51gr bbt 253 sizing UPDATED

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I bought the last .25cal 253 51gr mold. I set to casting some slugs using 40-1 lead they are coming out .2578 drive and forward band of .2560! Are these dimensions what they are designed to be? I had my barrel slugged and it measures .25 land and .255 grooves.  Should I have bought the other mold?

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[rsterneParticipant]

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Nope, I would say you got the right mould for your barrel…. but you may have to size the bullets down a bit…. I answered you more fully on the GTA….

Bob

[tnt76]

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Mine drop at roughly the same dia when I have a mould temp of over 400f and closer to design specs when mould temp is under 350f but wrinkles and HP point distortion become more abundant at the cooler mould temp.

[AlvinYorkParticipant]

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What alloy are you using? My bullets don’t usually come out to the specified size as I use something closer to Linotype (my own mixture). As Bob said, you probably just need to size them.

[teemuParticipant]

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I set to casting some slugs using 40-1 lead

[AlvinYorkParticipant]

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Thanks, Teemu. I skimmed over that bit.

I was trying to find the composition of wheelweights (they seem to be illegal here in the east) but I think there’s an antimony component in them . . . ? So maybe the 40-1 needs a pinch of antimony.

[edmundgeer]

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Here are the before groups shooting the HS#257 before the choke was removed at 80 yards and 30 yards.

Here are the 30 yard groups for the BBT 51gr sized down to .253 and .252 after choke removal.

I asked Bob what size bullet would work best in my chokeless condor .25 cal.  He told me that with the lands being .255 that should be the optimal bullet dimension. Well Mr. rsterne was correct. I have tried 3 different suppliers and 4 different sizes and found today during testing the 51gr BBT sized to .255 works best.  Below you can see my test at 40 yards of the NSA 60gr .25 cal, the 51gr BBT .254 cal, and the 51gr BBT .255 cal.

Wow what a difference .001 makes!  I cant express how pleased I am of the modifications and transformation of this rifle!

[rsterneParticipant]

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Great results…. thanks for sharing…. Quite a shocker what a difference 0.001″ can make, isn’t it?….  😮 :

Bob

[thierryaudibert]

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greats results, i have a new hope

thanks for sharing

[edmundgeer]

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greats results, i have a new hope

thanks for sharing

That is all we have!  So I cut the leade as best I could as I was having to use a block of wood to chamber each round.  Well that screwed it up and I was shooting all over the place, I couldn’t hit a grapefruit it was so bad.  I thought it was an Airline promotion because of all the frequent flyers I had.  So yesterday I took what was left of the barrel to a local gunsmith and had him true up the mess I made. To compensate for the slightly larger chamber I took my .253 sizing die and enlarged it to .2555 by chucking it up in my drill press and using 400grit around a drill bit.  It took a while but I got it right on the money where it drops the bullets .2555 on the money. The groups are not perfect but are huntable as seen below:

[SNEAKY_NL]

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greats results, i have a new hope

thanks for sharing

That is all we have!  So I cut the leade as best I could as I was having to use a block of wood to chamber each round.  Well that screwed it up and I was shooting all over the place, I couldn’t hit a grapefruit it was so bad.  I thought it was an Airline promotion because of all the frequent flyers I had.  So yesterday I took what was left of the barrel to a local gunsmith and had him true up the mess I made. To compensate for the slightly larger chamber I took my .253 sizing die and enlarged it to .2555 by chucking it up in my drill press and using 400grit around a drill bit.  It took a while but I got it right on the money where it drops the bullets .2555 on the money. The groups are not perfect but are huntable as seen below:

What was the distance?

[edmundgeer]

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40 yards.

[Author]

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