Compressed loads

[Ldigio21]

I have noticed that as I approach max loads the ES and SD improve. Some of my most accurate groups are where I wandered into pressure that was too hot and had to back off.
What I see consistently though is when filling the case to the neck with powder velocity and accuracy are the best.
Anyone else notice this?

 

[tydaws]

Yes Sir. More times than not, I seem to get the best ES & SD measurements with high load density.

 

[memtb]

While not as experienced as many here, as I primarily shoot and load for only one rifle. But, I've had really good accuracy with two different powders, both compressed…..one extremely so. memtb

 

[nealm66]

The only problem I've had is with long bullets like 245 bergers or 250 Atips and Lincoln log powder like n570 will seriously mess with concentricity.

 

[Chesterrose79]

Tipicaly a cartridge will perform better when there isn't much room left in the case. I've heard of some ELR guys using Kleenex to stuff inside the cartridge to compress the powder more. When you think about it when a cartridge of ready to be fired it's laying down. The air gap would be at the top. So the powder would burn slightly different at the top than bottom. A compressed load would burn more constantly.

 

[bfarms]

Yes. I run most of mine full. Just have to find the powder that will let me do it kinda safely lol. I just think it's from a more uniform burn as stated above.

 

[MagnumManiac]

There is a lot to be learned by the 'packing scheme' of the cartridge. Loose powder will burn differently from shot to shot.
This is why when you pick a load that is compressed, you use a technique called 'swirling' the powder charge into the case using a funnel. It causes powder to settle more uniformly changing the internal ballistics. You can see this yourself, pour powder in with a funnel, let it bridge and fall normally, then hold the funnel at an angle, pour the powder so that it rotates like a tornado around the funnels axis and then look at the powder height in the case…

Cheers.

 

[Ldigio21]

There is a lot to be learned by the 'packing scheme' of the cartridge. Loose powder will burn differently from shot to shot.
This is why when you pick a load that is compressed, you use a technique called 'swirling' the powder charge into the case using a funnel. It causes powder to settle more uniformly changing the internal ballistics. You can see this yourself, pour powder in with a funnel, let it bridge and fall normally, then hold the funnel at an angle, pour the powder so that it rotates like a tornado around the funnels axis and then look at the powder height in the case…

Cheers.

I use a 4" drop tube and pour the powder in slowly. Loads seem to appear the same height in the neck from case to case.

 

[MagnumManiac]

I use a 4" drop tube and pour the powder in slowly. Loads seem to appear the same height in the neck from case to case.

Works similar but swirling is considerably faster.
I tried different methods and this was the most consistent, even better than a vibrating plate because the powder didn't spill.

Cheers.

 

[FEENIX]

I have noticed that as I approach max loads the ES and SD improve. Some of my most accurate groups are where I wandered into pressure that was too hot and had to back off.
What I see consistently though is when filling the case to the neck with powder velocity and accuracy are the best.
Anyone else notice this?

Yes. I run most of mine full. Just have to find the powder that will let me do it kinda safely lol. I just think it's from a more uniform burn as stated above.

Yes, that's why some reloading manuals provide an approximate fill ratio. However, each powder behaves differently and has its optimum performance level, as Berger shows below.

If I can help it, below is my bullet seating depth preference.

(.338 Thor - NMI with 300 Berger .015" off the lands, 3.7" COAL).

 

[AZShooter]

I use several compressed loads. At one point I had a load so compressed the bullets would move out of the case after a short time of sitting! Either less powder or more neck tension was in order.

My friend told me his father used to buy bulk H4831 from Jensen's gunstore in Tucson back in the 60s. The powder was sold in bulk and you would leave with a large paper bag full of powder for very little outlay. His father would dip his 270 cases into the powder, scrape off the excess at the neck and seat a 130 gr bullet! Hows that for compressed loads?

 

[Varmint Hunter]

I avoid compressed loads, other than very mild compression. Compressed loads cause a variation in seating depth and can move bullets back out over time. Neither condition is ideal.

If you can actually hear or feel powder kernels crunching than the compression is excessive.

This is just my opinion based on my experience. Your mileage may vary.

 

[Bob Wright]

% case fill is a thing. Lol. It is all about efficiency. Lots of data and actual reloading to see what powder fills to what % of the brass volume at charge weight. Nosler load data shows this as one example.

 

[MagnumManiac]

I avoid compressed loads, other than very mild compression. Compressed loads cause a variation in seating depth and can move bullets back out over time. Neither condition is ideal.

If you can actually hear or feel powder kernels crunching than the compression is excessive.

This is just my opinion based on my experience. Your mileage may vary.

Many compressed loads, more so than not actually, are the most accurate and consistent because there is no air space that allows the powder to move into when the primer blast flows through the powder or over the top of it. Compression has no ill effects on the powder itself even if you hear crunching…

Cheers.