I do measure factory rounds like Winchester and Remington to see what they believe is a good/average OAL and crimp dimension for that cartridge and bullet combination. It really is a good starting point. Then plunk that "pill" to make sure it works well in your barrel.
starting to reload .380 question
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zxcvbob
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What I usually do when starting with a new semiauto cartridge is use a factory round for the initial setting on my seating die, then adjust from there. Put the factory ctg in the shellholder, lower the seating plug as far as it will go, and tighten the locknuts. Then seat one of my bullets and see what I have. Adjust as necessary.
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Rom828
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I have Remington 95gr FMJ RN, yesterday loaded 10 @ 2.6, 10@ 2.8 and 10 @ 3.0 to a COL of .980. I also have xtreme 100gr FMJ FP, will be loading same test rounds today with a COL of .945. Can't wait to test them and will be watching for anything strange. Thanks everyone for helping me keep my head straight.
Dframe
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Excellent starting point from xscvbob. I do exactly the same when loading a new bullet of the same weight.
1KPerDay
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Mine works fine...
http://youtu.be/nyTXWoq5ciY
I've found that my .380s like "max" loads for best accuracy with plated pills. YMMV, and you should work up as noted above.
lauderdale
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ROM why the drastic change of case length? .945 OAL?
vaalpens
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I am not loading 380 yet, but I do like to understand how decisions are made. The interesting part of your comment is where you indicate you stopped at 3.0gr. due to the shorter OAL. I assume this is due to the increased pressure of the shortened OAL that you stopped at 3.0gr. How did you calculate where to stop due to the shorter OAL?
LiveLife
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When my working OAL/COL is shorter than listed on published load data or my calculated bullet seating depth pushes the bullet base deeper in the case neck (subtract bullet length from OAL and measure from case mouth down to top of powder charge in the case), I anticipate higher chamber pressures and often reduce my start/max charges by .2-.3 gr depending on how much deeper the seating depth is as using the same max powder charge for shorter OAL will likely result in chamber pressures that exceed published max averages.vaalpens said:
For me, accuracy is everything and holes on target speaks volumes.
More consistent chamber pressures result in more consistent muzzle velocities that result in lower SD numbers and ultimately smaller consistent shot groups on target.
When I conduct load development with any new bullet/powder combination, I first identify the powder charge that will reliably cycle the slide and extract/eject spent cases. Then I focus on accuracy trends to see if the shot groups decrease or increase in relation to powder charge increase. If the shot groups decrease in size, this may indicate more consistent chamber pressures/more efficient powder burn/more consistent muzzle velocities. If the shot groups remain the same or increase (and that does happen with some bullet/powder combinations), then I will fine tune my loads from .2-.3 gr powder increments down to .1 gr increments.
If you look at the shot group pictures above, 100 gr RNFP plated bullet produced just over one inch shot group with 2.6 gr of W231/HP-38 but the 2.8 and 3.0 gr loads did not significantly decrease in shot group size. The flat point bullet results in longer bullet base that will seat deeper in the case neck and this may increase chamber pressure, perhaps significantly for small volume 380Auto case. So to me, with 3.1 gr as max powder charge, and since I got reliable slide cycling and extraction/ejection with 2.6 gr, I probably reached consistent enough chamber pressures at 2.6 with this particular bullet to produce accuracy and shot group size indicated that. If 2.6 gr powder charge did not produce consistent enough chamber pressures, my shot group size would have noticeably decreased as I approached 2.8 and 3.0 gr.
So if you were looking for a lighter target load, 2.6 gr would be ideal as it produced accurate shot groups while producing the lightest recoil that was a joy to shoot with a small frame/short barrel TCP 738. Remember, this load development was with a plated bullet meant for range practice and I wanted to identify a comfortable practice load for my wife.
If I was conducting the load development with a FMJ bullet with the same published OAL, I would have tested the higher 3.1 gr powder charge. Now, some may say why so much fuss over .1 gr? Well, I have seen quite a few guns blow up at the range and the rounds were loaded by match shooters familiar with reloading. When we did root cause analysis, we found their powder charges were consistent with scale readings but their scales were off, their powder measure drifted over several hundred progressive press cycles and their match loads exceeded the published max charges.
How do you know that your max charge of 3.1 gr or 5.0 or 6.0 is truly 3.1/5.0/6.0 gr? That's why I use check weights to verify the accuracy of my scales at the powder charge range I use and prefer to use fixed volumetric powder measure like Lee Pro Auto Disk that cannot drift powder charges even after 1000+ round reloading session. At dismay of many Dillon fans, I may end up using Pro Auto Disk on my 650 as many match shooters I competed with had to do QC check after 100 rounds and some as low as 50 rounds because their powder measure drifted.
Potatohead
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Not that unusual if you ax me, I have some little fat Sierra JHPs that I have to seat under .928 in order for them to function in my p238.
vaalpens
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bds, Thanks for the detailed response and taking the time to explain how you approach the process of finding a preferred load for a given combination of components and application. This process of being meticulous and the attention to detail is what finally convinced me to enter the world of reloading. I just have a few followup comments/questions though.
To be able to determine by how much your bullet is being pushed deeper, I assume you will need to know what the actual length of the bullet is in the published data. Is this data readily available? How do you compensate for the hollow base (Berry) or concave base (Xtreme) plated bullets when determining how the shorter COL could impact the chamber pressure?
In your original post I think you indicated you tested the accuracy at 7 yards. Will you also test the accuracy at say 10 or 15 yards just to see if maybe the higher charge will give you a better shot group, and then make you final decision?
To be able to determine by how much your bullet is being pushed deeper, I assume you will need to know what the actual length of the bullet is in the published data. Is this data readily available? How do you compensate for the hollow base (Berry) or concave base (Xtreme) plated bullets when determining how the shorter COL could impact the chamber pressure?
In your original post I think you indicated you tested the accuracy at 7 yards. Will you also test the accuracy at say 10 or 15 yards just to see if maybe the higher charge will give you a better shot group, and then make you final decision?
LiveLife
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While there are very slight variations in ogive and bullet length between manufacturers, I have FMJ/JHP and plated RN samples I can reference but you can also get bullet lengths by doing some online search. Usually, if a load data used FMJ/RN and you are using RNFP/FP bullet at shorter than listed OAL/COL, your bullet base will be longer and be seated deeper.vaalpens said:
This was a concern when Berry's MFG first released their hollow base bullets. What I found is that thicker plated bullets (Berry's indicate they are good for 1450 fps) could be pushed using jacketed load data without issues. With 115/124 gr HBRN-TP bullets, using my usual 1.135" OAL, I really do not need to make adjustments when using published lead or jacketed load data. Of course, Hodgdon has plated load data for Berry's bullets under (BERB) so using that load data takes the guess work out.
Long before X-Treme, Rainier Ballistics sold concave plated bullets and it was supposed to help expand the bullet base better to seal with the barrel. Well, I think Berry's hollow base design absolutely trumps concave plated bullet design. BTW, Winchester now sells true hollow base FMJ with exposed lead base and I load these without adjusting load data.
LiveLife
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Not for 380Auto with short barrel length.vaalpens said:
I usually conduct my accuracy testing of 9mm/40S&W/45ACP at 10-15 yards and verify "known" accurate loads at 25 yards.
Rom828
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I measured a box of Winchester white box ammo with a flat nose bullet and OAL was .945. OAL for the RN shows a max of .984. The difference is needed for the round to engage the feed ramp and properly chamber.
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