Armory Sponsor
Posted: 11/27/2008 8:58:38 PM EDT
|
Hey guys,
So I bought 500 lead 45cal 200 gr. semi-wadcutter bullets from my local supplier today and am trying to figure out the best overall length for my Kimber with this ammo. I've never developed a hard and fast procedure for this so I thought I'd get some input from you guys. What I did was seat the bullets until they just fit in my magazine (1.260"). I then dropped them in my barrel to see if they dropped all the way in. I noticed the 1.260" were flush with the barrel hood while my factory Federal Hydrashocks sat just below. I seated the bullet down to 1.250" and now the case head sits right where the factory loads sit. To try to determine a cause I got out the old Sharpie and colored the bullet along with the rim of the case to see where contact was being made. It looks like the 1.260" bullets are contacting the throat (and headspacing) on the leading edge of the bullet (see picture). There was no bullet setback when chambering either round. I'm thinking the 1.250" are the way to go but I'm not sure. (See pictures below for clarification) 
This is the 1.250" round sitting just below the hood of the barrel. 
This is the 1.260" round sitting flush with the back of the barrel hood. 
The round on the left is 1.250", the round on the right is 1.260". Notice the increased markings on the leading edge of the full thickness part of the longer bullet. Whatever starting OAL I decide on, I'll have to load up some live rounds and shoot them to see how they feed. I want to start with the max and work my way down. I've had problems with short rounds having their rim caught below the extractor causing FTFs. Is the method I described above a good one for determining max O.A.L. to start with? I'm open to any suggestions. What is your method for determining what O.A.L to use in your handloads for a auto pistol? Thanks in advance, DOC |
|
Whatever you do, be sure they are headspacing on the case mouth not the bullet. This condition should hold even for the longest case you own.
Trim a case to the recommended length. Drop into chamber and measure depth beneath housing using dial caliper gage. Do not just eyeball this. Seat a bullet in this case at some relatively long depth and rechamber. This should not headspace on the case mouth but will headspace on the bullet. Remeasure depth. The difference is the MINIMUM additional seating depth you need. I'd guess about 0.010" to 0.020" deeper would be even better. Also be sure this depth results in a round that is shorter than the magazine. To really get this right, you need to know the variation in case lengths within your population of cases. The longest case still has to fit in the magazine. |
|
The ogive shape of semi wad cutters means two factors determine the loaded length.
If they are a little too long in the chamber, the ogive jams into the rifling far enough that the gun is virtually locked shut and the loaded cartridge will be close enough to impossible to eject by racking the slide. Once the length for the chamber is checked, then they need to be checked in the magazine. The meplate edge drags on the inside of the magazine if the bullets are seated out too long. Put at least four or five loaded cartridges into the magazine to check if they will feed okay. One or two is insufficient as they are not fully inside the magazine. When switching bullet brands, you'll need to recheck the seating depth. SWC bullets from different manufacturers can have different dimensions that are too small to see, but won't seat to the same length so a slight change is needed. Been there, done that. |
|
An additional consideration is bullet diameter. You will see a similar change in chamber position depending on how big your bullet is. Between .451". .452" and .453", the same OAL will push the case further out of the chamber as bullet diameter increases. This is due to the leade angle in the throat.
I think in your case, the 1.250" OAL is the correct one. The 1.260" will be likely to malfunction as the gun gets dirty. |
|
Thanks guys,
Mike's system makes perfect sense. I tried it on several rounds and came up with a maximum OAL of 1.235. However, this is way too short for my gun. They jam because some rounds are moving too far forward in the magazine and the extractor is ending up behind the rim of the case. I'll probably be going back to the 230gr LRN bullets. In the meantime, I think I'll try the 1.250" with the remainder of these bulletes. They should be safe, as the rounds are entering completely into the chamber with about 15 thousandths to spare. Thanks again, DOC |
Armory Sponsor