Andy
01-24-2015, 12:48 AM
Hi everyone, this data may not be overly useful to the more experienced guys on here but I figured it might help out the new guys like me. I have learned so many great things from this board I wanted to share the wealth in whatever small way I can initially. Here is my bullet weight data from my 2nd ever casting session. This is my first casting session with the Lee 4-20 bottom pour pot, first time was with a borrowed cast iron pot and ladle so this includes me learning the ropes with this thing. Should at least be an easy-to-beat benchmark for anyone planning out what to get/what to plan on for yield.
Couple questions at the end if you feel like looking at them.
Info:
- Lee 4-20 bottom pour pot (pour spout was honed with valve grinding compound based on advice from this forum (thanks), almost completely eliminated the dripping.
- COWW +2% tin ingots into pot
- Pot kept at 700-800 degrees according to lyman stick thermometer
- Lee 120-tc 6 cavity mold
- Fluxed at start and at 1/2 full mark with frankfort no-smoke flux
- probably had at least 10% inefficiency due to technique mistakes from learning the new bottom-pour style
- Ohaus 10-10 scale
Bullet data:Total of 234 bullets measured- Center mass was roughly 116.5 grains so I divided into the following categories:
- Main group 116.0-117.0: 167 bullets
- High weight 117.0+-117.5: 21 bullets
- Low weight: 115.5-116.0-: 8 bullets
- Anything outside those numbers became a cull, also the "low weight" quantity would have been higher but I realized many of them were culls (rounded base) once I noticed the weight.
- 38 of the 167 main batch met my arbitrary "match grade" requirement of 116.4-116.6gr and also passed a detailed visual inspection. In this group, anything that had any minor inconsistent defect was returned to the main group. All bullets passed a visual inspection (no wrinkles etc) but the "match grade" inspection was very stringent. I have no competition plans but will use these once I am testing loads for accuracy.
- There were at least 5 "can't explain it" out-of-range over or under weight bullets. Everything looked fine but the light ones must have had an air bubble and I can't explain the heavy ones.
I would have had wider-range low/high groups but that was the most I could accurately discern with the scale tick marks without changing the weight on the scale itself. I started with a shorter weight range and 5 groups instead of 3 but realized I don't want to be sorting 9mm bullets into 5 categories given my intended purpose (mostly defensive training). After weighing I packaged into "standard," "plinking," (high and low groups) and "match" boxes, which seems to fit my purpose for this gun.
For what it is worth I had at least 15 lbs of lead in the pot and once you calculate it out, only 25% of that became bullets (between sprues, bullets scrapped when heating the mold, 10-20 glaring obvious culls, drip/overflow waste, couple pounds left in the bottom of the pot when done etc). And factoring for final culls only about 18-20% of the total weight became useable bullets. So, I can see why you don't want a 10lb pot, glad I have a 20 as this batch size is reasonable to me.
I didn't re-introduce sprues/culls to the pot as I was going, which could be done to increase yield before re-heat, wanted to see what I got out of a known weight.
Lessons learned:
- Aim the pour flow toward the handle side of the bevel on each sprue plate taper, this seemed to be a big deal to help fill the mold better and keep overflow from ruining the next bullet in sequence (pushing mold in toward the pot, not pulling).
- Setting 3-4 kept the alloy at 700-800 degrees (need to refine this more) with a full pot through half pot.
- With a 3/4 full pot of previously melted and cooled alloy, it took less than 15 min to get up to 700 degrees on the highest setting on the pot. This was great news based on what I had read.
- Using this pot was way more pleasant than casting over a stove pot with a ladle, much less heat on the user and far easier to get good pours with. Really worth the $60 unless you just can't spare it.
Questions:
- Are my weight categories reasonable given the purpose? Figure I would like the weight itself (ignore other factors) to affect groups less than 1" at 25 yds. Figure a 3-4" group is normal with this gun off bags.
- I kept having problems with the 1st and 2nd cavity (farthest away as you hold the mold) not filling out the bases fully (needed to be culled ~75% of the time), any ideas/tips?
- Very sick of bullets not falling from the mold, at least half the time I had to tap the bolt to get them to drop, is this normal and I just have to deal with it or is there a solution? With the 6 cavity your second hand is on the sprue handle so it is pretty slow/annoying to have to let go and pick up a mallet to tap the handle bolt. I smoked the mold but probably not as well as I should have.
Thanks, hope this is useful to someone
Andy
Couple questions at the end if you feel like looking at them.
Info:
- Lee 4-20 bottom pour pot (pour spout was honed with valve grinding compound based on advice from this forum (thanks), almost completely eliminated the dripping.
- COWW +2% tin ingots into pot
- Pot kept at 700-800 degrees according to lyman stick thermometer
- Lee 120-tc 6 cavity mold
- Fluxed at start and at 1/2 full mark with frankfort no-smoke flux
- probably had at least 10% inefficiency due to technique mistakes from learning the new bottom-pour style
- Ohaus 10-10 scale
Bullet data:Total of 234 bullets measured- Center mass was roughly 116.5 grains so I divided into the following categories:
- Main group 116.0-117.0: 167 bullets
- High weight 117.0+-117.5: 21 bullets
- Low weight: 115.5-116.0-: 8 bullets
- Anything outside those numbers became a cull, also the "low weight" quantity would have been higher but I realized many of them were culls (rounded base) once I noticed the weight.
- 38 of the 167 main batch met my arbitrary "match grade" requirement of 116.4-116.6gr and also passed a detailed visual inspection. In this group, anything that had any minor inconsistent defect was returned to the main group. All bullets passed a visual inspection (no wrinkles etc) but the "match grade" inspection was very stringent. I have no competition plans but will use these once I am testing loads for accuracy.
- There were at least 5 "can't explain it" out-of-range over or under weight bullets. Everything looked fine but the light ones must have had an air bubble and I can't explain the heavy ones.
I would have had wider-range low/high groups but that was the most I could accurately discern with the scale tick marks without changing the weight on the scale itself. I started with a shorter weight range and 5 groups instead of 3 but realized I don't want to be sorting 9mm bullets into 5 categories given my intended purpose (mostly defensive training). After weighing I packaged into "standard," "plinking," (high and low groups) and "match" boxes, which seems to fit my purpose for this gun.
For what it is worth I had at least 15 lbs of lead in the pot and once you calculate it out, only 25% of that became bullets (between sprues, bullets scrapped when heating the mold, 10-20 glaring obvious culls, drip/overflow waste, couple pounds left in the bottom of the pot when done etc). And factoring for final culls only about 18-20% of the total weight became useable bullets. So, I can see why you don't want a 10lb pot, glad I have a 20 as this batch size is reasonable to me.
I didn't re-introduce sprues/culls to the pot as I was going, which could be done to increase yield before re-heat, wanted to see what I got out of a known weight.
Lessons learned:
- Aim the pour flow toward the handle side of the bevel on each sprue plate taper, this seemed to be a big deal to help fill the mold better and keep overflow from ruining the next bullet in sequence (pushing mold in toward the pot, not pulling).
- Setting 3-4 kept the alloy at 700-800 degrees (need to refine this more) with a full pot through half pot.
- With a 3/4 full pot of previously melted and cooled alloy, it took less than 15 min to get up to 700 degrees on the highest setting on the pot. This was great news based on what I had read.
- Using this pot was way more pleasant than casting over a stove pot with a ladle, much less heat on the user and far easier to get good pours with. Really worth the $60 unless you just can't spare it.
Questions:
- Are my weight categories reasonable given the purpose? Figure I would like the weight itself (ignore other factors) to affect groups less than 1" at 25 yds. Figure a 3-4" group is normal with this gun off bags.
- I kept having problems with the 1st and 2nd cavity (farthest away as you hold the mold) not filling out the bases fully (needed to be culled ~75% of the time), any ideas/tips?
- Very sick of bullets not falling from the mold, at least half the time I had to tap the bolt to get them to drop, is this normal and I just have to deal with it or is there a solution? With the 6 cavity your second hand is on the sprue handle so it is pretty slow/annoying to have to let go and pick up a mallet to tap the handle bolt. I smoked the mold but probably not as well as I should have.
Thanks, hope this is useful to someone
Andy