Maybe the big jump does the same?
IDK, I haven't had any issues... but I did measure a couple Hornady 108gr ELD-M's and they were .243" at the bearing surface (shank) and the same .243" at their pressure ring, so there is a chance the Match Burners (with their fatter pressure ring) are indeed messing with some guys I guess...
That said, I'm a little OCD when it comes to bullet seating and want it to be as smooth and as consistent as I can make it and I think that probably helps.
I'm probably a little more crazy when it comes to brass prep than most (and of course, less crazy than others); I've spent a lot of time and $$$ trying just about every which way to clean brass for precision rifle... including: 3 different types of ultrasonic cleaners (up to and including the most powerful smaller commercial-type available), different soap/Lemishine combinations, a bunch of testing between wet and dry tumbling with a bunch of different types of media, and about 10+ different ways of wet tumbling (with pins, no pins, a small amount of pins, a lot of pins, a little water, lots of water, different numbers of tennis balls in the tumbler with the water, and just about everything in between)...
The main 2 reasons I've tried all that crap is:
#1 - Repeatability - decided since I can't control the brass being the same amount of dirty every load cycle, I might as well control it all being the same amount of clean every time.
#2 - Eliminating peened case mouths - yeah, wet tumbling works awesome, but wet tumbling without fucking up case mouths is much harder to figure out.
In the interests of seeing if there's anything special that I'm doing that might be helping, here's my whole brass prep regime I've settled on (for now):
(After firing, all my cases get annealed on an AMP, Aztec mode since all my brass is from the same lot.)
1. Deprime/decap
2. Wet tumble in rotary tumbler - 100 cases, 7L tumbler with 5lbs of SS pins and enough Pelican cut-up foam wedges to take up most of the tumbler volume before filling it all the way up with water and then adding a 1-2 second pour of Armor All Wash & Wax and 1/2 a 9mm case full of Lemishine - usually 30-45mins, never more than 1 hour.
My 2 "secret ingredients" are: the Armor All Wash & Wax is absolutely essential to me - it leaves a thin layer of wax behind on the cases and inside the necks post rinse that helps with sizing and later when I get to seating bullets. After trying the tennis ball thing, I decided it was a good idea to take up the volume of the tumbler so cases couldn't bounce around so freely, but the tennis balls were too heavy handed and actually seemed to agitate a small percentage of cases even more aggressively than usual... IDK how I thought of it, but I had some extra Pelican foam kicking around so I cut up a few pieces and put it in the tumbler and it worked pretty damn awesome... through experimentation I've now arrived at cutting up the foam into little wedges like girls use to apply makeup, it takes up the volume in the tumbler and keeps the cases from crashing into each other so hard, but the smaller wedge shapes seem to let the brass migrate around better (I'm still sort of playing with this, but it definitely helps big time).
3. Dry brass in brass dryer (food dehydrator type) 2-4 hours (depending on how cold my garage/outside is).
4. Lube with spray-on lanolin/alcohol case lube and swirling the cases around in a bucket (not aggressively, because I'm still trying to baby the case mouths).
5. FL size with a bushing die -0.003" under loaded round neck OD (for me that's a .268" bushing, my loaded neck OD is .271"), expander/decapping stem removed. (I use an LE Wilson die with a TiNi Redding bushing)
6. Mandrel die with .241" mandrel (TiNi Sinclair turning mandrel).
7. Dry tumble in vibratory tumbler and 20-40 grit corn cob blast media for 1 hour.
This removes the lube, but it is gentle enough where it leaves most of the Armor All wax behind on the inside of the necks, and the special
20-40 grit media is important because picking corn cob kernels out of 99% of the flash holes fucking sucks. I don't just do this too remove lube, the corn cob does put off some dust, not nearly as much as walnut media, but enough to where the dust does really seem to help at bullet seating... and I've also found that the usual/normal coarser grit corn cob media like Lyman and most others sell (that gets caught in all the flash holes) actually produces more/better dust than the finer 20-40 grit stuff so I still use some of the coarser stuff later...
8. Trim for consistency (or just if necessary), once my brass is all above 1.9" I'll be trimming every cycle so they're all uniform (I recommend one get a good trim tool so it doesn't suck and goes fast).
9. Inside neck chamfer (VLD type), always, ...but I only lightly deburr the outside of the necks if it's new brass and/or freshly trimmed.
For the chamfer I don't get too aggressive, I want the brass to either be silent or "whistle" on the cutting tool, I'm not trying to remove more material than I have to.
10. Prime
11. Powder
12. Bullet seating - I dip the base of the bullets in the coarse corn cob media just to grab a little extra dust to help with seating. It's the same sort of thing as guys do with graphite dry lube, but it's not as messy or heavy handed (I feel like the graphite is actually too slippery and masks if anything else is going on with the seating pressures). I'm actually still playing around with this step as I also like using a q-tip with a little lanolin/alcohol lube on it in the necks before seating too, just not totally sold on which method I prefer because they both work well...
- As an aside, after listing out all those steps, it's pretty funny that in another thread on the forum the other day, someone was giving me shit saying I'm lazy and don't put enough effort into my reloaded rounds and/or load development because I disagreed with them about OCW/ladder test nonsense.... if they only knew.