Brass spring back

[Scoob]

Some time ago I was reading something about the spring back of the brass after reloading and that it is important to finish your reloading asap after you rezised your cases on account that the tension will change if you wait too long. I ran a small test and noticed that the tension of the necks remaind the same even after a couple of days. What I did was run the cases through my Redding FL bushing die and kept them in the die for about 10 seconds, brass has a memory and will try to take back its form and I think that if you run them up and down the die in one fast stroke the time is too short for the brass to settle in its new shape. When I measured the necks after a couple of days I made sure the temperature was the same as when I sized them and I had the same reading so this must mean that it is possible to size and reload later.

Scoob

 

[jb1000br]

I think a lot of it has to do with how much you are actually sizing down. When i size for 0.0005 tension,moving the brass from .2925 to .2907) my case mic the same after many days...

but if you are coming from say .344 to .337 on a factory 308, you may get springback...

JB

 

[Scoob]

I have a 0.272 neck in my chamber and I use a 0.267 sizing button but there seems to be no problem. Maybe also the quality of the brass may have something to do with it, I use Lapua.

Scoob

 

[jb1000br]

so you move the brass from about .271 to .267?

once fired or several times?

 

[Scoob]

Yes I do, it is several times fired brass but I also use the 0.267 on new brass but then I also use the expander and with the several times fired brass I get 0.2665 with the 0.267 button. Is this not the right way? I use this size button with the Sierra 107 and the Lapua 105 SC.

Scoob

 

[jb1000br]

when you say button do you mean bushing?

 

[Scoob]

That is correct, I took the measure 0.2685 with the bullet inserted in the case and according to Redding I have to size back 0.001 so therefor I choose the 0.267 Bushing.

Scoob

 

[JamesnTN]

First, How do you know the seating pressure was the same?
Next are you seating your bullets using a big press or an arbor press, One thing I have found and got away from in seating bullets with My Dillon I don't have the feel in the handle as I do using an arbor press. what seats at 25 lbs and 50 lbs I can't feel so if you sort your loaded rnds in 5 lb seating range and cull the others, using the big press you will never feel or see this until on paper.
The thing of the test was using 22 Dasher brass and it sat for 2 weeks after resizing only and was compared to brass that was sized the day before. These were valid findings and something I had an idea of but until I saw similar happenings on some other brass that sparked the interest in performing the test.
Look for future tests and a report using a different device and checking seating force using different neck bushings and running the loads over the Chrongraph to get velcity numbers along with ES and SD.

 

[Scoob]

James

I am using a Rockchucker and I can understand that when you use different bushings you get different seating pressures and with the same bushing there will be different force between the Arbor and the RC but does it really make suchs a difference when you use one bushing for all you reloads on the force you use? I'm kinda new to all of this precize reloading so I guess I have a lot of learning to do but when you are seating bullets I thouht getting the bullet in as straight as possible was the way to go.

Scoob

 

[JamesnTN]

I have found that Neck Tension is just as a critical factor as getting the bullet seated straight.
I have tested loads of the same charge using different size neck bushings to find the results over the chronograph and on paper out to 300 yds of testing is enough in my tests to go with what works on the overall avg of group aggs and also low numbers over the Chronograph.
I do these test to ring out that last bit of accuracy and consistency as humanly possible in my match rifles and feel that finding the right neck tension is warranted in absolute accuracy if you plan to compete. with the money we invest in our match rifles dies and so on whats 20.00-30.00 for a few extra bushings to find what your rfiel likes?
I currently have 2 22 dasher barrels for the same rifle and the newest barrel likes a neck bushing .001 smaller than the old barrel, although I did not use this rifle at the last match I attended my girlfriend used my LG in HG class and came away with placing 6th in Group agg in St Louis with a 3.792 group and the 2nd smallest group of the day with a 1.362 in HG
If you just hunt or plink then theres no need in playing with different bushings to find what your rifle likes. But if you're serious on accuracy and consistent accuracy then yes by all means invest a few bucks and see for yourself. If I turely didn't feel it would make a difference I would defiently say so. I test my loads extensively and spend many hrs doing so with side by side comparisons using same powder charges and things such as neck tension,primers and seating depths with all the combinations I spoke of.

Posted is my new barrel load on the top left and also look at the velocity difference .1 grn makes as well folks says it doesn't make any difference in accuracy I have proven many times it does make a difference. The top right target the wind caught me as I pulled the trigger and droped that one shot out. So in all every little matter does count in accurate shooting.

 

[Scoob]

Ran a small test today with the neck tension. The lenght of a round with a Lap 105 SC is 2.815 with the bullet just touching the lands I set the Bullet seater that the bullet would be 0.020 into the lands which would mean a lenght of 2.835. I used the 0.268 and the 0.267 bushing and with both after I loaded the round they came out measuring 2.8255 so the round came out ± 0.010 shorter. Now I tried the 0.266 bushing and this time the round came out of my chamber measuring 2.8335 which is only 0.0015 shorter. This means that if I load in to the lands I need the 0.266 bushing for if not my bullets will enter the case deeper when chambering or should I try a 0.265 bushing. I have a 0.272 no turn neck.

Scoob

 

[jb1000br]

scoob -- measuring off the tip of the bullet is not a good way to gauge proximity to the lands...tips are variable.

JB

 

[Scoob]

I know that's why I use the Stoney point bullet comperator to do my measuring and this is how I got these readings.

Scoob

 

[JamesnTN]

Scoob,

I'm not following your thinking here at all. May I advise find the seating depth you desire and then with same powder charge and seating depth then on your test ammo change out different neck bushings with all the above being the same and see what shoots best for you. At this point don't worry with how much the bullet is being pushed back into the case just find what is the most accurate load you have with those procedures.
Once I load a rnd into my chamber I don't worry if it's being pushed back or not I'm shooting some 95 grn Bibs .045 into the lands past contact point and drilling em in 1 hole at 100 yds and about 3/4" at 300 yds.

 

[jb1000br]

OK, thats good,using the right tool)

When you said, after you "loaded the round it came out short"

do you mean when it came out of the die, or you loaded it in the rifle and ejected it? meaning the rifling is pushing the bullet back in?

i thought the former, but hte latter makes more sense after reading james' response.

JB

 

[Scoob]

First of all thank you guys for giving me all this advice andd I apologize if I'm a little hard to follow sometimes but English isn't my native language and this technical stuff doesn't make it easier for me.
Yes I do mean when I eject the round from my rifle, the bullet has gone back in the case a little with the 0.267 bushing and loaded 0.020 in to the lands but with the 0.266 it is about ok so I have loaded a couple of rounds with this bushing to see how it works out. Too bad we don't have much choice in good bullets around here. I got a new BR rifle coming up very soon and it would be nice to get it more or less right from the start. I have changed my powder for I have been using the N150 for some time but now I'm gonna be testing the N140 and I think and hope this powder will be better for my 26" 1 in 8" twist barrel for it is a bit faster.

Who said that finding a good load is easy :,

Scoob

 

[JamesnTN]

Scoob,

I hadn't seen what caliber you are using, the powder you mentioned leads me to believe you're loading for a 6 br.
If this is so varget and VV540 are two great powders for the 6 br.

Now may I offer some loading techinques I use.

First find the lands and begin with your test loads with the bullets about .002-.005 into them. Choose a bushing .002 under a loaded rnd for naked bullets and .003 for moly
Next pick a well known powder for your case, a primer and a good starting load, Start your charge at that level and load 3 rnds then up the charge .3 grns and load 3 more, keep doing this until you feel you are plenty hot enough. example...
6 br Varget powder CCI 450 mag primer 107 Sierra
load 1 29.0 grns
load 2 29.3
load 3 29.6
load 4 29.9
load 5 30.2
load 6 30.5
Do this until you are at max for your rifle.
Next look at ea target and determine the best looking group and or pattern. What you want to see is a 3 shot group in a triangular pattern. If you got lucky and drilled them into one hole retest that same laod a few times and see how it performs. If not take that best group you got and begin working with seating depth go deeper into the lands with the exact same charge on ea rnds you load in .005 increments from where you were initially to aprox .020 into the lands and do same backing off the lands.

Example:
32.0 grns Varget

initial seating depth. 3.00
3 rnds at 3.005
3 rnds at 3.010
3 rnds at 3.015
3 rnds at 3.020
3 rnds at 3.000
3 rnds at 2.995
3 rnds at 2.990
3 rnds at 2.985
3 rnds at 2.980

Ok after shooting these test loads using the exact same load of powder determine what is the best group. and if you are not satisfied with the best group and still need more testing pick the best group you have on seating depth.
Record this measurement on how far off the lands it is for future reference. Set your die to this seating depth as this depth is what your gun likes for that particualr bullet.
Now you have 2 other options pick your best powder charge you had and best OAL and then load that exact combo with neck tension changes with different sizing dies.
Once you determine which neck tension your rifle likes with the other combos of powder charge,seating depth and now neck tension if you are still not satisfied change primers and once you do a primer change you will then need to rework your powder charges and again do this in .3 grn increments starting say at 1.0 grns below where you were working up in .3 grn increments to how ever high you desire to go before you see pressure.
If all this fails try another powder and if that fails try a diffrent bullet. One thing using the same bullet it will always like the same distance from the lands or into which ever you se it liked best. If changing bullets you will need to start from the top of the list again and work in individual steps. Only make one change at a time and record them keep all your targets for reference so you can always go back and view what looked best and what was worse.
On my last barrel I went thru 5 different bullets 5 different powders and 2 different primers and still never had any luck so my barrel went back to the manufacturer for inspection.
If you need further help you can e-mail me at reloadersnest@msn.com