.308 Reloading Question (Size and Trim)

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12 years 1 week ago #15956 by Fausty0
.308 Reloading Question (Size and Trim) was created by Fausty0
I have been wondering about this for a while. When I reload I use the Hornady Spec book that kits come with to get all of the C.O.L., Max Trim, etc data that I need to make my bullets. Here is my questions though.

1.) A .308 rounds specs is a MAX C.O.L. of 2.810" with a Max case trim length of 2.005" However, I have been told by MANY veteran reloaders that they trim their cases down to 2.000" for a longer life expectancy. Is that true and even safe?

2.) So a .308's Max trim length is 2.005". I am using 150gr Hornady SST bullets which has a Specific MAX C.O.L. of 2.735" which is much lower than the basic .308 C.O.L. of 2.810". Here's where I run into my issue, after trimming my .308 case to 2.005" and seating the bullet, my round is still at a C.O.L. of at least 2.755" - 2.790" which is over the limit for the 150gr SST round. I have re-calibrated my calipers, checked my case length over and over, and have even trimmed cases down to 2.000" to see if I can get the correct C.O.L. Nothing... I

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12 years 1 week ago #15957 by LebbenB
Replied by LebbenB on topic .308 Reloading Question (Size and Trim)
Have you adjusted your seating die to give you the COL you need?

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12 years 1 week ago #15958 by Fausty0
Replied by Fausty0 on topic .308 Reloading Question (Size and Trim)
Yeah, If I set my seating die to any lower the bullet will be pressed to far into the cartridge making it a bit unsafe.

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12 years 1 week ago #15960 by VTIT
Replied by VTIT on topic .308 Reloading Question (Size and Trim)
That bullet has a cannelure doesn't it? That kind of limits the OAL unless you trim the cases. I can only tell you how I do it and you can see if it helps at all.

I have found book OAL is fine if you are using the same rifle that they design the round for, it's only what the book makers used to develop their listed data. I think they design so it will work okay in most firearms. But the ideal OAL is what works best in the rifle you are loading for, not what the book says.

So what I do is seat a dummy cartridge to the cannalure or seat to the book OAL whichever you are more comfortable with. Make sure it feeds smoothly ( I usually do 3-5 rounds and load a magazine with them and cycle the rifle with the charging handle). If that set up works fine and you don't see any signs of the ogive getting stuffed into the lands and grooves it will probably work and is a good place to start. You can also check the OAL before and after you cycle it and see if the bullet is pushed further into the case. If everything works and looks good you have a good place to start.

Then, once you have an OAL that will work, load some cartridges about a half grain apart and test fire them. I usually do at least 5 of each. Start low at the minimum charge, in a bolt rifle you can start a little below min with military cases, but I start at minimum for a semi-automatic. Make sure the rifle functions fine for ejecting, chambering etc. Increase charges until you reach book max. Fire them in that order until you get to the top loads OR until you see signs of excess pressure like the primer flattening out or mushrooming (extreme) around where the firing pin hits you may even see the headstamp letters getting flattened. If you see these signs before you get to the max, back off maybe 10-15% and say that's the max for your rifle. Some rifles will show high pressure signs before the max charge especially if you are using military cases.

After you find the max for your rifle you can start playing around with groups. After you find the best charge, do a whole series while varying seating depth in and out until you find the best point for accuracy. I find that my AR's don't like the bullet touching the lands and I have to seat a little shorter.

I have found that seating rifles rounds a little deeper doesn't increase the peak pressure like in a handgun load. Seating the bullet off the lands and grooves gives the bullet a little running start and doesn't raise the peak pressure as much in rifles. The best seating depth for me isn't usually a single depth but may be several thousandths wide. It also varies by the bullet shape and weight. I tried to use a seating depth tool but never had good luck with it (YMMV).

Again this is just my :twocents: just be careful and if you think it isn't safe, it probably isn't.
The following user(s) said Thank You: LebbenB, jtallen83

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12 years 1 week ago #15961 by LebbenB
Replied by LebbenB on topic .308 Reloading Question (Size and Trim)
Well written post!

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12 years 1 week ago #15962 by Fausty0
Replied by Fausty0 on topic .308 Reloading Question (Size and Trim)
Thanks VTIT, that's pretty much the logic I have been using but i was not entirely sure I was accurate and want to be as safe as I possibly can while making very accurate loads such as these. Thanks again!

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12 years 1 week ago #15963 by Sharkey
Replied by Sharkey on topic .308 Reloading Question (Size and Trim)

Fausty0 wrote: I have been wondering about this for a while. When I reload I use the Hornady Spec book that kits come with to get all of the C.O.L., Max Trim, etc data that I need to make my bullets. Here is my questions though.

1.) A .308 rounds specs is a MAX C.O.L. of 2.810" with a Max case trim length of 2.005" However, I have been told by MANY veteran reloaders that they trim their cases down to 2.000" for a longer life expectancy. Is that true and even safe?

2.) So a .308's Max trim length is 2.005". I am using 150gr Hornady SST bullets which has a Specific MAX C.O.L. of 2.735" which is much lower than the basic .308 C.O.L. of 2.810". Here's where I run into my issue, after trimming my .308 case to 2.005" and seating the bullet, my round is still at a C.O.L. of at least 2.755" - 2.790" which is over the limit for the 150gr SST round. I have re-calibrated my calipers, checked my case length over and over, and have even trimmed cases down to 2.000" to see if I can get the correct C.O.L. Nothing... I



Wow. I read every single word of this post and suddenly got woozie and passed completely out... :silly:

I'm just a big dumb guy man. You gotta give a little heads up when you are gonna post this brainy stuff... :)

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12 years 1 week ago #15964 by Siscowet
Replied by Siscowet on topic .308 Reloading Question (Size and Trim)
:twothumbs: excellent feed. I am going to bookmark it for when I start reloading for the 10.

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12 years 1 week ago #15967 by fire fighter
Replied by fire fighter on topic .308 Reloading Question (Size and Trim)
I am new to this forum so I hope I am not stepping on anyones toes,sorry if I am.Just took delivery of a LaRue 7.62 OBR w/Niteforce 3.5x15 optics.I know nothing about reloading I want to get into it,I was told to go with Redding does anyone on this forum use Redding. If you do could you please tell me what to buy for reloading equiptment, Thank You Very Much

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12 years 1 week ago - 12 years 1 week ago #15968 by VTIT
Replied by VTIT on topic .308 Reloading Question (Size and Trim)
Welcome Fire Fighter.
Don't worry about stepping on anyone's toes around here. I think most of us have pretty thick skin. At least I do anyway. I use a Redding resize die (if you click through the Sinclair ad on this page the part number is 749-004-274WS) I think it works pretty well. I also use their seating die (749-007-469WS on Sinclair). They make good stuff. I don't go for speed and more for accuracy when I load.

I have also had good luck with Lee dies. I especially like their resizing lube. It's more like a wax and I haven't (knock wood) stuck a case with it yet. I know some guys on here must use some other brands too and can probably steer you in the right direction.

HTH
Last edit: 12 years 1 week ago by VTIT.

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