inconsistent seating depth

nnn66

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I'm needing some of you guys with a lot of experience to help me out with a problem I keep running into. I'm reloading a few different calibers and it happens to me no matter which one I'm working with. I have been using RCBS dies...just the regular, lowest cost dies that they make....maybe that's the problem, so I would like recommendations on something that will work better. An example of the trouble I'm having is as follows:

Last night I was reloading for .338 Lapua. The load data showed that my minimum OAL should be 3.681, so I got my seating die adjusted and seated my first bullet for an OAL of 3.681. Then, I proceeded to seat the next bullet and I got 3.678....then the one after that was 3.683....then the next one was 3.677....so what is the deal? Why can't I just adjust that die and then get consistent results? This was with brand new Lapua brass, so I did not trim it or even measure the case length prior to loading, but this same thing is happening to me even when I do trim my brass. I checked to make sure all of the primers were properly seated, so I know that wasn't causing it....What am I missing?

Is it just the RCBS dies that I'm using or is there something else I'm overlooking? I would love to have some recommendations on better quality, easier to use dies, so please let me know what works best for you guys. Thanks!
 

Nysios

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More than likely you are seeing this spread because you are measuring COAL. If you take your bullets and measure them before loading you will notice a large spread of lengths. This is usually because of non uniform meplats (the tip of the bullet) Your dies do not push on the meplat to seat the bullet. You can either get a meplat trimmer to make them all uniform prior to loading or get a bullet comparator so you can measure to the ogive of the bullet and not the tip.
 

Nysios

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As for the better quality dies look into the Redding Type S competition series. I use them for the Lapua and love em.
 

ksthomas

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You didn't mention the make of the bullet being used, but don't woryy about it; this is perfectly normal. There's always going to be some variation in the bullet length, due to how they're formed. I've seen .015" in some fairly extreme examples, and I'm sure they occasionally go further than that. The important relationship here is the distance between the ogive and throat. Since the seater is actually seating off some point on the ogive, this relationship remains the same, but you see the difference in the OAL of the loaded rounds. If you check these same rounds on a comparator or ogive gage, you'll probably find that they're all within .001"-.002" of one another, despite the .006" difference or more you're seeing in OAL.

Don't worry about this, just make sure they clear your magazine and don't drag on the front of the box, and you'll do fine.
 
M

milo 2.0

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Alot of die companies are coming out with vld seater plugs, they grab the bullet farther down the ogive, not relying on the bullet tip to seat. I'm sure this would help, most .338 bullets that guys are using are this kind. Also you should use a comparator to measure coal, you didn't mention that, you'll get a more consistant reading. If you're using Berger's, just look at th tips, they're a mess.
Being the brass was new, your neck tension should be consistant, but sometimes it does pay to neck size. I'm assuming you're not running a compressed load, that can affect it also.
Also, if you think about it, your brass length doesn't really have anything to do with coal. Your brass doesn't come in contact with the shoulder part of the die to impede seating, and the neck is somewhat supported, but has to have tolerances to accomidate all brands of brass, thickness.
You're really only off .006", for the dies you're using, I'd say it's ok. Note, with that big of bullet, it helps to measure them with a comparator and maybe sort before loading.
 

Unknown

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Non uniform me plats are indeed the problem. I solved that issue by measuring length to the ogive for consistency, then take around 10 loaded rounds and average the c.o.a.l. This will give you an average c.o.a.l., and you can then set up your die to seat future loads to the ogive.

You will get better results if your loads are tailored to your rifle's throat, and you set the ogive to the jump that your rifle likes best....unless you use Berger bullets, most people find that 10 to 15 thou jump works best. You can play with jam fitting, but it is harder to control pressures, especially if you are using a less precise seating die.
 

nnn66

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Thanks for all the the replies! I feel better about it after reading what you guys have said. I am going to do some research on meplat trimmers, comparators and will look into finding some Redding Type S competition series dies. The bullets that I was loading last night are Lapua Scenar 300gr. I was using N560 and my load data showed that the min OAL should be 3.681. Most other powders seem to ask for OAL of 3.600 with this bullet, so I was a little concerned that perhaps it was quite critical that I be right on the money with the length. I think I'm close enough that I should be Ok. Thanks again for all of the responses!
 

Mike_Honcho

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I agree with the COAL explanation, but on the note of 'little things' that can add up - when was the last time you broke your die down and really cleaned it?


Good luck
 

McCrazy

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    All the responses so far have been solid answers.

    You didn't mention what press you are using but I assume it is a budget press since your dies are. If you are dealing with compressed loads another factor may be actual flex of the press. Also, the variation in amount of force you put into the lever while seating can have a negative effect.
     

    Nysios

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    3.681' is standard COAL for the 338 Lapua. I load my Scenars and Bergers to that length to fit the magazine.
     

    exx1976

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    I use a Forster Ultra Micrometer seater die for my precision .308 loads. Works amazingly well, but it probably costs more than your set of RCBS dies did. IMO, it's money well spent though.
     

    Fuzzball

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    "The load data showed that my minimum OAL should be 3.681, "

    Four major points;

    No, it didn't; book OAL is not a minimum or a maximum, it's only what the data development test team used in their rifle, which isn't your rifle.

    No rifle cares where the meplat of a bullet hangs in space, all that matters is the jump from start to impact with the lands.

    Best jump distance varies and the only way you're going to know what works best for your load in your rig is to experiment with seating depth.

    Varying OAL isn't from the dies, case trim length nor - usually - the press. It is caused by individual bullet variations and inconsistant press operation.
     

    Unknown

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    I get very good results with an RCBS junior press. As long as the ram is straight, and the shell holder is square to the die, you will find more improvement in your reloads by using high quality dies rather than a high priced press.

    Keep in mind that many top bench rest shooters reload at their benches....
     

    nnn66

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    I have done a bit more research on the bullet comparator and overall length gauge and I will probably order these today. For a bit more info....I am using a Rock Chucker Supreme as my press and the reason I have chosen the inexpensive RCBS dies is because absolutely nothing else was in stock when I needed to purchase dies. I would certainly like to have better dies, so I'm hoping to learn more about what my best option is. To answer the question about when I last broke down my dies and cleaned them.....I just opened the brand new package and was using them for the first time, so ....

    The rifle I'm loading for is a CZ 550 Magnum HET. I actually just purchased this rifle and have never fired it yet. These are going to be the first rounds I put through the gun. I just got my rings and scope delivered yesterday, so I'm getting closer to the time when I can take it out and pull the trigger.

    The reason I am using N560 as my powder choice is because it was the only powder I could find on the shelves when I went shopping for powder. On the Lapua website, it is a powder that they recommend for 338 Lapua with a 300gr Scenar, so I figured I would start there since this is the bullet and powder combination that I have available to me at the moment. I also looked up load data in my Lee manual and it showed minimum overall length should be 3.681. For many other powders with a 300gr Scenar it indicated a shorter min oal, but for N560, it says 3.681. Am I missing something? Does the min overall length not really matter? I have been doing some reading on using a bullet comparator and length gauge to seat bullets just off the lands....so, can you simply disregard the oal specified in the book and go by the measurement specific to your gun, regardless of the powder/bullet combination? Why does my Lee manual show that N560 with a 300gr bullet requires oal of 3.681 while another powder with the same bullet requires a min oal of 3.600? I guess I still don't have a good grasp of this, so I could use a clear explanation, please.

    I think I'm making a little progress in my understanding, so thanks to all of you who have contributed!
     
    M

    milo 2.0

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    I have done a bit more research on the bullet comparator and overall length gauge and I will probably order these today. For a bit more info....I am using a Rock Chucker Supreme as my press and the reason I have chosen the inexpensive RCBS dies is because absolutely nothing else was in stock when I needed to purchase dies. I would certainly like to have better dies, so I'm hoping to learn more about what my best option is. To answer the question about when I last broke down my dies and cleaned them.....I just opened the brand new package and was using them for the first time, so ....

    The rifle I'm loading for is a CZ 550 Magnum HET. I actually just purchased this rifle and have never fired it yet. These are going to be the first rounds I put through the gun. I just got my rings and scope delivered yesterday, so I'm getting closer to the time when I can take it out and pull the trigger.

    The reason I am using N560 as my powder choice is because it was the only powder I could find on the shelves when I went shopping for powder. On the Lapua website, it is a powder that they recommend for 338 Lapua with a 300gr Scenar, so I figured I would start there since this is the bullet and powder combination that I have available to me at the moment. I also looked up load data in my Lee manual and it showed minimum overall length should be 3.681. For many other powders with a 300gr Scenar it indicated a shorter min oal, but for N560, it says 3.681. Am I missing something? Does the min overall length not really matter? I have been doing some reading on using a bullet comparator and length gauge to seat bullets just off the lands....so, can you simply disregard the oal specified in the book and go by the measurement specific to your gun, regardless of the powder/bullet combination? Why does my Lee manual show that N560 with a 300gr bullet requires oal of 3.681 while another powder with the same bullet requires a min oal of 3.600? I guess I still don't have a good grasp of this, so I could use a clear explanation, please.

    I think I'm making a little progress in my understanding, so thanks to all of you who have contributed!

    I sure hope you cleaned the dies first, the rust preventative oil on them isn't conducive to accurate loading. Before you go loading a shit ton load of rounds, you need to work up to the load, pressure, speed and accuracy last. Don't get stuck on this coal stuff, bullet seating depth is where most accuracy comes from.
     

    nnn66

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    Thanks for your reply, Milo. Yes, I have cleaned the dies and I'm not loading up a whole bunch of rounds. I have actually been reloading for a few years and I have a couple of experienced friends who help me out some. I have worked up loads before, so I have a pretty good idea of what is involved, but I certainly still have plenty to learn. Since I'm just starting out with this caliber and, because it is a rather large caliber, I'm just trying to be extra cautious with it. So far, I have only loaded 15 rounds...5 each of three different loads. I thought this would be a good starting point, just to get a feel for how this gun is going to like the N560.

    This business about seating depth is definitely something I want to know a lot more about. I have been reading about it, periodically, but I'm still not very knowledgeable on the subject. When you say that bullet seating depth is where most accuracy comes from, I suppose you refer to adjusting how far off the lands a bullet is seated for each powder charge I try with a bullet until I find the sweet spot. As that relates to oal, I'm still a little confused as to why my manual asks for different min oal with every different powder. For instance, my Lee reloading manual give a minimum oal for 300gr Lapua Scenar with N560 of 3.681. This suggests to me that I should not allow my oal to ever be less than this measurement. Is that right? If not, why are they referring to it as "minimum overall length"? and would I ever want to have an aol longer than 3.681? It seems as if my manual suggest that it should be exactly 3.681, but I'm sure that can't be correct. As you can see, I'm still confused about this.
     

    exx1976

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    Yes, the amount of "jump" a bullet takes before contacting the rifling is what is being referred to.

    In order to start playing with seating depth, you need to first know what the chamber/throat of your rifle looks like. Hornady sells an OAL kit to do this. It uses a sliding rod with a set screw, and modified cases that screw onto this rod that you put in the chamber. There are videos of how to do it on YouTube.

    Alternately, I've heard of guys that will chamber an assembled dummy, standard COAL round, then stick a dowel down the muzzle end, and mark it. Then take just a bullet, and push it into the throat as far as you can with your finger, then stick the same dowel down the muzzle end. Measure the difference between the marks, add that to the COAL of the dummy round, and that's how long a round would be before contactng the rifling. You do NOT want to load rounds right on the rifling, bad things can happen.

    I'm sure someone will come along with more detailed information about this, but I just wanted to toss that out there quick for you.
     
    M

    milo 2.0

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    Thanks for your reply, Milo. Yes, I have cleaned the dies and I'm not loading up a whole bunch of rounds. I have actually been reloading for a few years and I have a couple of experienced friends who help me out some. I have worked up loads before, so I have a pretty good idea of what is involved, but I certainly still have plenty to learn. Since I'm just starting out with this caliber and, because it is a rather large caliber, I'm just trying to be extra cautious with it. So far, I have only loaded 15 rounds...5 each of three different loads. I thought this would be a good starting point, just to get a feel for how this gun is going to like the N560.

    This business about seating depth is definitely something I want to know a lot more about. I have been reading about it, periodically, but I'm still not very knowledgeable on the subject. When you say that bullet seating depth is where most accuracy comes from, I suppose you refer to adjusting how far off the lands a bullet is seated for each powder charge I try with a bullet until I find the sweet spot. As that relates to oal, I'm still a little confused as to why my manual asks for different min oal with every different powder. For instance, my Lee reloading manual give a minimum oal for 300gr Lapua Scenar with N560 of 3.681. This suggests to me that I should not allow my oal to ever be less than this measurement. Is that right? If not, why are they referring to it as "minimum overall length"? and would I ever want to have an aol longer than 3.681? It seems as if my manual suggest that it should be exactly 3.681, but I'm sure that can't be correct. As you can see, I'm still confused about this.

    I honestly don't know how Lee could recommend any seating depth other than magazine length. Maybe pressure started to spike at that seating depth, I'm not sure.
    Treat a load manual as a guide, not gospel, and work from it to come to your own conclusion. Every action, barrel-chamber combo will react differently, manuals just cover their asses liability wise. I have a buddy that tries to utilize the "most accurate load" tested from a manual, all I can say is fuck, and ask, what part of your gun resembles the one used for testing??????
    And don't get me started on taking a velocity estimation based off book loads.

    Sounds like you're using your head, so good luck and have fun with the new rig!
     

    wchartz

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    All of the above is good advice. I will add one thing that I found that greatly affects seating depth, especially when using VLD style bullets and the VLD seater plug. Neck tension or more accurately for this problem is resistance to seating. Using new Lapua neck sized brass and a Hornady comparator I was getting as much as .020" variation in depth (referencing the ogive). There was very noticable difference in seating pressure between individual rounds and all of the rounds required excessive seating pressure in my opinion. Some bullets actually had a ring around the circumference where the seater plug made contact that you could feel. If I could feel the ring, the round was very short. Lubricatiing the inside of the necks helped greatly in reducing the lenght variations. After the first firing the resistance to seating was much less and the lenghts were much more uniform. I believe the residual carbon from the first firing lubricated the necks enough so that the second and subsequent loadings were more consistent.