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bowhunter-tw

COAL and OAL question 30-30

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I just reloaded my first 30-30 cartridges. But I have some questions in regards to OAL and COAL. 
 

first OAL, when I measure my re sized once fired brass I measure between 2.035 and 2.04. The reloading books say to cut between 2.028 and 2.030. I do not have a trimmer yet so I omitted this step based on the slight difference in length and the info found online. Was this an incorrect assumption?

 

second, the COAL for this load is 2.550, the factory ammo I have is at a length of 2.05 - 2.1. Why would the factory load have such a short COAL, compared to the load data? 
 

to get the bullet to the cannelure I seated to a nominal depth of about 2.35, is this going to cause a problem?

 

I am using imr3031 powder. Rifle is a marlin 336. I did cycle them through the action, they all cycle and chamber seemingly fine. 

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1 hour ago, bowhunter-tw said:

I just reloaded my first 30-30 cartridges. But I have some questions in regards to OAL and COAL. 
 

first OAL, when I measure my re sized once fired brass I measure between 2.035 and 2.04. The reloading books say to cut between 2.028 and 2.030. I do not have a trimmer yet so I omitted this step based on the slight difference in length and the info found online. Was this an incorrect assumption?

 

second, the COAL for this load is 2.550, the factory ammo I have is at a length of 2.05 - 2.1. Why would the factory load have such a short COAL, compared to the load data? 
 

to get the bullet to the cannelure I seated to a nominal depth of about 2.35, is this going to cause a problem?

 

I am using imr3031 powder. Rifle is a marlin 336. I did cycle them through the action, they all cycle and chamber seemingly fine. 

First off your cases on this diagram has a max length of 2.039. This is a SAAMI spec, and I'm assuming that you haven't had your chamber measured, so your chamber might be shorter or longer. When you fire your case it will grow just like your finger nails do, so they need to be trimmed. Letting them go past the specified length causes a problem by the brass getting to far into the chamber area, when the case if fired the brass is not allowing the proper space the bullet needs to clear the chamber thus causing pressure. When you are loading for a case that you are going to crimp and they all haven't been trimmed to the same length they are probably not crimped in the same place on the cannalure, but with the 30-30 it won't make that much of a difference. As far as a factory round measuring less than your reloads, it probably wasn't the same bullet, so the cannalure probably wasn't in the same spot. If your rounds cycled through your gun ok, then give them a try. As your shooting and cycling them into your chamber check your bullets and see if they went further into the case, if not your crimping them ok. That 2.550 is the max length.

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So your cartridge length is really just controlled by case OAL and where the cannalure aligns correctly for crimping and you just have to make sure that the COAL is not greater than max. That makes sense. Looks like im going to need to buy a trimmer now.

one other question is when you measure your cases do you try and center your calipers on the case or do you measure from an outer edge? I tend to get measurements that vary by about .005 on the same case based on how the case is in the calipers, kind of difficult to make sure the case is squared up

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I also ran into another interesting issue, I have a cowboy 3 die set for 30-30 and after I resize the brass I cannot get a jacketed bullet to sit on top of the case mouth or start it to get it seated without setting up the expander die and running all the cases through it. The bullets are flat base, maybe thats why? But the cases seem very undersized at the mouth and my understanding is that you shouldn't need the expander die for jacketed bullets, just cast? Is it possible my decapper/expander in the sizing die isnt set low enough that it doesnt flare the mouth?

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I try to measure the center of the case when I measure. What you want to do is stay consistent, what you do with one case do to all. If you have a 3 die Cowboy set, most of those cowboy loads are lead, a little different between a jacketed bullet and a lead bullet. Check your instructions that are with the die.

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30-30 chambers are all over the board - they have been cut for over 125 years.  The SAAMI spec for the cartridge is a dwarf for most chambers and it head spaces off of the rim.   You want to reload for the rifle's chamber, and only that rifle's chamber.  You want to crimp in the cannular for the bullet you are reloading with, but what overall case length do you want to trim at for your overall cartridge length to be right?  It is a devil of a cartridge to load for to get right for these reasons.

I don't know about cowboy dies, but the expander should come back up through the neck of the case and open it up to allow you to seat a .308 bullet - you don't flare a case neck on a bottle neck case to seat a bullet?

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You have your terminology skewed. Case length is just that, length of case from base of case to end of neck or case length... COL is "cartridge overall length". That is " cartridge length from base of case to end of bullet". CBTO is cartridge base to ogive on bullet. And OAL is the sum of several components and not always a cartridge! OAL is an abused acronym! It could be used to measure the length of your boat, trailer, and truck pulling it, as in the overall length of the truck, boat, and trailer. As in the OAL of the three components. And yes you're die set up is totally scewed. If you live in tucson, I'll be glad to help you get your dies set up. Free! Don't feel bad most reloaders don't have a clue on how to set their dies up properly!

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Very nice offer to set your dies up for you, you should take him up on it if you are able to. That's good that you are being cautious as you learn to reload and I think it's good as you learn to go by the book. You should trim your cases to "square up" the case mouth but don't trim them too short if there is not excess brass to trim. Also, whether you trim or not, deburr/chamfer the inside and outside of the case mouth as that will help with bullet seating. Another good tool to have if you don't have one, is a cartridge headspace gauge, generally with a bolt gun you want to bump the shoulder back approximately .002-.003, with semi autos and lever guns you probably want to go .006 or so.

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On 10/14/2022 at 8:14 PM, L Cazador said:

You have your terminology skewed. Case length is just that, length of case from base of case to end of neck or case length... COL is "cartridge overall length". That is " cartridge length from base of case to end of bullet". CBTO is cartridge base to ogive on bullet. And OAL is the sum of several components and not always a cartridge! OAL is an abused acronym! It could be used to measure the length of your boat, trailer, and truck pulling it, as in the overall length of the truck, boat, and trailer. As in the OAL of the three components. And yes you're die set up is totally scewed. If you live in tucson, I'll be glad to help you get your dies set up. Free! Don't feel bad most reloaders don't have a clue on how to set their dies up properly!

unfortunately im in tempe, quite the drive from tucson. But I have reloaded quite a few cartridges since that post and learned a lot! I ended up buying a trimmer and headspace gauge (among MANY other tools lol) so am trimming to keep in spec and sizing to bump the shoulders between .002-.005” depending on the rifle. 

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