Bullet seating [Archive] - Glock Talk

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lomfs24
01-18-2010, 00:07
OK, I have been reloading for many years. I think I started reloading for a 22-250 when I was about 14 or 15. But I never was real serious about a lot of things. When the manual told me the O.A.L. I would load to that spec. Things chambered properly and I shot good enough groups to take countless deer and a few elk and tons of small game and varmits with reloads. I have reloaded for nearly every gun I have ever owned. Well, recently I have moved into a new world of shooting and I am starting to notice the people are posting on threads that they are seating their bullets to depths in relation to the chamber of the gun. For instance they are saying that they load the bullet to where it is touching the lands or they are loading .020 off the lands etc... How do you know how far off the lands your bullet is? I guess you could keep loading your bullets out until they don't chamber well anymore and then shorten them up. But is there a better way to get this kind of information?

And what is a good distance off the lands? Or is that more of a gun specific question? These may sound like dumb questions that I should already know but obviously I don't and I probably should. :whistling:

dudel
01-18-2010, 03:24
One of these helps
http://www.midwayusa.com/viewProduct/?productNumber=570611

RLDS45S
01-18-2010, 03:50
The Hornady LNL above is used in conjunction with the bullet comparator assembly.
Otherwise it does no good to use. Bullets vary in OAL, so the only consistent way to set up close to the lands is using the OAL Gauge with bullet comparator.

There is much more to this then using above tools.

Once you go to reaching towards the lands, you may well exceed the COAL of the magazine of the particular fire arm thus making it a single shot. The old rule of thumb applies that you need at least one caliber length of the bullet in the case neck. Some factory chambers are vary generous, and so you can have very little of the bullet in the case. Lots of other factors come into play. Not just a straight forward undertaking.

Your gun will tell what works.....but working out from the lands with 0.005" increments ought to be a good start. Jamming bullets into the lands is not a good idea for someone just starting out in this area.

srd
01-18-2010, 05:57
On my XP100's i would open up a case mouth until the bullet was finger tight . Mark the bullet with a marker and install in the chamber and close the action. Eject the shell and set the bullet back .005 and remark the bullet and repeat and check for marks. No marks..good to go. Played with seating depth from there. Keep in mind these are single shot pistols and as mentioned before if you have a magazine make sure the OAL will fit. I do my Contendors the same way.

dudel
01-18-2010, 06:11
The Hornady LNL above is used in conjunction with the bullet comparator assembly.
Otherwise it does no good to use. Bullets vary in OAL, so the only consistent way to set up close to the lands is using the OAL Gauge with bullet comparator.

Sounds like you need a better caliber of projectile :supergrin:

A bullet comparator will certainly help if you got inconsistent projectiles. A depth guage will get you in the ballpark. RCBS also makes a nice one with a round that screws in and out to set the OAL, but it really doesn't tell you how far the projectile is from the lands.

It's not a process for the timid or those looking for a quick solution. Lots of test rounds and lots of firing. If you don't have a good solid bench, a good rest and and target holder that isn't solid, it's going to be an excercise in frustraion.

Myke_Hart
01-18-2010, 06:12
Another way is to make your own gauge. Take a resized and trimmed peice of brass and cut 4 slots in the neck so that the bullet is just held by the neck tension. Seat a bullet as long as possible and chamber the round in you gun. Measure the OAL. Do this a couple of times. When you get the same measurement at least 3 times you have your maximum OAL. Back the measurement off .020 or whatever you would like to try. Shoot some test groups.

I still use the above meathod even though I have the hornady tool. Just to double check the tool. The tool uses its own brass. My method above is using the brass I will load with.:embarassed:

jaybirdjtt
01-18-2010, 09:31
Lots of good suggestions here. Word of caution.....if the bullet is seated to touch the rifling it takes greater presssure to force it into the rifling when fired. Alot of rifles produce greater accuracy if you seat the bullets just touching the rifling, however. So, you should consider reducing the charge a few grains if you seat this way. Interestingly enough, you'll still have the same velocity with the lighter charge. Over time, if your accuracy falls off it may be that your rifling is eroded and the bullets can be seated further out, assuming they'll still fit your mag. What is more "normal" is to have a 1/32" gap between the bullet and initial contact with the rifling. Too far back and you sacrifice velocity and accuracy. So, when working up loads, decide upon where you will seat the bullet and one variable will be eliminated.
Be sure to note the seating depth in your notebook!

fredj338
01-18-2010, 10:21
Many will tell you 0.01" off the lands for starting, then move it in or out to acheive best accuracy. It's just a rule of thumb though. Ever gun is diff & every bullet type as well. Mono metals, like the Barnes, like to be further from the lands, so there is no recipe that works for all bullets.
Without a bullet comarator, you can find the distance to the lands for a specific bullet by:
Usining a fired case, pinch the neck slightly to hold a bullet snug. Chamber it slowly & then remove & measure. Do it 5X & avg. That is the distance to the lands. The other way is to seat a bullet long into a sized case. Jamb that into the lands, close the bolt. Put a cleaning rod down the barrel & mark it at the muzzle w/ a Sharpie. Then unchamber, close the bolt & mark it again. Measure the distance & that is your OAL to the lands. Remember, unless you are shooting a single shot, all rounds mush fit the mag, so all this measuring can mean nothing if you are trying to make reliable & accurate ammo.

Pitbull
01-18-2010, 12:47
I have been reading alot about this recently and I found this the other day. I have not tried it yet but looks like it will work.
http://www.larrywillis.com/OAL.html

lomfs24
01-18-2010, 13:44
This has all been some very good advice. Thanks everyone. I will at least have a place to start. I understand the whole thing about seating the bullet into the land makes higher chamber pressures. The bullet has to build the pressure to start moving. It doesn't have a "running start" at the land. I would think that seating the bullet too far away would also have adverse effects in that it would be harder on the throat and possibly cause unneeded vibration in the action.
That is just a guess though.

dudel
01-18-2010, 18:04
I would think that seating the bullet too far away would also have adverse effects in that it would be harder on the throat and possibly cause unneeded vibration in the action.
That is just a guess though.


Bingo. To much jump can make the projectile enter the bore off center, accuracy suffers.

jaybirdjtt
01-18-2010, 18:18
This has all been some very good advice. Thanks everyone. I will at least have a place to start. I understand the whole thing about seating the bullet into the land makes higher chamber pressures. The bullet has to build the pressure to start moving. It doesn't have a "running start" at the land. I would think that seating the bullet too far away would also have adverse effects in that it would be harder on the throat and possibly cause unneeded vibration in the action.
That is just a guess though.

It is also a major contributor to poor accuracy as it allows the bullet to freebore and possibly engage the rifling at something of an angle, ever so small, resulting in a wobble. Anyway, alot of trial and error in the never-ending search for accuracy can be avoided by simply seating the bullet (as has been noted) 1/32" or .01" away or even touching the rifling. I like the idea of the case neck with slots on the Larry Willis website!

My 300 Weatherby never could get a 3 shot group under 1 1/2" and I sold it. Plus it took me 30 minutes to get in 3 shots because the barrel became so hot. Don't think I ever took it hunting! Inaccurate rifles are just not fun!