Danged Pinholes
- Thread starter Chris C
- Start date
Chris, at this point I would take what you have and see how they shoot. Try a few different loads. Figure that rifle out.
I would personally shoot a reasonably soft alloy with your current load. Like a 1.5Sb, .5Sn alloy. That loads doesn't generate lots of pressure so with good fit the rifle should be happy with a softer alloy.
I would also look at size diameter. Don't go too big.
I would personally shoot a reasonably soft alloy with your current load. Like a 1.5Sb, .5Sn alloy. That loads doesn't generate lots of pressure so with good fit the rifle should be happy with a softer alloy.
I would also look at size diameter. Don't go too big.
Chris C
Active Member
I'm embarrassed to say, Brad, I don't know how to come up with what you've suggested. I know what I have, but don't know how to "get there".
My barrel slugs at .3762" and I size my bullets to .377". With this bullet, my rifle likes 9.75gr Unique. Here's 10 shots at 50 yds off bags with that load.
My barrel slugs at .3762" and I size my bullets to .377". With this bullet, my rifle likes 9.75gr Unique. Here's 10 shots at 50 yds off bags with that load.
Ian
Notorious member
Your rifle might like Unique (I haven't met a rifle that didn't), but it doesn't like your bullet very much. Another opportunity to explore here: Groove dimension has no bearing upon the size of die you should select for your lube/sizer. The throat and chamber neck area are where you will find the important data regarding bullet shape and fitment. If you get the alloy and fitment more in line with what Unique likes in that rifle, and figure out just how much Unique to use, you should easily get MOA at 50 yards with that rifle.
This is starting to sound like trying to reinvent the wheel. From what I gather from your posts your happy with your current load, your groups are good and what your concerned with is the pin holes (solved) and increasing your keeper rate by casting better bullets. Working on your casting rhythm will no doubt make further improvements.
What Fiver was referring to is a Sn percentage higher than the Sb percentage which is exacerbated by casting too hot with too hot of a mold. (solved) If you do experiment with your alloy keep the tin lower than the antimony, never higher. Free tin in an Pb/Sb/Sn alloy can cause problems including tinning the barrel.
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What Fiver was referring to is a Sn percentage higher than the Sb percentage which is exacerbated by casting too hot with too hot of a mold. (solved) If you do experiment with your alloy keep the tin lower than the antimony, never higher. Free tin in an Pb/Sb/Sn alloy can cause problems including tinning the barrel.
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Ian
Notorious member
Here are some things to try. Drop back to seven grains of Unique next outing with the alloy you're using, and size your bullets to a few ten-thousandths smaller than the throat entrance, assuming your rifle actually has a step between chamber neck and throat entrance. In other words, make them as fat as you can make them and not bind the chamber neck. You need about a thousandth clearance minimum for safe bullet release from the neck. Also, give the bullet about ten thousandths distance to contact with the throat when a loaded cartridge is chambered. Work up from seven grains to about 7.8 in .2 grain increments. You might also try increasing the bullet jump in .005" increments and make some detailed observations.
OR
Switch to Alliant 2400 and start in around 14-15 grains and work up until you either close up the groups to a small hole or start crowding the pressure ceiling of your cartridge. It would be good to get out of that transonic rut you're in, and put pressure to the alloy you have a little differently. 2400 will tolerate you actually contacting the bullet to the throat, but still might not give the best groups, you'll have to try it both ways.
OR
Switch to Reloder 7 and start in the low 20's.
All this will get the peak pressure in different places, but get about the same peak pressure to start. Your alloy will show a distinct preference for one of these workups. That should tell you something about that alloy.
After that, go back to Unique and dilute your alloy as Brad suggested.
OR
Switch to Alliant 2400 and start in around 14-15 grains and work up until you either close up the groups to a small hole or start crowding the pressure ceiling of your cartridge. It would be good to get out of that transonic rut you're in, and put pressure to the alloy you have a little differently. 2400 will tolerate you actually contacting the bullet to the throat, but still might not give the best groups, you'll have to try it both ways.
OR
Switch to Reloder 7 and start in the low 20's.
All this will get the peak pressure in different places, but get about the same peak pressure to start. Your alloy will show a distinct preference for one of these workups. That should tell you something about that alloy.
After that, go back to Unique and dilute your alloy as Brad suggested.
Ian
Notorious member
You were bumping 25K and Unique peaks very fast. Your alloy didn't like that in combination with bullet shape and how it was fitting the throat.
Do you know why very soft lead works with black powder? Think about bullet designs that are typically successful with BPCR. Mull that over instead of worrying about BHN. I know, tough crowd. It's late and I'm trying to keep posts short and to the point.
Chris C
Active Member
Lots of information there, Ian. Thanks for all of it. Honestly, I don't know the measurement of my throat entrance! When I first got my rifle, I tried to do a pound cast and it took me 3 days to get the action open............and I didn't even get a good pound cast! Needless to say, it scared me enough that I didn't try it again. The only thing I've done is to slug the barrel. I'm not familiar with too many of the bullets used in BPCR, but the bullet I used for the target in post #17 was an Accurate Molds copy of a Lyman 375166. ( http://accuratemolds.com/bullet_detail.php?bullet=38-320E-D.png ) I'm going to contact the fellow who sent me the bullets and ask what his alloy mixture was. They sure did shoot nice in my rifle.