Bullet seating depth issues

[hounddawg]

CW gives good advice. I tune my load to the range I am shooting at. I have a couple of loads that are accurate at 300 but would fall apart at 600 or 800. Why do I use them at all? Less expensive bullets, less powder used, and less barrel wear for a substantial cost savings per round. Plus you don't have to worry about velocity inconsistency so less testing needed

[Metal god]

I'm using two sizes of Hornady hollow point boat tail match bullets, both 68 grain and 75 grain. I'm loading them in LC brass that's been sized so the shoulder is "bumped" .003", and neck sized using a Lee collet neck sizer with a .001 undersize mandrel. I'm annealing in between body sizing and neck sizing and all brass is trimmed to the same length

I'm concerned about your method and how little neck tension/bullet hold you have in a auto loader . I'd be worried about bullet set back ( OK not if the load is so compressed the bullet can't be set back ) but .001 is very little hold especially if you're annealing as well . My limited testing with bushing and collet neck dies has shown me that a .001 bullet hold will allow me to manually push the bullet deeper into the case just by pushing the tip into the bench by hand . That IMHO is to little of hold for an auto loader . What I've not done is go shoot those because I don't load my AR loads with less then .003 of hold YMMV .

I actually have a Lee collet die in 308 that is exactly as you describe and I've never fired a round that I loaded using that die because of the poor bullet hold I get with it .

The next thing I'd ask is if you have actually fired these heavily compressed loads . You were likely very close to bulging the case which will cause feeding problems . I load many compressed loads but have never deformed a bullet doing so . If you're deforming bullets , you're likely close to deforming other things as well .

I'm not there seeing what you're seeing so you may be gtg but thought I'd bring those few thing to your attention so you can look out for them .

[jetinteriorguy]

I seem to have plenty of neck tension judging by how much effort it takes to pull them. I'm using a mandrel that is undersize by .001, that's under the standard size mandrel, not just .001 under bullet size. I have shot six of these rounds during testing, primers were slightly flattened with no cratering and seemed to extract normal as far as I can tell shooting an AR indoors in a booth. Unfortunately I can't use my MagnetoSpeed on this rifle, just not enough room between the rail and brake for it to fit properly so I'm just watching for any drastic changes in POI and haven't noticed anything odd there to indicate a big change in MV due to a pressure spike.

[cw308]

There is compressed and too much compression , before you detected poblems seating , inaccurate seating must have been going on . Were you having accurate readings . I don't have a chronograph , have shot through my friends to see where I was . Now with a compressed load that isn't interfering with seating finding.a jump and maybe backing off on your load could get you better results . My neck tension with the standard die works well at .004 . I never used a crimp even when I tested with .001 but I shoot one at time form a bolt gun .

[jetinteriorguy]

I first seated them with a Lee die I had modified. I customized the seating stem with the two part epoxy that comes in a stick form. Because of the good fit the Bullets weren’t being deformed, so I didn’t suspect anything unusual happening. Eventually the epoxy started to crumble so I just cleaned it off the stem and gave up on that method. I would guess there was some seating depth inconsistencies but I didn’t specifically check since I didn’t suspect anything going on. The problem started when I got my Forster micrometer seating die, of course this is when I started checking the depths more scrupulously and hence started this thread to find out what might be going on.

[cw308]

I'm using the Redding Competition Seating Die with the Redding Competition shellholder set of 5 . Just like the Forster very accurate seating . Im glad you figured out what was going on , made for good conversation . Let's see how it plays out down range . I went down all those rabbit holes , now I settled down on one load and will shoot that until I need a barrel change , then start all over .

Chris

[Metal god]

I'm using a mandrel that is undersize by .001, that's under the standard size mandrel, not just .001 under bullet size.

Oh , I understand now . I thought you were .001 under bullet diameter . Thanks

[hounddawg]

try eliminating one potential issue at a time. sort out some bullets measure and record base to ogive and base to meplat measurements, seat them in unprimed cases with no powder. Measure base to ogive and base to meplat on the loaded rounds and compare the measurements to the unseated measurements. Actually one or two should be enough to identify if it is the bullet consistency or the dies is the issue

[jetinteriorguy]

That’s a good idea. I’ll give that a try. One other thought too, I think the jackets on these Bullets might be very thin, making them more susceptible to this issue. Right now the ones I have loaded are pretty good, I’ll know in a couple hours when I get to the range.

[cw308]

Jet
We're all on the hook waiting for the range report , see what you started , you have a audience .

How are you cleaning your brass , I'm not shooting quantity 30 rounds 3 10 shot groups . So it's easy for me to give alot of time preping my brass , I have a smaller caliber nylon cleaning brush wrapped with 0000 steel wool locked in my drill press to polish up the inside of the necks , makes seating like butter even with .004 tension. Used dry lube to prevent cold weld but with or without didn't see any change .

[stagpanther]

You mention LC brass--any chance it's made to NATO specs? Might need to turn the necks if they're thicker than "conventional" .223. Just a thought.

[jetinteriorguy]

Sorry for the delay, I did get to the range but got so busy with Christmas stuff I didn't have time to post last night. Things went real well, I shot two rounds of five shots each. I tried three seating depths based on previous records, first right at the lands, second .005" off the lands, and third .010" off the lands. Based on this limited test it looks like .010" might work. The first five in a somewhat cool barrel, my rifle was in the car all day at around 30 degrees, shot at just under an inch. The second round of five had the first four touching and then of course I pulled the last shot, but I knew I pulled that one so I still felt quite encouraged by the results. I may try a light crimp with the collet die as a comparison to see if it makes any difference. If the results stay the same then I may add this step just to be sure of no bullet set back.
This is my whole routine for loading. First I deprime, then clean primer pockets, then tumble for an hour in crushed walnuts with a dash of Bartenders Helper, then lube with a couple spritzes of lanolin mix, then size so the shoulder is "bumped" .003", then tumble again with a dryer sheet cut into strips for an hour to remove the lube, then neck size with the Lee collet neck sizing die with a .001" undersized mandrel, then trim if needed on a Lyman trimmer with a pilot that's sized down and polished so as not to affect the neck ID, then chamfer and deburr with my old RCBS tool on any trimmed cases, then prime with the Lee hand primer, then weigh my charge on an old RCBS 505 scale that I had calibrated in our instrument shop at work, then last I seat with a Forster micrometer seating die. Whew, that's a long sentence.

[cw308]

Sounds good to me . The only difference I full size and wet tumble , you covered all bases for sure and it worked out great. Was glad to be part of the conversations . Have a Happy & Healthy Holiday.

Chris

[jetinteriorguy]

I'd like to thank everyone for their help, great conversations and I learned a lot.