Seating depth question

[mxl]

I'm a newby to reloading and have done a few .380, 9mm and .45 acp using a Speer 14 manual. The manual gives max. cartridge overall lengths, and the cartridge overall length tested with each bullet type/weight. It does NOT give the seating depth or length of each bullet tested. I assume there are differences in length of the various manufacturer's bullets and some have hollow bases and some are flat which will effect case capacity. So, how do I know how far to seat bullets if I am not using the exact same brand tested? Is there available info giving all manufacturer's bullet dimensions so I can figure seating depth of the bullets tested? Is it even a concern if I start at min. charge and seat to the COAL tested? Thanks.

 

[jfh]

The reason you do not see the specific seating depth for the bullets is because semiauto calibers need COAL set by other criteria first--e.g., what fits in the magazine and more importantly, what will function reliably in your specific semiauto. To some extent, then, the published recipes reflect this fact.

Generally speaking then, the bullets available for each caliber are designed so that there will be no 'excessive' seating depth when seated for proper feed. Other parameters for a "good round" include checking the LOA by using your actual barrel to check it (see other threads here) or to use a MAX cart gauge.

If you 1) sort out a functioning LOA with some dummy rounds, and then 2) begin with a start charge recommended for that general type of bullet there should be no issue about safety due to seating depth variation.

The second issue will most likely be satisfactory function--that is, is the (start) load capable of retracting the slide, ejecting the case, etc., with its current spring setup? Does it "barely' do it, or is unreliable? Boosting the charge to the next / midpoint may than resolve the function problems.

The third step, then, can result in more load tweaking to result in 1) getting the ballistics you want / need, or 2) finding the most accurate load with this combination.

Jim H.

 

[mxl]

JFH, Thank you for the reply. I appreciate it. MXL

 

[jfh]

and thank you for the thank you, MXL.

In that earlier post, I forgot to mention that when function testing your dummies, you do need to check for LOA changes--that is, is the next tension tight enough to keep the bullet in place during the loading cycle. The crimp you use has some bearing on this as well, but it really is more an issue of case neck tension. Search this forum for more information on neck tension....

Jim H.

 

[1SOW]

The reloading data you use will give 'some' specific bullets for that COAL and charge data.

That's why several manuals are usually necessary to find your bullet and type. Many powder companies have good data that list several types of bullets available on the internet: Hogdon, Alliant, Vihtavuori and more. Some bullet companies do as well.

Failing to find your bullet, you can carefully start at the low end using data from 'similar' type and weight bullets, like "124/125gr, cmj/fmj rn" for Montana Gold, Winchester, Rem, etc .

If I've been loading 9mm 124gr FMJfmjrn at a COAL that works and decide to try 124gr fmjhp with a different brand bullet-same powder; I measure the old bullet length and compare it to the new. If the new bullet (same weight and coating) is .004 shorter, then my COAL will be about .004 shorter to get the same seating depth.

Record all your data in your log, and it'll turn into a great reference source for future loads.