Rifling; Shallow and Deep

P

Pahoo

New member
I have a basic knowledge about rifling, but have encountered a variety listings on Shallow and Deep grooved rifling. I have also noticed this in actual bores. I also understand some applications in some firearms but not so much, on others. All have been ..... :confused:

So I ask; What are the advantages on any particular firearm service. I am primarily addressing new ....:confused:

Be Safe !!!
 
For what it's worth and this is far from scientific, but the few rifles I have with shallow micro-groove style rifling seem to shoot just as good as my other rifles with deeper rifling grooves. I suspect it would make more of a difference with softer cast bullets...

Tony
 
Based on a one-rifle sample, my Dad’s Marlin 336C (bought about 1962 and never ever bore cleaned) had a 30/30 micro groove barrel that suddenly started shooting 5 gallon bucket sized groups. That suggests that maybe shallow groves rifling has a shorter use life. Maybe…
 
603Country said:
Based on a one-rifle sample, my Dad’s Marlin 336C (bought about 1962 and never ever bore cleaned) had a 30/30 micro groove barrel that suddenly started shooting 5 gallon bucket sized groups. That suggests that maybe shallow groves rifling has a shorter use life. Maybe…
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I might think more easy to lead up the grooves with sub-optimal ammo choice.
Cleaning might well correct that.
 
I cleaned it, trying to get some accuracy back, but it was too late. We had it rebarreled.

Dad didn’t clean rifle outsides or insides.
 
I second Hanshi. I have 0.007" deep rifling on my flintlock rifle. My winchester 70 has rather shallow rifling and FAT lands.

From my teachings, deep rifling was for soft lead and cast bullets, so it really digs in and imparts spin. Too hard a bullet, and deep rifling just leads to escaping propellant gas.
 
Jacketed bullets typically shoot most accurate when the barrel's groove diameter is at least a few ten-thousandths smaller than the bullet's diameter.

.309" diameter bullets fired in .308" groove diameter barrels have tested under an inch at 600 yards for ten shots.
 
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