How can I make a bullet depth gauge?

84jeepj10

I see all those depth gauges at the local market and want one but don't want to pay that much dan money for one. I mean come on it's a dummy case and some wire with a stopcollar and some accurate tic marks right?

Anybody made a good one? How?
My idea is to make a dummy case just like all my other cases, neck sized and length trimmed the same. But ream the inside of the neck so one of my bullets will slide freely with just a bit of resistance when greased. The seat the bullet in deep by hand and put a straight length of about 12" of coathanger wire through the flashole and once the 'gauge' is loaded in the rifle remove the bolt and use the wire to push the bullet up til you feel resistance. Then remove the dummy round and measure it and that ought to give you your chamber depth with your bullet/case. Another method of measuring the depth with it would be to mark the wire at the but of the case once you feel the resistance of the lands against the bullet. Then remove the case and push the bullet up with the wire until you hit the tick mark, stop, remove the wire, and measure the OAL.
DO yall think this could work accurately enough?

Vince

Outa' my league. I'll leave this one for the engineers amongst us.

Cheers, Vince

gelandangan

Cut the neck lengthwise all the way to the shoulder may work better because it uses the spring action of the neck to hold the bullet in place.

Just my 2 cents

Deleted_User_2665 · Super Member Joined: May 06, 2006 Posts: 380

About 3 and a half minutes with a dummy round and a magic marker can save a whole lotta fiddlefartin' around with expensive gizmos or afroengineered whatzits....

And be a ton more accurate cause it's got true neck tension holding a definate length....

My die boxes have a set up dummy round for each bullet I shoot in each chambering.........................

rrogacki

wildswalker wrote:

About 3 and a half minutes with a dummy round and a magic marker can save a whole lotta fiddlefartin' around with expensive gizmos or afroengineered whatzits....

And be a ton more accurate cause it's got true neck tension holding a definate length....

My die boxes have a set up dummy round for each bullet I shoot in each chambering.........................

Hey wildswalker, that's pretty good advice.

84jeepj10

I tried the magic marker trick. It helped but still doesn't give me a good measurement. When I do it I get two lengthwise marks in the black about halfway down the bullet where the ogive widens out all the way and they're about 1/4" apart (maybe a little less). I think if I cut the case neck and take off the burr. Put the bullet in just a little, mark it up with the marker and chamber it. It will slide down to the OAL of my chamber and give me my marks as well as a good idea of how much room I've got and if the bore is concentric with the chamber. Kindof a combination of the two ideas. The measure that and back off about 1/16" and the should be my loads max OAL. Whattya think.

fireball 3

hey jeep, I make a dummy round for each bullet per caliber also. However I made a case oal guage out of a 2pc radio antenna. After I take depth measurment I then w/ calipers, set my col .025" shorter. Works for me. The neck tension case trick does work but I just went 1 step farther was all. Dave Very Happy

84jeepj10

Hmm, I just happen to have a spare antenna as well. That would work to allow the bullet to seat and 'shorten' the antenna and make a more measurable piece. Thanks for the tip!

Deleted_User_2665 · Super Member Joined: May 06, 2006 Posts: 380

Just what do you need a "measurement" for anyway?

Unless you are using an ogive comparator, meauring COL is pointless beyond a generic reference point with regards to mag box confines anyway. That's an either it fits/feeds or it don't proposition......

Land engagement is land engagement no matter how it's looked at....either it's kissin' lands or it's not.

Once that's determined by marking the bullet (i've also used a candle, a match, an oil lamp, ect. also, to smoke the bullet) it's a simple matter to back off any amount you wish via use of a seater die and a dial caliper. Micrometer dies make things even simpler.

The whole thing is easily had less the voodoo and iffy home brewed tools...........

84jeepj10

I want a measurement from the butt of the round to the engagement of the lands. As a reference point so I can more accurately set my seating depth on my Lee Classic Loader without having to remeasure every time as I will have that extra little bit of data in my books for this type of bullet. Every bit of information I get I believe should be recorded for future reference. You never know when or if you may need it. Even if you feel it's trivial, I feel it's necessary for me to help me produce the most consistently accurate, safe ammunition I possibly can.

Deleted_User_2665 · Super Member Joined: May 06, 2006 Posts: 380

I'll reiterate....

Measuring COAL from bullet nose to case head will do no good as bullet noses differ within the same box even...reliable info by that means is not possible.

Measuring off the ogive with a comparator is slightly more reliable and considered SOP within the ranks of savvy reloaders...but bullet ogives can and do vary, and over time can produce skewed info to the unwary eye.

Investing in a micrometer seating die is likely the most reliable means to attain control over COAL in the context you seem to be worried about.

Dickin' with this stuff isn't trivial but only applies during load development 'cause once it's found out...the best is what you go with, and all that's needed in that regard is a dummy round for setting up a die. Only then if you tend to switch back and forth between other bullets as I do.

Per load development, I generally start out from scratch with bullets kissin' lands and work back from there, in increments of 10 or 15 thousandths depending on the confines of the mag box. Some throats are too long for that therefore requiring me to go with a maximum that will fit it the magazine and still feed properly.

I use a scientifical approach and have been guilty of keeping more than one dummy round on the bench with more than one (various) seating depth for the purpose of referencing back in case I went too far. The one that matters the most is the "hard copy" of that first quest for land engagment via the magic marker thing....that being the ultimate reference point.

Your safe accurate load point is mute given the fact you have sought to incorporate new nosler bullet design into old nosler bullet design load data without doing a start over load development.......

oscarj · Rookie Member Joined: Aug 10, 2007 Posts: 4

if you live near a barrell maker or can aquire a 20mm section of barrell in appropriate calibre neck size a case leaving projectile seated out further than it needs to be camber it lands will push it take it out slip on the barrell section measure with vernier caliper no matter which brand of bullet you use this will be your maximum oal once you subtract your 20mm barrell

Dawgdad

To take this thread even further away from you original question Shocked

....

Windswalker is speaking the truth. I reload for service rifle match ammo and to set the bullet to the same point off the lands every time requires a comparitor tool that measures from the head of the case to the ogive, the point where the bullet reaches the diameter of the lands. Because of the way hollow point bullets are drawn to the tip when they are formed, the distance from this point to the tip can vary greatly(.020"+). If you are using a flat seater die and all of your OAL's are dead on to 0.001, you may be up to .020 difference off of the lands. This could mean for a pair of bullets with the same OAL, one could be shoved into the lands and the other be .020 off. For most shooters who set the bullets to jump more than .040 or seat to magazine length in an AR, this will not be a noticable difference in accuracy in a properly developed load in the sweet spot of the pressure curve. BUT - If you need every bullet to hit in a 6" x ring at 600 yards, you will see the difference. Some of the VLD/Amax bullets will require a different seater stem (cup shaped or even do-nut like) to contact the side of the bullets not just the tip.

Another reason to know this distance, it is an indication of throat wear. As this number grows, your throat erosion can be tracked so you know when to adjust your bullet length again or get a new barrel. Evil or Very Mad

National match.us has a forum with a reloading section that discusses this in great detail.

dakota1

Dawgdad wrote:

to set the bullet to the same point off the lands every time requires a comparitor tool that measures from the head of the case to the ogive, the point where the bullet reaches the diameter of the lands.

From what I have read, and correct me if I am wrong, the seater die applys pressure on the ogive of the bullet, not the tip. If that is correct, wouldn't the differences in tip length be mute?

Bushmaster

True...Unless you are measuring the loaded cartridge with a caliper that measures from the tip of the bullet to the case head. This is where the rub comes in...One of the cartridge gauges solves this problem...