6.5 gas gun fine tuning

true story...and good advice. I have a load that shoots the hornady 103gr eld-x decently 3/4" @ 100 yards. Just got 200 87gr v-max in the mail today to develop a decent varmint load. Hoping for 3"@500 yards.
Ive got some figuring to do just to see how much neck tension I currently have. 003 should be enough. >.005 I'd think would be overkill.
My 6-284 has a tight neck chamber. I turn the necks for .001-.002 neck tension and load one at a time
For safety's sake you really need some pretty substantial neck tension on a gas gun. If that bullet gets pushed too deep into the case it can cause a catastrophic failure.

Those often don't end well.
 
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For safety's sake you really need some pretty substantial neck tension on a gas gun. If that bullet gets pushed too deep into the case it can cause a catastrophic failure.

Those often don't end well.
Fair point. I'm giving him what he asked for, not passing judgement on if it's sane or not. In a 6.5mm anything tighter than 0.003" is just going to yield the neck anyways, so he should have a decently wide range to play in as long as he can't push the bullets around by hand.

I crimp some of my AR rounds with a Lee FCD though. Never really taken to the seater crimp options.
 
Fair point. I'm giving him what he asked for, not passing judgement on if it's sane or not. In a 6.5mm anything tighter than 0.003" is just going to yield the neck anyways, so he should have a decently wide range to play in as long as he can't push the bullets around by hand.

I crimp some of my AR rounds with a Lee FCD though. Never really taken to the seater crimp options.
The Lee factory crimp die is what I use and highly recommend. It's much more positive and consistent than the traditional way we attempt to determine neck tension using bushing dies. There will always be variances in brass, especially reloaded brass as to how much "spring" there is in the neck. A good crimp pretty much eliminates the influence of that "spring".

All military rifle rounds that I know of require a crimp for that reason and for an extra measure of confidence the ammo will remain weather tight.
 
What effect have you seen on your ES when you apply the crimp?
I started paying attention to neck tension probably 5-7 years back after some discussions here.

I started with just one Rifle, my Remington .260 which was already shooting extremely well.

What I settled on was using bushing dies that gave me only enough tension so that I could barely seat a bullet by hand.

I then started appalling a light crimp. I set it visually, watching to see just when the collet closes and apply a little more pressure rather than a full stroke to give the strong, positive crimp that is applied to military ammo.

My ES immediately dropped into single digits.

I then started the same process with each of my others in turn using the exact same loads I'd been getting sub MOA accuracy with. Across the board, ES and groups both tightened up.

Mind you these were all loads that I had already spent a lot of time tuning for accuracy and ES and across the board they all improved.

I could probably set up a separate press for crimping with some sort of meter to to get the pressure exactly the same on each round but what I'm doing already works exceptionally well so I have yet to find a need to do so.
 
I started paying attention to neck tension probably 5-7 years back after some discussions here.

I started with just one Rifle, my Remington .260 which was already shooting extremely well.

What I settled on was using bushing dies that gave me only enough tension so that I could barely seat a bullet by hand.

I then started appalling a light crimp. I set it visually, watching to see just when the collet closes and apply a little more pressure rather than a full stroke to give the strong, positive crimp that is applied to military ammo.

My ES immediately dropped into single digits.

I then started the same process with each of my others in turn using the exact same loads I'd been getting sub MOA accuracy with. Across the board, ES and groups both tightened up.

Mind you these were all loads that I had already spent a lot of time tuning for accuracy and ES and across the board they all improved.

I could probably set up a separate press for crimping with some sort of meter to to get the pressure exactly the same on each round but what I'm doing already works exceptionally well so I have yet to find a need to do so.
I do the same type of process as you with my 5.56 ammo. I have a lee factory crimp die for 6.5 CM for my AR10. I never used it after I ran a full mag and found no change in seating depth after I extracted the last round. But if it is safer AND lowers my ES I think I will give it a try. Probably also save money by not buying the bushing die.

Thank you for the info
 
My crazy BENCHREST buddies - long time ago about bullet crimp's / crimping etc and that has stayed with me all this time, It will make a difference - just check it out for yourself do a few rounds & fire for effect BANG BANG ! providing your brass is in lots .
 
I started paying attention to neck tension probably 5-7 years back after some discussions here.

I started with just one Rifle, my Remington .260 which was already shooting extremely well.

What I settled on was using bushing dies that gave me only enough tension so that I could barely seat a bullet by hand.

I then started appalling a light crimp. I set it visually, watching to see just when the collet closes and apply a little more pressure rather than a full stroke to give the strong, positive crimp that is applied to military ammo.

My ES immediately dropped into single digits.

I then started the same process with each of my others in turn using the exact same loads I'd been getting sub MOA accuracy with. Across the board, ES and groups both tightened up.

Mind you these were all loads that I had already spent a lot of time tuning for accuracy and ES and across the board they all improved.

I could probably set up a separate press for crimping with some sort of meter to to get the pressure exactly the same on each round but what I'm doing already works exceptionally well so I have yet to find a need to do so.
I have never crimped anything and I have never been able to manually move a seated bullet seated with Lee seating die
 
I started paying attention to neck tension probably 5-7 years back after some discussions here.

I started with just one Rifle, my Remington .260 which was already shooting extremely well.

What I settled on was using bushing dies that gave me only enough tension so that I could barely seat a bullet by hand.

I then started appalling a light crimp. I set it visually, watching to see just when the collet closes and apply a little more pressure rather than a full stroke to give the strong, positive crimp that is applied to military ammo.

My ES immediately dropped into single digits.

I then started the same process with each of my others in turn using the exact same loads I'd been getting sub MOA accuracy with. Across the board, ES and groups both tightened up.

Mind you these were all loads that I had already spent a lot of time tuning for accuracy and ES and across the board they all improved.

I could probably set up a separate press for crimping with some sort of meter to to get the pressure exactly the same on each round but what I'm doing already works exceptionally well so I have yet to find a need to do so.
I wish I would have read your post 4 or 5 years ago on Neck Tension..
The 21st Century Mandrels iand Whidden Bushings have helped me tremendously. I've pretty much taught myself.It would have been nice to have someone like you Wild Rose to mentor me.
 
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I wish I would have read your post 4 or 5 years ago on Neck Tension..
The 21st Century Mandrels iand Whidden Bushings have helped me tremendously. I've pretty much taught myself.It would have been nice to have someone like you Wild Rose to mentor me.
Thanks.

I wish I'd had someone like me 40 years ago when I started reloading. I hate to think how many dollars and hours I could have saved not to mention avoiding a couple of catastrophic failures.

I'm still learning myself but I love to share what I've learned with people new to the game be that reloading or shooting. I don't want them to have to make the same mistakes I did along the way.

That's why this site is such a valuable asset. There's probably more than a thousand years of accumulated knowledge accessible on the site at any time. That's an invaluable resource.
 
loaded some more today. 87 gr vmax using h4350, superperformance, and rl 17.
found out new empty brass necks measured .271 and after seating .2735 at an oal of 2.650.
Was going to shoot earlier reloads but winds picked up to 10-15 mph. Expecting 2# of hybrid 100v tomorrow.
So is .0025 enough neck tension with out a crimp you all think?
 
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