Sinclair Expander Mandrel Die Test

[Jud96]

I recently decided to buy a Sinclair Expander Mandrel die and test it out compared to the standard dies I've been using. Today I compared concentricity of loaded rounds, 16 were sized with a standard Hornady full length sizing die with expander ball and then bullets seated with a Hornady seating die. The other 16 had just the bodies sized and shoulder bumped with the Hornady sizing die with expander ball removed and then had the necks expanded with a 0.282 mandrel.

The reason I tested such a random number of each, is because I already had 16 rounds loaded using just the standard die, so I loaded the same number with the mandrel die to have the same sample size. I measured concentricity with a homemade setup that I thought up. Later I'll build my own proper concentricity gauge, but that's a project for another day. I've used a setup like this before and have seen others do it as well. It takes a little practice getting use too but it's fast, simple, and precise nonetheless.

I added two pictures of notes I copied down showing the Total Indicated Runout (TIR) for each round I measured. The first list is from the standard sizing die, the second is with the mandrel die. This was with my .284 ammo, I'll do this exact test with my .308 Norma ammo in the near future as well. Please stay tuned for updates, more testing, and more data on the Sinclair Expander Mandrel Die. So far the results are pretty neck and neck, with the mandrel die taking the lead by just a smidge. I hope you all enjoy and find this as interesting and cool as I do haha. I love this stuff!

 

[birdiemc]

Very nice. I'm planning to do the exact same setup as soon as I have time for some loading, but plan to use a .0005 dti instead of dial indicator. Glad to see it worked out for you. Definitely looking forward to more results.

 

[Savage 12BVSS]

I'm in the process of this same test right now, waiting on the neck collett dies right now. Setting up a new press today that just arrived and I've been told the new dies are on the way. This is my focus and you give some excellent data to look at. I would have expected a bigger difference between them, of course any improvement is important. I am aiming for .001 TIR or less from all reloads as produced, we will see if that's a reality or not. Since both your tests are sub .002 you are pretty close, you are within .001 of where I want to be right now. Oh and by the way your runout indicator looks great.... Dave

 

[Jud96]

I'm in the process of this same test right now, waiting on the neck collett dies right now. Setting up a new press today that just arrived and I've been told the new dies are on the way. This is my focus and you give some excellent data to look at. I would have expected a bigger difference between them, of course any improvement is important. I am aiming for .001 TIR or less from all reloads as produced, we will see if that's a reality or not. Since both your tests are sub .002 you are pretty close, you are within .001 of where I want to be right now. Oh and by the way your runout indicator looks great.... Dave

Thank you Dave. I expected to see a bigger difference as well. I'm just using a standard Hornady seating die, and I think if I would have used a Forster Benchrest seating die or Redding Comp seating die I would have probably had less runout. I'm really happy with 0.002 and under runout for the dies I'm using. I had one flier in each set, the 0.006 runout round, but the rest were pretty decent. Benchrest and Long Range competition ammo is normally held to .002 or less runout, so I'm happy with my results. I have a few outside of that number, but the style of rifles I have and the shooting positions I use in the field, I don't think I'll notice those less true rounds.

 

[Savage 12BVSS]

I agree with you, will post a similar reply with numbers in next couple days, its stuff like this where you learn what works and what don't. Not heresay or book quotes but real true experience, Kinda' where the rubber meets the road.

 

[Jud96]

I agree with you, will post a similar reply with numbers in next couple days, its stuff like this where you learn what works and what don't. Not heresay or book quotes but real true experience, Kinda' where the rubber meets the road.

I couldn't agree with you more. When it comes to reloading and shooting, I want to prove or have it proven to me why this or that is better. I hear a lot of people talking about these dies, or this press, or this method and there's no proof of how it compares to what they previously used or what I'm doing. So this is mainly why I decided to do this comparison. I have heard a lot about the mandrel dies and I want to see if they really improve my loading and shooting results. So far they seem to improve my concentricity ever so slightly. I will however be testing ammo loaded with mandrel sized necks compared to ammo loaded with the standard sizing die with the expander ball for accuracy and velocity. I want to see if I can tell a noticeable difference in group sizes and in my velocity standard deviations.

 

[entoptics]

Good to see quantitative testing.

Question: Were the brass neck turned? In my experience, even quality brass will have as much as 0.001" neck thickness variation, and I've seen some as high as 0.002".

If the necks aren't turned, that extra runout could be "blurring" your results enough to make it difficult to distinguish the efficacy of each method.

Just a theory...

 

[Jud96]

Good to see quantitative testing.

Question: Were the brass neck turned? In my experience, even quality brass will have as much as 0.001" neck thickness variation, and I've seen some as high as 0.002".

If the necks aren't turned, that extra runout could be "blurring" your results enough to make it difficult to distinguish the efficacy of each method.

Just a theory...

Yes the necks were turned. I should have mentioned that.

 

[marchboom]

....I want to see if I can tell a noticeable difference in group sizes and in my velocity standard deviations.

Great test!

I try to get the best concentricity in hopes that accuracy will improve as TIR goes down. I'm going to try using gauge pins (of various diameters) and a Forster bullet puller as a pin holder to see if concentricity will improve over using just a FL Forster sizer or the Lee collet die.

But what I'm really interested in testing is 100 yd accuracy and SD and ES. Neck tension is a factor that I think will be much more controllable when using a mandrel.

 

[Alibiiv]

Great test!

I try to get the best concentricity in hopes that accuracy will improve as TIR goes down. I'm going to try using gauge pins (of various diameters) and a Forster bullet puller as a pin holder to see if concentricity will improve over using just a FL Forster sizer or the Lee collet die.

But what I'm really interested in testing is 100 yd accuracy and SD and ES. Neck tension is a factor that I think will be much more controllable when using a mandrel.

I have a set of Hornady Custom dies for the .270 Ackley, use a Sinclair mandrel die, my concentricity runs within .0005-.001ths with this setup. I am just curious if the resizing die itself controls runout. If one were to think of it, even .002 thousandths of an inch really is not the much runout when considering all of the moving parts and extraneous variables/steps involved with the reloading process. I know that we strive for the best, sometimes quality control is difficult to maintain.

 

[Welderboy11972]

I tested this method a few years back, when I started turning necks. Like you, I enjoy the "OCD" reloading...lol. I have way to much time on my hands after work and some weekends. Here's a few suggestions for your test....

Check sized brass before loading it.
Check 3 places on the sized brass.
Ones at the shoulder/ body junction ( slightly on the body)
Ones at about a quarter up on the neck
Ones at about a quarter from the end of the neck

After the bullet is seated.
Check the same 2 places on the neck
Check at the ojive of the bullet

I numbered each case and wrote down each measurement before and after seating the bullet. I used 2 different sets of Redding dies and tested the difference with both sets. One set used the ball expander. One set was with the bushing.

Have fun with your findings. I know I enjoyed it alot.

 

[BrentM]

I don't use a mandrel to control run out. I use a mandrel to control donut and tension.

I personally found that using a comp seating die with a floating head and spinning the case as I seat the bullet has taken my ammo to sub .002 and usually .001 and I rarely bother to check concentricity now. I use a Hornady concentricity tool.

 

[Greasegun]

I use a similar setup to test runout. V-block with a .0005" Interapid. You can narrow down your runout issues by checking inside the neck before seating bullets, then checking on the bullet after seating. Also I switched to a hardened vee block instead of the one in the pic (Cold rolled steel made in shop class 20 years ago) so my cases dont look all scratched up afterwards.

My redding die was imparting up to .010" runout on my necks (.223rem) with the mandrel installed. I get .004" or less with the sinclair setup. I can also turn my own mandrels for custom neck tension.

 

[Jud96]

I use a similar setup to test runout. V-block with a .0005" Interapid. You can narrow down your runout issues by checking inside the neck before seating bullets, then checking on the bullet after seating. Also I switched to a hardened vee block instead of the one in the pic (Cold rolled steel made in shop class 20 years ago) so my cases dont look all scratched up afterwards.

My redding die was imparting up to .010" runout on my necks (.223rem) with the mandrel installed. I get .004" or less with the sinclair setup. I can also turn my own mandrels for custom neck tension.

I surprisingly didn't see much difference in runout, as shown, between my mandrel sized brass and brass sized with a standard die. I'm comparing the two methods with the chronograph and for groups to see if there's a noticeable difference between them.