Modified Cases for OAL gauge

[Wolfdog91]

Ok so quick question here. For those who use the Hornady Over all length gauge with the modified Cases . Just how much difference do y'all see when using the store bought modified Cases vs ones made with fire formed brass for that particular rifle ? Like I've had people say the fired formed ones are better but haven't talked to anyone who's actually done a comparison. Also curious because I don't have a lathe to make my own so kinda stuck with the store bought ones. Just curious to see how much I could be missing I guess
Thanks

 

[WSnyder]

Just how much difference do y'all see when using the store bought modified Cases vs ones made with fire formed brass for that particular rifle ?

Well that all depends on how the rifle was chambered headspace wise. No way to know till you check. Could be on the short end and close to go gage or could be a bit longer or a lot longer.

 

[JFrank]

Ok so quick question here. For those who use the Hornady Over all length gauge with the modified Cases . Just how much difference do y'all see when using the store bought modified Cases vs ones made with fire formed brass for that particular rifle ? Like I've had people say the fired formed ones are better but haven't talked to anyone who's actually done a comparison. Also curious because I don't have a lathe to make my own so kinda stuck with the store bought ones. Just curious to see how much I could be missing I guess
Thanks

The only reason to use a fire formed case is to match the shoulder angle of the case to your chamber, most store bought modified cases will be close enough to get the job done. Headspace doesn’t matter because your not closing the bolt while using the L&L tool.

 

[jrb06]

As long as you always use the same case it should be consistence. The tool is a comparator and will give you a value, once you find the value to the lands and best on target you now have your set point. It really doesn't matter if you find .003 off lands shoots best measured by your gauge but it may really be .005 with a fired gauge to the lands the main point in keeping things the same every time your reload and measure.

 

[dellet]

If you’re using the tool to find base to ogive distance it can off as much as .020”.

Simply measure base to shoulder of your fired brass and compare that to base to shoulder measurement of the modified cases you are using. Sounds like you have more than one you can try.

 

[SeabeeKen]

Fireformed every time. I make a new one each time I replace barrels also

 

[Bottom Fodder]

Same modified brass on third same caliber barrel.

 

[Wolfdog91]

The only reason to use a fire formed case is to match the shoulder angle of the case to your chamber, most store bought modified cases will be close enough to get the job done. Headspace doesn’t matter because your not closing the bolt while using the L&L tool.

As long as you always use the same case it should be consistence. The tool is a comparator and will give you a value, once you find the value to the lands and best on target you now have your set point. It really doesn't matter if you find .003 off lands shoots best measured by your gauge but it may really be .005 with a fired gauge to the lands the main point in keeping things the same every time your reload and measure.

Ok that's what I was wondering..to me it didn't make a ton sense that a generic case wouldn't work just fine to just find the lands . Though I'm not the most educated on how shoulder bump can effect CBTO. That being said if a guy don't have a lathe or drill press how would y'all go about making cases ? I tired years back with a hand drill and it was just a miserable failure lol ...then again I was a lot younger and way more impatient so maybe it's time to retry ?

 

[dellet]

In a bottle neck case using the Hornady tool, you push the case all the way forward until the case contacts the chamber, then push the bullet forward until it contacts the lands. This distance will never change except with throat erosion.

Sadly, the instructions don’t use a disclaimer when telling you to measure from case head to bullet ogive. Telling you it is a completely pointless measurement unless you size your brass the same as the modified case. You are setting the distance from the shoulder to the lands and they want you to measure from the case head to the lands. Might as well by a hat based on your shoe size.

Easiest explanation is if you have zero clearance. Case head touching the boltface and shoulder touching the chamber. Bullet touching the lands.

Move the shoulder back .005” and you will in theory have that much head space, except the cartridge is now head spacing off the bullet, and can be jammed .005” into the bore. Remember the shoulder is no longer contacting the chamber and the cartridge can move forward. Your base to ogive measurement remains the same.

If you bump .005” less, the bolt won’t close without crushing the case. But the bullet will still be at touch because the case could not move forward. Your shoulder to ogive has not changed. But the Hornady tool says the cartridge base to ogive is .005” longer, and the instructions advise seating the bullet deeper will solve the problem.

Bottom line is depending on the difference in how the case used is sized, vs the one used for the measurement, you might be jumping when think you’re jammed. But what can be dangerous is to be jammed when you think you’re jumping. Not understanding how the tool works is problematic.

To make one you can either drill and tap an already fire case, keeping the hole straight is the problem, use many small steps up is the best answer when drilling without a press or lathe.

Or if you’re shooting a cartridge that has a longer parent case, 308 from 30.06, buy the longer modified case and form it in your die set up as normal.