Mandrel dies anyone?

[coyotekilla]

Anyone ever go from a std die or a mandrel and what difference did it make? Also how do I order the right die set for say a 6arc or 223?

 

[43.6N]

I’m trying out the Area419 die right now for my 6GT. Previously was using a Redding.

ES went from 20 to 8 on my most recent 20 shot string

just a small sample, but I’m pleasantly surprised.

 

[Lawnboi]

I used to mandrel after sizing and have moved over to premium dies like the A419 and SAC modular where one pull of the press sizes, mandrels and decaps.

I don’t think I could ever go back to more steps.

 

[43.6N]

@coyotekilla I must have missed the last part of your question about how to order the right mandrel die.

Here’s a video from A419 that explains mandrels and sizing pretty clearly:

 

[MCGHeel]

Just starting with 21st century mandrel dies and mandrels for 6arc. Sized some virgin Peterson brass. Gonna finish loading and hopefully get out to shoot this weekend. I’m using standard fl sizing die no bushings and I’m just using the mandrel to set the amount of neck tension I want. My example I ran the .241 mandrel through this brass thinking it will give about .002-.0025 of tension after spring back. If using a bushing die with the mandrels I think there may be a little more figuring to do but not certain. I’m sure others here will know. Following other feedback here since I’m just starting out with mandrel as well.


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[WhoGarrDen]

The video linked is spot on. How much neck tension you want is up to you... If your 6arc is in a gas gun, people typically recommend a higher neck tension (3-5 thou). Same for 223 if it's actually a 5.56 or 223-barreled AR.

Hiw much spring back occurs also seems to be voodoo, depending on the brass mfg, hardness (annealing vs not), etc. if a bolt gun, the easy button is sizing the mandrel 2 though under bullet diameter - you'll never get less than that, and if spring back puts you at 2.5 then no biggie. Start there and do some testing - smack your magazines around, maybe load 5 in the mag and only shoot the top 2 - then put 2 new rounds on top and do it again for ~10 rounds and then take those bottom 3 home and see if your seating depth was affected - add tension if so.

ETA - I took out my expander balls on my FL sizing dies and run the 21st century mandrel through after sizing. I haven't recorded any data that suggests it made a huge difference, but it gives me warm fuzzies. Even if it dropped my ES by 30 and SD by 5+, I'd never be able to shoot the difference or tell on paper.

 

[coyotekilla]

The video linked is spot on. How much neck tension you want is up to you... If your 6arc is in a gas gun, people typically recommend a higher neck tension (3-5 thou). Same for 223 if it's actually a 5.56 or 223-barreled AR.

Both the 223 & 6 arc are custom bolts. 1 is a tikka action, other howa. 26" heavy barrels at this point. 223 will put 5 under a dime. 6arc is with my smith being fitted with a brux. Best i could get it to do was .6 or .7 and inch was more common, just wasn't up to what I wanted it to do.

 

[TradLife406]

I’m trying out the Area419 die right now for my 6GT. Previously was using a Redding.

ES went from 20 to 8 on my most recent 20 shot string

just a small sample, but I’m pleasantly surprised.

Impact Shooting did a test. He did 10 without a mandrel and 10 with. The 10 with shot better and had the same results you did.

I've got an Eric Cortina expander mandrel for my Creed. I really want to add one for my 6 UM. Should I get another EC or the 419?

 

[MCGHeel]

Impact Shooting did a test. He did 10 without a mandrel and 10 with. The 10 with shot better and had the same results you did.

I've got an Eric Cortina expander mandrel for my Creed. I really want to add one for my 6 UM. Should I get another EC or the 419?

Is yours the mandrel sizing die or just the mandrel die? I’ve wondered about whether it’s worth to use mandrel sizing die rather than add another step to the process.


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[SloppyJ]

If you can combine the steps, it's worth it. I already had all of my dies and wanted to try the mandrel thing so I went with the 21st Century mandrel die and have different mandrels for different calibers. Does it help, yes a little, is it worth it, still undecided.

 

[MCGHeel]

If you can combine the steps, it's worth it. I already had all of my dies and wanted to try the mandrel thing so I went with the 21st Century mandrel die and have different mandrels for different calibers. Does it help, yes a little, is it worth it, still undecided.

So far my thought is if I have mandrels for the main calibers i shoot the cartridge wont matter i just get a fl sizing die for the cartridge. Using the frankford arsenal universal seating die for all cartridges. Causes an extra round through the press for each piece but my volume isn’t quite high enough to matter yet I think. Will see with more experience gained.


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[Hondo64d]

@coyotekilla I must have missed the last part of your question about how to order the right mandrel die.

Here’s a video from A419 that explains mandrels and sizing pretty clearly:

The Mighty Armory dies are very much like the Area 419 die.

John

 

[Vern400]

I noticed in 7 mm some of my bullets were pressing in very easily, and some were harder. It was very noticeable. That can't be good for accuracy.

So there are two things you can do: anneal the brass so it's all the same hardness, and thus the same yield strength. And control the ID of the case very accurately to give a very consistent interference fit.

So I started annealing and using a 21st century mandrel 0.002 under ACTUAL bullet size as measured with the micrometer. (That's a little bit anal I know). Now all the bullets feel the same in the press when I pressed them in.

My group sizes a 200 yd were reduced by about
0.25 in. As an average over five different groups of each. It's worth it for me. I noticed the concentricity got a little bit better too. The bullets going straighter into the chamber.

I'm doing my final load development now at 200 yards. That's my sighting range, and as long as there's no wind it's easier to see improvement or screw ups in a new load.

 

[MCGHeel]

I noticed in 7 mm some of my bullets were pressing in very easily, and some were harder. It was very noticeable. That can't be good for accuracy.

So there are two things you can do: anneal the brass so it's all the same hardness, and thus the same yield strength. And control the ID of the case very accurately to give a very consistent interference fit.

So I started annealing and using a 21st century mandrel 0.002 under ACTUAL bullet size as measured with the micrometer. (That's a little bit anal I know). Now all the bullets feel the same in the press when I pressed them in.

My group sizes a 200 yd were reduced by about
0.25 in. As an average over five different groups of each. It's worth it for me. I noticed the concentricity got a little bit better too. The bullets going straighter into the chamber.

I'm doing my final load development now at 200 yards. That's my sighting range, and as long as there's no wind it's easier to see improvement or screw ups in a new load.

Question about your process, because I am headed down this road now. Have a 7prc barrel i expect to be in hand in next month or so. I have ordered the burstfire induction annealer, and have 21st century mandrels ready to go. I get how the annealing will help and setting ID consistently with the mandrel. Does measuring the actual OD of your bullets add anything to this mix? Or does setting the ID of the case neck to a consistent number do the work of tightening things up? For me, I'm a little less concerned by the actual amount of the interference fit (so long as it's not so loose it causes bullet movement under handling/recoil), but I do want it to be nice and repeatable. I have exactly 0 experience with this so far, so genuinely asking if you think the extra step add much. Thanks and nice work on refining your process.

 

[Vern400]

Question about your process, because I am headed down this road now. Have a 7prc barrel i expect to be in hand in next month or so. I have ordered the burstfire induction annealer, and have 21st century mandrels ready to go. I get how the annealing will help and setting ID consistently with the mandrel. Does measuring the actual OD of your bullets add anything to this mix? Or does setting the ID of the case neck to a consistent number do the work of tightening things up? For me, I'm a little less concerned by the actual amount of the interference fit (so long as it's not so loose it causes bullet movement under handling/recoil), but I do want it to be nice and repeatable. I have exactly 0 experience with this so far, so genuinely asking if you think the extra step add much. Thanks and nice work on refining your process.

Good quality bullets without a cannelure are going to be extremely consistent on diameter where the bearing surface is to the barrel. But the tooling does wear over time it has to be replaced. So there can be a few ten thousandths of difference from batch to batch, or from manufacturer to manufacturer. I just wanted to understand where I was. Most of my bullets came out 0.3081 to 0.3083. I wasn't controlling temperature during the measurements so my bullets were functionally perfect. I think it was 78° in my shop.

Anyhow I used a 0.3060 mandrel and it worked great. I couldn't push the bullets in by hand by a large margin. I wasn't comfortable with less bullet pressing Force than that.
I think with the heavier recoiling 7mm PRC you may be in the 0.002 to 0.0025 range anyway.
If I have to pull a bullet with a kinetic puller I have to whack the wood block pretty hard three or four times to get the bullet out. If you got a 10 lb gun I don't see a problem. If your man enough to use a 7mm PRC mountain rifle at 6 lb, I might revise my story for you. But I can't take more than about 18 to 20 ft*lb of recoil and shoot well.
I would stop at a 280 AI and shoot it well. And I'm fine with an 8.5 lb deer rifle.

I did find that higher interference fits weren't always giving me cloverleaf groups. You're really going above and beyond annealing 100% and mandrel expanding to keep from jerking on your case mouth so hard. And I see some people on this forum collapsing shells... Dang. I think that's enough bullet seating Force.

I don't like talking about neck tension. It's an engineering misnomer. Bullet seating Force, and the force to release the bullet is what matters. That's a function of the thickness, the yield strength of the brass, and the coefficient of friction. I can feel that force my reloader. The annealing made the biggest difference, and the mandrel lead in shape helps reduce the required Force to expand. And I tumble and walnut media so I have a film of that burnt powder / rouge that makes the friction coefficient relatively stable.
Underperfect conditions I'm shooting 3-in groups at 500 yards and quite honestly that's good enough for me. If I miss a deer it is 100% absolutely my fault. The rifle is functionally flawless. And confidence is your friend when you're squeezing the trigger.

 

[MCGHeel]

Good quality bullets without a cannelure are going to be extremely consistent on diameter where the bearing surface is to the barrel. But the tooling does wear over time it has to be replaced. So there can be a few ten thousandths of difference from batch to batch, or from manufacturer to manufacturer. I just wanted to understand where I was. Most of my bullets came out 0.3081 to 0.3083. I wasn't controlling temperature during the measurements so my bullets were functionally perfect. I think it was 78° in my shop.

Anyhow I used a 0.3060 mandrel and it worked great. I couldn't push the bullets in by hand by a large margin. I wasn't comfortable with less bullet pressing Force than that.
I think with the heavier recoiling 7mm PRC you may be in the 0.002 to 0.0025 range anyway.
If I have to pull a bullet with a kinetic puller I have to whack the wood block pretty hard three or four times to get the bullet out. If you got a 10 lb gun I don't see a problem. If your man enough to use a 7mm PRC mountain rifle at 6 lb, I might revise my story for you. But I can't take more than about 18 to 20 ft*lb of recoil and shoot well.
I would stop at a 280 AI and shoot it well. And I'm fine with an 8.5 lb deer rifle.

I did find that higher interference fits weren't always giving me cloverleaf groups. You're really going above and beyond annealing 100% and mandrel expanding to keep from jerking on your case mouth so hard. And I see some people on this forum collapsing shells... Dang. I think that's enough bullet seating Force.

I don't like talking about neck tension. It's an engineering misnomer. Bullet seating Force, and the force to release the bullet is what matters. That's a function of the thickness, the yield strength of the brass, and the coefficient of friction. I can feel that force my reloader. The annealing made the biggest difference, and the mandrel lead in shape helps reduce the required Force to expand. And I tumble and walnut media so I have a film of that burnt powder / rouge that makes the friction coefficient relatively stable.
Underperfect conditions I'm shooting 3-in groups at 500 yards and quite honestly that's good enough for me. If I miss a deer it is 100% absolutely my fault. The rifle is functionally flawless. And confidence is your friend when you're squeezing the trigger.

Once I’m annealing I’ll mostly be doing your process, maybe without measuring the bullets. The rifle will probably fall around 11 pounds all done up so I don’t expect punishing recoil necessarily but also won’t be burning 100 rounds in a range day either. It’ll be for hunting so fairly low round counts overall. Will see how it goes. Thanks for answering.


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