Bullet Length in Relation to OAL

[scatterbrain]

Unclenick, what you have pictured would take a serious effort to accomplish and be very messy after firing. How much pressure would be required to release that bullet?

[Metal god]

Unclenick, what you have pictured would take a serious effort to accomplish and be very messy after firing. How much pressure would be required to release that bullet?

That would not happen , see below my opinion on that . I'll put that part in bold print .

I am laughing because the drawing I altered had what you are asking for.

Are you saying the first exaggerated image you posted shows what I was trying to say ?



If so I disagree , even though the head clearance is significant in the lower image . Both bullets engage the lands at the exact same spot when pushed fully forward . The image above says to me no mater how short you size your case head to datum the bullet will engage the rifling at the same time and distance . Maybe I'm wrong but I thought the whole point was the opposite of that . Meaning if one shoulder is bumped back .005 shorter then the next and both cartridges have the same COAL . The cartridge with the shorter shoulder bump will have it's bullet ogive .005 closer to the lands then the other after firing pin or ejector pushes them forward ? If the above image showed that the bottom image would have the bullet jammed into the lands ???

Your second exaggerated image does however



Although I don't think you need the exaggerated longer case neck being jammed into the rifling . Reason being IMHO that is not likely to happen because in most instances if you are at "trim to length" that extra .005 bump or even as much as .010 shoulder bump and the cases trimmed to length . The neck will not be pushed into the throat/leade/rifling . It's the very reason we have all the tolerances we do between case size and headspace size , to allow for the reloader to have inconsistent head to datum distances . However the ogive of the bullet will get closer to the lands which is what we are talking about here . At least that's what I've been talking about

[stagpanther]

Camming onto the bullet with the case mouth into the throat is a good way to bulge the brass or even potentially blow up a rifle--though I'm not sure that's what UN was intentionally showing in the revised exaggerated pics?

[Metal god]

-though I'm not sure that's what UN was intentionally showing in the revised exaggerated pics?

Agreed but it does show what could happen if you fail to trim "and" bump your shoulders back to far . It could happen , obviously not as much as the image shows but the tolerances can stack up and you could jam the neck into the throat . So although not likely IMO , I can see it happening .

In fact this makes me think that may have been happening to me when I first started reloading . I was getting sticky bolt lefts at start charges or just above . I now load those same components to much higher charges with out issue . There may be a couple things different now compared to when I started . However the glaring one is that I adjusted my dies per instructions which had me bumping my shoulders back .012 from fire formed . At the time I did not know that , I was just sizing my cases as instructed by the die manufacture . Obviously those rounds chambered just fine but maybe I was jamming the case neck into the throats . Interesting thought for me to contemplate , I guess some more testing and measuring is in order . Maybe I'll get to that just after I finish that primer kill test I never started

[stagpanther]

Agreed but it does show what could happen if you fail to trim "and" bump your shoulders back to far . It could happen , obviously not as much as the image shows but the tolerances can stack up and you could jam the neck into the throat . So although not likely IMO , I can see it happening .

In fact this makes me think that may have been happening to me when I first started reloading . I was getting sticky bolt lefts at start charges or just above .

Actually, I believe I did this very thing today with one cartridge of the very first groups I shot through my howa 300 wm after fire-lapping the bore with tubbs finishing bullets. I posted a pic of the result on the bolt action sub forum.

[stagpanther]

Concentricity isn't knocked anywhere by firing pin impact.

All belted cases have that issue next to the belt. Chamber headspace is typically .220 +.008" and case headspace is .220 -.008". The case head and belt stretches back several thousandths to the bolt face when fired.

A solution: https://www.larrywillis.com/

My reloading technologies belted magnum die came in and I just used it to do a batch of well-used 300 wm brass. It took me a few tries to realize that when they say use LOTS of lubricant--they mean slather it down good. Once I did that the collet would easily slide off the case, before I used enough I'd have to turn the case upside down and use the press to remove the collet from the case on the first few I tried.

As a side note, it's interesting that they say always headspace off the shoulder and not the belt. That requires a bit of extra attention since most gauges are geared to simply measure headspace off the belt. I assume it's the extra space off the shoulder that you might not be aware of that accounts for the extra wear and case stretch, as well as expansion above the belt (?).