Lee 356-120tc problem

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03-19-2018, 12:42 PM
Krp68

Lee 356-120tc problem

I'm shooting the Lee 356-120tc boolit cast from rang scrap and sized to .357 out of a m&p 2.0 9mm.

Whenever the gun starts to get a little dirty after a 150 to 200 rounds, the 356-120tc boolits start to hang on the feed ramp.

Just wondering if anyone else has had this problem and if you found any solutions? I have polished the feed ramp. Thanks

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03-19-2018, 02:00 PM
Yodogsandman

Increase your powder by a few tenths. I had that same problem (with the Lee 356-120 TC) starting with the starting load of 3.8gr Bullseye. Increasing the load to 4.0gr and cleaning and lubing the pistol fixed it. It might also help some if you water dropped from the mold to increase boolit hardness a little.
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03-19-2018, 02:49 PM
Krp68

Quote:

Originally Posted by Yodogsandman

Increase your powder by a few tenths. I had that same problem (with the Lee 356-120 TC) starting with the starting load of 3.8gr Bullseye. Increasing the load to 4.0gr and cleaning and lubing the pistol fixed it. It might also help some if you water dropped from the mold to increase boolit hardness a little.
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Thanks for the suggestions.

I am using WSF at 4.5 gr. and powder coating. If I'm not mistaken, I am towards the upper end for this powder. Maybe try a cleaner powder?

Would water quenching after powder coating add any hardness? I'm sure I'd lose any hardness gained from water quenching while casting during the powder coating process wouldn't I?

I'd really like to figure this out as the 356-120tc boolits shoot so well out of this m&p for me.

Thanks again.

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03-19-2018, 03:18 PM
adam_mac84

What is your OAL? I just ran 200 through in a training course yesterday. 4.2 WSF and 3.8 TG at 1.065. 100% reliability
03-19-2018, 04:18 PM
Krp68

Quote:

Originally Posted by adam_mac84

What is your OAL? I just ran 200 through in a training course yesterday. 4.2 WSF and 3.8 TG at 1.065. 100% reliability

I'm not home to check my books but I believe they are 1.060. They are seated to where the shoulder barely shows.

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03-19-2018, 04:43 PM
tazman

Depending on the throat in your particular barrel, you may be able to seat them out a little farther. Sometimes that helps feeding. You will need to test them in your barrel to make sure they don't jam into the rifling.
03-19-2018, 04:58 PM
Ed_Shot

I get really good results with WSF 4.5 gr. under a 120 gr boolit and an OAL of 1.060 should work fine. As tazman said, determine what the max OAL for that boolit is in your chamber and you might try a little longer OAL if you can. MY question is "how many magazines do you have and do you have the same problem with all of them?"
03-19-2018, 05:31 PM
Krp68

Quote:

Originally Posted by Ed_Shot

I get really good results with WSF 4.5 gr. under a 120 gr boolit and an OAL of 1.060 should work fine. As tazman said, determine what the max OAL for that boolit is in your chamber and you might try a little longer OAL if you can. MY question is "how many magazines do you have and do you have the same problem with all of them?"

I have 9 mags and they all do it. I determined the max OAL but I don't recall off hand. I do know that I have a .010 or so to play with so I will try to increase my OAL and see if that helps.

I know when I start getting a little crud build up on the barrel ramp and the boolits start hanging, I can stick my finger in the action and wipe it away and the sticking stops. Drives my crazy.

Thanks again

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03-19-2018, 09:50 PM
tazman

Are there machine marks on the barrel ramp where the fouling builds up?
If so, you may need to polish that area.
03-19-2018, 10:59 PM
rsrocket1

I shoot that same combo, but I use 5.0g WSF for an average 1182fps MV out of my M&P 9 with 4.25" barrel. I powder coat my bullets and size them to 0.356" with the Lee push through sizer and seat them to 1.05" to where the cone meets the case mouth. I use a separate taper crimp die on the 5th station of my LnL AP.

The 356-120-TC is on the right.

https://images3.imgbox.com/79/cb/sCryDdUe_o.jpg
03-20-2018, 01:02 AM
jcren

Not to be picky, but that one on the right looks way overcrimped. Hopefully it is just the light, but you should always have a pronounce case mouth on autofeeders that headspace there.
03-20-2018, 09:57 AM
Cosmic_Charlie

Polishing the feed ramp is good advise.
03-21-2018, 12:28 PM
Krp68

Quote:

Originally Posted by tazman

Are there machine marks on the barrel ramp where the fouling builds up?
If so, you may need to polish that area.

Yes, very faint machine marks running horizontally along the feed ramp. I'll try polishing and see if that helps also.

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03-21-2018, 01:38 PM
Tom W.

I was having trouble w/my new pistol. I was seating to 1.064 with my last two pistols and everything was fine. This new expensive pistol wasn't having any of it. I tried seating deeper, nd it worked somewhat, but nothing to trust my life with. I asked and found out that I wasn't belling my brass quite enough, and getting a very tiny ring of lead that I had to get a magnifying glass to see. It would do o.k. for three or four shots, then lock up the pistol with a failure to go into battery.
The next box of boolits I loaded i increased the bell just a tad, returned the COL back to 1.064 and after loading I took those to the range. They fired without a hitch.
I tried some of the others that I had previously and the same problem.
Hmmmmm.... I'll take those and run them through my Ruger.

The lesson I learned was that sometimes different pistols like different loads. Glocks and Rugers will eat almost anything. CZ's not so much.