Help with starting load for 6.5x55!

turps

turps

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I am trying to work up target loads for an M96. I have PRVI brass and CCI 200 primers, and 140 gr Hornady A-Max bullets, which I am hoping for big things from. After much googling here and elsewhere, I finally settled on IMR4350.

The problems start here: I have the Speer manual that came with my RCBS kit, and IMR very kindly gives you access to everything on their site, but official Hornady data is hard to come by without buying their manual. On top of that, the Speer manual lists starting/max loads of IMR4350 under a 140gr Speer SP as 34/36, but the IMR website suggests - for the same Speer bullet - a starting load of 41gr, working up to a max of 45! IMR doesn't distinguish between M94/M96 actions and "modern", but even for a commercial action the Speer manual's numbers are only 39/41.

My first question for the board is why the big difference between the two sources? With a range that big, I'm worried that erring on the side of caution will produce loads so light as to be insufficient to clear the barrel.

Second, none of those numbers are for the 140gr A-Max, and I don't have enough experience to guess at how big a difference the projectile makes to the equation; does anyone have Hornady's most recent data for the A-Max with IMR4350?

Thanks in advance.
 
most powder manufactures recommend starting loads of 10% less than the max load if your aren't sure.

I checked my Sierra manual but they don't list IMR4350 for 140gr bullets

but for caparison the IMR site lists IMR-4895 34.5grs to 37.8grs and my Sierra book lists 32.1grs to 38.6grs

so .9 grs difference in max charge, the test rifle listed in my book is a M96 Swedish Mauser

I would take the IMR max of 45gr and reduce it by 10% so...40.5gr and work up from there

my book was right on with the IMR data and they used a M96 rifle for testing


Good Luck, Alex
 
Hornady's latest book for the 6.5 x 55 with a 140 grain A-MAX and IMR 4350 powder calls for a starting load of 36.9 grains at 2300 FPS, and a max of 41.4 grains at 2600 FPS.
 
You may want to aneal the necks. I had 6.5x55 PRVI brass and the necks were very hard and I ended up with quite a few cracked necks. After
annealing the problem went away.
 
Cleftwynd said:
Hornady's latest book for the 6.5 x 55 with a 140 grain A-MAX and IMR 4350 powder calls for a starting load of 36.9 grains at 2300 FPS, and a max of 41.4 grains at 2600 FPS.
Click to expand...

Clefwynd. Are the loads in the Hornady book the same for A-MAX and SST 140gr with IMR 4350? Thanks
 
If in doubt, use the Hodgdon"s reloading center datas.
Difference in charge sometimes relate to different OAL. Also, not all the bullets create the same pressure, so using the specific manual of the bullet company you use is always a good idea.
 
Hornady states an OAL for the 140 SST at 2.905" and 3.025" for the A-MAX.


I should have stated that with my earlier post. My bad and thank you Baribal for reminding me. The COL is important especially for pressures, follow the guidelines closely. I would suggest you get the manual you need for what you want to load, or get components that are listed in the manuals you have.


140 GR. SPR SP IMR IMR 4350 .264" 3.030" starting 41.0 grains at 2486FPS 39,300 CUP maximum 45.0 grains at 2677FPS 46,000 CUP

taken directly from http://data.hodgdon.com/cartridge_load.asp
 
Cleftwynd said:
Hornady's latest book for the 6.5 x 55 with a 140 grain A-MAX and IMR 4350 powder calls for a starting load of 36.9 grains at 2300 FPS, and a max of 41.4 grains at 2600 FPS.
Click to expand...

The starting and Max numbers in the Hornady book for 6.5 140gr are the lowest I have seen and I have lots of loading data.
Do you think this is because of the long bearing surface on the Hornady bullet?
 
One can only guess, I have noticed a trend in load data with newer published info, a lot of it has been reduced from what it used to be. Could be for safety reasons, powder changes, bullet changes, who knows.
 
Dunk, Cleftwynd....lots of older M96's are still in use and being reloaded for so this is just their way of protecting themselves...these rifles are not getting younger. Not saying the Swede Mausers are not good actions...Ive owned a few and reloaded for them. (and would again given the oppertunity).

Fine if they want to publish that kind of data but they should make the 6.5x55 section like the 45-70 section so that can give guidance to Shooters who load for modern actions. You will so some older manuals listing loads for 140gr. bullet and 49-50gr. RL-22...nowadays the trend in a manual is more like 45-46gr. RL-22

About IMR-4350 40-45 is the range I would use, the data I have coincides with it.
 
In the recent past years, some people around the world experimented using low density charges of slow to very slow burning powders without fillers in order to achieve lower pressure at moderate velocity for use in old guns. In some cases, this lead to poor initial powder ingition and produced secondary explosion, destroying many old guns (sometimes completely, other times creating excessive set back / headspace). Another thing that can increase the "empty" space of a loaded case is the common practice of seating the bullet way out the case to reach the lands without adjusting the powder load to match the original given lenght (to match the original load density). In some military and other long throated rifles, if the load density is not adjusted, seating the bullet way out of the case can considerably increase this "free room" and substantially decrease the load density ratio.

In the newer SAAMI conventioned manuals, for some calibers (6.5X55 included) they tend to discard low density slow burning powders charges for overbore case capacity to avoid SEE.
There should be no real problem using slow powders (starting at IMR/H 4831 burn rate) as long as the powder fills the case to a ratio around 85% to 100% (or more) of the case capacity (when the bullet is seated). Also, in the "new" loads, the OAL is usually shorter than previously, to increase the initial speed of the bullet hitting the lands / grooves, which will decrease peak pressure.
Also, I am aware of at least two different SAAMI dimension specs for the 6.5X55, one showing smaller dimension than the other. This also explains why they use a lower MAP pressure than CIP.

While the different 4350 are not specifically known to produce SEE in the 6.5X55 (but it was recorded with other calibers since the "60s or '70s), it's always a good idea to start with conservative load densities (usually not less than 85%), just in case.

Keeping our loading manuals up to date is a very good way of keeping ourselves safe.
A whole lot of "old style" loads were shot in the M/94/96/38 familly of guns without any problems. But exceptions exists and SAAMI does not like exceptions. While we know these rifles can withstand pretty high "normal" pressures, we also know that pre-M/98 Mausers don't handle escaping gases from case head rupture very well and most of the failures reported since the last 15 years or so showed SEE symptoms.
Strong, modern actions usually are made to handle Magnum proof pressures, pressures that did not exist and were not even imaginable in the days when the old actions were made.

I think the reason why SAAMI did not make a separation between the "new conservative" pressure loads and the "modern pressure" loads is that the 6.5X55 is mostly a milsurp thing in the USA, where you don't see many newly manufactured guns chambered in 6.5X55 and even less made in the country... and since they are pretty protective, instead they think of the .260 Remington as the "modern" 6.5X55... Such thing does not exist in the CIP world, where the 6.5X55 did not change since a very long time. Also, their (SAAMI) lack of homogeniity in dimensional standard for the 6.5 case does not help at all to use it to modern pressures.

As previously said, matching the loads using the up-to-date loads printed by the component manufacturer (bullets and or powder) is the best and safest way to proceed.

Norma, in their No. 1 manual have a good explanation on the hazards of too little powder.
Hazard of Too Little Powder
It is obvious to every experienced handloader that it is important not to use too heavy a propellant charge in any given load. However many handloaders do not realize how critical it can be to use too light a propellant charge. This is a particularly critical consideration when using any slow-burning powder. Owing to heavy surface treatment, with inert (deterrent) chemicals that is necessary to slow initial combus¬tion, these powder types are harder to ignite. Generally, the "slower" the powder, the harder it is to ignite. Norma MRP and MRP2 (and similar propellant types from other vendors) fall into this category.

Should the handloader use too light a charge with such a propellant, ineffective ignition can occur. With such a small charge, much primer energy is wasted moving the charge and much primer heat are wasted heating the exposed case interior. As a result, the primer blast might only ignite a small percentage of the powder granules. The granules that are ignited can generate sufficient propellant gas to move the bullet only a few inches.

Because only a small percentage of the charge is ignited, relatively little gas is generated. Hence, as the bullet begins to move into the bore, pressure (and temperature) within the propellant plume decreases rapidly. As a result, the bullet slows and can even stop. In such a load, granules that the primer did not directly ignite do not ignite rapidly (before the buffet moves significantly), as would happen in any normal loading.

Cooling of the propellant cloud allows partially-reacted propellant gases to begin to condense onto the relatively cold, unignited propellant granules. This initiates a chain reaction: Condensation converts gas to a liquid, which dramatically reduces pressure (and temperature) inside the case, this results in even faster condensation, which results in an even more rapid decrease in temperature; once this process begins, almost instantly, chamber pressure drops to almost nothing and the bullet rapidly slows or stops.

Equally, this condensation rapidly transfers hem to the surface of the remaining granules. Since the preceding primer blast and ignition of some granules will have significantly heated those granules (often to nearly ignition temperature) and because some or ail the deterred surface may have burned away from many of the remaining granules (contrary to intuition, sufficiently rapid cooling can "put out" an ignited granule), subsequent ignition and combustion of remaining granules occurs extremely rapidly. The entire remaining charge, which is now located as a single lump directly behind the buffet, can hum before the buffet can move significantly.

As was first studied and proven by the Krupp Commission, circa 1888, whenever the ignited charge is located at one end of a relatively empty chamber (as in this instance). combustion generates a "standing wave" within the combustion chamber. This occurs because, as the charge burns, an initial pressure wave moves toward and reflects from the case head interior surface. Meanwhile, gas flow and changing pressure within the buffet end of the chamber can oppose the progress of the reflected wave. This can
Slow, stop or even reverse the direction of this pressure wave. Whenever this happens, pressure near the peak continues to increase - Las molecules continue to enter this zone (from both sides) faster than molecules leave it; all else being equal, the more molecules are in any given volume of gas the higher the pressure!
In the above situation, average chamber pressure will, no doubt, remain relatively low - often it will never reach normal peak chamber pressure; however, pressure near the peak of the "standing wave" can be several times as great as normal maximum chamber pressure! It is well proven that such a situation can wreck even the soundest gun. The resulting explosion can be lethal.

Generally, the bigger the case, the slower the propellant, and the colder the ambient temperature, the more likely this result is to occur.

CAUTION: Never use charges lighter than the suggested starting charge, as listed in a reputable, modern handloading manual.

NORMA - RELOADING MANUAL 2004 page 149
Click to expand...
 
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Thank you for posting that Baribal! It is nice to see some solid reasoning behind the published data, especially where safety is concerned. Makes me glad I always update all of my manuals!
 
For my M96, I loaded a 140 grain Hornady interlock infront of 34.5 grains of IMR4895. No over pressure signs and super tight groups at 100 and 200 yards.
 
I have a lot of experience loading the Swede for both Mausers and modern target rifles. 4350 is an excellent choice. I get very good accuracy out of that powder, although velocity is not as high as with slower powders like RL22. I use it as the powder of choice for short range. Up to 600 yards it outperforms the long range loads.

A word of caution. 6.5 bullets are very long. A long bearing surface can make pressures go out of sight in a hurry if there is an incompatibility with the chamber/throat/barrel. I have seen this once with a nice Swedish Mauser. A START load was way, way to hot. Had to pound the bolt open.

My advice to anyone testing a 6.5 for the first time. Start at the START load, and for the first shot, turn your head away from the sights - just in case.

Work up in 0.5 increments to see what works and where pressure starts. be prepared to bring some unfired ammo home.
 
As an adjunct to the previous post, the Privi brass I had years ago was quite thick, so I would suspect a diminished case capacity compared to other commercial brass. Another reason to be mindful of pressure signs and ultimate loadings. (I rarely go one or two grains above min load for old military actions)
 
The first loading information is for ALL 6.5x55 chambered guns. Includeing craig Jorgensons.
That's why the low numbers.

Some manufactures publish data for newer actions....hence the higher numbers.

Great variences can also be seen between European loadings of comercial ammo and their American counterparts.
 
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