Plastic wads don't need any wad pressure. Just set the rammer tube so that it just wiggles the scale when you seat the wad. You are compressing the wad cushion and getting too short a stack height.

 

YA...no need for wad pressure.

If it was 40# with Green Dot it's prolly more with 20/28 as well.

 

I reload on a MEC 9000. I have been reloading the following recipe without problems:
20 gauge gun clubs
W209 primer
3/4 oz shot
CB1075-20 wad
Green Dot 13.4 grains

Can't get Green Dot anymore but was able to get 20/28 which is a more dense powder. I am getting dished crimps with the following recipe:
20 gauge gun clubs
W209 primer
3/4 oz shot
CB1075-20 wad
20/28 15.4 grains

I have tried increasing the precrimp and increasing the crimp. I have not tried decreasing the wad pressure as I have the rammer tube set where MEC recommends. When I load a shell the wad pressure reaches 40.
Any suggestions?

steve haun

The wad pressure is the problem. as the others have said, you need no wad pressure with these wads. I have even used negative wad pressure to float the wad and let the closing crimp do the final seating.

This is the easy way to set any MEC for zero wad pressure:

First loosen the rammer clamp so the rammer slides up and down freely, then push it down so it will be too deep.

Size, prime and charge powder in a hull normally then seat a wad by hand, pushing it in only far enough to touch the powder.

Place the hull into the wad seating station then slowly lower the handle. The rammer will contact the floor of the shot cup and slide up as you lower the handle.

With the handle still down tighten the clamp screw and you're done. You now have zero wad pressure and you will not move the needle.

A more advanced technique is to float the wad. Raise the rammer tube so it seats the wad in the hull only far enough that you can drop shot and pre-crimp without shot overflowing. Having the shot level with the crimp fold line is usually good enough. Now pre-crimp and crimp as normal and let those actions seat the wad.

The last step is to decrease the crimp, not increase. Raise the crimping stem so it barely closes the hull, then turn it down 1/2 turn at a time until you get a flat crimp, then stop.

In the unlikely event none of this works, then just use an overshot card to get a flat crimp and be done with it. The 1/2" diameter OS card is the right size to just drop into the hull before you pre-crimp and it solves the problem instantly.

 

Wad pressure is an aspect of re-loading that's mostly misunderstood.

Back in the days of built up wad columns, containing card wads, felt wads, cork wads, over powder wads, overshot wads, etc. etc., wad pressure was very important, and lots of data stated how much to use.

With today's plastic wad columns, wad pressure is not needed nor wanted. Just push the wad down till it touches the powder is sufficient. Using heavy wad pressure will only cause the crimps to bulge after they sit a while. The compressed plastic wad will rebound and push the shot up hard enough to bulge the crimp and can pop it open.

Use little to no wad pressure, and all these bad things go away. Just a slight wiggle of the pressure gauge on the MEC press is all the wad pressure needed.

DLM

 

Thanks for everyone's help!

For clarification the wad pressure was 40 with the 20/28.

I adjusted the rammer tube up one notch and now the pressure gauge barely moves at the bottom of the stroke. However, my crimps are still dished.

This is the hottest listed load for 20/28 - 1250 fps. I would like to load the 1200 fps but I would expect the dishing to be even worse. These are published loads (alliant and claybuster) so I am strongly suspecting I am doing something wrong.

My crimp depth is almost identical to a store bought gun club. I don't have a swirl or an opening in the crimp.

I will try to back off my wad pressure even more and back off my crimp as suggested by Cerberus.

Would more precrimp help? How can I tell if I have too much precrimp?

Thanks!
steve haun

 

I just loaded that exact recipe on my MEC 600 Jr this morning. Shells look just like factory. Precrimp folds should be slanted about 45 degrees inward. Try backing off the crimp screw a lot, and then screwing it back in a little at a time, and testing the same shell, until you get the crimp you want.

 

This very close to my load with 20/28. Sounds like you may not be dropping 3/4 oz. Of shot. Weigh your charge on a scale to find out for sure.

 

Weigh both the shot and powder to make sure you are dropping what you really want.

 

Try decreasing the wad pressure to zero first. I agree with the others - it should just seat on top of the powder with zero pressure. That should make a big difference.

 

How bad is the dishing? Does it leave a hole in the middle such that shot leaks out? If not, I wouldn't worry about it. You probably are comparing the crimp on a factory 7/8 oz load with your 3/4 oz. reload.

 

I now have beautiful crimps!

I did two things:

1. I raised the rammer tube as outlined by Cerbeus. This helped but did not entirely fix the crimp.
2. I then backed off the crimp by turning the die out by 1/2 turns until the crimp was perfect.

Thanks for everyone's help!
steve haun

 

I now have beautiful crimps!

I did two things:

1. I raised the rammer tube as outlined by Cerbeus. This helped but did not entirely fix the crimp.
2. I then backed off the crimp by turning the die out by 1/2 turns until the crimp was perfect.

Thanks for everyone's help!
steve haun

Good to hear you got it worked out.

Your post was timely, I had just gone through this exercise loading the Case 20ga Promo Lite load and I needed to make the same crimp adjustments.

 

Cerberus:
Thank you!

 

That was fun and instructive too. I'm bookmaking this thread to refer folks to later as this question comes up a lot. I use GD and 20-28 for my twenty gauge, same loads, will probably look at this again when I finish my GD