Loading 7.62x51 Tracer

[ColinR]

Just as an update I loaded these tracer bullets in some old GGG cases with 41 grains of N140. 98% lit OK at a constant distance, probably about 300* yards. However the charge was insufficient compared with my .308 reloads and needed nearly 10 mils of elevation at 800 yards. The next lot I will load with N540 or N550 and will work up a load that better matches my ball reloads. Great fun though, especially since it was blowing a blizzard at the time of testing in Wales!

*They may have lit earlier but at the elevation required they dropped into view of the scope way out.

[WelshShooter]

That's the thing with tracer ammo. Even though the mass (~139gr) is similar to 155gr ammunition, it won't share the same ballistic coefficient so the elevation isn't going to match. The only way you can control this is to make the trajectory flatter, in this instance you'd need to aim for a higher velocity.

Just as an update I loaded these tracer bullets in some old GGG cases with 41 grains of N140. 98% lit OK at a constant distance, probably about 300* yards. However the charge was insufficient compared with my .308 reloads and needed nearly 10 mils of elevation at 800 yards. The next lot I will load with N540 or N550 and will work up a load that better matches my ball reloads. Great fun though, especially since it was blowing a blizzard at the time of testing in Wales!

*They may have lit earlier but at the elevation required they dropped into view of the scope way out.

Pfft, that's normal weather here!

[ColinR]

I think I'd be hard pressed (compressed!!) to get enough N140 into the case as the tracer is a much longer bullet. That's why I will give it a go with High Energy powders such as N540 and N550. No real purpose here just playing and interested to see if a match with ball is possible with the powders available.

I have to say Wales is a lovely country despite the weather. Once across the bridge onto the A449 there is little traffic and everywhere looks well kept and tidy. I always said that Wales was too good for the Welsh, but you sure do look after it well.

[WelshShooter]

I did find the powder was compressing with my .223 tracer (62gr) using Reload Swiss RS50 stick powder. I used Ramshot Tac in my .308 tracer loading which is a nice ball powder. I loaded 43gr - 47gr (at 0.1gr steps) of Tac with an overall length of 2.700". I don't recall feeling the powder getting overly compressed with this powder. Ignition ratio was the same for all loadings, with the 47gr loading having slightly less drop compared to the 43gr loading.

Haha, Wales too good for the Welsh?! If it's too good for us then it certainly does not belong to the English :flag5:

[jmc67]

If it helps here's my load experience with N140 and 155gr rounds in GGG brass.

viewtopic.php?f=11&t=29794

41gr was a pretty light load for me, and the speed of the bullet low as a result. I guess this would impact on how well the tracer ignites, as I presume friction with the air is a factor there - push it harder and you'd see more friction. 43gr N140 would be my recommendation based on what I saw with my 155gr bullets.

[ColinR]

[quote="WelshShooter"]I did find the powder was compressing with my .223 tracer (62gr) using Reload Swiss RS50 stick powder. I used Ramshot Tac in my .308 tracer loading which is a nice ball powder. I loaded 43gr - 47gr (at 0.1gr steps) of Tac with an overall length of 2.700". I don't recall feeling the powder getting overly compressed with this powder. Ignition ratio was the same for all loadings, with the 47gr loading having slightly less drop compared to the 43gr loading.

Haha, Wales too good for the Welsh?! If it's too good for us then it certainly does not belong to the English :flag5:[/quote

Probably as well it does not belong to the English because it would never be as nice. I love it there and if I was younger with the inclination to pack up a home I'd move there in a blink. I was looking at prices of houses and was amazed at what you get for the money and of course you have Orion!

[ColinR]

[quote="WelshShooter"]I did find the powder was compressing with my .223 tracer (62gr) using Reload Swiss RS50 stick powder. I used Ramshot Tac in my .308 tracer loading which is a nice ball powder. I loaded 43gr - 47gr (at 0.1gr steps) of Tac with an overall length of 2.700". I don't recall feeling the powder getting overly compressed with this powder. Ignition ratio was the same for all loadings, with the 47gr loading having slightly less drop compared to the 43gr loading.

Haha, Wales too good for the Welsh?! If it's too good for us then it certainly does not belong to the English :flag5:[/quote

Probably as well it does not belong to the English because it would never be as nice. I love it there and if I was younger with the inclination to pack up a home I'd move there in a blink. I was looking at prices of houses and was amazed at what you get for the money and of course you have Orion!

[ColinR]

If it helps here's my load experience with N140 and 155gr rounds in GGG brass.

viewtopic.php?f=11&t=29794

41gr was a pretty light load for me, and the speed of the bullet low as a result. I guess this would impact on how well the tracer ignites, as I presume friction with the air is a factor there - push it harder and you'd see more friction. 43gr N140 would be my recommendation based on what I saw with my 155gr bullets.

I just had a look at your data. Interesting the spread is fairly consistent around the 30fps mark. Best I get is with weighed Lapua cases and weighed 155 SMK is around 13 fps. I'm going to see how much N140 I can get into a case without compressing the load and see where that takes me, as well as loading some with N540 and N550. 41 grains N140 was certainly too light for these 139 grain tracers, but it gave me some parameters to work with. I'll also try some N135 and see where that goes. I still have some 250 tracer bullets so enough to experiment.

[jmc67]

I just had a look at your data. Interesting the spread is fairly consistent around the 30fps mark. Best I get is with weighed Lapua cases and weighed 155 SMK is around 13 fps. I'm going to see how much N140 I can get into a case without compressing the load and see where that takes me, as well as loading some with N540 and N550. 41 grains N140 was certainly too light for these 139 grain tracers, but it gave me some parameters to work with. I'll also try some N135 and see where that goes. I still have some 250 tracer bullets so enough to experiment.

I wouldn't read too much into the spread of data for mine - it was my first attempt at loading for 308 (or indeed any bottleneck cartridge), I don't weight the cases or the bullets, so my prep is far from being as meticulous as it could be.

[ColinR]

If you can maintain a fairly consistent spread you are not doing too much wrong especially with military cases where the volume can vary a lot. Having said that GGG cases do seem to weigh consistently to a fairly small margin. I have a Magnetospeed V3 too and I am always surprised to see the spread usually results from one that is way out from the rest. I weigh charges on a very accurate RCBS Chargemaster - I once checked 50 thrown charges on a 5.0.5 and all were within 1/10th of a grain of what was dialled in - so I don't expect 1/10th of a grain more or less would account for a huge difference in velocity and I do a weight check every time before I use it. Weighing the charge and the bullets is pretty much finite, but really to assess cases their water volume is altogether a more accurate way to select the same - but too much pfaff.

I am told the SD function on the Magnetospeed gives a better guide to accurate loading, but I cannot for the life of me get my head around the principle as I am far from being a maths buff. Seems you can have exactly the same spread over different test results but different SD value.