Best way to find seating depth of the lands

[couesfreak23]

Hi guys wondering how you find seating depth when developing loads. I've read many ways of doing it. Such as removing firing pin/spring from bolt, and resizing or cutting the neck slightly on a case and putting a bullet slightly in, then put the case in rifle chamber and slowly close the bolt all the way. Then slowly pull back the bolt and remove case/bullet and measure for coal which would be the measurement to the lands. Then back of the lands slightly. But when I did this and took some loads out to the range I immediately showed signs of high pressure and stopped shooting. so know ive just been going with oal from hornady book. So any info or techniques would be helpful. Also the best group ive gotten with the oal from hornady book and the load I came up with was lil under 1in at 200 yards.

[WampusCat]

Lots of ways to skin this cat, but IMHO the best is to use a Hornady (formerly Stoney Point) Overall Length gauge and a modified case for your specific caliber. This will let you remove the bolt and insert the device directly into the chamber with the bullet of your choice. Set your bullet in the case mouth and slide the rod forward until the bullet contacts the rifling. The sliding rod will stop and you can tighten a thumb screw to lock it down. Then remove and measure.

 

I would also recommend measuring off the ogive rather than the bullet tip. You will be much more consistent off the ogive. Eliminating variables is the name of the game.

 

You should do this several times using consistent pressure with different bullets from the lot to be certain.

[lancetkenyon]

Take a fired case, without resizing the neck.

Take bullet of choice, and put a tiny dab of rubber cement and spin on bearing surface of bullet.

Seat bullet into case very long.

Place round into chamber and close bolt.

Open bolt very carefully and apply pressure to case so the ejector does not pull case to the right while ejecting round.

Measure to ogive.

 

Repeat 3-5 times.

 

If you were getting pressure right away with your first load, even if you were jammed into the lands, you started your load development way too high. Start LOW and work up.

 

I am glad you stopped shooting right away.

[rossislider]

http://www.amazon.com/Hornady-Overall-Length-Gauge-straight/dp/B000PD01SI

 

As suggested above.

 

What caliber and where do you live? I might be able to help you out.

[Titanium700]

 

If you were getting pressure right away with your first load, even if you were jammed into the lands, you started your load development way too high. Start LOW and work up.

 

I am glad you stopped shooting right away.

^^this^^

 

And yes measuring off the ogive is most consistant.

I never measure OAL, only off ogive.

[apache12]

Not to pirate this thread but I tried the fired case with a bullet somewhat tight in the neck method. And it was a pretty random result. I was not measuring to the olgive so maybe that's it

 

But here are my readings. Any thoughts on thy so varied

 

270 win 130 gr hornady sp

 

3.36.00

3.31.95

3.35.80

3.31.80

3.31.60

3.32.40

3.32.05

3.31.90

 

I'm either a horrible measure expert or I just need to spend the $30 on the hornady oal and a ogive tool.

[GreyGhost85]

Yup. Need to measure to ogive. I take a blown out brass and just barely bump it with your resizing die. Just barely. Stuff a bullet in the case with your hand (it should fit pretty tight) and cycle the round. It'll push the bullet back to the lands. Measure to ogive

[C. Cordova]

Yes, a comparator is a necessity. The Meplat is more than likely where you were getting you variation. Also, depending on how tough it is to close the bolt, the bullet may be getting stuck in the lands and pulling out of the case a bit when you eject it.

[couesfreak23]

http://www.amazon.com/Hornady-Overall-Length-Gauge-straight/dp/B000PD01SI

 

As suggested above.

 

What caliber and where do you live? I might be able to help you out.

[couesfreak23]

http://www.amazon.com/Hornady-Overall-Length-Gauge-straight/dp/B000PD01SI

 

As suggested above.

 

What caliber and where do you live? I might be able to help you out.

 

I'm shooting a 30-06 and live in tucson... And I do have the comparator from hornady so oal pretty much are almost exact... But as for powder I started at thee lowest powder charge on hornady book and still got high pressure signs do you think I had bullet jamed into lands

[Red Sparky]

Don't use just one book for loads. I found this out when I started loading .38 semi-wadcutters using Unique powder. My Hornady book for minimum loads was +P or over for that load according to two other books. Good thing I only loaded 100 rounds and was using a .357 Mag, a S&W 686, to shoot them. So try to average three books or take the lightest load from all three books.

[STOMP442]

First off get one these. These are the handiest things to have around.

 

http://www.sinclairintl.com/reloading-equipment/measuring-tools/bullet-comparators/sinclair-hex-style-bullet-comparators-prod34262.aspx

 

This is how I do it for my rifles.

First I seat the bullet long in the case and chamber into the rifle forcing the bullet into the lands and into the case. When looking at the bullet after ejecting the case you should be able to see some shiny square marks on the bullet. This is where the bullet engaged the rifling. I take some steel wool to the bullet and buff out the shiny marks and just bump the bullet a bit back into the case using the seating die in the press and chamber in the rifle again and check for shiny marks. I do this until I can just barely see where the bullet is touching by just leaving a single shiny line on the bullet. I then use the Hex Nut comparator and record my measurement to the ogive. I don't like my bullets at the lands or jammed so I will usually subtract .025" and use this number as my seating depth. Once in awhile a bullet will prefer to be in the lands but in my experience .025" off seems to be the sweet spot and still allow magazine feeding.

[willhunt4coues]

I too suggest getting the Hornady Comparator and the Hornady OAL guage with modified case. This will be the easiest and very accurate,

[lancetkenyon]

What bullets were you shooting? Some of the best shooting match bullets (Sierra Match Kings) have the worst meplats for measuring COAL. Even Berger Hybrids/VLDs have some variation in the meplat. So measuring COAL is pointless (no pun intended).