So I've gotten a LabRadar over Memorial Day this year, and have been testing my loads I've been using for my 4 inch Model 66-3 over the few months.
I use a variety of headstamps, and they have been fired and loaded at least 10 times so far, so the cases got hardened, I even found my first split case mouth on a piece of Armscor brass yesterday before loading.
I mainline Accurate #9 btw, great powder, ok case fill with my loads,
Being that I own a K frame, with their forcing cone relief cuts I am VERY conscientious of overpressure ammo. I avoided loads in my Lyman 51st edition and sub 158 grain bullets like the plague. Seriously 13.4 to 14.9 of Accurate #9 seems excessive to me, but they were using CUP measurements, the max load was about 43,000 CUP.
I currently only use data from Hodgdon's RDC from their website, and it called for 12.4 to 13.8 max with a WSPM, which I understand as being hot, but they do use PSI as a measurement. However Speer's website using their bullets also only call for 12.3 to 13.7 max (a deeper OAL too), but they used CCI 500 standard SPPs.
So I figured, "I'll just do like 12.3 starting and 13 grains for my max."
On average, I will load between 12.6-12.8 grains with my 158 grain Zero JHPs and 11.5 to 12.5 grains for 158-162 grain LRN from Bear Creek Supply. I try to load COAL to be around 1.580-1.590" on average, I switch between CCI 500s (Std SPP) and 550s (SPM primer). Found relatively little difference in velocity aside from tightening the SD by 5-10 fps.
My 12.6-12.8 AA#9 loads will do about 1120-1180 fps on avg, even switching between the CCI 500/550 made little difference. So I ASSUME it's a safe load (under 35,000 psi). I always shoot at about 60 Fahrenheit at my indoor range. Extraction stickiness was always about the same between these loads, with lead loads being a bit easier on average (figures, less pressure for the same charge.)
I have to say, I read a lot on forums and load books, they always say to look for primer and extraction signs for pressure.
My primers will usually be rounded or flat, depends on the cartridge's headspace in that moment, I usually discount that in revolver loads for approaching max, never had a blown or cratered primer with my relatively midline loads.
I loaded to 13.5 using CCI 500s, slightly more difficult extract, nothing I had to pound out, avg Vel of about 1190 fps. Better SDs too, one of the cases I had to use considerable thumb pressure to extract, but the rest were only sticky, about 5-8 pounds thumb pressure.
The thing that makes me most puzzled so far is stickyness of extraction. My loads, I'm pretty sure are not near 35,000 psi, most likely their around 32,000 to maybe 33,500 psi at most due to tolerances.
Let me say this, I have ALWAYS had sticky extraction, with the exception of my 12.3-12.4 grain and below loads using 158 grain JHPs loaded to ~1.580" or shorter COALs, with CCI 500s, the extraction always required around 5-8 pounds of thumb pressure on my ejector rod before they pop out, around 1/8 inch of travel before they drop into my palm, usually around 1-2 of them are the culprit for harder extraction, the rest of the shells only take about 4-5 pounds pressure and like 1/8 inch of travel to pop free.
I've read from other forums that on .357 and straight walled handgun cartridges, stickiness isn't a good indicator on pressure, I've tested this theory with .38 special plus p plus loads I've cooked up recently, and honestly, that's probably true. I used a 110 grain XTP under around 8.7 grains of Accurate #5, a load that should be around like 22,000 to 23,000 psi with a crimp on the cannelure ~1.440" COAL in both my Model 15-3 and Model 66-3.
Keep in mind Hodgdon only stated 7.7 - 7.8 grains of #5 and a 110 grain XTP, and their max pressure was around 20,000 psi, which is SAAMI's max pressure for .38 Spec +p, a Mean Sample Maximum Pressure of 21,500 psi is allowable for an average batch of max pressure stuff.
I loaded these 110 grain XTPs to 8.7 grains of Accurate #5. That's difference of roughly 10% increase in charge weight. This was what Sierra's 6th Edition considered "+p"
So I'm pretty sure my stuff shot AT LEAST 22,000 psi.
Result? I got like 1108 fps on average out of both guns (roughly), great fireballs, a loose yoke on my 15-3 after about 150 rounds, and a great Treasury Load for my 66-3. But here's the kicker, on this supposed "+p" load, ALL 100 rounds fell free from BOTH GUNS. I then loaded this same components using Sierra's 3rd Edition, 9.2 grains of AA#5, this time only using my Model 66-3, and this time got 1210 fps out of a 4 inch barrel, only then did I get slight extraction stickiness. I don't think this load exceeds 30,000 psi, most likely 25,000 psi.
So this got me thinking, is sticky extraction (on a full cylinder) really a good indicator of approaching max pressure or overpressure? After all .38 cases are basically shorter .357 cases, the case thickness is basically the same. If pressures of ~25,000 psi cause stickiness in my gun, and my .357 Mag loads only cause the SLIGHTEST stickiness when loaded up to 12.4 grains using standard SPPs (likely around 28,000 psi load), then are my 12.6-12.8 grain #9 loads REALLY overpressure when the stickiness gets a bit worse?
I use a variety of headstamps, and they have been fired and loaded at least 10 times so far, so the cases got hardened, I even found my first split case mouth on a piece of Armscor brass yesterday before loading.
I mainline Accurate #9 btw, great powder, ok case fill with my loads,
Being that I own a K frame, with their forcing cone relief cuts I am VERY conscientious of overpressure ammo. I avoided loads in my Lyman 51st edition and sub 158 grain bullets like the plague. Seriously 13.4 to 14.9 of Accurate #9 seems excessive to me, but they were using CUP measurements, the max load was about 43,000 CUP.
I currently only use data from Hodgdon's RDC from their website, and it called for 12.4 to 13.8 max with a WSPM, which I understand as being hot, but they do use PSI as a measurement. However Speer's website using their bullets also only call for 12.3 to 13.7 max (a deeper OAL too), but they used CCI 500 standard SPPs.
So I figured, "I'll just do like 12.3 starting and 13 grains for my max."
On average, I will load between 12.6-12.8 grains with my 158 grain Zero JHPs and 11.5 to 12.5 grains for 158-162 grain LRN from Bear Creek Supply. I try to load COAL to be around 1.580-1.590" on average, I switch between CCI 500s (Std SPP) and 550s (SPM primer). Found relatively little difference in velocity aside from tightening the SD by 5-10 fps.
My 12.6-12.8 AA#9 loads will do about 1120-1180 fps on avg, even switching between the CCI 500/550 made little difference. So I ASSUME it's a safe load (under 35,000 psi). I always shoot at about 60 Fahrenheit at my indoor range. Extraction stickiness was always about the same between these loads, with lead loads being a bit easier on average (figures, less pressure for the same charge.)
I have to say, I read a lot on forums and load books, they always say to look for primer and extraction signs for pressure.
My primers will usually be rounded or flat, depends on the cartridge's headspace in that moment, I usually discount that in revolver loads for approaching max, never had a blown or cratered primer with my relatively midline loads.
I loaded to 13.5 using CCI 500s, slightly more difficult extract, nothing I had to pound out, avg Vel of about 1190 fps. Better SDs too, one of the cases I had to use considerable thumb pressure to extract, but the rest were only sticky, about 5-8 pounds thumb pressure.
The thing that makes me most puzzled so far is stickyness of extraction. My loads, I'm pretty sure are not near 35,000 psi, most likely their around 32,000 to maybe 33,500 psi at most due to tolerances.
Let me say this, I have ALWAYS had sticky extraction, with the exception of my 12.3-12.4 grain and below loads using 158 grain JHPs loaded to ~1.580" or shorter COALs, with CCI 500s, the extraction always required around 5-8 pounds of thumb pressure on my ejector rod before they pop out, around 1/8 inch of travel before they drop into my palm, usually around 1-2 of them are the culprit for harder extraction, the rest of the shells only take about 4-5 pounds pressure and like 1/8 inch of travel to pop free.
I've read from other forums that on .357 and straight walled handgun cartridges, stickiness isn't a good indicator on pressure, I've tested this theory with .38 special plus p plus loads I've cooked up recently, and honestly, that's probably true. I used a 110 grain XTP under around 8.7 grains of Accurate #5, a load that should be around like 22,000 to 23,000 psi with a crimp on the cannelure ~1.440" COAL in both my Model 15-3 and Model 66-3.
Keep in mind Hodgdon only stated 7.7 - 7.8 grains of #5 and a 110 grain XTP, and their max pressure was around 20,000 psi, which is SAAMI's max pressure for .38 Spec +p, a Mean Sample Maximum Pressure of 21,500 psi is allowable for an average batch of max pressure stuff.
I loaded these 110 grain XTPs to 8.7 grains of Accurate #5. That's difference of roughly 10% increase in charge weight. This was what Sierra's 6th Edition considered "+p"
So I'm pretty sure my stuff shot AT LEAST 22,000 psi.
Result? I got like 1108 fps on average out of both guns (roughly), great fireballs, a loose yoke on my 15-3 after about 150 rounds, and a great Treasury Load for my 66-3. But here's the kicker, on this supposed "+p" load, ALL 100 rounds fell free from BOTH GUNS. I then loaded this same components using Sierra's 3rd Edition, 9.2 grains of AA#5, this time only using my Model 66-3, and this time got 1210 fps out of a 4 inch barrel, only then did I get slight extraction stickiness. I don't think this load exceeds 30,000 psi, most likely 25,000 psi.
So this got me thinking, is sticky extraction (on a full cylinder) really a good indicator of approaching max pressure or overpressure? After all .38 cases are basically shorter .357 cases, the case thickness is basically the same. If pressures of ~25,000 psi cause stickiness in my gun, and my .357 Mag loads only cause the SLIGHTEST stickiness when loaded up to 12.4 grains using standard SPPs (likely around 28,000 psi load), then are my 12.6-12.8 grain #9 loads REALLY overpressure when the stickiness gets a bit worse?
