Strange problem here. Need advice

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I have a 300 wsm that shoots really well (.5 moa) but only with new Win brass. With previously shot brass I can barely keep it inside an inch. I have tried different dies, neck, and full length. I uniform flash holes, trim length everytime, deburr and have even tried neck turning. I sonic clean then tumble to make sure everything is spotless. What gives here, I now have 250 cleaned, prepped brass that I just dont use much cause I just go buy ragged looking bagged brass, put it through a lee collet die and I'm good to go. Frustrating!!!!

I should mention I've developed many new skills trying to figure this out and I'm getting great results with other rifles and chamberings so it hasn't been a total waste.
 
Do you prep the new brass exactly like the fired brass?

~ Neck wall thickness uneven.
~ Sizing die not concentric, inside and outside.
~ Cases need neck reamed instead of neck turned.
~ Cases are trimmed after sizing, correct?
~ Neck tension varies, results in inconsistent pressure.

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Treat the new brass the same as your fired, do everything the same then shoot and compare.
 
Lodi said:
Do you prep the new brass exactly like the fired brass?

~ Neck wall thickness uneven.
~ Sizing die not concentric, inside and outside.
~ Cases need neck reamed instead of neck turned.
~ Cases are trimmed after sizing, correct?
~ Neck tension varies, results in inconsistent pressure.

~~~~~~

Treat the new brass the same as your fired, do everything the same then shoot and compare.
Click to expand...

I have checked wall thickness yes. Brass doesnt come new very consistent when new.
I dont have a cocentricity gauge. It is on my wish list though and I have thought this but I have three different dies...?
Cases are sized then trimmed yes.
Neck tension seems consistent after going through the lee collet neck die, about 5 thou if I remember correctly. I use this die on new brass just to round the necks as the come pretty beat up.
 
Try weighing how much water a fired case holds compared to a new (unfired) case.

Put a dead primer in each case, zero the scale for each piece of brass before adding water. Add water (I put a few drops of rubbing alcohol in the water to break surface tension) with an eye dropper or syringe until it reaches the mouth of the case.

If there is a significant difference you may have to bump your load slightly in the fired brass to get the same results as you get with the new brass.
 
Have you chronied your loads???

Sometimes to get the ideal harmonics, you need to increase or decrease powder charge.

I have an Anchutzz mod 1574, 308Win, that loves 7.62x51 surplus. It doesn't care what or where the milsurp ammo comes from, it just shoots everything into an inch or less.

It doesn't like off the shelf commercial loads of any type. Usually shoots it around 3 inches.

I checked everything I could out. Velocity, straightness of loads, different powders and primers, even used IVI cases to reload. Nothing worked.

Finally, an old, now deceased friend suggested I borrow a small base die and try that. I did, the groups shrunk by half.

The next thing I did was to match the bullet weight and shape to the milsurp fmj. Again the groups shrank to about 1 1/4 inch.

Then, something really simple. The bullets were seated deeper in the case by .040.

Now it shoots handloads consistently under an inch, as long as I do my part.

It only shoots the Hornady 30309 1B bullet that well though. I stopped there so there are likely others in that shape/weight range that will shoot well also.

One other thing, this rifle has a relatively different twist rate. 1-13 appx.

That's probably why it doesn't like anything over 150 grains.

I don't use this rifle much and it only comes out when I'm looking to shoot something different or I don't have anything loaded for the 6.5x55. That's why I haven't bothered with developing other loads and maybe lighter varmint type bullets for it.
 
CyaN1de said:
Try weighing how much water a fired case holds compared to a new (unfired) case.

Put a dead primer in each case, zero the scale for each piece of brass before adding water. Add water (I put a few drops of rubbing alcohol in the water to break surface tension) with an eye dropper or syringe until it reaches the mouth of the case.

If there is a significant difference you may have to bump your load slightly in the fired brass to get the same results as you get with the new brass.
Click to expand...

Thanks I think your onto something here. But what do I do after I come up with the difference in volume. I've ladder tested different charges, seating depth ect, with no improvement. I haven't gone above about a half a grain above my load with new brass though because I've noticed slight primer cratering. Think I should experiment a little hotter or lots colder? I do have a cheap chrony that shows volocity near the same with new or used brass.
 
It could be something other than the brass ie bullet, or powder load. Have you tried different bullet manufacturer? what bullet is in your factory load? I have had rifles not like a powder that another rifle in the same caliber shot real well. Went to another powder and it shot great. Just my .02
 
Back to the drawing board. Look up fireforming and then you work up a load that gives you accuracy, with the fireformed brass. Your not alone, we all started the same way.
 
Have you considered annealing the necks. This will directionally make the neck tension more consistent.

I had some 6.5x55 brass (PRV... from tradex) that was suffering cracked necks after one firing. I now pre-anneal and the problem went away. If I'm being fussy about accuracy (target or long distance gophers) I anneal the necks also.
 
iceman2 said:
It could be something other than the brass ie bullet, or powder load. Have you tried different bullet manufacturer? what bullet is in your factory load? I have had rifles not like a powder that another rifle in the same caliber shot real well. Went to another powder and it shot great. Just my .02
Click to expand...

I haven't even chambered a factory round in this rifle. I shoot the 168 berger, 165 gmx and the 208 amax for long target practice. I have the same problem with every bullet.
 
Assuming I have decoded this thread properly:

0.5 moa in handloads with New brass
Over 1 moa with same brass, now once fired
Same bullet, primers & powder charge.
Sizing is done either Full OR Neck with same results.

Two things come to mind:

The crimp is being effected in the fired brass. Annealing may fix this.

Case Volume is changing. Use your same "recipe" for your loads, but try walking the powder in 0.2 grain increments up & down. If you are close to Max loads, then just one step up.

Also, if the new cases show a slightly smaller capacity than the resized fired onea (do this test 3 or 4 times - difference could be as small as < 0.5 of a grain), you could try seating the bullet 0.005 or 0.010 deeper into the shell to account for the volume. If you are using "belted" bullets and are fixed on seatign depth, you could also shave a few extra thousandths off the length to get the same case capacity, then seat as normal.

Of course there is always one other possible solution - find a different powder to work with, and develop an entirely new load with it using only pre-fired brass.
 
I would check the run out on a loaded round and compare with both types of brass, although usually it's a bullet and/or seating depth problem, but it must be something related to brass prep, what make of dies are you using?
 
Any chance it could be something to do with the gun? Oversize chamber? or even an out of round chamber causing the brass to expand unevenly?

Definitely try a different set of dies. If you're using high end dies, try some cheaper ones and see what difference it makes. Or if you're using cheap ones, try some more expensive ones.

Measure the outside dimensions of re-sized brass vs the new brass and check the internal volume as well.
 
Thanks for all the input guys, I now have a lot of different things to try out. I am leaning towards cocentricity as the culprit though as I dont crimp, I have lee, rcbc, redding dies and I have load developed with many bullets and many powders. I'll buy a gauge to check loaded rounds but how does a guy check for a bad chamber? Simply by measuring fired brass?

This could be great if its the barrel, I would "HAVE" to get a new one to "SAVE" money on brass. The wife would totaly buy that one lol!
 
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