Liner hole sizing?

[Scota4570]

I pulled a 36 cal SMR out of the safe and shot it. A friend is interested in buying it.   I assembled it years ago.  At the time I thought it was better to open up the liner to 0.062".  A few grains of 3F go into the pan while loading.  It shoots fine.  I am now thinking it may be a good idea to install a new Kibler liner and leave the hole as made.    We did find that light charges were more fun and still accurate enough.  Leaking less from the vent may be better for a small caliber?

Thoughts? 

Thanks,

Scot

[Daryl]

Are you closing the frizzen before loading-OR-how are you aware that a frew granules are coming out the vent?

[Daniel Coats]

If it shoots fine leave it alone.

[t.caster]

.062 is a most excellent touch hole size. Since it shoots fine, leave it alone. It should last for years!

[Dphariss]

.040” will work, most of the time, I made one like that just for a test. But I would not want one significantly under .062” for actual use.

[JJMarsh]

I pulled a 36 cal SMR out of the safe and shot it. A friend is interested in buying it.   I assembled it years ago.  At the time I thought it was better to open up the liner to 0.062".  A few grains of 3F go into the pan while loading.  It shoots fine.  I am now thinking it may be a good idea to install a new Kibler liner and leave the hole as made.    We did find that light charges were more fun and still accurate enough.  Leaking less from the vent may be better for a small caliber?

Thoughts? 

Thanks,

Scot

For a .36 caliber Southern Mountain Rifle (SMR), your approach makes sense. A 0.062" vent liner is on the larger side for small-bore rifles — it can increase fouling and gas leakage, especially with light charges. Replacing it with a Kibler liner (standard ~0.028–0.040") should improve consistency and reduce pan contamination while still igniting 3F reliably.

Since you’re already seeing good accuracy with light loads, the smaller vent will likely enhance that further. Just ensure your prime (e.g., 4F) is dry and finely granulated to compensate for the reduced flash channel. If your friend plans to shoot small game or paper, the tighter vent will be a worthwhile upgrade.

[smylee grouch]

I know many that have drilled their vents out to .070 and it, that practice has been talked about positively here many times. IMHO your current vent is just fine. 

[Daryl]

I've opened whitelightning liners to
.062 as a "standard" to improve ignition.
.062" to .072" works for me.

[Scota4570]

Because of good arguments both way and my inability to leave well enough alone, I ordered a fresh liner.  Liners are easy to change.  I have access to a Garman chronograph.  I can test before and after for velocity and standard deviation.  My intuition is that with a small bore letting to much gas leak might be a detriment.  IF it were a large bore I'd leave it alone based on consensus wisdom. I'll see how it pans out.  I can always open it up again.