Dasher Sizing Problem

[xswanted]

Hey guys,

I have an issue I can't figure out.

Fired brass in my Dasher measures .271.

I have a full and a neck sizer from Redding. Both bushing styles.

Using a .266 bushing, my sized brass measures .266. However about 10% of them will not have any tension on the bullet.

I tried a .264 bushing and the sized brass comes out .2655.

Have used with and without the expander ball.

I'm lost. My gun is not shooting and I believe it's a neck tension issue. This gun was consistently in the .2s at 100 yards and now it's not even a .7 gun. 200 yard groups are over 2".

It's never done this. Any ideas?

Gun has about 1600 rounds down tube. Been well cleaned. Never heated up.

Load is 31.5 or 32.8 of varget depending on the conditions. Lapua brass. Rem 7.5 primers.

Any ideas??

 

[Chfcemerson]

Did you turn your necks? Have ypu anealed the necks? I have experienced the same issue from time to time. Boils down to a bad piece of brass. Mark em..(I file a small mark on the rim) .size them down and just use them for foulers,

 

[xswanted]

Did you turn your necks? Have ypu anealed the necks? I have experienced the same issue from time to time. Boils down to a bad piece of brass. Mark em..(I file a small mark on the rim) .size them down and just use them for foulers,

Yes I forgot to mention the necks were turned on all prices of brass. I turned very little to clean things up. No annealing has been done.

Does a guy get rid of the bad brass? This stuff has been shot roughly ten firings each.

 

[savagedasher]

Yes I forgot to mention the necks were turned on all prices of brass. I turned very little to clean things up. No annealing has been done.

Does a guy get rid of the bad brass? This stuff has been shot roughly ten firings each.

Neck turning is the reason . My brass is wore out And I have the same problem Larry

 

[Chfcemerson]

Yeah...little soldiers that have been in ten battles have earned the right to be retired.

 

[savagedasher]

Yeah...little soldiers that have been in ten battles have earned the right to be retired.

Try 25 my neck are wore out . Larry

 

[Chfcemerson]

Yeah thats the downside of turning necks, it certainly reduces case life expectancy.

 

[dmoran]

xswanted -

My suggestions and suspicions:
- Inspect the crown, with a magnifying glass, jeweler loop, or bore scope.
- Inspect the throat (bore scope) and entire barrel.
Have seen crowns that "go south" do exactly what your describing, and also from a throat that is washing out.

Also from me, have never seen brass going south from a Dasher open up the grouping that bad. Thin necks have never failed me before the pockets and/or web. I have always turned my necks to at least .0105" and some sets thinner yet, and never had issues of the necks giving out (on a note, I don't anneal my Dasher brass).

Good Luck
Donovan

 

[Gina1]

Have you tried annealing your brass ? Brass gets a "spring" after being fired a number of times.

Gina

 

[Jet]

Follow Donovan's advice. With 1600 rounds fired your issue is likely due to barrel wear and is not brass related. If after inspection all looks well try shooting the rifle off someone else's bench set up (front/rear rest).

Good Shooting

Rich

 

[effendude]

It sounds like you have work hardened your brass. Sizing down .005 each time for 10 firings will cause issues if you don't anneal. You noticed that you have inconsistent neck tension on your reloads. Anneal your brass, monitor seating efforts on the loads. Make 10 new pieces of brass and see if accuracy comes back. Don't overlook rifle issues, but I'd place money on the brass being the issue.

Scott

 

[dkhunt14]

Yeah thats the downside of turning necks, it certainly reduces case life expectancy.

I would like to know how turning reduces case Life? Matt

 

[effendude]

I would like to know how turning reduces case Life? Matt

I too am anxiously awaiting this explanation!

 

[xswanted]

Thanks to all.

First things first will be to scope the gun this afternoon.

 

[xswanted]

Well I went and shot with twice fired non turned brass.

The brass still will only size down to .2655 with a .264 bushing.

Bullets seated with equal tension all measured the same as far as neck and OAL.
Measured each load of powder.

Shot it if of two different rests.

I found that my bolts holding the gun I to the stock were ever so slightly loose.

I fired three more groups after tightening them and the last three of five were a tight little cluster. The other groups were okay however it looked like it was stringing. I'm thinking possibly settling down back into the laminate stock??

Taking it to work to bore scope it.

 

[BoydAllen]

Yes, I think that there could have been some resettling after tightening. I tend to loosen and then start new when I find that a rifle has action screws that are not as tight as they should be., Starting from loose, I take up the slack, then stand the rifle on its butt, thump it on the support surface to settle the recoil lug into the bedding, and then progressively tighten in about three stages going from front to back. Even so, I expect some settling.

 

[Sheldon N]

Well I went and shot with twice fired non turned brass.

The brass still will only size down to .2655 with a .264 bushing.

You mention sizing both turned and non-turned brass with the same bushing. The one thing you didn't tell us is the neck OD measurement of a loaded round, which makes me wonder if perhaps you are perhaps making errors in selecting which bushing to use in each circumstance.

The crucial thing to measure when selecting a bushing is the neck diameter of a loaded round with the bullet seated. This gives you a rough approximation of how thick the brass of the neck of the case is. What you want to have after you size the case is a neck that measures roughly .002" smaller than the OD of a loaded round (at least as a starting point). This will give you a reasonable level of tension to hold the bullet in place.

The measurement of a fired case only tells you how large the rifle chamber is, letting you know if you have enough clearance.

Using the same bushing on turned and unturned brass would be wrong, because they have differing neck thickness. If you squeeze the brass down to the same size, one will be too loose and/or the other will be too tight on the bullet. (assuming no expander ball is used)

So the question is.... what is the neck OD of a loaded round with your neck turned brass, and what is the OD of a loaded round with your non-turned brass?

 

[billlarson]

send 4 fired cases fired 4 times. to Harrels......... smile here after...
bill

 

[xswanted]

You mention sizing both turned and non-turned brass with the same bushing. The one thing you didn't tell us is the neck OD measurement of a loaded round, which makes me wonder if perhaps you are perhaps making errors in selecting which bushing to use in each circumstance.

The crucial thing to measure when selecting a bushing is the neck diameter of a loaded round with the bullet seated. This gives you a rough approximation of how thick the brass of the neck of the case is. What you want to have after you size the case is a neck that measures roughly .002" smaller than the OD of a loaded round (at least as a starting point). This will give you a reasonable level of tension to hold the bullet in place.

The measurement of a fired case only tells you how large the rifle chamber is, letting you know if you have enough clearance.

Using the same bushing on turned and unturned brass would be wrong, because they have differing neck thickness. If you squeeze the brass down to the same size, one will be too loose and/or the other will be too tight on the bullet. (assuming no expander ball is used)

So the question is.... what is the neck OD of a loaded round with your neck turned brass, and what is the OD of a loaded round with your non-turned brass?

A loaded round measures .271 both turned and unturned.

Wrong......a loaded case measures .268 both turned and unturned

I have a micrometer however I didn't use it today so down to the thousandths is as close as I can get.

When I turned this brass I took very very little off. Just enough to clean up any discrepancies between them. However with lapua brass I don't believe it was necessary. All cases are trimmed, I don't recall the trim length.

 

[xswanted]

After inspection with the bore scope......

Looks like I'm missing anywheres from .4-.6" of rifling at the throat. Time to set it back I guess. I've only shot two other guns out and don't remember them loosing accuracy this quick.

Anyhow......how far should I set it back? It's a 26" barrel.

And secondly, this still doesn't really explain the tension problems with the brass. Or does it??

Thanks again guys.