Question on using a Sinclair mandrel for uniform neck tension

[giannid]

So I've been reloading for awhile now and I've been hearing about taking out the expanding ball out of your dies. As reloaders, I think all of us have had some neck tension problems in the past whether we've know it or not. Sizing with a FL die without the expander and running a sinclair mandrel die makes sense to me. I'm not the type of guy who's going to spend time turning the necks on my cases so I think this is the next big thing. I've never done it like this before but I'm going to try it with the 6.5 Grendel as the cartridge is new to me and I'll be loading for it soon. Do you need a bushing type die for this or is it better to just use a quality full length die for this as the neck size is really finished with the mandrel? Any lube like graphite use on the inside of the case when using a mandrel? What mandrel are you guys using for the 6.5 grendel? Looks like Sinclair offers 3, the carbide one, stainless steel expander and stainless steel neck turning. Not sure what the difference would be between them.

[Randy99CL]

With an everyday sizing die the neck is squeezed down to some small dimension and then opened again with the expander. Works the neck more than necessary and sometimes forces the neck out of alignment with the case body.

With a bushing die (with no expander) the neck is only squeezed down a few thousandths (which you control with the size of the bushing) to ensure consistent neck tension. Should increase accuracy and brass life.

[Klem]

A Forster FL die without using the expander gives .003-.004:" neck tension with Lapua brass.

[centerfire]

A Forster FL die without using the expander gives .003-.004:" neck tension with Lapua brass.

I am using Forster dies and I still size the necks with a mandrel. I have both size mandrel and can't tell the difference in performance between the two (.001). I think .004 interference is too much and unnecessary.

Another option is a custom Forster neck size.

[Klem]

I think .004 interference is too much and unnecessary.

.

I disagree, especially for an auto loader. I have been doing this for some time and have yet to split a neck. The loaded bullet is the mandrel. The ammo is as accurate as I imagine it could be.

I use mandrels, neck turning and a neck bushing-die for my 6.5x47 bolt gun but sometimes wonder if normal dies would be noticeably less accurate. In an auto loader I am convinced all that effort and money would be wasted.

[giannid]

I am using Forster dies and I still size the necks with a mandrel. I have both size mandrel and can't tell the difference in performance between the two (.001). I think .004 interference is too much and unnecessary.

Another option is a custom Forster neck size.

Which mandrels are you referring to when you say you have both? Looks like sinclaire offers three in 6.5

[Randy99CL]

JMO but I don't see where the mandrel is an advantage if it takes an additional step. And doesn't the neck have to be squeezed down so the mandrel can open it up again?

I like the 6.5 Guys videos on precision loading and they use Redding bushing dies. They pick the bushing so that the expander ball just barely kisses the inside of the neck. They pick the size of the ball to set neck tension.
That way the neck isn't overworked and the brass is done in one pass.

I recently bought two sets of Hornady Match Grade bushing dies for my bolt guns and was disappointed that they don't make them in 6.5 Grendel but as Klem says I think that much precision is wasted on a semi-auto.

[Bearcatrp]

I have a mandrel from K&M for 6.5 CM from when I reloaded for the creedmoor. Tried it on the 6.5 Grendel brass. To big. Every bullet was easy to push in case if I didn’t crimp. Decided to just use my Hornady dies take care of expanding correctly when I do full length resizing. May still order a custom mandrel in the future.

[giannid]

I've always been a big fan of Forester dies and have a forester coax press. Seems like the dies for the 6.5 by forester are hard to come by right now. So you guys think I should skip the sizing die with bushing, not use the mandrel, and just get a Forester full length die set?

[Randy99CL]

I've always been a big fan of Forester dies and have a forester coax press. Seems like the dies for the 6.5 by forester are hard to come by right now. So you guys think I should skip the sizing die with bushing, not use the mandrel, and just get a Forester full length die set?

Obviously if you want the Forester set get them; I know lots of reloaders swear by them.

I watch lots of videos and talk with many reloaders and many are trying and liking Hornady dies. They are good quality and produce good ammo; possibly not quite as precise as Redding or Forester or the top $$$ pieces but I like them better than my RCBS, Lee and all others in their price range.
I especially like their seating die as it has a sliding sleeve that orients the bullet in line with the case and has interchangeable seating stems for different shaped bullets.

You can get a set for about $32 and they still have the free bullet rebate so they're almost free. Try them and if you don't like them you can sell them.

[centerfire]

Which mandrels are you referring to when you say you have both? Looks like sinclaire offers three in 6.5

There are only two sizes regardless of material. I have both sizes (-.001 and -.002) in 24, 26, and 30.

I've always been a big fan of Forester dies and have a forester coax press. Seems like the dies for the 6.5 by forester are hard to come by right now. So you guys think I should skip the sizing die with bushing, not use the mandrel, and just get a Forester full length die set?

I have 6.5 Grendel Forster dies. They took months to receive, worth the wait.

[centerfire]

I disagree, especially for an auto loader. I have been doing this for some time and have yet to split a neck. The loaded bullet is the mandrel. The ammo is as accurate as I imagine it could be.

I use mandrels, neck turning and a neck bushing-die for my 6.5x47 bolt gun but sometimes wonder if normal dies would be noticeably less accurate. In an auto loader I am convinced all that effort and money would be wasted.

I don't think .004 is enough to split necks. However, none of my gas guns set back/forward bullets with .003. I have never seen a change in accuracy with that much tension. I have however, seen a noticeable change in ammunition consistency with mandrel sizing. What's the point of that much neck tension if you don't need it?

[Klem]

I have a mandrel from K&M for 6.5 CM from when I reloaded for the creedmoor. Tried it on the 6.5 Grendel brass. To big. Every bullet was easy to push in case if I didn’t crimp. Decided to just use my Hornady dies take care of expanding correctly when I do full length resizing. May still order a custom mandrel in the future.

Bearcat,

Measuring a KM mandrel comes to .26430 ". A bullet is .2640-.2641. That means after using the mandrel the neck is actually wider than the bullet, by a fraction. It's not being held by anything other than elastic springback of the brass after coming off the mandrel. To be fair, the KM mandrel is not designed to be the step prior to loading the bullet. It just widens the mouth a min amount so the cases fit on their neck-turning stubs. It is designed for neck turning, not bullet seating.


Mandrels are designed to expand necks, which is what expander stems in a sizing die are also doing. You want to constrict the neck to a specific amount less than the diameter of a bullet; .001-.002" for a bolt gun, and .003-.004" for a gas gun.

Yes, we want necks that are as perfectly round as possible. Outside squeezing (only) of a sizing die does a pretty good job of this by itself. And when the bullet is finally inserted it becomes a proxy mandrel. There's no space laterally for the bullet to displace into so even if it is soft it will still push the neck out until it comes up against the inside walls of the die and forms a perfect circle. Sure, there's going to be some longitudinal displacement of the bullet and maybe a mark where the seater is pushing on the bullet (like Sierra's TMK bullets which are soft with a very thin gilding). The only time I can see an expander stem in a sizing die actually being worthwhile is if the case mouth is badly dented and needs reforming into a circle. If your cases look fairly concentric before being sized, and are not badly dinged by the ejection port or damaged out of the box then I think sizing die expanders are overrated. Brass straight out of the box can benefit from being properly sized with the expander stem but after that, they will always be wider than a bullet.

[Popeye212]

I've always been a big fan of Forester dies and have a forester coax press. Seems like the dies for the 6.5 by forester are hard to come by right now. So you guys think I should skip the sizing die with bushing, not use the mandrel, and just get a Forester full length die set?

They are available I bought the bench rest sizing die from Midway (on sale) and the Micrometer seating die from Midsouth I can get the part numbers if you need them.

[Klem]

I don't think .004 is enough to split necks. However, none of my gas guns set back/forward bullets with .003. I have never seen a change in accuracy with that much tension. I have however, seen a noticeable change in ammunition consistency with mandrel sizing. What's the point of that much neck tension if you don't need it?

I am not getting into an argument over the difference of .001" neck tension. Certainly not on a gun forum. If it is important then by all means, you know more than me.

Notice I suggest a range of neck tensions for bolt guns and gas guns. Neck tension is an average with a Normal curve distribution. While you aim for it you never get exactly, 003" for all your bullets in a batch. Some will be .0025 and some .0035. One or two will be .004". With all your careful loading some of your rounds will be .004".

...and as you say .004" is not enough to split necks. So let's not split hairs.