Reloading 7.62x39

[Rumple]

Hi All,

I've been reloading handgun and shotgun for a few years now and recently decided to start shooting IPSC rifle and acquired a Norinco Type56...My local gunshop sells steel cased, berdan primed ammo at R11.90 each, so I decided to venture down the rabbit hole of rifle reloading... I have finally been able to source all the components and equipment to reload, but have a problem with the bullets...The standard COL for 7.62x39 is 56mm, if I seat these bullets at that length I end up with less that 3mm of the bullet in the case neck, I have measured the distance to the rifling in the chamber and this appears to be correct. According to the internet the seating depth should at least be equal to the diameter of the bullet. When I seat the bullets at that depth I have a COL of 50.2mm. Granted my measuring technique is not state of the art but that seems like a big difference to the rifling of the barrel.

The bullets that I bought were Silver Rapids 123gr 7.62x39 , I have messaged them in this regard (and am waiting for a response) but I would like to know if anybody has used these bullets with a Norinco Type 56 and how deep they seat these bullets?

[oafpatroll]

The bullet profiles differ substantially which will make up a fair bit of your shortfall. Your jacketed example is longer and pointier. Suspect that if you seat your coated bullet off a comparator, i.e. match ogive to ogive, measurement you'll be fine. Drilling a neat sub calibre hole inone of the flats of an M10 or M12 nut and filling I slot in the opposite face makes for a usable comparator add on for you vernier.

[Ds J]

Silver Rapid bullets are lead bullet. Your bought cartridges contain bullets with a copper alloy over a lead (or steel) centre. There is more volume for the same weight, and thus the Silver Rapid bullets are shorter.

Ask around at your club. Others should give you the correct measurements.

[Tripodmvr]

A jump of 6mm is nothing to be worried about. If feeding from the magazine is a problem, lengthen the COL to make sure that 80% of 7.82 = 6,25mm is seated against the case neck. That is enough to ensure a good grip.

[Rumple]

The bullet profiles differ substantially which will make up a fair bit of your shortfall. Your jacketed example is longer and pointier. Suspect that if you seat your coated bullet off a comparator, i.e. match ogive to ogive, measurement you'll be fine. Drilling a neat sub calibre hole inone of the flats of an M10 or M12 nut and filling I slot in the opposite face makes for a usable comparator add on for you vernier.

Ordered one of these

https://sudamix-ring.co.za/product/sudami-bullet-comparator-ogive-30/
https://sudamix-ring.co.za/product/comparator-body/

[Rumple]

A jump of 6mm is nothing to be worried about. If feeding from the magazine is a problem, lengthen the COL to make sure that 80% of 7.82 = 6,25mm is seated against the case neck. That is enough to ensure a good grip.

Thank you for the reply.

[Rumple]

Silver Rapid bullets are lead bullet. Your bought cartridges contain bullets with a copper alloy over a lead (or steel) centre. There is more volume for the same weight, and thus the Silver Rapid bullets are shorter.

Ask around at your club. Others should give you the correct measurements.

Nobody at our club shoots 7.62x39 and I'm starting to realize why

[Tripodmvr]

You are not reloading for ultra precision. 3 MOA might be good enough for your purposes, but I can assist with Quick Load to give safe and optimum loads. COL will be the least of your worries. Some European calibres even jump as much as 10mm.

Create a functional cartridge that goes bang every time and feeds and ejects reliably. You can then concentrate on your shooting ability.

[oafpatroll]

Nobody at our club shoots 7.62x39 and I'm starting to realize why

A good few at mine do and they use their own stubby round nose bullets cast from the cheapest Lee mold. I can't remember seeing one having a storing of any sort. I don't think you have even the beginning of a problem on your hands

[Rumple]

Update: Thanks to @Tripodmvr for the advice and the load data from Quick Load 

Loaded 5 rounds with the suggested minimum load, just to see if the gun cycles and what the group is like and to see how fast the load is. Fired my first round with one round loaded (in case there was a slam fire) all good bit lower than normal (could be from all the banging on the barrel to get the slug out ). Case landed about 5 meters from the shooting position. Loaded 2 rounds , second shot was almost in the same hole as the first still low, second round cycled. Took the second round out and measured it, it was the same length as when I loaded it, and no obvious damage from being chambered. Fired 3 rounds over the chrono (I did not start with the chrono as I was not sure about the accuracy and I have "murdered" a chrono once before ) Only one shot registered on the chrono two were the same reading which is indicative of a false reading... Quick Load said it should read 1970 fps and it read 2045 fps. I did apply a light crimp so that could account for the difference, but all in all I'm happy with the results    

[Tripodmvr]

How far was the chrony in front of the muzzle?

[Rumple]

How far was the chrony in front of the muzzle?

About 6 meters...

[Tripodmvr]

Have a look at the calc below. This is at node 6 1/2 and barrel time of .933ms. There is a safety factor of 4000psi to the max pressure, so the action should not be hammered. Charge of 20,7gr. You need to check with the chrony as more pressure sometimes leads to a higher burning rate. Speed should be close to 2200fps.

Node 8  19gr on the node. pressure 38000 psi
 
Node 7  19,9/20,00  2140fps pressure 43000psi

Node 7 might be the best choice. An extra 60fps is going to mean very little higher at 100m.

[Rumple]

Back from the range....

After running some rounds over the chrono with the higher load (20gr / Avg 2107 fps), I tried to shoot a group at 25 meters and it shoots all over the show. My last shot (in the center of the target) was with a factory round. The 2 holes in the target are not "keyholing" its just that the paper is loose on the cardboard as I checked behind them. I am a complete noob when it comes to rifle reloading so any ideas are welcome to try improve the accuracy of my loads.  Any advice would be appreciated.

[Ds J]

How was accuracy with other reloads?

How is accuracy with bought ammunition?

How does the reloads' speed compare to the bought ammunition?

Don't worry - it is usually just one or two tweaks to get things much better.