Lee 7mm08 collet die too much neck tension?

[Cooper]

Hi all

I recently changed presses. As in I’ve stopped using my Lee press with the breech lock and started using my Forester C0 AX.

I removed the breech lock from the 7mm08 Collet Die and fitted an aluminium lock ring for the CO AX press.

I’ve used Collet dies in the Co Ax before (308/6.5 creed) straight off I was getting way too much neck tension like inside the case .275 (projectiles are .284) no matter how much I back the die off.

Any way I removed the decapping Mandrel and measured at .272 just with cheap verniers. In mm that is 6.98mm

I am think Lee has put the wrong Mandrel in from factory??? I don’t own a 270 Winchester do there is no way I could have swapped die parts. 270 runs .277 projectile which I would have correct neck tension for?? Thoughts

I’ve ordered a .282 Mandrel so this should fix the issue

[Tiger650]

I have a couple of lee collet dies and they are very sensitive to adjustment, also hardness of necks causing "spring back".
The opposite issue to yours.
Keep us posted re effectiveness of the larger mandrel.
Do you mind if I ask where you ordered the mandrel ?

[Blr243]

The other day I was bump sizeing som 308 cases and when I tried by hand to test fit a 308 pill it appeared to be too tight by initial observation ...but then when I attempted to seat them in my press ( flat base Pills not boat tail) they went straight in just right no prob. Have you tried to seat the pills in your press yet and if so how do they feel ?

[in2anity]

I concur with Blr's line of thinking. Particularly if they are a BT pill, it might be fine. I'd at least shoot some groups to see if it's adequate for your needs.

[Cooper]

I have a couple of lee collet dies and they are very sensitive to adjustment, also hardness of necks causing "spring back".
The opposite issue to yours.
Keep us posted re effectiveness of the larger mandrel.
Do you mind if I ask where you ordered the mandrel ?

Oz Gun Mart for the Mandrel. I’ve bought some from there before. Including a under size one for .223. I use that in my 222 as find it gives a bit more consistent neck tension with the flat base projectiles I use. I also think the physically longer neck of the 222 plays apart.

I’ve experienced Harding or spring back with 223 cases. I usually anneal every three reloads now.

[Cooper]

I concur with Blr's line of thinking. Particularly if they are a BT pill, it might be fine. I'd at least shoot some groups to see if it's adequate for your needs.

I have only being using Boat Tail projectiles 139gr SST and 139 gr SPBT Hornady interlocks. Which kind of masked the problem. It still shoot ok group.

Then I swapped to new Norma cases (no case prep- just loaded and shoot) and the groups tightened up and I put it down to the barrel having more then 100 rounds down it and the Norma cases being better or more consistent.

I’ll be happier sizing the neck just the required amount.

[Blr243]

Early Sunday morning for some reason I got curious about the neck tension subject again so I grabbed my expensive dial caliber and some recently sized 308 cases. I also grabbed an accurate internal micrometer By first using the internal Mike and then useing the dial caliber the measure the mike pins I was averaging 305/306 on the insides of my necks. And when I seated pills in these cases the last few days they all felt just right no problem, but cooper is talking 9 thou difference so maybe they are way too tight. One of the best things I ever did was lash out and get a good quality dial caliber that reads thou We all have experience with slide calibres that has increments so small we can’t read them, so we then go digital but then they just die or always have flat batteries, and they lie to us occasionally when we Are useing them ...I feel so much better with a decent dial caliper that I can read super acutely any time without wearing glasses Nothing wrong with new toys every week. That’s why we go to work ....and as long as we hide them and dispose of the packaging mostly we won’t get found out.

[in2anity]

I’ll be happier sizing the neck just the required amount.

Yeah fair enough - and those sized mandrels are a convenient way of controlling it. Less work on your brass also. I use custom sized ones myself.

Nevertheless I’d guess you’d only see a difference in groups if you were shooting from fully supported.

[JohnV]

Sounds like that mandrel is the wrong size .

[SCJ429]

I think you are on the right track, you have a mandrel for a .277 bullet. I understand that the mandrel is usually .002 smaller than the bullet you are trying to seat. Not that you can size your 7mm brass inside neck down to .282 because brass has a habit of springing back. It should be good enough to give you some very light tension right through to heaps of tension you may want for some hunting loads.