270 Win case stretch?

[TimberHunter]

Last year I started with a hornaday FL die set and bumping the should back .001-.002 would result is approx .010” of total case stretch. I gave up because I was concerned about making the brass brittle and having case separation so I shot factory ammo last year.

I recently got an RCBS FL set and bumping the should back approx .002 results in the case stretching .008”. Less stretch than the Hornady so that good but .008” each time result in needing to trim nearly each time I resize. Is that excessive? Should I be worried about brass life and case separation? If I could get 4-5 reloading out of each case, I’d be happy.

This rifle is a hunting rifle, that is why I’ve stayed away from neck sizing.


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[TimberHunter]

*update*

I tried a neck sizer RCBS and it lengthened the total case by approx .004-.006. So less stress than the FL by approx .002-.004 but the shoulder was not moved back at all (and the shoulder shouldn’t be moved back when using a neck sizer)


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[JuddStrow]

You could always try annealing your brass go try to mitigate the work hardening of it. Maybe get an extra reload out of the cases.

 

[TimberHunter]

You could always try annealing your brass go try to mitigate the work hardening of it. Maybe get an extra reload out of the cases.

Thanks for the info, I’ve considered that. To your knowledge, does it see abnormal for bottle neck rifle cases to stretch .004-.008 each time the are sized? Is there a general rule of thumb for how many reloadings id get with that kind of case stretch?


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[JuddStrow]

Thanks for the info, I’ve considered that. To your knowledge, does it see abnormal for bottle neck rifle cases to stretch .004-.008 each time the are sized? Is there a general rule of thumb for how many reloadings id get with that kind of case stretch?


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For my .308 win in a savage with what seems like a pretty loose chamber for factory rifle


Much of it depends on the brass manufacturer.

I have hornady brass that seems like it stretches way more than my other brass every firing and has to be trimmed back.

Yet if i use the R-P stamped brass, i think i trimmed it after its first firing and have 3 or 4 reloads on them and havent had to trim again.

And after thinking about it, i dont think annealing will help you much, if it makes the brass softer, in theory it would flow more.

So maybe neck size only with light neck tension(alot long distance comp shooters use very light neck tension, and the bullet gets fully seated when the close their bolt on the rifle).

Either way, it might be worth experimenting with some other brands. I would check into Nosler brass. Lapua and Norma are awesome, but spendy.

I havent had good luck with winchester(split neck on first firing a few times).

 

[dude1000]

I have currently been reloading a batch of 24 Nosler cases in 270 and got 4 neck sizes on them before they were starting to chamber tight. The cases will stretch until they are constrained by the chamber dimensions which is what starts to make it difficult to close the bolt. I just resized with a Hornady FL die and bumped the shoulder .002 which did necessitate trimming about a third of the batch as they exceeded max case length after 5 firings. Heres a good quick article on the process. https://www.sinclairintl.com/guntech/setting-up-a-full-length-sizing-die-/detail.htm?lid=16134

I have a Tikka T3 superlight that seems to have a generously sized chamber. If you are only using the rounds in your rifle you could give neck sizing a try a few times to see if it continues to chamber. If you can get a few firings on the cases before pushing the shoulder back you'll be able to measure your true chamber dimension and minimize the amount of work when FL sizing.

 

[TimberHunter]

I have currently been reloading a batch of 24 Nosler cases in 270 and got 4 neck sizes on them before they were starting to chamber tight. The cases will stretch until they are constrained by the chamber dimensions which is what starts to make it difficult to close the bolt. I just resized with a Hornady FL die and bumped the shoulder .002 which did necessitate trimming about a third of the batch as they exceeded max case length after 5 firings. Heres a good quick article on the process. https://www.sinclairintl.com/guntech/setting-up-a-full-length-sizing-die-/detail.htm?lid=16134

I have a Tikka T3 superlight that seems to have a generously sized chamber. If you are only using the rounds in your rifle you could give neck sizing a try a few times to see if it continues to chamber. If you can get a few firings on the cases before pushing the shoulder back you'll be able to measure your true chamber dimension and minimize the amount of work when FL sizing.

Thanks for the info, after firing facorey ammo, most are approx 2.536-2.531. Once I FL size and bump the shoulder back, my cases are near max length or over it. That is with one firing and one resizing.... I have now tried two different FL dies and they do similar things.

The ammo will only be used my gun, but I need to it always cycle when I’m hunting. Is neck sizing going to allow me to always cycle it?


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[Piscatory_4]

If you just neck size you shouldn't get much stretch after the first firing. First firing, size and trim maybe .010", then only 1-2 thou trim on next few sizings until FL sized then maybe a little more trim on that one. I have the rcbs precision mic for 270win and I have to set the FL sizing die as normal(cam over) to get same measurement with the precision mic as the post fired case. The precision mic measures to the shoulder of case, maybe not as accurate as an attachment to calipers but good for comparison purposes.

 

[dude1000]

Its tough to say whether it will always cycle without trying it. If you can get a few trips to the range after neck sizing only you'll get a good idea whether you'll run into issues chambering while hunting. Definitely something you'll want to have confidence in as hunting season is upon us.

Have you been measuring the case before initial firing or just pre/post sizing? Do you have a comparator gauge or are you just measuring OAL?

 

[TimberHunter]

Its tough to say whether it will always cycle without trying it. If you can get a few trips to the range after neck sizing only you'll get a good idea whether you'll run into issues chambering while hunting. Definitely something you'll want to have confidence in as hunting season is upon us.

Have you been measuring the case before initial firing or just pre/post sizing? Do you have a comparator gauge or are you just measuring OAL?

I do have a comparator Hornady gauge to measure how much I’m bumping the shoulder back.

I spoke with a very helpful Hornady customer service tech and we came to the conclusion that my chamber on my gun may be closer to the max Sami spec and the RCBS and Hornady dies are close to the min Sami specs.

So essentially when I FL size, I make the case longer and skinnier and when I fire it, it gets shorter and fatter and the cycle continues to repeat itself.

I just can’t understand how I gain approx .006” total OAL on the case when I neck size the brass...? Maybe it’s the expander that pulls on the brass and lengthens it? I attempted to polish the expander on both the FL Hornady and the RCBS but that didn’t seem to help with the brass stretching.

On a side note, I only have approx .002” of neck tension not matter if it’s the RCBS FL or Hornady FL or the RCBS neck sizer...


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[TimberHunter]

If you just neck size you shouldn't get much stretch after the first firing. First firing, size and trim maybe .010", then only 1-2 thou trim on next few sizings until FL sized then maybe a little more trim on that one. I have the rcbs precision mic for 270win and I have to set the FL sizing die as normal(cam over) to get same measurement with the precision mic as the post fired case. The precision mic measures to the shoulder of case, maybe not as accurate as an attachment to calipers but good for comparison purposes.

I have no problem testing each round in my gun right after I finish reloading them... I only plan on loading approx 4 or 5 boxes worth of ammo each year so I don’t have an issue checking each loded cartridge for fitment.

But my concerns stems from if I get a small piece of dirt or dust in my gun while hunting and then the loaded cartridge that previously fit in the gun no longer does and potentially makes me miss an opportunity. But that’s just an idea I have stuck in my head and it may not really be a legit concern...?


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[JG358]

But my concerns stems from if I get a small piece of dirt or dust in my gun while hunting and then the loaded cartridge that previously fit in the gun no longer does and potentially makes me miss an opportunity. But that’s just an idea I have stuck in my head and it may not really be a legit concern...?


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Not really a concern IMO. I've got tight (min spec) chambers in several riffles and never had a failure to chamber issue due to crud. As for your stretching issues, I'm kinda at a loss as I have brass that has been reloaded 4-5 times that I have yet to have to trim. I just neck size. I'd throw a go/no go gauges in there to see how loose that chamber is.

 

[Piscatory_4]

I have no problem testing each round in my gun right after I finish reloading them... I only plan on loading approx 4 or 5 boxes worth of ammo each year so I don’t have an issue checking each loded cartridge for fitment.

But my concerns stems from if I get a small piece of dirt or dust in my gun while hunting and then the loaded cartridge that previously fit in the gun no longer does and potentially makes me miss an opportunity. But that’s just an idea I have stuck in my head and it may not really be a legit concern...?


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How difficult is it when you size and withdraw the case? 270 seem to always be more difficult to pull out off the die for me so I always worry I'm stretching out the length a bit. I have a lee FL sizer that cases move in and out of really smooth and not much drag. Have you adjusted the die to just bump shoulder and does it cam over hard, light, or none at all?

 

[Bel72]

I just can’t understand how I gain approx .006” total OAL on the case when I neck size the brass...? Maybe it’s the expander that pulls on the brass and lengthens it? I attempted to polish the expander on both the FL Hornady and the RCBS but that didn’t seem to help with the brass stretching.

I've had a similar problem, case got longer when necksizing, it came down to me not getting enough lube on the inside of the caseneck. I did the switch to Imperial Dry Neck Lube from Redding, and got a better application of lube inside the caseneck.

 

[TimberHunter]

Its tough to say whether it will always cycle without trying it. If you can get a few trips to the range after neck sizing only you'll get a good idea whether you'll run into issues chambering while hunting. Definitely something you'll want to have confidence in as hunting season is upon us.

Have you been measuring the case before initial firing or just pre/post sizing? Do you have a comparator gauge or are you just measuring OAL?

I have a box of half shot Hornady whitetail ammo that shoots around 1” with my gun. Total brass length of the factory loaded not shot is between .2.531-2.533. Shot ammo from the same box was between 2.537-2.535

Using the comparator gauge, the shoulder of the factory loaded ammo was .001-.002 smaller than the once fired in my gun factory ammo.


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[TimberHunter]

How difficult is it when you size and withdraw the case? 270 seem to always be more difficult to pull out off the die for me so I always worry I'm stretching out the length a bit. I have a lee FL sizer that cases move in and out of really smooth and not much drag. Have you adjusted the die to just bump shoulder and does it cam over hard, light, or none at all?

When using the Hornady FL die, pulling the case out of the die is difficult. That’s why I believe Hornady FL die stretches the case more than the RCBC dies.

RCBS does seem to be fairly smooth but both FL die and neck die stretch the case around .004-.006. I still can’t understand why when I neck size my case gets longer..?


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[TimberHunter]

I've had a similar problem, case got longer when necksizing, it came down to me not getting enough lube on the inside of the caseneck. I did the switch to Imperial Dry Neck Lube from Redding, and got a better application of lube inside the caseneck.

I’m using unique case lube by Hornady. I make sure the expander ball in the die is lubber and I put a fair amount all the way around the inside of the case mouth of each case.

I have Hornady one shot that I will be trying later this afternoon on some once fired in my gun federal brass (using neck size die) hopefully it helps


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[dla]

Last year I started with a hornaday FL die set and bumping the should back .001-.002 would result is approx .010” of total case stretch. I gave up because I was concerned about making the brass brittle and having case separation so I shot factory ammo last year.

I recently got an RCBS FL set and bumping the should back approx .002 results in the case stretching .008”. Less stretch than the Hornady so that good but .008” each time result in needing to trim nearly each time I resize. Is that excessive? Should I be worried about brass life and case separation? If I could get 4-5 reloading out of each case, I’d be happy.

This rifle is a hunting rifle, that is why I’ve stayed away from neck sizing.


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By definition, when you move the shoulder back, you lengthen the neck. So don't be surprised at the trimming.
But, when you neck size, and you don't muck with the shoulder, trimming should not be necessary. I use a Lee collet-style neck-size die on my 270Win casings and it is possible to set the collet such that it pinches at the neck/shoulder junction - which would lengthen the brass.
I don't anneal, so when I used to Full-Length resize I'd get maybe 4 loading out of the brass before some would start splitting.

 

[mtswampfox]

I do have a comparator Hornady gauge to measure how much I’m bumping the shoulder back.

I spoke with a very helpful Hornady customer service tech and we came to the conclusion that my chamber on my gun may be closer to the max Sami spec and the RCBS and Hornady dies are close to the min Sami specs.

So essentially when I FL size, I make the case longer and skinnier and when I fire it, it gets shorter and fatter and the cycle continues to repeat itself.

I just can’t understand how I gain approx .006” total OAL on the case when I neck size the brass...? Maybe it’s the expander that pulls on the brass and lengthens it? I attempted to polish the expander on both the FL Hornady and the RCBS but that didn’t seem to help with the brass stretching.

On a side note, I only have approx .002” of neck tension not matter if it’s the RCBS FL or Hornady FL or the RCBS neck sizer...


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lubing inside the neck? been playing with the lanolin/alcohol lube and find it may be better than imperial. stand the cases up give them a quick spritz so the necks get hit good,,let sit for half hour minimum will last for several days if needed. then run thru cob to clean off lube

 

[TimberHunter]

lubing inside the neck? been playing with the lanolin/alcohol lube and find it may be better than imperial. stand the cases up give them a quick spritz so the necks get hit good,,let sit for half hour minimum will last for several days if needed. then run thru cob to clean off lube

Yes I’ve been living the inside of the case neck with a lot of lube, some with unique some with one shot.

I decided to pull out the expanding ball on my RCBS neck die to see if they was casing the case stretch. With the expander removed and the case lubed I still got on average .004” of case stretch
Leads me to think that when the die makes the neck skinner the neck also grows


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