First form-1. How much clearance for .22lr ?

[DAV88]

Hello ladies and gents. This is my first post on here. I'm from the DPR of MD and building my first suppressor. I got my form-1 back last week and started the building process today. I have not drilled out the plugs because I understand the form-1 is not a license to experiment so I come here for some expert knowledge. Is 19/64 a big enough hole for 22lr? That's .076875 bigger than the round or almost .30cal.

One last question, if I install a wipe at the end, am I allowed to replace that myself when it wears out?

Thanks for your help and before anyone says to search, I did. There wasn't a general consensus on how large or small the holes needed to be.

[partsguy22]

9/32" is the min. I'd go with I believe the rule of thumb is .060" over projectile size and adjust from there based on alignment "errors" if you are drilling them on a drill press the larger bore gives you more margin for error

I'm not sure about the wipe

[T-Rex]

Yes, you can still replace wipes. The ATF/NFA hasn't released an official ruling contradicting this.

McMaster:
8789K212 for 1/8" sheet
8789K412 for 1/4" sheet

[DAV88]

Yes, you can still replace wipes. The ATF/NFA hasn't released an official ruling contradicting this.

McMaster:
8789K212 for 1/8" sheet
8789K412 for 1/4" sheet

That information on the wipe material and where to get it is exactly what I was looking for. Thanks a lot! I took a look at this thread, viewtopic.php?t=50571 and didn't see whether people were using extra soft, soft, or medium soft.

[John A.]

If you are confident that everything is right, 17/64" is what I'd use.

With that said, even with a .400" hole, 22 still sounds good through it if it's a decent design.

[CMV]

I use 17/64", but am not drilling freeze plugs with a cordless drill. So depending on how uniform the FPs are, how well they fit the tube, how precisely you can measure center, how accurately you can drill center, etc should increase your fudge factor from that min diameter.

I had accuracy issues with my 10/22 integral and increased bore size incrementally until it went away. I went to 9/32, then 19/64, then 5/16! I noticed no perceivable difference in sound level going that big

[John A.]

That is my experience as well.

Even with large baffle bores, 22 is still quiet.

I shoot 22 through my 9mm can all the time.

[mcrump]

I read that .06 is the drill size over bullet size to allow for misalignment using a drill press. So what if one is using a tool room lathe. Baffle to wall clearance is .002. Punch a starter hole with a center drill, drill slightly undersize final hole size and ream to finish. As an example I routinely finish bore size 0.250 for a 22 bullet and never had a baffle strike. I always thought that tighter was better but could be completely wrong in my thinking. Is there an advantage to opening up the bore clearance?

[T-Rex]

Tighter bores can and will yield greater dB reductions. Not necessarily appreciable, though. The tighter bore, however, can adversely effect the projectiles flight. A larger bore allows gas and projectile to flow w/o impeding the path of the other. As John stated, designs for larger calibers can have great results for .22. Though, their overall volume will also be greater than a dedicated rimfire design. You're product shouldn't rely on a .25" bore over one that is .30". Focus on baffle design and you're results be promising.

[mcrump]

Curious then. Has anyone tried progressively larger bores? Say I have 8 baffles and the first is bored 0.250 and each successive baffle is .005 larger making the end cap bore 0.29 in diameter. Taking it even further, if each successive bore was .010 bigger than the last, then the exit bore would be 0.330. Theoretically, the accuracy would be better but would the decibels be greater (at least to any noticeable degree).

[John A.]

Curious then. Has anyone tried progressively larger bores?

Yes, people do it all the time. Especially to take into consideration stacking tolerances.

[mcrump]

But is accuracy better without increasing the decibel levels?

[John A.]

Too many variables where sound is concerned.

Besides, even switching host guns, different atmospheric conditions and even different lots of ammo can make the db meter different on any given day.

And most people here can attest that db readings are somewhat of a joke in this industry.

As for your question about accuracy, it isn't hurt by enlarging the bore holes.

Accuracy is a lot better with enlarged bore holes than they are with baffle strikes