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Bullet contacting powder during seating 6. 5 Creedmoor
- Thread starter badmatrix
- Start date
Jim Watson
New member
Compressed loads of extruded powder are ok if within the normal range of weight for the round. What is IMR 2350?
I assume you mean imr 4350. If so, yes this is most likely a compressed load. Looking at data for that bullet with imr 4350 it shows as a compressed load at max.
Compressed loads can make getting consistent seating depth difficult in my experience. But its not uncommon or unsafe, provided you are within published data and work your loads up. Personally i avoid compressed loads whenever i can as i have found them to be more trouble than they are worth.
Compressed loads can make getting consistent seating depth difficult in my experience. But its not uncommon or unsafe, provided you are within published data and work your loads up. Personally i avoid compressed loads whenever i can as i have found them to be more trouble than they are worth.
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Yes. If you look through Hodgdon's load data for the 6.5 CM, they list the 143-grain ELDX, and you will see the maximum load of IMR 4350 is 42.8 grains, and the capital letter "C" is next to it. C stands for compressed.
Heavily compressed loads can distort cases or damage the seating ram of the Redding Competition Seating Die (whose instructions warn against using it for compressed loads). However, a lightly compressed load has the advantage of locking the powder into position. In the literature, you can find examples of loads that change performance due to vibration from transport, settling the powder into a denser pack. A slightly compressed load is not easily compacted by vibration because of that locking effect. All the Federal GM308M ammunition with 168-grain MatchKing bullets that I've ever pulled down were always lightly compressed loads. Some powders seem immune to the packing effect, while others see measurable changes, and you just have to try them to see what happens with your component combination. Assemble some at home and drive around with them in your vehicle for a couple of weeks before going to the range and comparing them to the same load assembled with hand tools at the shooting bench under those same conditions. A chronograph will tell you if the performance is different, though one author actually got sticky bolt lift from the ones assembled at the range (a high-pressure sign).
Heavily compressed loads can distort cases or damage the seating ram of the Redding Competition Seating Die (whose instructions warn against using it for compressed loads). However, a lightly compressed load has the advantage of locking the powder into position. In the literature, you can find examples of loads that change performance due to vibration from transport, settling the powder into a denser pack. A slightly compressed load is not easily compacted by vibration because of that locking effect. All the Federal GM308M ammunition with 168-grain MatchKing bullets that I've ever pulled down were always lightly compressed loads. Some powders seem immune to the packing effect, while others see measurable changes, and you just have to try them to see what happens with your component combination. Assemble some at home and drive around with them in your vehicle for a couple of weeks before going to the range and comparing them to the same load assembled with hand tools at the shooting bench under those same conditions. A chronograph will tell you if the performance is different, though one author actually got sticky bolt lift from the ones assembled at the range (a high-pressure sign).
BTW, you will note that compressed loads are shown for stick powders but not for spherical powders. They are more dense and don't compress well. Moreover, the Norma manual says:
Obviously, if a gun is pointing downhill, the gap is then between the case head and the powder rather than between the powder and the bullet, so it doesn't actually matter where the space is. Further, from their description of the reason this does not apply to extruded powders, the space that is always in some adequate measure between the grains. This suggests the compression needs to be fairly firm to cause the problem because there is always some space, even between spherical grains, but a quick glance at load data doesn't appear to have anyone compressing spherical propellants, so this must be known in the industry. The one exception I can think of is Hornady used to make a line of Light Magnum ammunition, which had highly compressed loads of spongy, elastic spherical powder that expanded and overflowed the cases when a bullet was pulled. But that stuff was so soft it would not carry a shockwave well, and the sponginess probably meant there was a fair amount of gas space within the grains. In any event, that product line is gone, and the powder was never on the reloading market because conventional handloading tools couldn't do the compression.
Norma 2013 Reloading Manual said:One of the disadvantages of a ball powder is it must not be compressed. There must always be a small air gap between the powder and the projectile into which the initially generated gasses can expand. If the charge is compressed, there can be pressure waves within it of such magnitude as to damage the weapon.
Obviously, if a gun is pointing downhill, the gap is then between the case head and the powder rather than between the powder and the bullet, so it doesn't actually matter where the space is. Further, from their description of the reason this does not apply to extruded powders, the space that is always in some adequate measure between the grains. This suggests the compression needs to be fairly firm to cause the problem because there is always some space, even between spherical grains, but a quick glance at load data doesn't appear to have anyone compressing spherical propellants, so this must be known in the industry. The one exception I can think of is Hornady used to make a line of Light Magnum ammunition, which had highly compressed loads of spongy, elastic spherical powder that expanded and overflowed the cases when a bullet was pulled. But that stuff was so soft it would not carry a shockwave well, and the sponginess probably meant there was a fair amount of gas space within the grains. In any event, that product line is gone, and the powder was never on the reloading market because conventional handloading tools couldn't do the compression.
You might be getting a compressed load with that powder charge because you indicated that you are seating at 2.8010. That is 0.009 shorter than SAMMI recommended OAL.
I find that with the long ELD-X bullets, you should expect that the OAL should be longer than normal recommendations because the tip is so long.
There is about 0.622 inches of bullet tip in front of the ogive, with a bullet body of about .810 inches. That would leave 0.541 inches of bullet in the neck at the stated OAL.
Even if the OAL you listed was a typo and you actually seated at 2.810, you still have a 0.532 length of bullet body back into the cartridge with that very long bullet, compared to an older type bullet with less of a pointy tip. Seat the ELD-X bullet out at least 0.010 longer at 2.820 and see if the compressed load goes away.
I suggest you do the same longer seating with ELD-M bullets also.
A 147 ELD-M has a bullet base to tip of 1.464 with a Base to Ogive of 0.800.
A 143 ELD-X has a bullet base to tip of 1.432 with a Base to Ogive of 0.810
A 140 ELD-M has a bullet base to tip of 1.371 with a Base to Ogive of 0.700.
All have a 0.175 boat tail.
As a comparison with an older design bullet, the 140 gr. SMK has a bullet base to tip length of 1.304 so at a 2.801 OAL there would only be .502 inches in the cartridge to compress the charge.
0.04 inches could be the difference between a compressed load and not having a compressed load.
I find that with the long ELD-X bullets, you should expect that the OAL should be longer than normal recommendations because the tip is so long.
There is about 0.622 inches of bullet tip in front of the ogive, with a bullet body of about .810 inches. That would leave 0.541 inches of bullet in the neck at the stated OAL.
Even if the OAL you listed was a typo and you actually seated at 2.810, you still have a 0.532 length of bullet body back into the cartridge with that very long bullet, compared to an older type bullet with less of a pointy tip. Seat the ELD-X bullet out at least 0.010 longer at 2.820 and see if the compressed load goes away.
I suggest you do the same longer seating with ELD-M bullets also.
A 147 ELD-M has a bullet base to tip of 1.464 with a Base to Ogive of 0.800.
A 143 ELD-X has a bullet base to tip of 1.432 with a Base to Ogive of 0.810
A 140 ELD-M has a bullet base to tip of 1.371 with a Base to Ogive of 0.700.
All have a 0.175 boat tail.
As a comparison with an older design bullet, the 140 gr. SMK has a bullet base to tip length of 1.304 so at a 2.801 OAL there would only be .502 inches in the cartridge to compress the charge.
0.04 inches could be the difference between a compressed load and not having a compressed load.