Bullet Seating Depth

[JackOfAllTrades]

The problem with a OAL precision mic, is that they don't have the same shape Ogive as the different bullets.

The best way to know the distance from the bolt face to the lands is to make a cast of the chamber with Cerosafe with the bolt closed. Find the ogive of every bullet where it just reaches the cal/diameter of the inside land face. Compare this to the cast of the chamber

-Steve

[sakoshooter]

I haven't done it since this thread started. But I've done it that way before.  I certainly don't have that many bullets/loads to validate for each gun.

My question to you is.. Now that you know exactly the distance of ogive to lands is, what have been your experiences with even a few of those loads regarding accuracy?

-Steve

Steve, Only shot once since I adjusted my seater die and accuracy was good. I seated that batch .025 off the lands. Now I'll try em farther off and with a slightly reduced load, touching the lands.
As far as meplat goes: It could make a difference on some bullets but I did my measuring using Swift Scirroco, Barnes TTSX, TSX and X, Nosler BT and some Speer and Sierra HP bullets. Also TBBC and Swift A Frames have a very small, flat meplat with no exposed lead so measuring should be pretty consistent. When using an exposed lead tip bullet, you might want to measure a few just to get a good average. Even with that I'd venture to say that it is much more accurate than smoking or using a felt marker like I'd done for years. I do not have a chamber gage and was thinking of getting one until I'd read about this idea. I'm happy with my measuements now.

Yes, I used a small wood dowel down the barrel. A brass rod or old cleaning rod could also work fine. Anything with a flat end where it touches the bullet tip.

[KillBilly]

If you use a comparator you don't have to worry about the lead tips. Comparators measure from the ogive and are the best way to go in my opinion.

[Schwag173]

I normally seat just a few thousands off the lands but have been considering experimenting with some loads touching the lands. I'm looking for better accuracy.

I, too, normally try to seat my bullets a few thousandths off the lands but I discovered something by pure accident: While loading for my new 7mm Weatherby Mag I was having rotten luck with all the different powders, bullet weights and brands I tried.  I was loading some 175s and switched to loading 165s but had forgotten to reset the seating depth.  The result was a COL of 3.220" (standard COL is 3.360").  I remember thinking to myself, "What the hell, nothing else has worked" and decided to try a group that deep.  The same 165s that had grouped 3" at maximum length now grouped under 1/2 an inch!  Pure dumb luck, but I'll take it.       

[high country]

I normally seat just a few thousands off the lands but have been considering experimenting with some loads touching the lands. I'm looking for better accuracy.

I, too, normally try to seat my bullets a few thousandths off the lands but I discovered something by pure accident: While loading for my new 7mm Weatherby Mag I was having rotten luck with all the different powders, bullet weights and brands I tried.  I was loading some 175s and switched to loading 165s but had forgotten to reset the seating depth.  The result was a COL of 3.220" (standard COL is 3.360").  I remember thinking to myself, "What the hell, nothing else has worked" and decided to try a group that deep.  The same 165s that had grouped 3" at maximum length now grouped under 1/2 an inch!  Pure dumb luck, but I'll take it.       

I mentioned that earlier....try it!

[sakoshooter]

I normally seat just a few thousands off the lands but have been considering experimenting with some loads touching the lands. I'm looking for better accuracy.

I, too, normally try to seat my bullets a few thousandths off the lands but I discovered something by pure accident: While loading for my new 7mm Weatherby Mag I was having rotten luck with all the different powders, bullet weights and brands I tried.  I was loading some 175s and switched to loading 165s but had forgotten to reset the seating depth.  The result was a COL of 3.220" (standard COL is 3.360").  I remember thinking to myself, "What the hell, nothing else has worked" and decided to try a group that deep.  The same 165s that had grouped 3" at maximum length now grouped under 1/2 an inch!  Pure dumb luck, but I'll take it.       

Just to make sure I"m understanding you correctly: If you left your seater die set from loading 175gr bullets and then seated 165gr bullets, wouldn't the OAL be the same? If so, I guess you're saying that the 165s were seated out as far as the 175s?
Or are you saying you seated the 165s just as deep into the case so the OAL was less leaving a jump to the lands?
Please clarify for me. I'm a little slow this morning.

[JackOfAllTrades]

If you left your seater die set from loading 175gr bullets and then seated 165gr bullets, wouldn't the OAL be the same?

Within many brands, a lighter bullet is often shorter OAL, and/or shorter from the ogive to the tip. Seating a lighter bullet may have drastic OACL length if a dies was set/inteded for even the same brand/design of a heavier bullet.

-Steve

[high country]

it all depends on the shape of the bullet. take a berger out  and put a silver tip for a 30-30 in its place and it will be a huge difference. comparators that measure on the diameter of the intersect with the ogive are the preferred method, although......there are many ways to skin a cat.

[luvtohnt]

So I am new to this reloading thing and am not real familiar with the terms. But my brother-in-laws dad uses a method that seems to be a bit quicker than what was described earlier for distance to the lands. He has a case from each of the calibers he owns that he made a cross cut in the neck of the case and then pushed the brass inwards a little. You can put what ever bullet you are loading in the case, chamber the dead round, and slowly remove the dead round. When it comes out it gives you the exact measurement to the lands for that rifle and bullet combo. I think that is what sako was going towards with the black line on the bullet. I think another benefit to this would be you only have one case laying around for each caliber rather than a case for each caliber/bullet combo. Again I may be all wet behind the ears, but it would be nice to know what some pros think.

Brandon

[Skyvalhunter]

Yea thats what alot of the reloading books tell you to do.

[Schwag173]

 [/quote]
Just to make sure I"m understanding you correctly: If you left your seater die set from loading 175gr bullets and then seated 165gr bullets, wouldn't the OAL be the same? If so, I guess you're saying that the 165s were seated out as far as the 175s?
Or are you saying you seated the 165s just as deep into the case so the OAL was less leaving a jump to the lands?
Please clarify for me. I'm a little slow this morning.
[/quote]

The die had been adjusted for the conical-shaped Hornady 175s.  The plumper shape (ogive) of the 165 Sierra Gamekings caused them to be seated much deeper than intended.  The result was a short COL. 

[JackOfAllTrades]

The result was a short COL. 

Finding a more accurate load by accident is not our goal as reloaders. Let this be an eye opener to readers here; Measure your first round of a new recipe, (once changing anything from a previous bullet/component from the previous loading operation), and consult your load book before loading a potentially hazardous situation.

-Steve

[sakoshooter]

 

Just to make sure I"m understanding you correctly: If you left your seater die set from loading 175gr bullets and then seated 165gr bullets, wouldn't the OAL be the same? If so, I guess you're saying that the 165s were seated out as far as the 175s?
Or are you saying you seated the 165s just as deep into the case so the OAL was less leaving a jump to the lands?
Please clarify for me. I'm a little slow this morning.
[/quote]

The die had been adjusted for the conical-shaped Hornady 175s.  The plumper shape (ogive) of the 165 Sierra Gamekings caused them to be seated much deeper than intended.  The result was a short COL. 
[/quote]


Gotcha. I assumed by your earlier post that you were shooting 'like' bullets of slightly different weights in which the ogives would be very similar.

I'm not saying that the 'rod down the barrel' idea is better than a bullet chambering tool. I just said you could do it with for cheap with what's laying around the house and be pretty darn accurate also.
The ogive is taken into consideration with the 'rod down the barrel' because you're doing your measuring(for every different bullet)with the bullet's ogive slightly touching the lands.

[NRA4LIFE]

For my bolt actions I will color the bullet with a sharpie and work the seat down so the bullet is just touching the lands.  With much experimentation, I have found in my Brownings that is the optimum seating.  Unfortunately that did not work in my BAR as the overall length of the shell was too long and they did not cycle properly.  Those I seat in the cannelure and crimp.