Compressed charge

palmer_mike

Well-Known Member
Ok so my latest issue with reloading is......

I have prepared my cases by fl resizing trimming to book trim length chamfering and re-priming.
i have prepared a dummy round to book length which fits rifle and magazine well.

im now ready to fill the cases with powder in half grain steps from book start of 43gn to book max of 48gn.

i was just checking what the max load looked like in the case and it's flush with the case mouth!
to get a charge that is down below the neck (ie won't be compressed when I seat the bullet) I have to go down to 45gn).

do I just go from start load to 45gn and avoid compressing loads or do I go all the way up to book max and squash the powder in with the bullets (this concerns me a little).

all the best,
mike
 
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In case it makes any difference this is in .308win with 150gn hornady interlock. Federal once fired brass, fl resized and trimmed to book length. Powder is imr 4064.
using the lyman book I'm working on a start of 43gn and max of 48gn........
 
In case it makes any difference this is in .308win with 150gn hornady interlock. Federal once fired brass, fl resized and trimmed to book length. Powder is imr 4064.
using the lyman book I'm working on a start of 43gn and max of 48gn........

Change the book.

The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.
 
Change the book.

The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.

Which would seem to fit with what the case can hold without compressing the powder.........
but imr load data also gives start and maximum the same as the lyman book.

the lyman book does say the maximum charge would be compressed, I'm just surprised about the amount I'd have to compress it to get the bullet in!

also I was told to go for the data from the powder manufacturer as the most reliable.....

now unsure of what to do, might start at lyman/imr start load and stop at 45gn (which would not be compressed (a lot less rounds to test, lol)
 
Have you been testing progressively and getting no signs of pressure up until the compressed loads Mike, or are you loading a wide range of loads including the compressed loads in anticipation of testing them all at once?
If the second is the case then you might just get a satisfactory load long before you need to go that far and may end up pulling them.
 
Which would seem to fit with what the case can hold without compressing the powder.........
but imr load data also gives start and maximum the same as the lyman book.

the lyman book does say the maximum charge would be compressed, I'm just surprised about the amount I'd have to compress it to get the bullet in!

also I was told to go for the data from the powder manufacturer as the most reliable.....

now unsure of what to do, might start at lyman/imr start load and stop at 45gn (which would not be compressed (a lot less rounds to test, lol)

There are so many variables.... for instance if you use Norma cases rather than Fed you can get a couple more grains in.

I've used 47.5grs IMR 4064 in these (level with neck base) with a Sierra SP following the Speer Handbook, but using an OAL of 2.82".

45.0grs only made 2600 FPS.:oops:
 
Interesting fact. Over the 20 years I have been reloading the manufacturers have got far more cautious and I notice a lot of loads are now presented at reduced strength. Obviously afraid of litigation.

JCS here probably presents the simple answer in choosing a powder that fills the case better. 8X57 as usual makes good sense. I use VHT N140 usually. Lots of folks on here have moved to TR140 which usually required about 1Gr more.

Compressed loads by reputation are scary to work with as a novice but so long as you go carefully as you have described then you should be fine. (CAVEAT: You must be sure what you are doing is safe)

Work up slowly looking for signs of pressure. Flattened or cratered primers are usually the first indication.

Frankly you don't have to go nuts on a load with decent accuracy to shoot 100yd Deer. 1000 Yard target loads are a different animal all together.
 
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Have you been testing progressively and getting no signs of pressure up until the compressed loads Mike, or are you loading a wide range of loads including the compressed loads in anticipation of testing them all at once?
If the second is the case then you might just get a satisfactory load long before you need to go that far and may end up pulling them.

The second option,
I'm just preparing loads so I can test them progressively when I can next get use of a range for a few hours.
 
Change the book.

The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.


Lyman manual, an antique? You believe? Not for a second!

Taking the Hornady load at face value, with a 2.800" (SAAMI) COAL (assuming that's just right for the chamber throat which is dubious with factory rifles, their freebore usually being MUCH longer these days), and fairly heavy (Lapua or RWS) brass, QuickLOAD says that you get all of 50,233 psi PMax with 44.9gn IMR-4064 and the 150gn Hornady Interlock SP #3031, compared to the cartridge's SAAMI MAP (maximum average pressure, ie peak is allowed to exceed that) of 60,191 psi - not quite an efficient load, even though it'll suffice for any British deer at short ranges and may give excellent results in terms of precision etc. However, a typical factory rifle typified by Remington 700s is usually given a large amount of freebore these days which further depresses pressures and velocities, so you'd be unlikely to achieve that modest 50,000 psi taking pressures back into what was regarded as the norm in the early days of smallbore military rifles and crude smokeless propellants around 120 years ago!

A point which is constantly made in handloading manuals, and constantly ignored by most users, is that the combinations only apply when all listed components are used. In the Lyman data, that's a Remington case which comes from the factory pretty thin-walled and therefore with an enhanced internal capacity. For normal calculations and comparisons, as used for example in QuickLOAD, the exact case capacity is determined by weighing a fireformed unsized case empty followed by level-full with water to obtain the 'overflow water capacity', this then converted to volume in CCs. In my 'minimum-SAAMI' (ie 'tight') .308 match rifle chambers, the water capacity of fired cases varies from 56.0 to 57.4gn depending on make. In a relatively 'slack' factory rifle chamber, the Remington case capacity will be at least 57gn, possibly as high as 57.5gn, it being one of the thinnest on the market.

Stick those values into QuickLOAD, and you get a 105.8% charge fill ratio (with seated bullet at 2.800" COAL) and 59,323 psi with a 57gn H2O capacity case, 104.8% charge fill ratio and a computed 58,113 psi for a 57.5gn case. With a decent length drop tube on the powder funnel, allied to a slow charge pour and obtaining a swirl motion in the funnel top, I would expect the actual powder compression to be modest in both examples.

However, use the Lyman load with a heavy Lapua case, worse an IMI model at 56.0gn H2O capacity or less and things get a bit hairy with 108% fill-ratio and a PMax that exceeds the maximum allowed.

If anything in this mix can be described as 'antique', it's the powder as IMR-4064 was introduced by DuPont Industries in 1935 for military smallarms cartridges (hence its name Improved Military Rifle) and has changed little since. It's one of the most versatile propellants in its class and usually gives superb results in cartridges with similar characteristics to .308 Win - that's why it's been around for nearly 80 years and still sells well.

Right, what to do about powder up to the case-mouth? Mike, as JCS says use a modest length drop funnel - MTM does a reasonably priced multi-calibre kit incorporating a 4-inch funnel.

http://www.mtmcase-gard.com/products/reloading/powder-funnel-AF7.php

Forster does a longer (and considerably more expensive) metal drop tube model

http://www.forsterproducts.com/catalog.asp?prodid=700677

Both are available from Hannams Reloading Limited. The Forster funnel plus a slow / swirl pour will take the powder level down to the bottom of the neck. However, as noted, if you're using any case other than Winchester or Remington, drop that maximum load to 47gn anyway to take account of case volumes. As always, start well below and work up and look for good results rather than velocity for its own sake, unless you intend to take up 1,000 yard FTR match competition.
 
Data from powder manafacturors tends to be stiffer both because it's older and more likely to have measured pressure by CUP instead of more sensitive piezo and because some manafacturors are more risk averse nowadays. Also as joked by Hodgden in one of the manuals somewhere they like people to use more of their product!

As a beginner it's best to use the spefic data for your actual bullet from the manafacturors data eg Hornady in your case. Use the same components and you should be fine.

As you get more experienced you can compare different manafacturors data and make your own judgement eg vihtavuori publish stiff load data for modern cartridges, Nosler are optimistic on velocity and some loads are quite stiff, Speer are generaly accurate and used to publish quite stiff loads (eg 308 and RL15) Hornady are generally about bang on.
 
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As you get more experienced you can compare different manafacturors data and make your own judgement eg vihtavuori publish stiff load data for modern cartridges, Nosler are optimistic on velocity and some loads are quite stiff, Speer are generaly accurate and used to publish quite stiff loads (eg 308 and RL15) Hornady are generally about bang on.

Interesting that you find Viht quotes 'stiff' loads. I'd have said the exact opposite for many cartridges. In the case of .308 Win, many Viht maxima are weirdly low, in particular some N140 loads. If you look across the manuals, there is a large variation in Viht N140 and N150 loads for a single bullet.

Handloading Manual Data for 175-180gn Bullets and Viht N140/150 in .308Win
Source
Case / Primer
Bullet(s)
Barrel / Rifle
Max. Charge / MV
Vihtavuori
Lapua / unstated
175gn Berger / Sierra MK
610mm (24”) Test barrel
41.4gn N140 / 2,501 fps
43.5gn N150 / 2,573 fps
175gn Lapua Scenar-L
41.4gn N140 / 2,635 fps
42.1gn N150 / 2,638 fps
Sierra
Federal / F210M
175gn Sierra MK
26” / Savage 12 BVSS
No data N140
41.8gn N150 / 2,500 fps
Berger
Not declared
175gn var. Berger match
24” test barrel
42.1gn N140 / 2,490 fps
No data N150
Hornady
Hornady / F210
178-180 various
22” / Winchester 70
No data N140
42.7gn N150 / 2,400 fps
Nosler
Nosler / F210M
Various Nosler 180s
24” Lilja test barrel
43.0gn N140 / 2,547 fps
44.5gn N150 / 2,576 fps
Lyman
Rem / Rem 9½
175gn Sierra MK
24” test barrel
43.5gn N140 / 2,651 fps
45.5gn N150 / 2,701 fps
178gn Hornady A-Max
43.8gn N140 / 2,614 fps
45.2gn N150 / 2,637 fps
QuickLOAD-1
RWS / unstated
175gn Sierra MK
22” / Howa (2.795” COAL)
43.7gn N140 / 2,609 fps
46.0gn (C) N150 / 2,608 fps
QuickLOAD-2
175gn Sierra MK
22” / Howa (2.900” COAL)
44.9gn N140 / 2,626 fps
47.5gn (C) N150 / 2,638 fps


When one looks at older US manufactured propellants (or originally US manufactured, as no extruded varieties are made in the whole country anymore), all of the data are old. I have the main manuals going back 30-40 years and the same values are quoted today for most IMR powders for instance as four, five and six editions ago. So, unless the company has decided to do an across the board retest, they were all conducted back in the days of copper pellet measurements (CUP). In fact, precious few even used this type of pressure barrel when I started handloading, a much more common method in the '70s and '80s being case-head expansion, this very carefully measured and maximum loads based on the load preceding that which produced an expansion figure equal to or greater than a set value which was deemed to be too hot. When some of these published loads were later retested using pressure barrels they had to be revised downwards.

Another factor which affects maxima, is that the testers often don't test the charge weights you see in the manual. This is the case where results are shown in 500 or more usually 1,000 fps bands displayed as columns on the page. Half a dozen loads are prepared covering a likely range and fired in the test barrel with pressures and velocities recorded and graphed. (All done manually at one time, but it goes directly into a PC nowadays.) The top load may achieve or exceed the maximum allowed pressure, more likely doesn't. However, by graphing charge weights against velocities and pressures, a central straight line is drawn up through the dots and two things extrapolated from it - the charge weights that should give exactly 2,500, 2,600, 2,700 fps etc velocities as that is how the data is shown, and also at what point the central graph line would hit the maximum allowed pressure. Now imagine, that in a display that shows velocities in 1,000 fps steps and that on average 1.5gn powder takes you up a step, that central predictor line says you break 60,000 psi in .308 Win with a 1.4gn increase over the previous velocity based increase? eg 44.0gn is calculated to give 2,700 fps, but the 45.5gn needed for 2,800 fps runs at 60,200 psi on the graph line. Simple, the maximum charge as published becomes 44.0gn, not the more likely 45.4gn because that's what the manual's published page format dictates.

Say then that the bullet company starts to worry about the idiot who ignores all caveats and does something stupid with the data. A general downwards weighting might be applied to protect the manufacturer, or the maximum pressure to be applied is dropped a few ,000 psi below the CIP/SAAMI MAP value. Before you know where you are, you quote maximum loads 2-3gn below the true maximum. Some companies take a different approach - Speer uses the heaviest available (smallest capacity and hence highest pressure) case generally available in its .223 Rem and .308 Win loads.

So far as MVs are concerned, two approaches are used. Some companies publish velocities obtained from test barrels. These are made to the exact CIP or SAAMI internal dimensions, and a finishing reamer true to the SAAMI or CIP minimum tolerance chamber is used to chamber that blank with the freebore and throat / leade angles also exactly as specified by the techical governing authorities. The problem with that was that when users of the manual came to duplicate those load combinations, they only rarely achieved the stated MVs, in fact were often wildly below them. It was OK whilst chronographs were expensive laboratory grade instruments, but as soon as the masses got the, the powder manufacturers faced a wall of complaints about inaccuracy, nay people went further and accused them of dishonesty. So, many (but not all) published data also uses results from a real factory rifle to show representative MVs. Nosler amongst some others still publishes data obtained from test industry spec test barrels and universal receivers, hence 1894's comment that its data are 'optimistic on velocity'.

None of this is a criticism of handloading manuals or their compilers. Take two identically specced and chambered barrels from a single manufacturer and you may well get different pressures. The manual producer has no control over the user's quality control procedures or whether he/she ignores all warnings and recommendations about use, whether the finished result will be carried across Arizona in high summer in a pick-up until it becomes too hot to touch. ...... and so on .... At the end of the day, the published data are recommendations for guidance and sensible application. Very occasionally published loads turn out too 'hot', more usually they're on the mild side. For general purpose sporting use and short to mid-range target shooting something within the published values will work more than well enough and unless one has a very specific high-performance need, accurate mild loads that produce low stresses and wear on the firearm are to be welcomed. In fact, most people's handloads are likely lower pressure these days than off the shelf factory ammo - performance sells in the finished ammunition market.
 
The one-cal book states the following. (which I load to)
Hornady 150gr interlock #3031sp
Vhit N140
I use either federal and or laupa brass
CCI 200 primer
COL 2.735
start load; 39.3 (2300fps)
Max load; 45.8 (2700 fps)

I have found good accuracy at around 42.5 then again at 44/44.5 then again at 46 (this is above max so should not be done)
This is in a 18" barrel with 1:10 twist

Speeds are not huge but then none of them have ever bounced off a deer, and I wouldn't like to try and catch one.
 
I wouldn't say that manufacturers have not updated loads for IMR powders. I was recently called by a friend who was concerned because the load of IMR 4350 he was using in his 30-06 was listed as near maximum despite his recollection that it was a mild, starting load. When I asked where he got the data, he said it was in his first edition Lee book. I reminded him that the data he used was downloaded from Hodgdon's site, not the Lee book. My newest Lee book shows data matching Hodgdon's site data. Lee gets it's data from Hodgdon, directly, so I can only assume that this was updated data. A thin example but it's off the top of my head.

As to the Lyman book being antique, I agree: "Not so!"
Lyman, formerly Ideal, is one of the oldest suppliers of reloading equipment in the world. Lyman was using pressure guns back in the early sixties when Hornady and Speer and Sierra were taking educated guesses at pressures and running their velocity data from Tipico Time-Meter Chronographs. It has been said that Lyman (Ideal) was almost single handedly responsible for the evolution of reloading in the US. I would not be quick to dismiss their data.

As to data itself. As Laurie said, in the end, it is just intended as a guide. Anyone who takes it as an absolute didn't read the disclaimer from the maker and is being naive. As mentioned, barrels used for pressure guns are very precisely machined in every respect, and the pressure gages calibrated for the individual barrels at great cost. I can tell you from first hand experience that they are exceedingly expensive. A barrel from a commercial rifle -same length and chambering- could hardly be expected to deliver the same results even if the exact same ammunition was used.

Now take the average reloader at home. He had his data in front of him but he's using a different case, once fired in someone elses' rifle and FL resized, the same bullet, different primer, different LOT# of powder, the bullet seated .010" off the lands instead of to the data's spec and fired in a factory rifle with a barrel 2" shorter than the test barrel the data was generated with.

And yet, the reloader's brows knit in puzzlement when his results are not the same as what the data 'promised'. Go figure! How could that be?? Silly.

As to compressed charges: I use them. If your data produces a compressed charge, that's fine. My Hornet loads have Lil Gun powder to the top of the case mouth and I crunch a bullet down on it. Nothing blows up. With many powders, minimum and maximum are the same compressed charge of powder.~Muir
 
I wouldn't say that manufacturers have not updated loads for IMR powders. I was recently called by a friend who was concerned because the load of IMR 4350 he was using in his 30-06 was listed as near maximum despite his recollection that it was a mild, starting load. When I asked where he got the data, he said it was in his first edition Lee book. I reminded him that the data he used was downloaded from Hodgdon's site, not the Lee book. My newest Lee book shows data matching Hodgdon's site data. Lee gets it's data from Hodgdon, directly, so I can only assume that this was updated data. A thin example but it's off the top of my head.

As to the Lyman book being antique, I agree: "Not so!"
Lyman, formerly Ideal, is one of the oldest suppliers of reloading equipment in the world. Lyman was using pressure guns back in the early sixties when Hornady and Speer and Sierra were taking educated guesses at pressures and running their velocity data from Tipico Time-Meter Chronographs. It has been said that Lyman (Ideal) was almost single handedly responsible for the evolution of reloading in the US. I would not be quick to dismiss their data.

As to data itself. As Laurie said, in the end, it is just intended as a guide. Anyone who takes it as an absolute didn't read the disclaimer from the maker and is being naive. As mentioned, barrels used for pressure guns are very precisely machined in every respect, and the pressure gages calibrated for the individual barrels at great cost. I can tell you from first hand experience that they are exceedingly expensive. A barrel from a commercial rifle -same length and chambering- could hardly be expected to deliver the same results even if the exact same ammunition was used.

Now take the average reloader at home. He had his data in front of him but he's using a different case, once fired in someone elses' rifle and FL resized, the same bullet, different primer, different LOT# of powder, the bullet seated .010" off the lands instead of to the data's spec and fired in a factory rifle with a barrel 2" shorter than the test barrel the data was generated with.

And yet, the reloader's brows knit in puzzlement when his results are not the same as what the data 'promised'. Go figure! How could that be?? Silly.

As to compressed charges: I use them. If your data produces a compressed charge, that's fine. My Hornet loads have Lil Gun powder to the top of the case mouth and I crunch a bullet down on it. Nothing blows up. With many powders, minimum and maximum are the same compressed charge of powder.~Muir

Andy, As ever a full & detailed extrapolation of accrued knowledge, gained over time,... I would certainly lean on your advice over reloading matters, pretty much like a Granpa!:D:tiphat:
 
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