Bullet weight to case pressure and more questions [Archive] - Glock Talk

PDA

View Full Version : Bullet weight to case pressure and more questions


CAH21SF
08-29-2011, 20:54
1)Im new to reloading and have question about bullet weight to case pressure. I am currently reloading .45 's and I have seen a common pattern of the higher weight bullets with lower powder ranges compared to the same bullet design but lighter weight with just a tad bit more for its powder range. Is this because it takes more energy to move the heavier bullet?
2) Brass, I have read the thread on good and bad brass. Now if you have several makes of brass of all three categories. How does this affect the accuracy of the load or what difference would I see?
3) Maximum published load, if im not seeing over pressure issues in a load that was at the maximum charge. Can I consider that a safe load to shoot consistently?
4) Last and final question. When testing a load for accuracy do I test at a range that I am most accurate at and hope it to be accurate at a futher range? I am currently (sad to say) most consistent at a measly 20 feet. I cant shoot for s%^& at 25 yards. What are your thoughts other then the obvious (more practice)?
Thanks
Chris

PCJim
08-29-2011, 22:25
1)Im new to reloading and have question about bullet weight to case pressure. I am currently reloading .45 's and I have seen a common pattern of the higher weight bullets with lower powder ranges compared to the same bullet design but lighter weight with just a tad bit more for its powder range. Is this because it takes more energy to move the heavier bullet? What you are observing is correct. For a given powder, you will use less charge for a heavier bullet. Max pressure is determined by SAAMI for every cartridge. Physics states that it takes slightly longer (microseconds) to move a heavier object compared to a lighter object, given the same force being exerted (pressure). Max pressure is developed, not while the bullet is still in the case, but after the bullet has begun moving down the barrel. If you use the same powder charge for a heavy bullet as for a lighter bullet, the developed pressure will be greater with the heavier bullet because the heavier bullet cannot be moved as fast down the barrel to provide the required increasing volume in the barrel (behind the bullet) within which to relieve the pressure.
2) Brass, I have read the thread on good and bad brass. Now if you have several makes of brass of all three categories. How does this affect the accuracy of the load or what difference would I see? For general plinking loads, it has no noticable effect. Especially at the distance you refer to in #4. If loading for long distance accuracy, you would want to sort your brass and use only the best you can. In the case where you are trying to make a bug hole at 300 yds., consistency in case volume, bullet weight, COL, etc all make a big difference
3) Maximum published load, if im not seeing over pressure issues in a load that was at the maximum charge. Can I consider that a safe load to shoot consistently? Yes, FOR THAT FIREARM. THAT BEING SAID, you are obviously new to this hobby. I strongly caution you to stay away from full house loads until you have a very firm knowledge of what to look for in pressure signs, and have some experience under your belt. A simple distraction can easily result in some bad juju.
4) Last and final question. When testing a load for accuracy do I test at a range that I am most accurate at and hope it to be accurate at a futher range? I am currently (sad to say) most consistent at a measly 20 feet. I cant shoot for s%^& at 25 yards. What are your thoughts other then the obvious (more practice)? You cannot reasonably test accuracy at 7 yds. You reload to your capabilities. If you cannot hit a 6" bull at 25 yds, what good is a super accurate round? You are probably referring to your capabilities while shooting freehand. Try using a rest and see if your accuracy improves. If it does, then you can start pursuing a more accurate handgun load.
Thanks
Chris

Hope that is somewhat clear....

CAH21SF
08-29-2011, 22:54
You were crystal clear thanks. You hit it right on the head im shooting freehand. Would a sandbag work?
Thanks again
Chris

Outdoor Hub mobile, the outdoor information engine

PCJim
08-30-2011, 12:13
For most shooters, having an external device (ie sandbag) to help steady the firearm greatly improves accuracy.

fredj338
08-30-2011, 13:26
I'll agree w/ Jim on everything but max listed loads. While they SHOULD be safe, never assume, always work upto max loads. The problem is they are tested in a diff platform & often slightly diff components, So when going to max loads, everything can affect presures from OAL to primer, bullet & case choice.
Accuracy testing @ anthing less than 50ft is pointless IMO. Just about any gun & ammo will shoot one ragged hole @ 21ft. So sand bag rest, the forearms not the gun, & test @ a min of 50ft. Accuracy is relevant. If you shoot factory ammo into 8" @ 25yds, then that is YOUR acuracy benchmark. If your reloads are under 8", they are shooting better than the factory.

CAH21SF
08-30-2011, 20:17
I'll agree w/ Jim on everything but max listed loads. While they SHOULD be safe, never assume, always work upto max loads. The problem is they are tested in a diff platform & often slightly diff components, So when going to max loads, everything can affect presures from OAL to primer, bullet & case choice.
Accuracy testing @ anthing less than 50ft is pointless IMO. Just about any gun & ammo will shoot one ragged hole @ 21ft. So sand bag rest, the forearms not the gun, & test @ a min of 50ft. Accuracy is relevant. If you shoot factory ammo into 8" @ 25yds, then that is YOUR acuracy benchmark. If your reloads are under 8", they are shooting better than the factory.


At my first session of shooting my first reloads I started at 3.7 up to 4.0gr each set increased by .1 incraments with 10 rounds of each. I inspected each one with no defects of any found.

Thanks for the info on accuracy testing. That's about the only thing I have came acrross in my reading of reloading. I was also wondering where to support gun/forearms, so thanks for that as well.

So I unloaded all of the 4.0 batch and reloaded at 3.7 being that was my most accuate after my second test. Im going backpacking this weekend, so i need plinking rounds. Being thatI was free handed on the first and second test sessions. I think I'll do a third supported and at a longer range.
:bowdown:
chris