The Accurate Reloading Forums
Seating Depth and bullet length

This topic can be found at:
https://forums.accuratereloading.com/eve/forums/a/tpc/f/2511043/m/781101586

11 June 2007, 07:47
ldpace
Seating Depth and bullet length
My results with reloading have been somewhat inconsistent. In trying to be accurate with seating depth I noticed overall length would vary from shell to shell without touching the die. I then started carefully checking the bullets. 168 Sierra Match Kings(308). I check the seating depth by measuring the c.o.l. About one third of the bullets have a very irregular nose. One side of the hollow point extends up substantially above the other. I then measured the bullet length and found the irregular bullets to be .012 longer that the normal bullets. I have been seating these bullets .012 deeper than the normal bullets and I am sure this has adversley affected my results. I thought SMK's were good quality. I have two boxes of 100 and both seem to have this problem. I know the bullets should be seated in relation to the land/ ogive distance but as long as the bullets are the same length measuring the c.o.l. should give you the same length. Is this normal to find that much inconsistency in the bullets? Any suggestions?
11 June 2007, 08:01
Dwight
If you don't like the irregular tips then Sinclair has a tool to clean them up. I don't clean mine up and I shot a .125 group yesterday.
If you are having trouble shooting the little tip irregularity is not the problem. Unless you are shooting BR matches then you don't have much to worry about. Set them up to be .010 to .015 off the lands and you should do okay provided they fit the mag box but if you single fire then it makes no difference.
11 June 2007, 08:17
Jon
A perfect bullet is preferred of course but I don't believe the extreme tip of the bullet has a significant effect upon accuracy. However, seating depth does. I had the same problem as you with the soft lead tips on spire point bullets. When they get dinged during mfg. or shipping the length can vary by .015" or more. Now I use seating dies that do not seat by pushing on the TIP of the bullet. The cone shape of the seater pushes the copper jacket and does not touch the tip. The COL (measured with a caliper) will always vary but the position of the ogive should remain constant. There are devices for making an accurate measurement from ogive to the base of the case. Maybe someone can recommend one?
11 June 2007, 08:20
Bullet94
quote:
ldpace
I then measured the bullet length and found the irregular bullets to be .012 longer that the normal bullets. I have been seating these bullets .012 deeper than the normal bullets and I am sure this has adversley affected my results.


Your seating die shouldn’t be seating your bullets from the bullet tip, but from somewhere on the ogive. So bullet length shouldn’t effect seating depth to the lands since your bullet touches the lands somewhere on the ogive. You need to get a bullet comparator. Check out this link -


http://www.sinclairintl.com/cgi-bin/category.cgi?catego...em=09-600&type=store
11 June 2007, 17:41
ldpace
Thanks
I have been measuring the col from tip and not the ogive. That is the problem I was refering to. This varied seating depth has been affecting accuracy. I will order the "Comparator" in the link above and that should solve my problems.
11 June 2007, 18:01
mho
The Bullet Comparator does not resolve any issues you may have with varying seating depth, it just allows you to measure bullet or cartridge length over the ogive, as opposed to over the bullet tips. Your seating die won't seat your bullets any differently regardless of how you measure them. Yes, it is a good idea to get the Comparator, but not for the reasons you state.

Bullet tips vary quite a lot, as you have noticed. Bullet ogives also vary - as you'll establish once you get the Comparator. But ogives vary less than bullet tips, so the effect you measure should not be quite as pronounced.

We all live with the fact that our bullets vary (even when measured properly over the ogive). I personally doubt your accuracy problems arise from
quote:
varied seating depth has been affecting accuracy

And if it does, there is little you can do about it - short of trying to adjust your seating die for every bullet, which would be an exercise in futility. If you have accuracy problems, my guess is that they lie elsewhere.

Since you are getting into reloading gadgets to help improve your reloading process, consider getting one of these (and the appropriate modified cases for whatever calibers you shoot):

http://www.sinclairintl.com/cgi-bin/category.cgi?catego...=CFG-2000&type=store

That will allow you establish what seating depth is max for your chamber, and quantify how far off the lands your bullets are. I find this a useful tool - in addition to the Comparator.

- mike


*********************
The rifle is a noble weapon... It entices its bearer into primeval forests, into mountains and deserts untenanted by man. - Horace Kephart
11 June 2007, 18:07
Hot Core
quote:
Originally posted by ldpace:
...Is this normal to find that much inconsistency in the bullets? ...
Yes.

Try going to this link and learn how OCL is converted to ODL.

Best of luck to you.
11 June 2007, 19:12
Reloader
Just set the die with a COAL known to be correct for said rifle and seat all of your rounds. Don't get carried away with making every round the exact length from tip to base unless you measure every bullet and know they are the same length.

Good Luck

Reloader
12 June 2007, 03:47
Bullet94
ldpace

If you’re loading to fit in a mag then you don’t need a comparator. All you have to do is make sure that your OAL (measured from the bullet tip) is short enough to fit in your mag. For 308’s I believe mag length is 2.800. Take one of your bullets and set your seating die so the loaded cartridge measures 2.800. Then load the rest of your cartridges without adjusting your seating die. Once done measure your cartridges from the base of the case to the tip of the bullet (using calipers). Find the longest OAL measured to the bullet tip and then seat that bullet farther into the case (using your seating die) until it measures 2.800. Your seating die is now set for all your cartridges to fit in your mag. Run all your loaded cartridges back through the seating die again and you should be good to go. Once this is done take another case and make a dummy round (no powder no primer). You now have your seating die set so that your longest cartridge will fit in your mag and a dummy round you can use to set your seating die (using this brand and weight bullet).

Loading longer than mag length is another story and your 168gr SMK’s will probably shoot real nice when fed from your mag.
12 June 2007, 04:23
GSP7
Idspace. As stated above get a bullet comparator(stoneypoint/hornaday-same thing) to attach to your caliper.

The tips all vary on all bullets so you need to measure from the Ogive.

use the Ogive measurement now instead of the bullet tip.

I finaly got a stoney point ogive comparator after averageing my "too the lands" measurements from the tip for a when i started reloading.

Another thing is after you document a certain bullet col for a paticular rifle. Remeasure it again after 200-400 rds through the barrel as the lands at the throat wear/errode or "breakin" Big Grin.
12 June 2007, 06:26
Buliwyf
Talk with the Sinclair Techs about the Davidson Seating Depth Checker prior to making your final decision. I recommend measuring overall length using ogive.
12 June 2007, 07:27
Bullet94
If you are trying to load for accuracy, with OAL’s longer than mag length, you might try this (copied from another forum) –

quote:
You never state what equipment you are shooting but there are some pretty universal rules about seating a bullet. You first seat the bullet to a given depth and then work up with the charge. To do otherwise might lead to a pressure excursion. Do you know how to read pressure in a rifle case??? If the radius of the primer is gone,the bolt lifts hard,you can see the extrusion of brass back into the elector hole,see the machine marks on the bolt face in the brass or the primer flat falls out of the case the load may be a bit hot. BUT, this can and will happen regardless of where the bullet is seated if you tip the powder bottle too much. Here's a very easy way to develope a load:
1)-Set the bullet into the lands(if you can reach them) as much as the neck tension of the case will allow.
2)-Start with a minimum listed powder charge-10% for the bullet weight
3)-Work the powder charge up till the groups get as small as they will get.
This depends on the rifle.
4)-After getting as small a group as the rifle will shoot at the jam,back the bullet off.002/.003 at a time and see if the groups improve.Depending on the rifle they may or may not.
5)-If you decide on trying another bullet back the powder down and go back to the jam length and start again.
What this saves is guesswork. If the bullet is seated HARD into the lands then the only way to go with it is shorter. If the bullet is seated HARD into the lands and you have a safe working load pressures will NOT increase as the seating depth is shortened. If you, at any point,. get pressure signs, STOP. Back off the powder and start up again and see if it repeats. Be aware that a load shot at 70 degreesF. may not be a safe load at 100 degrees F.Back a load off when you change ANY part of that load including changing lots of the same brand of powder. Never assume anything;prove it to yourself. There is not really a lot of rocket science in rifles; experience is much more important

14 June 2007, 02:56
Dwight
quote:
Originally posted by ldpace:
Thanks
I have been measuring the col from tip and not the ogive. That is the problem I was refering to. This varied seating depth has been affecting accuracy. I will order the "Comparator" in the link above and that should solve my problems.


I don't believe that where you are concerned is a problem and maybe the accuracy problem is something else. That little irregular tip does not stop me from winning matches.

Is the rifle bedded and barrel floated? That really is an essential variable. In the loading process there are many essential variables that you need to be concerned with. The best shooting will come from consistency with your processes once you figure it all out.
Good Luck to you.
14 June 2007, 19:38
ldpace
The rifle is bedded and floated, cryo treated, 11 degree crown, and Tubbs final finish. I was never concerned about the irregularity of the tips affecting accuracy due to flight characteristics. The tips irregularity affected the bullets overall lenght and if you are measuring your seating depth from base to the tip of the cartridge the seating depth will vary accordingly. I now realize you must measure the seated depth from the ogive in order to eliminate the variable of bullet length. Varying seating depth by as much a .012 will affect your accuracy. You live and learn.
15 June 2007, 03:47
Dwight
Your seating depth is not varying unless you have a weird seater. The seater presses on the ogive to seat the bullet and not the tip. The OAL is varying due to the tip irregularity. All mine vary in OAL and no affect on accuracy at all.
15 June 2007, 04:54
OLBIKER
Just curious.Do you seperate your Bullets by weight???
15 June 2007, 06:11
ldpace
I have not been separating them by weight.

Dwight, I do have a weird seater, me. I was measuring each finished cartidge and then adjusting the seater as necesary and re-seating to make the finished cartridges the exact same length from base to tip. Obviously not the proper way to do it. I am the weird seater.
15 June 2007, 06:53
Dwight
I think you see it clearly now. You were seated all the same until you started messing with it. No need to sort your bullets by weight. I don't sort mine and have no problem hitting the 1/16" dot at a 100 yds.

Now that you have the seating puzzle solved work on getting a consistent neck tension.
15 June 2007, 11:13
Bullet94
quote:
ldpace
I do have a weird seater, me


Now that’s funny. Kinda like the nut behind the butt.
15 June 2007, 18:33
Hot Core
quote:
Originally posted by ldpace:
...I was measuring each finished cartidge and then adjusting the seater as necesary and re-seating to make the finished cartridges the exact same length from base to tip. ...
Don't be too hard on yourself because it is quite common for that to happen when you are first starting out.

There are a good number of things similar to that in Reloading that the "Manuals" could easily explain, that for some unexplainable reason, they don't. Once you realize it, it really makes you wonder "why" they don't.

Misleading the Beginners, when it is totally unnecessary, really hacks me off. Pitiful!
15 June 2007, 20:23
Dwight
quote:
Originally posted by ldpace:
I have not been separating them by weight.

Dwight, I do have a weird seater, me. I was measuring each finished cartidge and then adjusting the seater as necesary and re-seating to make the finished cartridges the exact same length from base to tip. Obviously not the proper way to do it. I am the weird seater.


Take it slow and easy as you try and make perfect bullets. If you have a nigh enough power scope (24-36) you will see how groups can open up merely on you place your cheek on the stock. If you can put 5 in one hole and then the next group is 1/2" do you blame it on your loads or the guy pulling the trigger. We are not machines so keep it in perspective.
15 June 2007, 20:34
Dwight
Other variables that affect groups. Placing the thumb on top of the grip versus along side the stocke above the trigger makes a difference. Holding the stock with the non trigger hand versus free recoil makes a difference. Clean barrel versus fouled barrel makes a difference. Swivel studs can really ruin groups.
15 June 2007, 21:57
onefunzr2
quote:
Originally posted by Hot Core:
quote:
Originally posted by ldpace:
...I was measuring each finished cartidge and then adjusting the seater as necesary and re-seating to make the finished cartridges the exact same length from base to tip. ...
Don't be too hard on yourself because it is quite common for that to happen when you are first starting out.

There are a good number of things similar to that in Reloading that the "Manuals" could easily explain, that for some unexplainable reason, they don't. Once you realize it, it really makes you wonder "why" they don't.

Misleading the Beginners, when it is totally unnecessary, really hacks me off. Pitiful!


Perhaps its a legacy from the time when most handloading bullets were of the roundnose design; not as susceptible to tip damage as spitzers.