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Discussion Starter · #1 ·
My question regarding Max loads is one of my reloading manuals. Lees modern reloading 2nd edition shows a max load of 22.4 gr. of 1680 with a 180 grain jacketed bullet pistol load with a pressure of 37,000 PSI. When I go on the Hodgdon web site it says for a 180 gr SSP bullet max is 30 gr. of 1680 with a pressure of 27,000 PSI. Which is correct? And why such a huge discrepancy in pressure it make no sense 7.6 more grains equals 10,000 PSI less PSI.
 

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The SSP bullet has a long nose and shorter base section than the 180 xtp. The xtp or similar style bullet will have more bearing surface against the bore and will develop more pressure.

All that said, 22 gr of 1680 is on the low end of what most of us load with a 180 jacketed bullet. I have not had any issues with a case full of 1680 be it a jhp, jfp or spire point. By case full I mean 100% load density up to the base of the seated bullet. Each of these bullets will have a different seating depth inside the case which will determine how much powder will fit without compression. You will likely find your best load results somewhere in between those two numbers you found in the published load data and the max load will not be the same for every type of bullet even if they are the same weight.
 

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For reference, in an Encore rifle barrel, I shot over 1k rounds with 32gr AA1680 and 200gr FTX. A batch of brass had been loaded 46 times and primer pockets still tight. Load with confidence.
 

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For reference, in an Encore rifle barrel, I shot over 1k rounds with 32gr AA1680 and 200gr FTX. A batch of brass had been loaded 46 times and primer pockets still tight. Load with confidence.
What kind of velocity are you getting with that load? I'm running 26.2gr of lilgun behind a 180gr hotcor at 2300fps.

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Once again, it is hard to overstress the importance of focusing on seating depth and percent fill instead of OAL.

My WC 680 loads (milsurp version of 1680) do great at 98% to 100% fill with either 180s or 200s.

Some have claimed good results with compressed loads, but I did not like the results at all.
 

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2,200fps. No fire or flame thrower effect, but it was a 24" barrel.
I'm going to have to try some load development with some 1680 in my contender and encores. How's the accuracy? I haven't shot this load in my contender yet as I just picked it up but my mgm encore barrel I get about 3/4 inch groups at 100 yards.

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I'm going to have to try some load development with some 1680 in my contender and encores. How's the accuracy? I haven't shot this load in my contender yet as I just picked it up but my mgm encore barrel I get about 3/4 inch groups at 100 yards.

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1.5 moa at 200yd. Dropped fast after that so never shot further. Longest kill was 156yd iirc. Went diagonally thru a decent body buck and found the bullet, perfect mushroom.

I still use the 200ftx in my 358win that I trim the neck short to be IN public land legal. Puts very nice holes thru deer at 2,650fps.
 

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I still remember that lambasting, Bill delivered to me suggesting load data with 1680 under a 180ssp back when there was no or very little data!! (Long ago here) Explanations where attempted but in the end his board his rules! He was correct I did not have pressure test equipment, only personal experience reloading & working up loads.
Today and for probably a decade now, guys have discovered 1680 under that 180 ssp, can be loaded past book loads for the 180 357 mag pistol bullets. 100% its because of seating depth & bearing surface.
CW
 

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Discussion Starter · #10 ·
Ok . Well understood . Longer bullets less bearing = less pressure .That 180 gr. SSP bullet seems very similar to the Speer 180 Hot Core stated above. I my have to switch over once these SSP's are gone. I wished Hornady they still made them.
 

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Bearing surface is part. But seating depth is more. Less seating means more volume for the expanding gas. THAT equates to less pressure if everything else is equal.

CW
 
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