Everyone’s feeling for jam is different. What would you consider a hard jam ? I’m all over touch as it is. Maybe .005 jam
The same way I tell bullet is touching the lands
1. Open and remove Bolt
2. Drop a bare bullet into chamber, (keep trying until it goes in pointy end first)
3. Lighty tap bullet into lands against the base with the cleaning rod inserted through chamber end to ensure bullet is securely in place and not loosely in place.
Now to mark /measure
4. I insert cleaning rod from the muzzle until it just stops on the tip of the bullet, slowly and lightly so you don't dislodge the bullet you just lightly tapped into place
(must have blunt tip or attachment on end of cleaning rod to bottom out on meplat)
then Using thin tape I mark the cleaning rod at the very end of the muzzle for a reference, do this very accurately by moving head side to side and line tape up perfectly with the muzzle end.
5. Now with rod marked and still inserted through the muzzle, Tap bullet out of rifling
6. Insert and close bolt
7. Re-Insert cleaning rod through the muzzle until it bottoms out on the boltface
8. Mark this location with tape
9. Measure the distance between the right side of each piece of tape and this gives you
OAL of that particular bullet "just touching the lands"
Now go seat a bullet into a case with this OAL using the bullet you just used
Comparator can now be used to measure Ogive Seating depth
This is my ZERO Point, of just touching the lands,
By using this method...You know exactly the bullet has just stopped at the rifling, and where,,,and
There is no need to "Smoke" a bullet < mark up a Bullet, (Dykem a bullet because this method is exact.
ALSO---!!! if you do this at the beginning of a new barrel and save the dummy round you just made.....
.....You can monitor accurately your throat erosion of the rifling over time by repeating steps 1 -9
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Seating a bullet into the case by using the bolt will give false/different readings depending upon case neck tension vs lands resistance and is not an accurate way of measuring jam.
As well the rifling can grab the bullet and slightly pull it back out of the case to any degree.
(anyone who has opened their bolt and dumped powder into the chamber and magazine knows this!
I am SERIOUS!, I have heard this happens to people!!!)
Neither is measuring the amount of rifling engraved on a bullet an accurate way of measuring Jam,
,since the ogive can match the contour of the lead angle
(IE: A contact patch of the rifling on the bullet can show .040" engraving when actually it has just began to touch because the two surfaces are virtually parallel to one another)
Tilt both your hands at a 45 deg angle to the left and then move your right hand until it just touches your left...
Do you have 6 inches of forced hand engagent or did they just touch?
