LEE TL309 230 5R -- what are you sizing the gas checks to?

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lawboy
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LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by lawboy »

For those gas checking this mould, what diameter are you sizing the gas checks to when you crimp them onto the bullet base?
308? 309? 310? 311? 312? 313?
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80hp
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by 80hp »

lawboy wrote:For those gas checking this mould, what diameter are you sizing the gas checks to when you crimp them onto the bullet base?
308? 309? 310? 311? 312? 313?
Size the gas check to the same diameter as you would size the bullet.

For the 300 blk there are only 3 practical diameters for cast bullet sizing, .309", .310", and .311". Cast bullets need to be .001"-.002" greater than bore diameter ( normally .308" ). With any larger than .311" you run the risk of exceeding the maximum neck diameter of .334" for the 300 blk. Then you may have the fun of 'mortaring' your AR to free a stuck round. Also, the neck of the cartridge needs room to open up on firing to release the bullet or pressures will increase.
If someone has 'slugged' the bore and throat of their barrel and made a chamber cast to find the barrel's exact dimensions, then they might be able to go outside of these limits.

When you try a gas check on the Lee 230g, you may find accuracy decreases.
The gc is a band-aid for only one of the Lee 230's three major problems.
-The front driving band is too small, usually around .305". It needs to be the same diameter as the base of the bullet, at least .309".
-The tumble lube grooves normally cast too small.
-The boat tail. With the fast twists of 300 blk barrels, the bullet needs as much lead in contact with the barrel as possible to spin it. On both of the Lee 230 molds I used, the only groove diameter part was a narrow band between the boat tail and the tumble lube grooves. Of course, someone may get lucky, and get a mold that casts oversized bullets that can be sized to a usable diameter.

Powder coating is another practical solution. I am trying two coats of powder coating to increase the diameter of the bullet to the proper size to see if I can improve it's accuracy.
M.
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lawboy
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by lawboy »

Thanks for the info.
I think I will start at .308 and test everything up to .311.
Can't hurt, I guess.
ih8unot
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by ih8unot »

lawboy wrote:Thanks for the info.
I think I will start at .308 and test everything up to .311.
Can't hurt, I guess.
An undersized, uncoated lead bullet will cause fouling.
lawboy
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by lawboy »

ih8unot wrote:
lawboy wrote:Thanks for the info.
I think I will start at .308 and test everything up to .311.
Can't hurt, I guess.
An undersized, uncoated lead bullet will cause fouling.
Understood. I have been using standard liquid alox lube on them with fine success in terms of preventing leading.
What I am trying to correct is the poor accuracy. I am hoping the gas checks correctly sized will do that.
No way to know but to try it!
ih8unot
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by ih8unot »

Try pc and you'll probably do better.
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skeet1
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Re: LEE TL309 230 5R -- what are you sizing the gas checks to?

Post by skeet1 »

I have been using this bullet with an aluminum gas check. Out of the mold, the bullet measures about .310" but I don't own a .310 sizer but have a .311 and that is what I use. It is a little messy because when I size in my RCBS lubrisizer with Carnuba Red lube, the lube oozes out the top of the die and I have to wipe it off. I am contemplating getting a .310 die. However this bullet does seem to shoot well when I shoot it supersonic with no leading.
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