View Full Version : Bottom Limit of Powder Charge?
Good afternoon,
I'm working up a plinking/close-range load with Benchmark using 55gr Hornady FMJ's out of a 16" Noveske Rogue Hunter barrel (Noveske Match Mod0 chamber). I started at 24.0gr (starting load obtained for the "55 GR. SPR SP" projectile from Hodgdon's reloading data site) and have been working down from that in order to obtain a load using the least amount of powder that would still cycle the action and lock back on an empty magazine reliably.
Using this same methodology with 8208 XBR powder, as I went lower in powder charge, the brass would become sooted up progressively down the neck and body of the case as I went to lower and lower powder charges. So, I set my powder charge at the lowest amount of powder that would only allow the case neck to become sooty.
Even at 21.5gr of Benchmark, I never observed the body of the cases becoming covered with residue, and the action still cycles reliably and locks back on an empty magazine. Should I keep going lower until something gives, or is this a dangerous strategy to employ (meaning I should just keep it at the minimum charge Hodgdon recommends)?
Thanks for the help,
tw
May I ask why? Most of my experience involves max or near max loads for best accuracy. I would not go below Hodgdon's min unless you really know what you are doing.
Also, is there a reason you using extruded powder for 55gr FMJ's? Extruded powders are typically only used for match loads. Try some ball powder for cheap 55gr FMJ's. It's typically cheaper too.
I get this stuff on BPS points and all they carry locally is extruded powders when I've gone in and looked. In other words, free extruded costs less than cheap ball.
As to 'why' I'm doing this, it's mainly for ammo used at indoor matches (<50yds) and for practicing (again, <50yds most of the time, definitely <100yds). The less powder I can get away with and have safe, reliable operation of the firearm, the better in terms of cost per round and for wear and tear on the mechanism. All-around 'win', unless I'm shooting for accuracy at distance. At least, that's the theory behind it.
I thought I read somewhere a long time ago that very small charges of slower (that is rifle) powders in a case with a lot of room can detonate. I would talk to the powder manufactures before going too low.
Leaveammoforme
02-04-15, 17:02
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lonestardiver
02-04-15, 21:32
Yes small charges of powder can detonate... H110 is a good example if I recall correctly.
I understand the economy of what you are trying to do...is 3 grains of powder per round going to make a huge savings gain?
3 grains > 10%, so, in my mind, non-negligible. However, that's not the only reason for trying to minimize powder used (within safe limits); I'd also like to use as light a load as possible for reasons of minimizing wear as well (and a light-shooting load isn't a bad thing for gun games either, is it?).
Weeeelll, I'm asking so that I can find out what happens when you go below published charges. Only one way to find that out without doing it myself and destroying a firearm and possibly injuring myself. So...just the facts please. All I needed was you to say that low loads have an increased chance of hang fires due to such-and-such a reason. Thanks, bub. Have a good'n.
Correct. The charge weight doesn't only have to do with cycling a semi action and getting a projectile through the bore. It also has to do with volume of case filled. Obviously different powders have different volume at a given weight.
If you have to ask....then you should not be going below published charges. Some of my most accurate loads are near the bottom of charge range in 223. No reason to go any lower. 1-2 grains of powder will not break the bank. You can have roughly 350 accurate loads or 370 that may hang fire and get someone hurt.
You're not getting enough pressure for the case to fully expand before the ash fills the chamber and case. There's a loading tip an older reloader shared with me that works for some powders, but not all. You take a sized case, fill it up to the top with the powder you want to use. Weigh the powder. Multiply that number by .803 (80.3%). That will give you a mild load that will be close to an optimal barrel time node. Check it against published data to make sure your not over max. Adjust the seating depth till you get the accuracy you want.
I've used this method to fireform converted cases. It nice to get sub-moa accuracy while fireforming cases. I've also checked it against all of my hand loads using QuickLoad and measured case capacities to estimate any dangerous pressures. Id be more cautious with ball powders as if seen some be over max and some pretty far under min loads. Wouldn't do it with powders that are not listed in published data for that caliber and bullet.
I also use it to get a measure of velocity for adjusting the burn rate in QuickLoad when changing lots of powder.
Leaveammoforme
02-04-15, 22:38
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"If someone has to ask, they should not do it"... You learn by asking questions. And if someone has to ask because they don't know, then they are being smarter than those who would go about it without asking if anyone has tried before them.
I would not do this at all. Benchmark has only done well for me at the top end... around 25 grains. Going low is doable in that the powder is somewhat bulky. But when you're getting blow by because the case isn't expanding, then you're changing the function of the system to some extent... and allowing fouling and stuff back into the bolt area.
But that's the thing; I'm not getting blow-by with Benchmark. I did with lower charges of XBR. The cases are shiny and clean all the way up to the neck with Benchmark. I'd never want to load a case that was getting blow-by even down on thee case's body, for the reason you stated; fowling in the bolt area, and (potentially) increased chamber fowling.
After getting this feedback, I think I'll probably just load around 23.0 or 24.0 gr and, maybe, at some point see what the accuracy works out to, if I get some time on my hands.
Thank you for the assistance, gentlemen.
I would not do this at all. Benchmark has only done well for me at the top end... around 25 grains. Going low is doable in that the powder is somewhat bulky. But when you're getting blow by because the case isn't expanding, then you're changing the function of the system to some extent... and allowing fouling and stuff back into the bolt area.
I would normally be with you on 23 or 24 gr. But when I run Benchmark it just seemed to group a little better on the hot end. If it's short range blaster ammo, I suppose it doesn't matter too much though.
I would normally be with you on 23 or 24 gr. But when I run Benchmark it just seemed to group a little better on the hot end. If it's short range blaster ammo, I suppose it doesn't matter too much though.
All of the extruded powders I've tried (XBR, Varget, H322, Benchmark) seem to group best at or around the max recommended load.
What's the standard for ball powder to be used in short-range plinking/practice ammo? TAC? Something else?
All of the extruded powders I've tried (XBR, Varget, H322, Benchmark) seem to group best at or around the max recommended load.
What's the standard for ball powder to be used in short-range plinking/practice ammo? TAC? Something else?
AA2230 has worked very well for me, but I haven't seen it in a while. It is kind of dirty though.
For the most part, I don't really have a preference on ball ammo as I only use it for 55gr FMJ ammo, but the cleaner the better. Right now I have a lot of TAC, so I'm starting to load that. H335 is another popular option.
W748 and TAC are nice. H335 is flashy as hell... but suited for 55s.
I get almost all of my powder via bass pro rewards points, so I have to work with what they have available, and I've never seen a pound they sold that wasn't $32.99 or $34.99. BUT, expensive/free (without having to go through the trouble of selling it after I purchase it) is much cheaper than paying $25 cash. Otherwise, I'd use 'cheap' ball powders I could find.
W748 and TAC are nice. H335 is flashy as hell... but suited for 55s.
You're essentially following the same process as people who are determining sub-sonic rounds that can still cycle the action and doesn't cross into supersonic. When I developed my subs for .300 I started at the published medium for sub-sonic and went down in .2 increments. When the action didn't cycle, I knew that the previous load was the lowest that would work.
Anyway, if you want a comparison between benchmark and any other powder let me know your bullet, barrel length, twist, coal base to tip, and case capacity in H2O grains.
Thanks a lot, Wyo. Will let you know if I need a comparison. I appreciate it.
You're essentially following the same process as people who are determining sub-sonic rounds that can still cycle the action and doesn't cross into supersonic. When I developed my subs for .300 I started at the published medium for sub-sonic and went down in .2 increments. When the action didn't cycle, I knew that the previous load was the lowest that would work.
Anyway, if you want a comparison between benchmark and any other powder let me know your bullet, barrel length, twist, coal base to tip, and case capacity in H2O grains.
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