Redding Seater Die and Compressed Charge

[trodrig]

I notice that with a compressed charge (10.2gr N105), I have to crank the seater die down more to get the same average OAL as with an uncompressed charge (8.4gr of N350). This is with new Starline 38SC brass and MG 115 JHPs'. Has anyone else noticed this? I rationalized it as being expected due to the increased pressure required to compress the powder column. Just wondering if anyone else has ever run into this issue when developing loads with different powders.

Thanks,

Thomas

[HSMITH]

The powder pushes back and the bullet moves back out some as the die lifts off the round before it stops. Keep an eye on these loads. Toss a box of them in the floor of your truck and ride them around for a couple weeks, see if the bouncing and vibration causes them to get longer. One of the 9mm loads I shoot will get longer when I do this, enough longer to cause problems.

[trodrig]

I use the U-die, do you think that will help by holding more tension on the bullet? I'll measure after having the rounds in the truck for awhile as well.

Thanks,

Thomas

[Chills1994]

I took one of my Redding Micrometer Adjustable Seating dies apart.

I guess in actuality the stem that seats the bullet floats based on spring pressure.

I never could figure that out, why Redding designed it that way.

I would think a Better way is to have it all thread together and use a set screw or two to lock everything together.

Yeah, an EGW/Lee Undersize die might help with that.

[HSMITH]

Nope, I use U-dies as well and they can still migrate. It does help, but it won't stop it if the compression is hard enough.

Chills, that is the beauty of the Redding die, the stem floats as the case and the bullet are aligned and when they are everything comes tight as it goes up and finally seats the bullet. The whole affair is tapered inside so it can align everything before holding it tightly aligned and then seating. I am referring to the Competition Seating Die, don't know if your die is the same or not.

[trodrig]

So, I'm assuming that some powders are easier to compress than others. Do you have any record of which powders seem to be more prone to backing the bullet out? I'm using N105 in this case.

Thanks,

Thomas

[HSMITH]

105 is basically the same consistency as the powder that pushes bullets out on me, 3n-37. Some powders do compress easier like a flattened ball or a flake type powder, the difference though I think is that they have a lot more air in them from the drop to begin with where powders like the 2 VV powders mentioned have very little air in them and drop at a high density out of the measure.

[Ace38super]

I had experienced problems with the Redding CSD with a compressed charge as well. The OAL variation was wild. I was looking for 1.235 and got anywhere from 1.232 to 1.239. My load is 8.8 4756 with Zero 125 JHP. While this may not impact much it did not make me happy, especially since I use one for .45 (not compressed) with great results. I took the thing apart, cleaned, adjusted and finally placed it back in it's case for good. I went back to the Dillon seating die and now have no issues.

[Chills1994]

heck, 1.232 to 1.239 ain't bad at all. when it jumps from 1.1xx to 1.25x and then back down into the 1.1's, that's when I get nervous.

I always put my rounds primer end up in those plastic flip top lid ammo boxes. If there are any issues with funky OAL's it's really easy to spot that way.

Anywhoo, here's a pic of the Redding MABSD taken all apart:

I say get rid of the spring entirely.

Have a threaded shaft on the seater plug, which would thread into the adjustment knob on the far right. Said adjustment knob would have a set screw to look everything together.

Springs fatigue...

[gm iprod]

HSMITH

The main advantage with the Redding is that the spring and floating guide allow the bullet to be more correctly aligned before it all gets jammed into the case. The spring allows the bullet to be eased into position, BUT it is responsible for not always (but only under certain conditions) allowing the bullet to be seated bu only spring pressure instead of being stopped and properly position by a positive stop in the die. I have often thought along the same lines and would suggest you get a replacement spring from Redding and shorten it a turn at a time. See what effect this has on allowing the bullet to come to a proper stop.

The best way to get more tension on the projectile is to use an undersized expender plug. As this is what regulates the diameter of the case where the bullet is seated, not the sizing die. Once sized the expander takes it abck out to "x" inches and that is the tension. If you undersize then re-expand you are working the case and it will become brittle and crack at worst or become less elastic and loose grip at best. Always size your cases the minimum amount required to hold a projectile and expand the minimum amount to do the same.

For some calibres I have an expander that has been polished down .0005" under what is considered normal, a freind of mine uses .001" under. This takes care of any powder pushing problems without the need for aggresively working the case mouth.

[trodrig]

gm_iprod,

Agreed that not expanding so much is the best way to achieve tension on the bullet. I use the U-die and only expand enough to just allow the bullet to stay on the case when it comes out from the KISS feeder. I might be able to back the powder funnel off just a touch more to expand a little less but, I'll wait to see if I have problems with the loaded rounds 'growing' first.

Thanks!

Thomas

[HSMITH]

gm, that is exactly what I was trying to convey. I use that exact set up for all of my loading, but I use a .003" undersize powder funnel for 9mm and use it to flare only, when loading 40 I use the 9mm funnel to flare only, and when loading 45 I use the 44 cal funnel to flare only. Tension is best preserved and it smooths the operation of the press dramatically.

EDIT, I have NO issues with the CSD and OAL variations. When checked with a collimator my OAL is within .002". When measured with calipers to the end of the bullet the variations can be a LOT more than that, and someone not understanding the system could believe it to be a problem. A seating die that contacts the end of the bullet will appear to this person to make more consistent ammunition when in fact it does not.

Edited January 16, 2009 by HSMITH

[gm iprod]

HSMITH,

I just wanted to make sure I had the right end of the stick. OAL is less important than ogive length, as you measure it.

Anyway,

I don't like the U dies they work the case too much, whether you expand one way or another. I did not say don't expand, in fact the correct expander is more important than the sizing die. If the case is undersized and the not expanded correctly you can deform the rear of the projectile (the most important part) by hammering it into an undersized neck of a case.

The best accuracy with 9mm I have ever achieved was using a Dillon sizing die, a .003" undersized expander and a Redding competition seating die, Dillon or Redding Profile crimp about <.003" under straight and Sierra or Zero JHP's. The ammo was amazingly reliable in a very fussy Tanfoglio. Not Major I must add.

I did not get the chance to use Montana Gold bullets but I did try plenty of others. All did not like non expanded / just flared cases. Accuracy suffered.

For 38Super Major, again Dillon Sizer (and the next best was Redding), .002" undersized expander and Dillon Seater, Dillon Crimp about 0.004' - 0.005" under straight. I measure crimp based on original outside diameter of cases actually used with the particular bullet seated, then dies adjusted based on that size. Case thicknesses vary from batch to batch and maker to maker.

For NRA AP, low power factor so overfilled not an issue, Dillon size and std Dillon expander and Redding Comp Seater, Dillon Crimp die and sod all at that, barely 0 0.002" under straight.

Edited January 17, 2009 by gm iprod