Where to determine bump from....shortest or longest?

[Davey Boy]

I have some .308 Fed brass on its 3rd and 4th firings.
Brass on my 3rd firing ranges from 1.6130 to 1.6260 (16 pcs)
Brass on its 4th firing ranges from 1.6245 to 1.6280 (12 pcs)

Measured with Hornady Comparator.

Rifle is a bolt action so I want to just bump .002.

Obviously I want to base the bump off the longest length ...... right? I'm not sure.

So from 1.6280 down to 1.6.260 ...... that only covers a few of the brass that are long enough, so just proceed and do all the rest at 1.6260 regardless of their original fired length?

I have been neck sizing after the initial FL sizing, and just annealed both lots of this brass.
All this brass is trimmed after each firing using the Lee Quick Trim set to the same setting each time.

Also why so much variation or is this not considered that much variation in brass.


Thanks for responding in advance

Dave

 

[J P Brown]

Did you push the primer out before measuring...
The wheeler accuracy website ( I think that's right, member Alex wheeler) has a good video of finding the headspace length, normally I would say work off the longest length but I have had cases that are still a bit tight doing that. Basically take the firing pin out, and go by feel.

 

[jsudduth]

I use the method in the Wheeler Accuracy video. Watch video entitled 'Sizing Brass'.

https://www.wheeleraccuracy.com/videos

JS

 

[M-61]

Have you experienced any difficulty in closing the bolt on a cartridge?

 

[Davey Boy]

Have you experienced any difficulty in closing the bolt on a cartridge?

Only on one of these pieces I had trouble closing the bolt.

I was just given 20 Winchester brass .308 that using the same type of measurement they vary from 1.6200 to 1.6255.
This is 1 fired brass but not from my gun.

I've seen Wheeler's site and way of doing it .... so may have to take out my firing pin and try it that way.

Also yes all the primers have been removed.

Thanks
Dave

 

[Davey Boy]

Ok so I took all the firing pin, extractor and ejector out and all the 3rd fired brass all went in easily. HMMM!
Also had to use a dowel to push out the case as I removed the extractor. Can I leave the extractor in to make it easier to with draw the case.

Tried to put a Win case that was given to me and they would not go in, so I guess I will try to FL size a little at a time to see where they go in easily, and then use that measurement for all the rest when it comes time to bump the shoulder. Am I on the right track here?

 

[Davey Boy]

I have access to Lee Collet, Dillon and Redding dies to FL size. Which would be the better to Size with initially and then after when bumping is needed. Can bumping be done with the NS Lee Collet die? Thats what I have been using up to this point. But now want to bump .002 as don't want excess headspace and case separation.

 

[Davey Boy]

Now am confused I had to bring the Fl size down to 1.6220 so that I could chamber the Win brass that was given to me. But I have a Lyman headspace / trim lenght guage that they won't go al the way in. Why is that when my fired brass has 1.6280 it will chamber no problem. https://www.lymanproducts.com/brands/lyman/case-prep-tools/case-gauges/rifle-headspace-gauges.html I'm lost. Up to this point I have been using the Lyman guage to make sure it was Ok whether I NS or FL. Anybody?

To make it fit into the Lyman guage I have to set the die up as per instructions, case holder just touching die. I do that and I get 1.6190. Can't figure out how I'm going to come up so I can just bump .002 I used the Dillon FL die.

 

[74Bronco]

im guessing the once fired brass from another gun has a chamber with a few thou larger dia from base to sholder , and your having to sqeeze them back down to your tighter dia chamber to get them to go with a ez bolt, not a shoulder datum issue, body diameter or taper difference. just a thought

as a examble, forming 6mm slr from new brass the fl die never hardly touches the body area , but once fired brass from a obviously very large body diameter reamer from my remmy 243 chamber when going thru the same die as new brass it takes a pretty good pull to squeeze that fired brass back down.

 

[Richard Coody]

I use the method in the Wheeler Accuracy video. Watch video entitled 'Sizing Brass'.

https://www.wheeleraccuracy.com/videos

JS

I have watched the wheeler video. Method is used to find your max COL with different bullets.

Seems to me that as soon as the bullet pushes into the throat, well before the lands you will begin to get resistance.

I like to know where that hard jam is at the lands.

Really until you get consistent fired brass measurement you are just guessing. I would bump the longest 1 to two thousands and keep measuring my fired brass until i get consistent measurements

 

[Richard Jones]

I have watched the wheeler video. Method is used to find your max COL with different bullets.

I like to know where that hard jam is at the lands.

1. You didn't watch the correct video. Watch "sizing brass."

2. What's your better method?

"Seems to me that as soon as the bullet pushes into the throat, well before the lands you will begin to get resistance."

Say what?

 

[Davey Boy]

Yes I think he did misunderstand what I was asking.
I want to bump .002 when resizing but my brass is all different measurement to the shoulder so I wanted to know where to start.
Think I will start at the longest one and bump .002 and see if that works on all of them.

 

[SheepDog]

You really want about .002" of clearance between your shoulder on the loaded case and the shoulder area of the chamber.
I would ask are the longest cases (base to shoulder) causing resistance when chambered?
If not then you still have some clearance. If they do resist the bolt closure then you can size them gradually until that resistance is gone. Measure the length and then you go .001 to .002" more.

 

[Davey Boy]

I'm would think so, but have now FL so that they all fit in my Lyman headspace guage, so there is no way to tell until next time . But I started the die higher and slowly brought it down till they all just fit in the HS guage. Next time I have one that doesn't chamber I will keep it aside and well marked so I can experiment with them. I normally just neck size until they don't chamber, and only one didn't chamber so figured it was time to FL the whole group of them.

 

[SheepDog]

That HS gauge has no comparison to your chamber. Chambers are cut long, short, fatter and skinnier than specs. Head space should fal within the tolerances but they don't always.

 

[Davey Boy]

That HS gauge has no comparison to your chamber. Chambers are cut long, short, fatter and skinnier than specs. Head space should fal within the tolerances but they don't always.

Yes that is true, but up to this point I have just adjusted dies as per instructions and used the HS guage but would like to just bump. Knock on wood I haven't had any case separtions yet, but don't want any either. Figured just bumping .002 would help. The primer pockets should go first I hope.

 

[shoot4fun]

Any of that brass starting to get a bright ring all the way around just above the case head?
That much difference in your measurements says to me there is something wrong.

 

[Iowa Fox]

Its always a crap shoot and a guess. I spin the barrel on tight to the go gage, then measure the go gage with the tools I have. Before I put the bolt back together I use the Alex W method and use both numbers which are usually about .001 to .0015. Record the numbers in your reloading log book for that barrel & action. Watch your brass carefully for unusual signs

 

[Davey Boy]

Any of that brass starting to get a bright ring all the way around just above the case head?
That much difference in your measurements says to me there is something wrong.

No not yet. But am watching each piece carefully. They have only been fired 4 times and I load for the slower nodes.
I use the bent paper clip check for any indents.

I am recording all this data to see if it makes sense down the road.

Just curious, have any of you experienced a complete case separation, and what does happen other that the half of the casing left in the barrel can be a bear to get out. The unkown is what is causing me some concern and that it why I want to treat my brass like gold, not due to being more expensive, but toward the safety side.