Newbie, looking for a sanity check

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  • Sharpeneddark

    Ultimate Member
    Mar 20, 2013
    2,292
    Westminster
    Hi all!

    I've recently completed my first batch of .308 reloads and just wanted to have a sanity check, to make sure I've done everything correctly and nothing seems out of spec. Mostly because the numbers between IMR's load data and Hornadys seems to be different

    What I have:

    Hornady 150 gr Interlock SP bullets (Item number 3031)
    IMR 4895 - one set of rounds loaded to 42.6 gr and a second loaded to 44.0 gr.
    The cases are trimmed to approx 2.005".
    The bullet is seated to 1/2 cannelure (not crimped).

    First, I loaded 42.6 because the IMR data sheet said this is starting load for 150 gr rounds. Later, after I seated my load of rounds, I thought it may be prudent to get the Hornady book and see what it said. It says the range for 4895 with their bullets is 37.7 to 44.7. This has me a little concerned for the rounds I loaded to 44. Especially when it comes to the seat depth. The Hornady book says COL for this round should be 2.735. With my rounds seated to 1/2 cannelure, per the book's instruction, my COL is averaging 2.750". Should I be concerned and pull apart my 44 gr loads and reduce powder or reseat the bullets?

    I also have some FMJ-BT bullets I want to try. Item number 3037 in the book. That COL says it should be 2.700", but when I made my dummy round, COL was 2.716". Am I doing something wrong or am I over thinking this by a lot and my loads should be safe to try?

    Thanks for the advice!

    Edit: One last thing I forgot to mention. I'll be shooting these out of an AR-10. 18" 1:10 twist barrel.
     

    j8064

    Garrett Co Hooligan #1
    Feb 23, 2008
    11,635
    Deep Creek
    I don't shoot an AR10 platform. And you're building rounds for your rifle, not mine.

    My reloading books have a range of 40.0 to 45.0 gr of IMR-4895 behind 150 gr bullets in .308. COL on those is 2.685".

    Based on everything I read in your post, you're within reason. If it was my rifle...I'd fire some test rounds at low end of your reloads and work up from there.
     

    BigDaddy

    Ultimate Member
    Feb 7, 2014
    2,235
    Lee list 42.6 as the start weight on 150 gr jacketed bullets for IMR 4895. It lists a min OAL of 2.800. Max load 47.3.

    I don't know how to make sense out of OAL (I reload for a bolt gun). Lee lists about 20 powders and OAL's from 2.6 - 2.8. Your difference of 0.015 in OAL, as far as decreasing air space in the rifle case and increasing pressure, is not significant. Not all bullets in the same box have the same OAL and not all 150 gr jacketed bullets have the same length.
     

    Sharpeneddark

    Ultimate Member
    Mar 20, 2013
    2,292
    Westminster
    I don't shoot an AR10 platform. And you're building rounds for your rifle, not mine.

    My reloading books have a range of 40.0 to 45.0 gr of IMR-4895 behind 150 gr bullets in .308. COL on those is 2.685".

    Based on everything I read in your post, you're within reason. If it was my rifle...I'd fire some test rounds at low end of your reloads and work up from there.

    Thanks!

    Lee list 42.6 as the start weight on 150 gr jacketed bullets for IMR 4895. It lists a min OAL of 2.800. Max load 47.3.

    I don't know how to make sense out of OAL (I reload for a bolt gun). Lee lists about 20 powders and OAL's from 2.6 - 2.8. Your difference of 0.015 in OAL, as far as decreasing air space in the rifle case and increasing pressure, is not significant. Not all bullets in the same box have the same OAL and not all 150 gr jacketed bullets have the same length.

    Also thanks for your response! I'm not exactly sure I want to approach the 2.8" threshold. I like having a little playroom in the mag. After reviewing the book, my eyes automatically ignored the red filled area. Apparently, for this seating depth, 46.4 gr is max. So I should have a bit of play room up and above my current higher load of 44 gr.

    -----------------

    One final question, and this may be specific to those who have reloaded .308: Should the powder come all the way up to the shoulder of the case, or even a little above it? That seems like a lot of powder, but I figure that there needs to be a fair bit of air in between the grains. I ask because a lot of what I've read says to be sure not to double charge. I don't see how that would be possible in .308 as a second charge would easily overfill the cartridge.

    Thanks again!
     

    BigDaddy

    Ultimate Member
    Feb 7, 2014
    2,235
    I forgot to mention, I might try a load in between the weights you mentioned, but I have OCD.

    I've loaded for 223, 22-250, 243, 280, 30-06 and 338 and I've never used a powder that I could double charge and not notice the powder spilling out the top. If you are off the reservation and doing something weird with pistol powders in rifle cases, I'm sure you could double charge.

    Compressed loads are not unheard of in the rifle world. Handguns, the 45 LC being the best example, have a lot of space between the bullet and the smokeless powder. Not so much in the rifle world. If your scale is accurate and you grabbed the correct can of powder and the correct caliber brass, you are OK with powder up to the shoulder.
     

    Sharpeneddark

    Ultimate Member
    Mar 20, 2013
    2,292
    Westminster
    I forgot to mention, I might try a load in between the weights you mentioned, but I have OCD.

    I was thinking the same. I still have 25 cartridges to load to make an even 100. I may make them 43.3 or something as a split middle.

    I've loaded for 223, 22-250, 243, 280, 30-06 and 338 and I've never used a powder that I could double charge and not notice the powder spilling out the top. If you are off the reservation and doing something weird with pistol powders in rifle cases, I'm sure you could double charge.

    Compressed loads are not unheard of in the rifle world. Handguns, the 45 LC being the best example, have a lot of space between the bullet and the smokeless powder. Not so much in the rifle world. If your scale is accurate and you grabbed the correct can of powder and the correct caliber brass, you are OK with powder up to the shoulder.

    I thought so. It was just repeated ad naseum (and for good reason) to not double charge. Even when the videos were using .308 as their example caliber (and some used .223). Nothing I read/watched said that the powder load should be at around the shoulder of the case for rifle rounds. So...it made me curious. And, I tend to be cautious, maybe to a fault, when handling flammable materials.

    Anyways, thanks for all your advice and support. I feel much better about what I've done so far and look forward to testing it out at the range!
     

    Blacksmith101

    Grumpy Old Man
    Jun 22, 2012
    22,163
    The manuals give the load data ranges for their test set up. Each variable in the set up effects the final numbers. The numbers posted are for the exact combination of bullet (weight, type and brand) manufacture, brand of case, specific primer, lot of powder, tested in that particular firearm or test barrel with the chamber that was reamed. That is why they always say to reduce the load and work your way up when anything changes.

    If two manuals agree it is just coincidence, even their burn rate charts aren't the same. But by checking multiple manuals you keep from doing something really stupid like finding a typo or miss reading something.

    How full the case is depends on both the charge weight and the density of the powder you are using. Less dense powders fill the case more for the same weight of charge. If your charges don't fill the case half way the potential exists for a double charge, more common with reduced loads and handgun cartridges. If you have room for a double charge consider using a less dense powder. There are still people who will double charge a case that overflows but you can't cure stupid but blown up guns can.
     
    Last edited:

    Pinecone

    Ultimate Member
    MDS Supporter
    Feb 4, 2013
    28,175
    This is why you start low and work up.

    I use the OCW method of developing loads for rifles. This is based on starting 10% lower than your choosen max load, then incrementing up by 0.7 - 1.0% per increment. This way, if one increment is safe, the next will not be dangerous. It may show pressure signs, but will not hurt anything.

    You then shoot these loads round robin to determine accuracy nodes and scatter nodes.

    THEN you work on seating depth.

    Many people start with the max length they can do, in case this is jammed into the lands (huge pressure jump when you do this). That way, any short COAL is safe, as there will be some jump. Unless you get REALLY short, but even then, the pressure should be less than jammed.

    http://optimalchargeweight.embarqspace.com/

    If I am doing plinking rounds, I pick a mid range load and have fun. :)
     

    CXD Arms

    Member
    Feb 27, 2014
    64
    Anne Arundel
    Whenever you are working up a load, you should start at the bottom of the recommended range for the powder and bullet weight.

    The issue with the OAL is that a 150 grain bullet from one manufacturer WILL NOT be the same length as another brand. Even with one brand such as Hornady, a 150gn FMJ-BT will have a different length than their 150gn Soft point (assuming they have one, just speaking hypothetically)

    Changing the powder charge as well as the seating depth is a change of 2 variables which can really skew your results.

    If you are loading for a semi automatic, your max OAL is either the magazine dimension or the chamber length with respect to the rifling. As someone already pointed out, if you are working near a max charge, if the bullets is jammed into the rifling, bad things may happen.

    I prefer to measure length from the ogive because it is a better, consistent standard which, when I've found a powder charge that groups together, I can then adjust seating depth from that bullets ogive to determine how much free bore will affect accuracy, and then possibly adjust the charge if the velocity changes to a point that the rounds are not longer consistently grouping. Measuring from the ogive once I know the chamber dimension provides a better way to control my variables.
     

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