21st Century Undersize Expander Mandrels for 6.5mm Stainless Steel



These undersized expanders are for 6.5mm.

These fit into either of the STD or Tall 21st Century Expander Die Body (purchased separately). Also the Gen X Expander Die Body. Click here for those

They are in .005″ (half thousandths on an inch) increments and stamped so on each expander.

For example:  The engraved sizes are 0.″, 0.2610″, 0.2615″, 0.2620″, 0.2625″, 0.2630″, 0.2635″, 0.2640″, 0.2645″, 0.2650″

Custom expanders are deemed by manufactuers as non returnable items. 

Stuart’s Tips:
Please note: Like most machined products there are tolerances. What we measure, with good equipment (good micrometers), is in the range of up to 0.0002″ (two ten thousandths of an inch) either side of the actual stamped size. Total variation 4 ten thousandths of an inch. For many people this would be acceptable, but for some others, maybe not. Therefore, we are pointing this out before you purchase!
We have another brand which are much more accurate and precise in actual size. Due to those being Ground to Size (as opposed to machined to size). But, naturally are more expensive too.
As a suggestion, usually at least a couple of sizes will be required anyway. So if you are concerned which to choose first, then maybe start with a size 0.oo1″ less than calibre and try it, then maybe later add another. A size above or a size below as required. Very many people do email and ask us to choose the size for them. We don’t. We wish we could help, but we cannot know this because we can’t know how much actual neck spring-back will occur with YOUR brass.

2nd note: We are disappointed to have to say this, but if you will be using Hornady brass in either 6mm or 6.5 Creedmoor with any good dies (in fact especially any Neck bushing type FL die) and then expect that you can use an expander system to help overcome the irregular effects of this brass, you will be disappointed and frustrated for sure. We feel forced to mention this because we have had to deal with some many reloading problems which some customers are having. After buying lots of nice dies and other nice tools like this and get poor results. It’s all because of poor brass. The brass might look good externally but it has very high springback and is particularly tight in the shoulder/neck junction area. No expander will correct it. It springs back to where it was and the reloaders don’t figure out this is what happens. Bullet seating will be irregular and inconsistent and some bullets (particularly Hornady ELD’s etc) and will show compression rings where the seater stem contacts if bullets are seated below this area. If you wish to do a some precision reloading and precision shooting…BUY GOOD BRASS is our advice from lots of experience