BlueBoy69

Some info I sent some friends from the local rifle club about making low-velocity ammo now that the import of IMR's Trail Boss is banned due to the European REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation coming into force.

I'm starting to use Vihtavuori's N32C 'Tin Star' as a substitute for Trail Boss.

The bulk (load) density of Trail Boss in a 100% filled case, non-compacted/compressed, is 0.310 g/cm³ (grams per centimetre cubed). Tin Star is about 0.459 g/cm³, Unique 0.593 g/cm³. So quite low density, but not as low as Trail Boss. For note, ball powders are commonly around 0.910g/cm³ and stick (single perforation) around 0.840 g/cm³.

Trail Boss also has a relatively low energy density of 3,090 kJ/kg (kilojoules per kilogram), with Tin Star at 3,040 kJ/kg, so slightly lower. For note double base flake powder Unique is around 4,550 kJ/kg and Bullseye is 5,158 kJ/kg.

So as you can't get Trail Boss any more (I've still got two tubs), try Vihtavuori's N32C 'Tin Star'.

6 hours ago, Popsbengo said:

You have to upset other posters by disagreeing to get an answer 😁🤣

It does seem that way?

Look for 'ullage' if you want to see one of my rants, that or 'reloading data RS60 flame temperature'.

On 8/22/2019 at 10:25 AM, Popsbengo said:

I've just finished reading "Experimental Studies of the No. 41 Primer and Ignition of 5.56-mm Ammunition (ARL-TR-3922)(2006)".  Very interesting and worth the read for those of a technical mind.  One quick take-away finding was that the primer combustion only penetrated into 40% of the powder charge and (later in the paper) that powder compression close to the seated bullet impedes full combustion.  Compressed loads are sub-optimal in their experimental findings.

The findings that it's the primer that propels the bullet forward into the lands is very interesting:

Abstract From "Primer Output and Initial Projectile Motion for 5.56- and 7.62-mm Ammunition - ARL-TR-7479 (2015)"

"A novel technique for quantifying the initial motion of projectiles in unmodified small-caliber ammunition (5.56 and 7.62 mm) is demonstrated. Evidence that the primer launches the bullet into the engraving process prior to propellant burning is presented. The impulse resulting from the primers' (Nos. 41 and 34, respectively) output is measured and compared with the bullet momentum"

 

Thanks for digging those papers out BluBoy

Glad the reading suggestions were of interest.

For more on the previous subject and ullage effects, try these.

Flame-Spreading Processes in a Small-Caliber Gun (ARL-TR-4181)

Simulation Of Asymmetric Shot Start In Small Caliber Ammunition

Spit-Hole Effects on the Ballistics of a 7.62-mm Cartridge (ARL-TR-6785)

The Effects of Propellent Position on Small Caliber Ballistic Performance

9 hours ago, No i deer said:

A new Laurie Holland on the block.....

New? I've been here for for some time (2015), but I normally just get ignored. This even though doing this sort of has been my job for years.

9 hours ago, No i deer said:

You would expect the magnum primer to be hotter and produce a higher velocity.....

Even more confusion.....

It's most likely to do with how the primer output pressurises and ignites the propellant bed. Pressurisation of the bed, before full ignition, affects the projectile's initial motion, its debulleting from the case, and its initial motion into the bore.

The US Army Research Laboratory (ARL) has been doing an awful lot of fundamental research into this sort of thing. Most likely to do with the development of their new small arms cartridge.

It's all pretty complex and I don't profess to fully understand it enough to explain it more than I have already. It's covered in a load of non-classified papers that the ARL have released to the public. I've listed a few papers below for people who are interested in reading about it.

A Study of the Engraving of the M855 5.56-mm Projectile - ARL-TR-4743 (2009)

Experimental Studies of the No. 41 Primer and Ignition of 5.56-mm Ammunition (ARL-TR-3922)(2006)

In-Chamber Primer Force and Case Pressure Measurements of the 5.56-mm Cartridge - ARL-TR-5862 (2012)

Novel Diagnostics of 5.56 Ammunition Interior Ballistics (2012)

Primer Output and Initial Projectile Motion for 5.56- and 7.62-mm Ammunition - ARL-TR-7479 (2015)

Progress Toward a Multidimensional Representation of the 5.56-mm Interior Ballistics (ARL-TR-4903)(2009)

I have all these and more in my technical documents library if you can't find them online or what more data on the subject.

Plenty of data online, but that isn't generally pressure tested.

The only pressure-tested data I could find locally in my library (physical and electronic) and online was from Western Powders.

Unfortunately this means only Accurate and Ramshot powders. Anyway, the data from the Western Powders reloading manual is below.

I've got a 24" barrelled Marlin 1895 XLR in 45-70 Gov. with a Leupold Vari-X IIc (3-9x40) scope on it (see pic).

With plinking loads, 405 gr cast at about 900-950 fps, it's very pleasent and a real pussy to shoot.

Medium power, 405 gr cast at about 1350-1,450 fps, so duplicating old BP loads, is a good compromise for practice.

It's quite a handful on fill house loads, 300 gr at +2,100 fps, and if you aren't used to the recoil, scope kiss is a real problem (as two people at the club can testify too).

Personally if you are going shoot boar, I'd get a Marlin 1895 SBL and put a ghost ring sight, reflex sight, or long eye relief low-power scope on it. It makes scope kiss impossible and following the target easier.

Here goes.

Barrel length 26".

I can't remove the accidental double image post, or update to a single more suitable one, even though I've deleted them both and then saved?

In general, probably the Lyman reloading manual that is now up to its 50th Edition. It covers lots of rounds, with lots of manufacture's bullets (including their own cast) with lots of different American and some European powders.

The Lee manual is OK, but a bit basic and seems to just be a compilation of loads of free sources of reloading data (aka those supplied by the powder and bullet manufacturers).

There are plenty of other manuals, but they are often just for one manufacture's bullets, such as: Barnes; Berger; H&N; Hornady; Nosler; RWS; Sierra; and Speer. These, for obvious reasons, tend to be Americentric with regards to powders. If you use bullets specific to one of those manufacture's, then go with one of them. Personally, I feel the Berger manual is made-up by using QuickLOAD, as many of the recipes, when punched into the program, result in the same or very similar figures. Far too similar for comfort and safety.

As with regards to 'American' powders I am, as no doubt many others are, aware that many are not actually American, but sourced from around the world then sold under American branding.

You then have all the free data, or paid for in their hard copy versions, so either webpage based, or PDF documents from, to name but a few: ADI (Thales Australia); Alliant; Accurate (Western Powders); Barnes; Hodgdon; Hornady; IMR (Hodgdon); LOVEX (EXPLOSIA a.s.) Norma; Nosler; Ramshot (Western Powders); Reload Swiss (Nitrochemie 'Wimmis' AG); Vectan (Noble Sport); Vihtavuori; Western Powders; Winchester (Hodgdon).

As Laurie has mentioned previously, many of these sources (hard and electronic) do not agree with each other, have data tailored to work safely in the oldest of guns chambered for certain cartridges, and many other quirks.

As to what you should get, well that depends on what you want, what you have and what you can get. I've got most of the above, either in hard or electronic copy if you want me to check something specific.

Once you’ve chosen a source you’ve then got the choice of where to start. As Catch-22 said, many start loads are way below 15% of the max charge. Personally, I start at around 10% below the max and work up, noting the ambient temperature when firing. The latter is important as many powders can be highly temperature sensitive, primarily at higher temperature, but also below. Though the latter is not something to worry too much about here in the UK.

Carl,

You don't happen to have a few 25-20 cases too do you as I'm getting a bit low

Neil

im now about to do a .22/270 wsm for fun shooting

 

barrel life will be an issue

.22/270 WSW! Crikey, the 223 WSSM was already considerably overbore with its 50'ish grain water capacity, the 22/270 WSM will be nearer the high 70s. Barrel burner indeed

http://www.realguns.com/calculators/rgbarrelburnerindex.html