The importance of seating pressure



  • I wanted to create another thread so as not to clutter up the .223AI thread. The target immediately below is representative of how my .223AI is presently shooting: (as I said, I made a turret adjustment between the 5 shot group and the individual shots)

    1HonapCl.jpg

    Here is two groups shot immediately before the above target with the exact same load, nothing changed. All except the brass used for these groups below was kept out of the normal process and had varying amounts of imperial wax inside the neck. From none at all to greased up fairly well. This was brass used during setup of the sizing die as well as brass that was actually fired and then sent to whidden to have the sizing die made.
    8QpUTXil.jpg
    jZ0hLggl.jpg

    Same exact load, same exact specs on all the components, but I could feel significant differences between them regarding how much pressure was applied during the bullet seating process. The results are apparent. The brass that was treated with my "normal" process produces extremely predictable results on the target and had very uniform seating pressure across all the rounds. The brass with non-uniform seating pressure produced 3/4moa or marginally better.

    This is a prime example of why shooters that can not shoot better than 1/2moa often have significantly different views on both equipment and processes as compared to shooters that do consistently shoot better than 1/2moa. Getting 1/2 to 3/4MOA is quite easy with TS Customs rifles and quality components offered today. However you must be on top of all the variables to consistently get better than that. Seating pressure is probably one of the most important aspects of this process and likely one of the most overlooked by novice reloaders.



  • Did more or less seating pressure group better or does it not matter as long as it is uniform?



  • Within reason, it doesn't seem to matter as long as it's uniform. However if you are on either extreme, it can definitely cause issues.



  • So for a guy like me who doesn't have custom dies, or even bushing dies, is there other ways to control the neck tension? I have Forster dies now which are way better than the RCBS I had before. I have also now learned that either wipping the necks with Q tips or running the brass through the rice again helps.



  • @norcal_in_az Mainly it is about the process. Good equipment helps, but understanding the process is important, otherwise the good equipment will go to waste.

    For instance, unless you neck turn, the brass will always have some non-uniformity in case thickness up along the neck. Even after turning, it doesn't all come out. So consider the people that do not use expanders in their dies and instead only neck size or FL size without expander. Where does the non-uniformity get pushed to?

    Right... inside, where the bullet goes. If using an expander, it will keep the non-uniformity to the outside, where it doesn't matter nearly as much. So, a nice polished expander on the decapping stem, and having that decapping stem be loose to move around and align itself a bit is important.

    Making sure to use smooth dies will help. I polish my dies with flitz. Both the inside of the die and the expander ball/mandrel. This when combined with the use of imperial wax makes the sizing process effortless. Despite that, the uniform application of wax is paramount to ensuring each piece is sized just as the previous was. A dry case followed by 5 greasy cases and you'd absolutely see a difference in the dry case. The same amount of lube in the same areas is a good practice to get into.

    Deliberate and methodical operation of the press is also critical. You can't expect the same results on a case that is ran into the sizer hard to have the same treatment as a case that is run up super slow and gingerly.

    The lubricity uniformity of the inside of the neck is important. This is why I love the rice method so much. The carbon/fouling deposit inside the case mouth is pretty uniform after firing. The rice smooths out what parts are not uniform, but largely leaves the residue in place. This residue absorbs some uniformity problems between components and also allows a more consistent bullet release than bare metal. With stainless tumbling I had to sort my loaded rounds into much larger and more diverse batches due to the significant difference in pressure during seating. So, anything you can do to keep the surface of the case necks in good shape is a plus.

    Neck turning is another thing that can really help with seating pressure consistency. Those material deformities I was referring to earlier can be largely fixed by proper turning. Uniform thickness will result in a much more uniform behavior from case to case.

    Annealing is another step that helps a ton. Brass of the exact same makup and thickness will still behave differently if it is of a different elasticity from the other pieces. So annealing will significantly help keep them behaving the same.

    Clean bullets is another thing to consider. If not clean, at least uniform in their lubricity. I've worked with bullets that showed up kind of oily before, and it was a disaster. They had to be washed free of it before they would shoot at all. Keeping your hands free of lubrication and contaminants during the seating process is important, for if you deposit some junk on the bullet while you're situating it over the mouth... it will result in non-uniform lubricity from bullet to bullet.

    Keep a good chamfer on the inside of the case mouth. A hard edge there will cause the case to scrape bullet material and bind it up between the bullet and the case neck during seating. Make sure there's a smooth transition.

    I have more thoughts... but if you have any specific questions just ask.



  • @orkan thanks for the detailed reply. That does help a ton.



  • What is your case lube routine?
    I have Imperial wax and just barely touch it every case with my fingertip and work a film all around it.
    Should any go inside the neck?
    I did buy some Flitz just to polish dies and other metal around here.



  • @hypo said:

    I have Imperial wax and just barely touch it every case with my fingertip and work a film all around it.
    Should any go inside the neck?

    I do the same thing, just spin it between my fingers for the outside. I then use a q-tip and put a very very light swab around the ID of the case neck. This helps the expander move smoothly.



  • Thanks. I may be adding a dry tumbler in the future to get the wax off and for reloading after the initial case prep and firing.

    I do like the wet tumbler for giving nasty range pickups the first cleaning.
    Will probably consign all my range pick ups to be blaster ammo for the AR.

    After going through my Lapua 30-06 compared to the Lake City 223, it is a whole lot less work getting it ready to shoot again.



  • @hypo said:

    I do like the wet tumbler for giving nasty range pickups the first cleaning.

    Yup... it's great for cleaning stubborn things. It still has a use, it's just not in my precision rifle process anymore.



  • @orkan said:

    This helps the expander move smoothly.

    Are you using the expander ball on the sizing die, or is this done in a separate operation as with the 21st century mandrel die?



  • @ragnarnar I have expanders in all my FL sizing dies. I have separate expanders that I use for neck turning and various other jobs, but as a matter of course I use a expander on the decapping rod in every FL die I use.



  • @orkan said in The importance of seating pressure:

    @hypo said:

    I have Imperial wax and just barely touch it every case with my fingertip and work a film all around it.
    Should any go inside the neck?

    I do the same thing, just spin it between my fingers for the outside. I then use a q-tip and put a very very light swab around the ID of the case neck. This helps the expander move smoothly.

    Orkan - when sizing, how do you feel about using Imperial Dry Neck Lube media for lubing the case neck vs the very very light touch of Imperial Sizing Wax on the ID of the case neck? Do you think you can get just as good of results when using the Imperial Dry Neck Lube on the necks when sizing, or does it not seem to give as good of results as using the very very light coat of Imperial Sizing Wax method you use?

    When sizing, I use a Redding Type S Bushing die with expander ball. I have already tumbled my cases clean in rice prior to sizing. I then coat the outside of the case body in a light film of Imperial Sizing Wax up to the shoulder (but not on the shoulder) and then dip the case neck in the Imperial Dry Neck Lube media and size the case. The cases seem to run smoothly to me, but was wondering if I am leaving anything on the table vs using your method of the Imperial Wax on both the outside and ID of the case neck and then tumbling in rice?



  • @catamount1

    I suppose I’m curious as to why you do it your way compared to just waxing the whole case and ID of the neck?

    I use a full length die with the wax and have experimented with both the expander ball and a separate mandrel expander. In both instances I’m able to obtain very low or no runout and consistent shoulder setback 1.5 thou.

    If I had found one method to be better or more consistent, I would have gone that way, but because they’re more or less equal I go back to the faster method.

    I guess what I’m getting at again here is why are you doing it how you are? Somebody correct me if I missed some technical detail, but if you’re getting equal runout and setback with both the wax versus dry lube, I’d say the only thing you’re leaving on the table is time.



  • @catamount1 I've not used the dry lube in this capacity enough to have formed an opinion.



  • @tackyp said in The importance of seating pressure:

    @catamount1

    I suppose I’m curious as to why you do it your way compared to just waxing the whole case and ID of the neck?

    I use a full length die with the wax and have experimented with both the expander ball and a separate mandrel expander. In both instances I’m able to obtain very low or no runout and consistent shoulder setback 1.5 thou.

    If I had found one method to be better or more consistent, I would have gone that way, but because they’re more or less equal I go back to the faster method.

    I guess what I’m getting at again here is why are you doing it how you are? Somebody correct me if I missed some technical detail, but if you’re getting equal runout and setback with both the wax versus dry lube, I’d say the only thing you’re leaving on the table is time.

    Happy to share how I came to the method I've been using (not saying it's the best or only way by any means). I actually thought it was a pretty common way that lots of precision reloaders used, but maybe I'm wrong. There are several reasons why I use this method with the Imperial Sizing Wax on the case body and the dry neck lube on the neck (I had also read way back when not to lube the shoulder because it can cause dents from the sizing die if lubed).

    The instructions in the Redding Type S FL Bushing die actually recommend using the Imperial Dry Neck Lube for the necks when sizing, so that is one of the reasons.

    Also, years ago, I used to use one of the spray waxes and did not like them, as they did not work consistently. I actually had a case get stuck in the sizing die once with a spray wax many years ago. The other problem back then was that the powder tended to sometimes stick in the neck when loading due to the spray wax (I did not tumble brass back then). I figured there had to be a better way, so did a lot of research and read product reviews and found lots of folks were using the Imperial products, especially Imperial sizing Wax along with the Dry neck lube for the necks.

    I was so impressed with how the Imperial products worked, I never looked back (also no messy pads etc ). It's very fast and clean. Honestly, for me at least, I personally think it would be faster to take the case neck and dip it into the dry neck lube media than it would be to try and coat the inside diameter of the neck with sizing wax. The way I do it, It's almost one fluid movement in that I just touch the sizing wax before grabbing a case, as I grab the case I spin it in my fingers which coats the case body, and then dip the neck in the Imperial Dry Neck lube media which coats both the inside and outside of the neck. Then place it in the sizing die.

    With this method I don't have to worry about cleaning lube out of the necks or having powder stick to the inside of the necks (I believe dry neck lube is just graphite/carbon). When the case comes out of the sizing die, the outside gets quickly wiped with a towel and is ready to go - no need to tumble again.

    I also set up my die to bump the shoulder back 1.5 thousandths.

    At any rate, it has been working well for me, but was curious about the different way Orkan was using. I was just wondering if he or anyone else had tried/tested both and had any data as to the benefit of using the wax on the inside of the neck instead of the dry lube. Maybe sometime I will test both methods and see if there is any difference.



  • @orkan said in The importance of seating pressure:

    @catamount1 I've not used the dry lube in this capacity enough to have formed an opinion.

    Thanks for the feedback Orkan!



  • @catamount1

    If it’s working for you keep it going man. A consistent bump and low runout are all that I care about, and if you’re able to accomplish that then I wouldn’t worry about it.

    I, and I think most others here, size/whatever then tumble then load. I’m worried about the potential for strange pressure spike if I miss some lube on the case.

    If I ever start tumbling first I’ll probably consider dry lube.

    Thanks for the reply



  • @orkan said in The importance of seating pressure:

    variabl

    I completely agree that neck tension is important when you are trying to eek out all the accuracy you can.

    For me I find it easier to maintain consistent seating pressure by putting a bit of dry lube on the inside of the case neck just before seating. I use a q-tip to apply -- 3 twists, 3 cases, then reapply to q-tip...essentially make what you do consistent.

    I have shot groups like above at distance with variable neck tension vs consistent and have seen similar results -- NOT EVERY time will the shots fall out of the group but fliers seem to occur more often with inconsistent neck tension.

    I actually will place rounds that seat different than the rest in the right side of my case and use them for short range shots or sighters/fouling shouts.

    My 2 cents.



  • @orkan said in The importance of seating pressure:

    Making sure to use smooth dies will help. I polish my dies with flitz. Both the inside of the die and the expander ball/mandrel.

    Orkan - is using flitz to polish your die a one time thing, or do you polish your die with flitz each time before using it to size cases?



  • @catamount1

    I use it periodically to clean everything back up good. I polish it very well the first time then after that, it’s more of a cleaning regiment. Not sure if that’s really necessary but it worked for me.



  • @catamount1 said in The importance of seating pressure:

    Orkan - is using flitz to polish your die a one time thing, or do you polish your die with flitz each time before using it to size cases?

    I'll use it any time the die gets roughed up. Brass can build up on various places at times, and it will work good for that. Most often, I'll do it once when the die is new... and not again for a very long time.



  • @orkan
    @bull81

    Thanks for the replies.


 

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