tolerances/diameter

500bfrman
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tolerances/diameter

Postby 500bfrman » Thu Nov 18, 2010 9:26 am

I have 500 bfr that is 503 throats. I was wanting 504 bullets. My question is do I order 504 mold, or do i need to order 505 and size to 504. My question is in regards to the tolerances that statest he average diameter would be 504, so theoretically there could be places where it is under 504? I don't mind sizing to 504 and getting mold at 505, I will be running them through the sizer to lube anyway. I will be using this as PB so no gas check and diameter/fit is extra critical. thanks

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mtngun
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Re: tolerances/diameter

Postby mtngun » Thu Nov 18, 2010 3:03 pm

Personally, I like my bullets to drop out about 0.002" bigger than the size-to diameter. That leaves some wiggle room for the occasional bullet that doesn't fill out so great, or if the diameters decrease as the mold gets hotter, or if I want to experiment with a larger sized diameter.

Sizing has gotten a bad rep because of all the crap sizing dies. If the die is made right, sizing does not hurt accuracy, and like you say, you gotta run them through the lubrisizer, anyhow.

BTW, how does your BFR shoot with the 503 throats ? Was there some logic behind making them oversize, or is this just another case of crap tolerances ?

It is your call, I am not going to tell you what to do, except to include a note with your order reminding me that you will be sizing to 0.504". That does help. Otherwise, I try to hit the middle of the tolerance range, with varying degrees of success. :roll:

500bfrman
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Re: tolerances/diameter

Postby 500bfrman » Thu Nov 18, 2010 6:42 pm

I have had several 500 s/w bfr's and they have all had 503 throats. I actually prefer that to my xframe which is 500ish at best and sometimes it seems when you mesure it they run 499ish. Anyway I am able to hold five shots in an inch at 30 yards. Which tells us that i am a terrible shot :lol:
but when we consider this 440 grains going 1700 fps it adds another variable to the mix.

So you are saying for you personally( and yes I know this is just you and everybody's different) but you if you wanted to shoot 504 bullets you would cast to 506. this makes sense to me after I have thought about it.

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Re: tolerances/diameter

Postby mtngun » Thu Nov 18, 2010 7:00 pm

500bfrman wrote:So you are saying for you personally( and yes I know this is just you and everybody's different) but you if you wanted to shoot 504 bullets you would cast to 506. this makes sense to me after I have thought about it.

Yes, that would be my ideal.

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Re: tolerances/diameter

Postby mtngun » Wed Dec 01, 2010 4:40 pm

Hope it works out for you. :)
Image

500bfrman
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Re: tolerances/diameter

Postby 500bfrman » Wed Dec 08, 2010 12:15 pm

Dan,

I got the molds today. they look great, and super fast turnaround time. I ordered from you and from a gun dealer that had the gun in stock and I still don't have the gun, but the molds are here from you. I had a question about the weights though on the receipt.
It states 715 and 535 grains. I ordered 700 and 525 I am pretty sure. wondered why the higher numbers. doesn't bother me just wondered. thanks again.

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Re: tolerances/diameter

Postby mtngun » Wed Dec 08, 2010 2:11 pm

That's just the way it turned out.

Normally, I use clip-on WW, but lately I've been using some store-bought WW ingots. I have not done a density check on the store-bought stuff, but I wouldn't be shocked if it includes tape-on weights, which are nearly pure lead, making the overall mix more dense. I'll try to do a density check on my store-bought WW vs. home smeltered clip-on, and report back in a few days. It does seem like the weights have been climbing since I began adding store-bought ingots to the pot.

I haven't been losing sleep over it since there is no tolerance for as-cast weight. The tolerance spec'd on the program is the variation from one cavity to the next. As long as both cavities are the same weight, the mold passes. It's not feasible to have any other type of weight tolerance, especially for a mutt alloy like WW, because the customer's WW may be slightly different than mine.

You're the first of my customers to so much as comment about a bullet being a little heavier than the nominal specified weight. Most people expect a bullet to drop out heavy because that's how it usually works with Lyman, RCBS, NEI, LBT, etc. molds. On the other hand, I have received complaints and comments for being a few grains too light, so I've always tried to err on the heavy side.

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Re: tolerances/diameter

Postby 500bfrman » Wed Dec 08, 2010 6:14 pm

interesting. and yes I prefer heavier then lighter. thanks for the great work you do.

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Re: tolerances/diameter

Postby mtngun » Thu Dec 09, 2010 10:50 am

K, I tested the density on the pot that was used to test your mold, and compared it to the density of home-smeltered clip-on WW.

The clip-on WW was 0.43% less dense. If tested with clip on, your bullets would have weighed 712 grains and 532.7 grains.


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