Help ! 40 S &W

[243winxb]

Make sure the screens/timers maintain correct spacing. Long time since i had a chrony. Any one remember the card board with the wire used as a sky screen.

[pt4u2nv]

Make sure the screens/timers maintain correct spacing. Long time since i had a chrony. Any one remember the card board with the wire used as a sky screen.

My unit is all one pc...no spacing to worry about.

[9.3X62AL]

Something ain't right.

"Standard" velocities in 40 S&W/175-180 grain bullets with 4" barrels run about 950-975 FPS. I carry that bullet weight, and don't mess with any others. Most fixed-sight service-grade pistols in 40 S&W "assume" this load is being used (sighting, spring rates).

I've slugged A LOT of 40 S&W barrels, including several Sigmas. They are UNFAILINGLY .400" or .401", unlike the variance seen in 9mm throats and grooves. I'm glad that got cleared up.

I just mic'd the expander stem in my RCBS 40 S&W/10mm die set--.3965". The expander spud in the Lyman Multi-Charge expander die set is .3980". MUCH better for loading cast boolits of .400"-.401". I'm still not certain what your actual boolit diameters are, but you DO NOT need .403". Just the brass-working from the under-sized RCBS sizing die to the over-sized boolit will set up early brass failure, and likely deform your bullet as well. From .3965" to .403" is a HUGE jump. Most modern die sets--especially for autopistol calibers--"assume" jacketed bullet usage. Do a "tale of the tape" on your pistol's fired brass vs. its dimensions on sized brass--you'll likely get an eye-opener there, too.

Assuming your velocities are correct from the Chrony, you are overloading your ammunition. The early retirement of your brass and the "wiping" of headstamps is further evidence of same.

[afrance]

I just received a response from Ramshot/Accurate's ballistician after showing them Speer's response that "8.7 - 9.7 grains of AA #7 was a tested load with our 180 gr GDHP bullet".

"Alan,

We can only confirm our own data.

We test in SAAMI certified test barrels and 8.5 grains is definitely the maximum for a 180gr JHP whatever the make.

Regards

Johan Loubser

Ballistician

Ramshot/Accurate Powders"


Definitely a prime example of needing more than one reliable source of loading data to cross reference and ask questions if those sources differ from one another. I wonder how often this particular load contributed to kabooms in 40 S&W.

[Jayhem]

Wow. Lesson learned! Use only the load data published by the POWDER manufacturer, not a J-bullet manufacturer!

[pt4u2nv]

I just received a response from Ramshot/Accurate's ballistician after showing them Speer's response that "8.7 - 9.7 grains of AA #7 was a tested load with our 180 gr GDHP bullet".

"Alan,

We can only confirm our own data.

We test in SAAMI certified test barrels and 8.5 grains is definitely the maximum for a 180gr JHP whatever the make.

Regards

Johan Loubser

Ballistician

Thanks for help in this matter Alan. I appreciate all the leg work. Now back to the original issue.....finally got some closure on the high pressure issues I thought I had with the cast and obviously "J" bullets , which was certainly justified No Thanks to Speer.

My "new " chrony was sending bad info, all FPS were approx 300 - 400 FPS faster than they were actually being sent down range. Double checked all my loads with a friends chrony right behind mine and all readings on mine were way high. His chrony was reading right at levels the bullets were supposed to be doing. Thanks all for the great help, learned alot about cast boolits thru this isssue and hopefully this will help others in the future. What a relief to finally find out it was not me , my boolits, or loading techniques.

Thorns though to Speer for sending me on a wild goose chase on overloading their bullets, compounding my problems when using their bullets to find out what was going on pressure wise when I thought it was my cast boolits.

[sheepdog]

Thorns though to Speer for sending me on a wild goose chase on overloading their bullets, compounding my problems when using their bullets to find out what was going on pressure wise when I thought it was my cast boolits.

This is the same Speer that public denounced Lee factory crimp dies as "dangerous", warning people not to use them for fear of high pressures. But keep in mind Speer is owned by Blount the parent company of RCBS

[jimkim]

I just received a response from Ramshot/Accurate's ballistician after showing them Speer's response that "8.7 - 9.7 grains of AA #7 was a tested load with our 180 gr GDHP bullet".

"Alan,

We can only confirm our own data.

We test in SAAMI certified test barrels and 8.5 grains is definitely the maximum for a 180gr JHP whatever the make.

Regards

Johan Loubser

Ballistician

Ramshot/Accurate Powders"


Definitely a prime example of needing more than one reliable source of loading data to cross reference and ask questions if those sources differ from one another. I wonder how often this particular load contributed to kabooms in 40 S&W.

This is strange. Hornady 7 shows 9.4gr AA#7 as a maximum load for their 180gr bullets, and Sierra V shows 9.2gr of AA#7. Could they all be wrong? I wonder if the newer AA#7 might be hotter.

[dardascastbullets]

OK I did of little more "testing" of some different powders, loads etc to try to figure out this issue. Loaded up some Dardas 155 gr Cast "store bought " boolits, 155gr J Bullets, from Hornandy, and 2 different alloys of my cast boolits. BHN of 15 on one and 9 on another just to eliminate the sizing or hardness issues. Rechecked the bore dia at .401 , bullets checked at .403 . All loaded at min loads with AA#5, AA#7 and Unique. Chrony was reading from 1100 to approx 1235 FPS on all of the loads lowest being the 170 gr cast of mine. I also shot these same loads thru a friends 40 ( S&W also) His gun registered the same FPS as mine so that eliminated the issue being the gun. I also shot a few of his J bullets he loaded and got 1232 FPS on a load he chrongraphed at 1150 avg. That being said he could have also got a reading of 1232 that just showed up as a high for him and not the avg. I now have borrowed his chrony to try this weekend to see if my new chrony is just not reading correctly. If his is consistant with mine I do not know where I will go next. Note: Plans are to check a box of factory ammo at this time also.

Comment on working up the load and look for pressure signs is great but I can't get off the min load at this point with any boolits cast or J without crazy chrony readings and high pressure signs. OAL has also been played with and still no changes in readings.


This is beginning to wear on me as I have tried everthing suggested by you all and all I know and nothing seems to change the high readings. I am also going to get another gun or so of mine that I had chrongraphed with an older chrony to compare notes against the new one but I am afraid I will find the chrony is fine.

Sir,

I must interject - your mention that the bullets 'checked at 0.403"' I assume were the bullets that you casted? I ask this because I size all of my 10mm's to 0.401".

Matt