Seating depth

Seating depth

  1. shermr
    shermr
    Seating a bullet too deep in a semi-auto case such as the 9mm, 40 S&W, and 45 APC can raise pressure to a dangerous level. Proper crimp needs to be applied to keep the bullet from moving in the case during chambering and firing.

    Large revolvers will handle higher pressure much better than a semi-auto, or a Airweight sunbbie.

    Anyone have any experiences they would like to discuss?
  2. OMJ
    OMJ
    The seating depth can affect pressures but in the 1000's of 9mm and 45ACP rounds I have loaded I have never experienced bullet jump in those calibers, Bullet JUMP is the key wording here, It would defy physicís to have a bullet jump backwards ( going onto the case deeper ) because the projectile is heaver then the case and the basic function of an auto loader makes that darn near imposable. Now if the projectile is being crammed into the case because of the bullet meeting some resistance and the action is pushing on the case wellÖ Thatís a different story and weíve got bigger problem to think about then crimping.
  3. OMJ
    OMJ
    The calibers you listed all head space on the case mouth, If one were to put a traditional crimp on those rounds the cartridge would chamber to deep and other problems would arise, Most likely constant misfires because the primmer would not be hit hard enough or at all. You can put a roll crimp or a side crimp on cartridges that chamber on the case mouth but again I find it totally unnecessary for the cartridges you listed.
    If you are having bullet jump happening with 9mm, 40 S&W or 45ACP I would look at the dies you are using and verify that are set up properly, The case walls of all three of the rounds you listed get thicker towards the base of the case, When I run my brass through the sizing die I always need to flare the case mouth to properly seat the projectile and am meet with some ristance about 3/16 in, That’s the wall thinness coming into play, It would take a hole mess load of force ( like a press ) to get the bullet to go deeper.
  4. OMJ
    OMJ
    Iím new to this site and donít want to come off sounding like a now-it-all but I sit at the reloading bench a lot, I have experimented and discovered many things at that bench, But nothing like you have posted about. I have experienced bullet jump in my 30-06 when I grabbed target ammo for hunting ammo, I seat my bullets WAY out on my 06 for target work but they are only single loaded into the chamber when shooting for groups, When I loaded three of the target rounds in my magazine after the first shot, I had a big mess in my mag because the other two bullets jumped forward from the recoil and that was it for that days hunt.
  5. OMJ
    OMJ
    The other experience I had with bullet jump was making 450 Bushmaster brass from 284 brass, There was not sufficient neck tension to hold onto the projectile when that monster recoiled and I was having problems, The 450 BM round also head spaces of the case mouth, So I modified a 45/70 factory crimp die to put a SIDE crimp on the cartridge about 3/32 down from the case mouth, That way the correct dememtions were there for proper head space.
    The Bottom line here is if you need to put any type of crimp on your rounds you listed use a roll crimp and have a set of micrometers to verify your not going to far. Also if that loaded round doest make a clear and distinct THUNK when dropped into your barrel ( when taken out of the slide ) itís not right!!
  6. defcon4
    defcon4
    OMJ, I am confused by your post. I believe you are using the term 'bullet jump' where you should be using the term 'bullet set-back'. Bullet jump is the amount of free space between the bullet ogive and where the bullet first touches the rifling. I believe the OP was concerned with what happens when someone seats a bullet too deeply. Also when a cartridge has an improperly or loosely crimped bullet the bullet can be 'set-back' further into the cartridge case upon firing due to recoil effect. In either case pressures can increase dramatically.
  7. defcon4
    defcon4
    To clarify my previous post concerning a bullet being set back upon firing. I was referring to the cartridges in the magazine having their bullets set back due to the recoil effect.
  8. shermr
    shermr
    I recently purchases some 124 grain Remington Golden Saber bullets for the 9mm. I found that if I seated the bullet to the to the seating depth for a Hornady XTP the bullet was seated too far. The Golden Saber has a power band at the bottom of the bullet, if the bullet is seated too far below this band a proper crimp cannot be applied because the bullet is .348 above the band and .355 around the band. Loading data for the XTP showed a C.O.L. of 1.060", factory Golden Saber C.O.L. is 1.120". I am thinking that an over pressure situation could develop with +P velocity load and a bullet seated deeper than factory ammo.
    Has anyone fould information for seating bullet seating depths recommended by bullet manufacturs? Since not all bullet makers publish loading manuals it is difficult to determine seating depth without a trip to a sporting goods store with a micrometer in hand.
  9. NotTwoShure
    NotTwoShure
    In the early 1980’s I experimented with the crimp on .38’s for paper-punching practice and to develop my speed loading skills. This was in the days before the mighty wonder nines and .40’s. I expanded, belled, the case mouth as little as possible to seat the semi-wad cutters and with a very light almost negligible crimp. It was a disaster even with target loads. The rounds did move forward preventing cylinder rotation. With the .45 ACP, I do not crimp any more than is necessary to “Seal” the round. I have not experience any trouble with either the ball or JHP reloads and I feed four Kimbers and a Glock. I do not use max pressure loads with any rounds after developing my pet loads. I do not have the time or will to load rifle rounds. All of the information I have read since 1974 does indicate a danger even with the type of case loaded, primers and seating depth. FYI.
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