Throat job, Advice Needed

[arcticbreeze]

I have been reading here for a while but this is my first post. I just got my new Edge 40 from Dawson Precision so i had to run to the range and give it a whirl. I am using a lee six cavity 401-175-TC to cast my own bullets and i am having a problem with them not fully chambering (only was able to shoot four rounds out 100). I suspect that my Bullet sizing die not at specs. My sizing die is suposed to be .401 but after lube sizing they are .403. I also slugged my barrel and it is a tad under .401 in the groove (i am not sure if thats the correct term, I mean the larger diameter, is that the Land?). I took a loaded round and colored it with a sharpie and dropped it in the chamber with the barrel out of the gun and can see where it stops at shoulder of the bullet witch is wider than the chamber throat. I am talking about where the case mouth would head space not the free bore before the rifling. A factory round that measures .400 on the bullet just above the crimp drops in the chamber just fine. I just want to be sure that it is my bullets are to wide and not my chamber to narrow. Tonight i loaded some rounds at various lengths from 1.12 up to 1.20 OAL with the .403 sized boolets and the depth at witch the bullet will seat directly corresponds with the OAL so it is definetly not my crimp or brass. Is it normal for the sizing die to allow that much overage. If so, should my gun be capable of accepting that much with cast lead? Or do you thing I should have the barrel throated. Please forgive my ignorance if the terms i am using are exactly correct.


Thanks in advance everyone

Marc

 

[arcticbreeze]

This pic is not great but here it is. The boolet was colored with a sharpie than inserted into the barrel. It drops into about a 1/8' from fully chambered. It is hard to see but the red arrow is pointing at the mark left by ledge where the case rim normally spaces. This boolet is seated at 1.135 and .402 in diameter.

 

[Jim Watson]

You are going to have to size smaller or seat deeper. Probably both. If you seat deeper you must adjust the load to not run pressures up, the .40 is very sensitive on that.

See if the sizing die maker will replace the die with a correct one.

 

[rcmodel]

Truncated cone bullets are especially problematic in many guns because the full diameter of the body runs out until the body breaks to the cone.
In many respects, you have to treat them like SWC bullets, and seat until the full dia. body is clear of the leade.

Lyman suggests an OAL of 1.100" with their very similar 175 grain TC cast bullet.

I think you just need to seat deeper until the TC bullet shoulder clears the leade.

The .403" sized bullet should be O.K. in your .401" barrel unless they expand the cases to the point the cases won't fit in the chamber.

I would not recommend deeper throating, because it would effect accuracy with more rounded bullet shapes you might wish to use.

rcmodel

 

[arcticbreeze]

They do expand the cases but i do not have a clearance problem. The problem is that i can't get reliable feeding from the magazine. I would really prefer even longer, STI 40 S&W is built on the 1911 frame and prefers closer to 1.20. Since I cast my own I can't find anything other than a tc type of mould.

 

[rcmodel]

Oh!
1911 won't feed normal length .40 S&W ammo. I see!

Well, have you tried factory loaded jacketed TC bullets like the WWB 180 TC-FMJ?

They are loaded to 1.130" OAL.
If it works with them, I guess you need a .401" bullet sizing die.

If it won't work with them, I believe I would call Dawson Precision and see what they want to do about it.
Maybe they missed throating it when they built it?

Regardless, a 2 grand gun should work with reloads.


rcmodel

 

[Jim Watson]

Laser Cast has a roundnose .401 meant for .40 cals on 1911 actions. I don't know whose mould it is, but probably something from Magma.

And as to the $2000 gun, it probably has one of those "minimum match chambers", actually undersize that they love to advertise. Not for oversize cast bullets.

 

[RogersPrecision]

I'd suggest having a competent 1911 smith throat the barrel using a throating reamer.
The 40SW is often loaded out to 1.240" OAL for use in the 1911 platform.

 

[Riss]

I get the same problem with my G-35 with a KKM barrel and 180 gr Lead TC boolits. Have to seat them deeper or gun will lock up tight or not go into battery at all. Seems a nice tight throat and the full diameter of the TC lead do not like each other. Just seat them deeper and back off the powder charge a 10th and all will be good again.