientations, as a sanity check. You've used up some of your tolerance stack, so care is in order.

If you do get some and have a way to check (surface plate? lathe ways?) please post the straightness of what you get. I think I have ordered some of that and got a little more wobble than spec, but I might be misremembering. Or, it doesn't take much tender love from UPS to change that spec by a lot :-(.

Good luck, the price is certainly attractive!

[Screwball]

We are all adults, and can make our own decisions…

I personally will not fire a suppressor on a firearm if I haven’t checked alignment. If there is a change of that setup… like I pulled the muzzle device for whatever reason… I’ll check again.

I won’t normally recheck. Make sure the muzzle device and can are not faulty and be sure they mount up correctly. If an issue arises… recheck alignment.

I likely will have less to worry about with my main suppressor, which is a Griffin Bushwhacker 46. If I mount it on an AK, those 0.46” holes will take a lot of issues to cause a baffle strike… but I’ll still check. If I swap a 0.30” end cap, worst thing likely will be a new end cap. But I rather not have to spend $80 on a new end cap…

I got a bunch of rods from a forum that talks about building your own suppressors… it was linked from AR15.com. I will apologize that I do not remember the name, but they were extremely cost effective and straight. Was nice because I got into suppressors right when I wanted to add a bayonet lug on my M1A. Good tools to have, even if just installing a muzzle device.

[23JAZ]

Can you share which ones have a straightness spec? I just spot checked a few and they have precision ground ones that have a diameter tolerance, but I didn't see any that had a straightness spec. Maybe I'm not looking in the right place.

I ask because the precision ground was the first thing I thought of, but when I checked several pieces on a surface plate, none of them were particularly straight.

I ended up springing for the Geissele ones.
What would be the best diameter for checking alignment on a 9mm?

[helothar]

I would not take the risk, but it's your can.

Don't pay 80 bucks for a Surefire or Geissele. Buy the appropriate size drill rod from McMaster Carr, cut it to length and chamfer the ends. They run about 20 bucks last time I checked.

i'm guessing chamfering is to not damage the bore? sorry for the probably dumb question but would something like this work fine to chamfer these: https://www.amazon.com/Deburring-External-Chamfering-Stainless-Silver-2/dp/B09NQC21XQ/ref=pd_sbs_2/130-1202367-7701354?pd_rd_w=LZrso&pf_rd_p=cd718a0c-f7e0-41b6-9f23-6496d85d1998&pf_rd_r=GHRPEAQYCQPKFPZPHVPQ&pd_rd_r=b1f4196e-02d0-4dd1-bec9-a2c7092e17a9&pd_rd_wg=GdSCe&pd_rd_i=B07ZSFH918&th=1

[whomever]

What would be the best diameter for checking alignment on a 9mm?

I'll defer to the experts:

"The Geissele SAG is manufactured from hardened steel that
has been ground 0.002” under nominal bore diameter. The
outside diameter of the SAG is finely finished and straight to
0.001” over its length. Geissele hardens the SAR so that it
will not wear by sliding exposure to abrasive powder residue,
pull burrs if it slides against misaligned baffles nor allow
abrasive particle to imbed into the surface of the gage.
There can be a wide variation in barrel bore diameters and
bore straightness. 0.002” under nominal bore diameter has
been found to be the best size of the SAG that will fit most
barrels. The long length of the SAG aligns the gage to the
bore; it is not necessary to have a very tight fitting gage with
the long length of the Geissele SAG."


https://geissele.com/amfile/file/download/file/24a720321ee71666eb1c4b98ead55ebb/product/35/

[whomever]

i'm guessing chamfering is to not damage the bore? sorry for the probably dumb question but would something like this work fine to chamfer these: https://www.amazon.com/Deburring-External-Chamfering-Stainless-Silver-2/dp/B09NQC21XQ/ref=pd_sbs_2/130-1202367-7701354?pd_rd_w=LZrso&pf_rd_p=cd718a0c-f7e0-41b6-9f23-6496d85d1998&pf_rd_r=GHRPEAQYCQPKFPZPHVPQ&pd_rd_r=b1f4196e-02d0-4dd1-bec9-a2c7092e17a9&pd_rd_wg=GdSCe&pd_rd_i=B07ZSFH918&th=1


Yes, just so you're not gouging the bore, and perhaps to make it easier to slip past baffles.

I wouldn't buy the tool, I'd just use a fine file or grind it. Anything that knocks off the corner and leaves a smooth surface would work.


(Alternatively, tell your wife you need to buy a lathe to mount the suppressor :-) )

[23JAZ]

I'll defer to the experts:

"The Geissele SAG is manufactured from hardened steel that
has been ground 0.002” under nominal bore diameter. The
outside diameter of the SAG is finely finished and straight to
0.001” over its length. Geissele hardens the SAR so that it
will not wear by sliding exposure to abrasive powder residue,
pull burrs if it slides against misaligned baffles nor allow
abrasive particle to imbed into the surface of the gage.
There can be a wide variation in barrel bore diameters and
bore straightness. 0.002” under nominal bore diameter has
been found to be the best size of the SAG that will fit most
barrels. The long length of the SAG aligns the gage to the
bore; it is not necessary to have a very tight fitting gage with
the long length of the Geissele SAG."


https://geissele.com/amfile/file/download/file/24a720321ee71666eb1c4b98ead55ebb/product/35/
So with .350” lands and .354” grooves. I should be good with a .348” rod?

[Casual Friday]

i'm guessing chamfering is to not damage the bore? sorry for the probably dumb question but would something like this work fine to chamfer these: https://www.amazon.com/Deburring-External-Chamfering-Stainless-Silver-2/dp/B09NQC21XQ/ref=pd_sbs_2/130-1202367-7701354?pd_rd_w=LZrso&pf_rd_p=cd718a0c-f7e0-41b6-9f23-6496d85d1998&pf_rd_r=GHRPEAQYCQPKFPZPHVPQ&pd_rd_r=b1f4196e-02d0-4dd1-bec9-a2c7092e17a9&pd_rd_wg=GdSCe&pd_rd_i=B07ZSFH918&th=1

That would work, but I just spin the edge on a disc sander.

[Casual Friday]

The drill rods from McMaster Carr come in 3ft or 6ft lengths. I bought a 3ft chunk and cut mine out of the center of the rod where in theory it should be the straightest. I don't have any specialty measuring tools but it rolls smoothly over a thick pane of glass with no discernible wobble. When rotated inside the bore, the reveal on either side of the rod does not change in relation the suppressor. I store it in a chunk of the hard cardboard tube it shipped in that I cut to length.

If I were running a 9" or longer suppressor with a tight bore for caliber, I might opt for the straightest rod I could get my hands on, but for a 6" YHM Turbo T2 I'm perfectly comfortable with the one I'm using.

[whomever]

So with .350” lands and .354” grooves. I should be good with a .348” rod?


That's what Geissele seems to say.

FWIW, I just miked my 22 and 30 cal rods and got .214x and .297x.

I don't think it's critical; the idea isn't that the gauge is a slip fit in the bore, it is that there is ore rod inside the barrel than is sticking out into the suppressor, so gravity aligns the rod with the bore. In theory you could use a 22 rod for any bore size by rotating the rifle 360 degrees and watching the rod/suppressor clearance as you go. Heck, that's probably a good idea in any case, as is rotating the rod as mentioned above.

You definitely want the rod setting on the bottom of the bore - if it tilts now you have to wonder how much error that is causing.

[23JAZ]

That's what Geissele seems to say.

FWIW, I just miked my 22 and 30 cal rods and got .214x and .297x.

I don't think it's critical; the idea isn't that the gauge is a slip fit in the bore, it is that there is ore rod inside the barrel than is sticking out into the suppressor, so gravity aligns the rod with the bore. In theory you could use a 22 rod for any bore size by rotating the rifle 360 degrees and watching the rod/suppressor clearance as you go. Heck, that's probably a good idea in any case, as is rotating the rod as mentioned above.

You definitely want the rod setting on the bottom of the bore - if it tilts now you have to wonder how much error that is causing.
According to SAMMI nominal bore diameter for 9mm is .346” so I ordered .3437” with a +\- .001 diameter tolerance and a +|- .005” straightness tolerance. It was the closest they had without going over.

[23JAZ]

Ok I got the 3’ tight tolerance rod from McMaster. I work in manufacturing quality so I had one of my engineers put the rod on a lathe. He cut it in half and squared and chamfered all edges. Roll tested on our granite table for flatness on both was good and the diameter it spot on.
So anyway now I have two 9mm alignment rods and I only need one. I’d be more than happy to give it to someone that needs it. All I ask is you cover shipping. Shitty mods, if this should be in Karma please let me know and I’ll post it there.
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