Expanding Mandrel - Match grade rifle

[forty_caliber]

I've seen some information suggesting that separating the process of FL resizing into, 1) FL body and then 2) neck sizing with a mandrel, is advantageous over the more traditional method of FL resizing with an expander ball all at once.

I'm a dyed in the wool full length sizing guy. I don't think neck sizing only is worthwhile for my use case so let's keep it strictly FL.

I've had excellent results with the traditional method. I'd like to get your thoughts. Will this make enough difference to spend $100 on a mandrel die setup and add a step to the process?

.40

 

[jmorris]

Only way I have found to know what works best is to try out different methods.

Some stuff I FL size and others I don’t even do a full neck size, just the portion that has to hold the bullet.

I was never really impressed with one of my Van Norman .22 Hornet barrels until I figured that last part out, now it shoots just under .4 groups at 100 yards.

You don’t know until you try it and what works for one might not work for another and vice versa.

As far as mandrels go Lee has their collet style die that sizes to the mandrel vs dragging an expanded back through (#1&3 from the left).



Sinclair also has an expanding die that you can get just about any mandrel for.
https://www.sinclairintl.com/search/index.htm?k=mandrel&avs|Manufacturer_1=SINCLAIR INTERNATIONAL



Both are well under $100.

My most accurate groups are fired using custom dies that are machined for my “under” chambers and necks on the brass are turned so they never get an expander ran through them. That’s just benchrest stuff though, I don’t go to that extent for most things.

 

[AJC1]

I've seen some information suggesting that separating the process of FL resizing into, 1) FL body and then 2) neck sizing with a mandrel, is advantageous over the more traditional method of FL resizing with an expander ball all at once.

I'm a dyed in the wool full length sizing guy. I don't think neck sizing only is worthwhile for my use case so let's keep it strictly FL.

I've had excellent results with the traditional method. I'd like to get your thoughts. Will this make enough difference to spend $100 on a mandrel die setup and add a step to the process?

.40

There are several ways to go about doing this but I always use my full-length sizing die to start. The easiest way to try it is to use a collet puller and a gauge pin bought off of eBay or Amazon. I use expander mandrels sold by 21st century. I bought the equipment for case neck turning

 

[Ruger 15151]

As far at expanding the necks;

1. Expander balls impart neck run-out and that's why precision shooters remove them from their sizing dies

2. Bushings make the OD of the necks round but if your brass has any neck wall thickness variation, that is pushed to the ID which can cause inconsistent neck tension around the bullet depending on the brass

3. Expander mandrels are the only way to have a concentric neck ID. (My preference)

As mentioned, you can purchase a collet bullet puller and pin gauge to expand you neck to the desired neck tension. This is probably the cheapest solution because pin guages can be found on Amazon for very cheap. However, most guys will just purchase an expander mandrel die that will accept several different expander mandrels. Sinclair and 21st Century Shooting makes them as well as expanders for various calibers. if you want .0015 - .002 neck tension, you will want to purchase the mandrel that is .002 smaller than your loaded round neck diameter. 21st Century Shooting also makes additional mandrels that are ground in .0005 increments so you can find the exact neck tension for your rifle.

As mentioned previously, Full Length sizing is the way to go.You mentioned that you are a die hard FL sizer guy so this is for the rest who are on the fence.

Here is Erik Cortina - Manager at Team Lapua and World Class Shooter



Top shooters all full length size every time. If you are annealing, your bass will not be overworked and your primer pockets are going to loosen up long before the rest of your case gives up.

Hope this info helps

 

[forty_caliber]

As far at expanding the necks;

1. Expander balls impart neck runout and that why precision shooters remove them from their sizing dies

2. Bushings make the OD of the necks round but if your brass has any neck wall thickness variation, that is pushed to the ID which causes inconsistent neck tension around the bullet

3. Expander mandrels are the only way to have a concentric neck ID. (My preference)

As mentioned, you can purchase a collet bullet puller and pin gauge to expand you neck to the desired neck tension. This is probably the cheapest solution because pin guages can be found on Amazon for very cheap. However, most guys will purchase an expander mandrel die that will accept several different expander mandrels. Sinclair and 21st Century Shooting makes them as well as expanders for various calibers. if you want .0015 - .002 neck tension, you will want to purchase the mandrel that is .002 smaller than your loaded round neck diameter. Also, 21st Century Shooting also makes additional mandrels that are ground in .0005 increments so you can find the exact neck tension that you rifle prefers.

Hope this info helps

Thanks for the confirmation. Ordered a setup from Sinclair for 6.5 and .308. along with some dry neck lube... $70. I'll give it a try and see how it goes.

.40

 

[JFrank]

I've seen some information suggesting that separating the process of FL resizing into, 1) FL body and then 2) neck sizing with a mandrel, is advantageous over the more traditional method of FL resizing with an expander ball all at once.

I'm a dyed in the wool full length sizing guy. I don't think neck sizing only is worthwhile for my use case so let's keep it strictly FL.

I've had excellent results with the traditional method. I'd like to get your thoughts. Will this make enough difference to spend $100 on a mandrel die setup and add a step to the process?

.40

IMO - No
I don’t use any expander ball in any FL dies. Wilson and Harrell’s bushing dies use decapper rods only,
The debatable issue that a bushing die push un-even brass neck thickness to the inside is about the least of my concerns as we are talking about.0005 if anyone can really measure the difference on paper at less than one thousand yards I’ll stand corrected’
On a side note a mandrel & die should only cost about fifty bucks total and I’ve used them as a final step with inconclusive results feeling that extra moving of the brass gave less consistent NT
YRMV of course
J

 

[lightman]

I use the Sinclair die and mandrels for the cartridges that I have to neck turn. Its a quality tool.

 

[Walkalong]

Buy either a Sinclair mandrel and body, or a 21st Century Mandrel and body.

Both are high quality. Money well spent, especially if you are not neck turning.

 

[Offfhand]

Ditto on what Mr. Walkalong said above, and add KM Precision for high quality neck expanding mandrels.

 

[AJC1]

One thing to consider for precision ammunition is dwell time. I use a 10 count on my 6br cases and 308 precision loads.