Newbie with OAL questions

[djcantr]

I'm brand new to reloading. I've read a fair amount, but I'm getting mixed information with OAL. I'm loading on a Lee Pro 1000 using mixed .45 ACP brass, CCI primers and J&K Bullets 230 grain lead round nose bullets. I'm starting with Win 231 powder and their loading data suggests 4.3-5.3 grains of powder for this combination. I'll be shooting these loads from a 3" Ultra Carry II. The 3" 1911s are known for being finicky about feeding reliably so I'm planning on starting with 4.9-5.0 grains of powder for a little hotter load but still well under max load. These are just rounds for shooting at the range. That gets the basic info out of the way, on to my questions concerning OAL.

Their load data specifies a max OAL of 1.2". I tried that and it looks very short. The factory ammo I've been shooting measures 1.264"-1.273". If I load to the factory length, the shoulder of the bullet is slightly above the mouth of the case. Loading to where the shoulder is even with the case mouth gives me an OAL of 1.228". Loading to that length would seem right to me, but I'm a newbie.

Why would the reloading manual suggest a max OAL of 1.2"? I understand that loading to an OAL shorter than suggested would raise the pressure and could be dangerous, but how would loading to a longer OAL than suggested change things?

 

[bossman]

It may have to do with the type of bullet they're using. The longer col should lighten the load with the same amount of powder. I use 1.25 col with all my 45 acp. They work in all my guns at that col. I may go up or down with the powder but the col remains the same. I think max col is 1.275.

 

[djcantr]

Thank you for your reply. I guess I'll just get to loading some so that the shoulder on the bullet meets the case mouth, around 1.228".

 

[zxcvbob]

1.2 is probably just the length of the loaded rounds they tested with, not a maximum (or a minimum.) Did they use exactly the same bullet? If so, you should strongly consider using that length. If you're using a different bullet, load them where you think they need to be, and take 1.2" under advisement when adjusting the powder -- if you load them a lot shorter, pressures will be higher so don't go all the way to the max. If you load them a lot longer, maybe don't start all the way at the bottom for your minimum load. But it's really the seating depth that matters for getting the powder right. The OAL has more to do with feeding and chambering reliably.

Of course the OAL and the seating depth are related, but it's based on the length of the bullet. That can vary quite a bit if the nose profile is different.

 

[djcantr]

The bullets I'm using are about .02" longer than bullets I measured that I pulled from some S&B FMJ and Federal TMJ. It seems I should be loading to a longer OAL just due to that anyway.

 

[Jim243]

Why would the reloading manual suggest a max OAL of 1.2

That is what the publisher of the data tested the load at.

I understand that loading to an OAL shorter than suggested would raise the pressure and could be dangerous

The amount of pressure is based on the amount of powder and the space within the case it has to expand before the bullet starts to leave the case.

but how would loading to a longer OAL than suggested change things?

Bullets are slightly wider than the diamiter of the barrel. The cylinder or chamber of a firearm is also slightly wider than the barrel to hold the cartrage and bullet. If you jam the bullet into the "lines and groves" (rifling) of the barrel, it makes it harder for the bullet to leave the case and builds up more pressure for the powder to push the bullet out of the case.


Hope that helps
Jim

An OAL of 1.20 is pretty standard for a 230 grain 45 ACP bullet. But will depend on mfg and profile (shape) of the bullet.

 

[BDS-THR]

For most 230 gr RN bullets, 1.25" OAL worked well for me in all the pistols I have used.

You do not need to use the OAL listed on published load data as testing barrel fixtures (not real pistols) are used to measure chamber pressures and using published OALs WILL NOT ensure reliable feeding/chambering of finished rounds in your pistols.

Determining OAL should not be a guessing game and I use the following process for semi-auto loads whenever I use a new bullet:

1. Make sure resized cases drop freely into the barrel chamber. If not, adjust the resizing die to ensure the cases are resized full-length (bottom of resizing die almost "kisses" the shell holder/plate) and fall in freely into the chamber.

2. Determine Max OAL - Make a dummy round (no powder/primer) and perform the barrel drop test with the barrel out of the pistol starting with the SAAMI max OAL until the dummy round falls into the chamber freely with a "plonk" and spin without hitting the start of rifling. To determine the amount of taper crimp to return the flare back to flat, I usually add .020" to the diameter of the bullet (So for 9mm .355" diameter bullet, .375" taper crimp and for .356" bullet, .376" taper crimp).

3. Next determine Ideal OAL - Load the Max OAL dummy round in the magazine and manually release the slide without riding the slide with hand. Incrementally decrease the OAL until dummy round reliably feed/chamber. Depending on the pistol/barrel used, Ideal OAL that will work reliably will vary. If you are reloading for multiple pistols, use the Ideal OAL that will work reliably in all the pistols. FYI, most jacketed/plated RN bullets have worked well for me at 1.125"-1.135" OAL in various pistols.

4. Then conduct powder work up using Ideal OAL and published start-to-max load data. Regardless of the scale used, I highly recommend the use of check weights to verify the accuracy of powder charges to 1/10 of grain - http://www.midwayusa.com/product/493216/rcbs-standard-scale-check-weights-605-grains

Not all factory/aftermarket pistol barrels have the same groove diameter, leade length, rifling type as used in the test barrels to develop load data that result in different high pressure gas leakage and may require different powder charges to produce same chamber pressures. If you do not have a chrono (or can't use one because you are shooting at indoor ranges), I typically use consistent shot group sizes as indicator of consistent chamber pressures without exceeding published load data (when shorter OALs are used, I often use a slight buffer headroom near the max load data - maybe .2-.3 gr less).

Variations in the published load data are often due to variations in reloading/testing components (i.e. type/nose profile of bullet nose and how deep the bullet base is seated inside the case neck, etc.).

Starting with the published start charge (or 10% below max), load 10 rounds of each increment of .1-.2 gr in powder charge. If using shorter OAL than published/typical for bullet type, I will decrease my start charge by .2-.3 gr. For initial range trip, 3 rounds are shot at 7-10-15 yards and shot groups are compared to identify charge range that reliably cycled the slide/extracted cases while looking for accuracy trends (usually 2-3 powder charges will stand out). On range trip #2 and subsequent trips, I will verify most accurate powder charges with 5 round shot groups at 7-10-15 yards (Typically, I will use 3 consecutive range tests to verify the accuracy of particularly accurate loads).

Conducting full work up allows you to identify the most accurate powder charge for the particular bullet/OAL combination and lighter target/plinking loads that still produce accurate shot groups while reliably cycling the slide/extracting the spent cases.

Some large flake powders like Unique, Promo, etc. may not dispense to .1 gr consistency when using powder measures. Do not get discouraged by this as I still get accuracy from these powders even with .2-.3 gr variations. Go by the shot group sizes.

 

[1SOW]

Their load data specifies a max OAL of 1.2".

Sir, if you look again, you won't find the word MAX in front of the load data oal.
The load data in the manual is actually the MINIMUM safe oal for that load.

The OAL load data gives will result in the pressures and speed the manufacturer saw with that load.
If you load LONGER than the load data oal, the pressures will be LESS. Less pressure is safe to load.

So if it shows an oal of 1.20 and you load 1.25, the load pressure and speed will be a little less than the shorter oal would give. No problem.