I am just starting to reload 308 Winchester for my son's Savage bolt action. The manuals I have state 2.015 or 2.005; how long do you trim your cases for 308?
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What length do you trim your 308's
- Thread starter Crossbow1
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- 308 case lenght
I don't anymore until absolutely necessary. A lot of people don't realize that the internal dimensions of your action allow more room for longer case necks. If they don't need to be trimmed then I don't trim them. I used a tool from Sinclair to get my reading.
Edit : when I do trim I trim to 2.010
Edit : when I do trim I trim to 2.010
Definitely 2.005. 2.015 seems really long. If I remember correctly, my Remington 700 SPS started having stiff bolt closure around 2.010.
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This wasn't FGMM, but I definitely shot it in that rifle. I believe these were once fired Federal cases. That rifle has since been rebuilt, but I still have those reloads. I'll pull them out tomorrow, disassemble a few and let you know. Maybe they needed a shoulder bump or something if that doesn't sound right to you.
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If FGMM shot out of that rifle, then it will take 2.010" long cases cuz FGMM brass is that long from the factory. You would have some pressure signs from the pinched case mouth otherwise.
I'd look into bumping the shoulders a hair. A Redding Body die allows you to do that without disassembling the ammo.
I might be wrong on this one since I'm going off memory, but I believe the MAX length for .308 Win is 2.015, and the trim-to length is 2.005. So trim your cases to 2.005 and when they grow to 2.015 knock them back again.
Here's the SAAMI spec if you want to check it out - http://www.saami.org/pubresources/cc_drawings/Rifle/308 Winchester.pdf
Here's the SAAMI spec if you want to check it out - http://www.saami.org/pubresources/cc_drawings/Rifle/308 Winchester.pdf
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Chambers in factory rifles are very long, but I still trim, but as long as the shells are less than 2.015" they're good to go. If you want them perfect just take the shortest shell and trim them all to that length.
I use an RCBS Lathe type trimmer with a 3-Way carbide cutter. I trim after every shooting as the tool not only trims but chamfers and de-burrs as well. I trim to 2.010 for no other reason than it's an in-between number.
You can let your cases grow in length until they get to about .010" of the second shoulder (end of chamber) and still be safe. I trim everytime because it lets me trim quickly, not having to remove a lot of metal, and I want totally uniform cases. I also use this time to give a close inspection of the case, especially with my hooked tool to inspect the inside of the case for developing case head separation grooves.
I keep several hundred cases "in rotation" so it's only a matter of processing a batch as it fills the bin. It's not like I'm trimming before every loading session as I have brass prepped far in advance and in large quantity.
You can let your cases grow in length until they get to about .010" of the second shoulder (end of chamber) and still be safe. I trim everytime because it lets me trim quickly, not having to remove a lot of metal, and I want totally uniform cases. I also use this time to give a close inspection of the case, especially with my hooked tool to inspect the inside of the case for developing case head separation grooves.
I keep several hundred cases "in rotation" so it's only a matter of processing a batch as it fills the bin. It's not like I'm trimming before every loading session as I have brass prepped far in advance and in large quantity.
I found some LC63 Match cases the other day. Resized them and some were 2.035" long. They chambered fine. Thinking they were on their last leg, I sectioned one and to my surprise I found no thinning of the case walls. That's amazing. Why is stuff do cheaply made these days?
I prefer to run the necks long. 2.005 is too short. Looks wrong. I suggest you find the actual length of your chamber.
I prefer to run the necks long. 2.005 is too short. Looks wrong. I suggest you find the actual length of your chamber.
I don't revere the Hornady manual as gospel.
Perhaps you cannot comprehend the concept of totality of circumstances as applied in the other thread. Let me explain it once again:
1. Over max
2. Tight chamber
3. Marginal component
1+2+3=Failure
Perhaps you cannot comprehend the concept of totality of circumstances as applied in the other thread. Let me explain it once again:
1. Over max
2. Tight chamber
3. Marginal component
1+2+3=Failure
Here is the shortest 308 chamber in existence:
http://forum.accurateshooter.com/index.php?action=dlattach;topic=3751116.0;attach=866923;image
It calls for 2.025" as the absolute max case length.
Factory chambers are quite a bit longer.
http://forum.accurateshooter.com/index.php?action=dlattach;topic=3751116.0;attach=866923;image
It calls for 2.025" as the absolute max case length.
Factory chambers are quite a bit longer.
Max length is what your chamber will allow. As all loading manuals do, they give trim lengths and charges that may be quite modest compared to what actually may work well for you. My rifle will chamber a piece of brass as long as 2.04".
You are right. The OP stated that he was just beginning to reload and I don't think his intention was to measure his chamber to find maximum length it would allow. SAAMI spec is a good starting place for a new reloader.
To be honest, I've never done any experimenting with accuracy and trim length. If there is a difference between 2.005 and 2.04, I'm not sure I could shoot it. Have you noticed significant (or insignificant) changes in accuracy when varying the trim length?
Nah, no accuracy differences I could measure. To tell you the truth, I just need a clean case mouth for a nice chamfer/deburring, and try to trim as little as possible, just to get the clean, square case mouth. The tumbling peens the mouth a bit.
As the chamber length is different from rifle to rifle, as long as it's not made by the same reamer, consistently.
You want a Chamber Length Gauge, to measure the max case length, from there you set your desired trim to length, depending how close you want to be, it has it advantages, more consistent pressure can reduce es/sd.
It will help if you are using slow burning powders and high performance cartidges, as it will greatly reduce carbon build up in your chamber, as the closer the neck is to the second chamber shoulder, the faster the brass will seal the chamber.
This means it will reduce the backflow that gets into unsealed chamber clearances.
Following a realoding manual trim length is of course safer, if you don't know what you are doing.
And it kind of says itself you have to monitor brass stretching beforehand, so you know what is safe to trim to, and add a bit of clearance for safety.
Sinclair Chamber Length Gage | Sinclair Intl
So telling the OP that trimming to 2.xxx is the optimal trim length for his rifle, is wrong.
I let the brass grow to desired length and trim it every time after on the Giraud.
Inconsistent neck length affects Neck Tension, as many other variables.
I also turn the primer pocket uniformer lighlty at the set depth, every case every reload, to ensure even primer seating for the life span of the case.
And expand and turn the case every firing.
ANd anneal every 2-3 frirings.
Each to they're own though.
You want a Chamber Length Gauge, to measure the max case length, from there you set your desired trim to length, depending how close you want to be, it has it advantages, more consistent pressure can reduce es/sd.
It will help if you are using slow burning powders and high performance cartidges, as it will greatly reduce carbon build up in your chamber, as the closer the neck is to the second chamber shoulder, the faster the brass will seal the chamber.
This means it will reduce the backflow that gets into unsealed chamber clearances.
Following a realoding manual trim length is of course safer, if you don't know what you are doing.
And it kind of says itself you have to monitor brass stretching beforehand, so you know what is safe to trim to, and add a bit of clearance for safety.
Sinclair Chamber Length Gage | Sinclair Intl
So telling the OP that trimming to 2.xxx is the optimal trim length for his rifle, is wrong.
I let the brass grow to desired length and trim it every time after on the Giraud.
Inconsistent neck length affects Neck Tension, as many other variables.
I also turn the primer pocket uniformer lighlty at the set depth, every case every reload, to ensure even primer seating for the life span of the case.
And expand and turn the case every firing.
ANd anneal every 2-3 frirings.
Each to they're own though.
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Reloading manuals also provide a "trim to" number that will keep the case short enough that it won't be a problem for the rest of it's life. For most, they'll end up tossing (or loosing) their brass after a few reloads and it won't have grown enough to be a problem. Cases will expand the most during their first one or two firings. After the initial firings the brass will expand in length a far lesser amount, assuming "sane" powder loads.
Is the 22 PPC the gauge you'd use for a .223/5.56 ?
Is the 270 Winchester the one you'd use for a 6.8 SPC II ??
Is the 30 carbine the one you'd use for the .308 Winchester??
Seems like they have weird descriptions for each case gauge.
Thanks!
Yes just get the corresponding caliber diameter. Not sure why the use the most obscure caliber possible as a reference/example.
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