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Old June 16, 2013, 03:19 PM   #1
stubbicatt
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SVT40, Finn D166 load development

OK fellas. I'm about to embark on the development of a rough equivalent of the Finn D166 load for 7.62x54r. Of course I solicit any data or admonishments so that it works properly, and safely.

I do not have a Finnish Mosin Nagant, but I keep my eyes peeled. I do have an old Ishevsk 91/30 and a Tula SVT 40 which will be my workhorses. The SVT40 is a more accurate rifle, so the following is my plan.

The Lapua webpage posts N140 data for this bullet at 36.4 grains starting load and 40.0 grain as the max, also listed as their "accuracy" load. From the burn rate charts, N140 is only one digit faster than RL15. Data on RL15 in the 7.62x54r is sparse, but I intend to start at 36.4 grains with a max load of 40.0 grains of RL15. The bullet is the D166, 200 grain, rebated boat tail Lapua bullet. Brass is Wolf brand brass from about 10 years ago. I figured for primers I would use the CCI military #34 primer. I do not have a whole bunch of brass, so I have thought this through, and here is my plan.

PRESSURE TEST:

Fire one each 180 grain factory new round in each rifle. Mic the case head before and after firing, to gage expansion. This will be my primary method of evaluating pressure. The x54r (or x53r if Finnish) is a lower pressure cartridge, I think max is somewhere around 40 to 45K PSI, so gaging pressure signs in this cartridge will be more difficult I would think than say, a 308.

Full length resize the few fired cases I have, and mic them after loading. I do not expect that the web area will return to new, unfired dimensions, but it is a data point that may prove useful, I don't know.

Starting at 36.4 grains, load 2 cartridges each at 1/2 grain powder increments, until the 40 grain ceiling. First fire a cartridge of a given charge weight in the stronger, but less accurate, Mosin Nagant and examine for any obvious pressure signs. Then, assuming no adverse pressure signs, fire its companion in the SVT 40. Take velocity readings with the chronograph as additional data points. Mic fired cases to determine whether they are approaching my measurements for working max pressures.

Since this cartridge headspaces on the rim, I figure I'll use my Stoney Point case comparator tool to measure headspace using the .4" ring, as it were a 308, as an additional data point to gage pressure by how much longer the distance is from the case head to the case shoulder. I figure the lower pressure cases will stretch less in this dimension. --We'll see.

From the Vihtavouri website, they have some posted velocity figures for the ammo they produce, and I reckon I will use this figure as an indication of pressure.

ACCURACY

Once max pressure is determined I figured I'd load 3 each of bullets at whatever is determined to be max load, and ratchet them down in .3 grain increments until I reach a powder charge floor, arbitrarily set at 2 grains below maximum pressure, and gage these rounds for accuracy at 100 yards in the SVT40, as it is the more accurate rifle between the two I have. I realize 3 round groups are statistically inferior to 5 round groups, or better, 10 round groups. But with a chronograph, I figure I can at least get a pretty good idea of grouping ability and consistency in velocities.

Then, voila! With the remaining bullets I have, I should have a pretty decent accuracy load for the SVT 40. The one thing I think I will do at some point if I continue to handload for this rifle, is anneal the cases and buy a custom FL die for the SVT 40. This due to the relatively longer distance to the shoulder than unfired, or resized brass, exhibits. I figure to FL size this brass will lead to early case failure, seeing as the shoulder gets set back so far with a conventional RCBS die.

Seriously, though, I solicit any suggestions or advice which will help in arriving at an accuracy load for this rifle.
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Old September 19, 2013, 01:22 AM   #2
Bollocks
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SVT 40's have fluted chambers which makes a mess of brass cartridges. I gave up loading for my SVT 40 because of this.
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Old September 19, 2013, 07:18 AM   #3
stubbicatt
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Is your brass any uglier than say HK roller locked fired brass? Or is it actually damaged by the chamber fluting in the SVT40?

Thanks Bollocks.
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Old September 22, 2013, 12:07 AM   #4
Mueller
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Do you know what the port pressure is for the SVT? because if you don't and use the wrong powder you can beat the SVT to death.

Gas operated rifles are designed with certain limitations in mind and just like a M1 Garand/M14 using the wrong powders, usually to slow, but sometimes to fast can have serious consequences for the rifle and occasionally the shooter.

The other problem with the D166 loading is the chamber cut, the chambers on the Finnish modified rifles were cut specifically for the D166 load hence the D stamping encountered on most Finish capture/rebuilt rifles.

To short a throat and you could be seating the bullet into the lands, which means reducing overall, which means reducing powder charge to keep pressures at a safe level.

Also the SVT was not intended to use the Heavy ball (185) or the D166 (200) but the light ball (147-152) and may not be very accurate and recoil and action operation could be severe, leading to battering of the receiver and reduced life, remember the SVT was made in the 1940's and while robust it is a wartime design and rather delicate all things considered.

CCI 34 are Mil spec primers equivalent to Magnum primers (intended for Ball powders), so keep that in mind if you choose to work up loads.

Better bet would be to load a 150 gr bullet for the SVT and save the D166 for the Ishvek 91/30.

I have 3 Finnish rifles, A model 39 with the D stamp, a M91 Czarist stamped 91 with both Weimer republic acceptance and proof marks and D stamp indicating Finnish use and finally an Ishvek PE sniper also with D stamps, all 3 are accurate with a version of D166 load assembled with Lapua components and powders.

Hope this helps.
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Old September 22, 2013, 09:38 AM   #5
stubbicatt
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Mueller. I appreciate your sincerity, but where are your authorities? Your sources? For statements such as the SVT40 was developed for the light ball ferinstance? I do not know for sure, (which is why I asked my initial question) but I have read elsewhere on the internet that this is not true. I had read that the soviets were transitioning from heavy ball to light ball at the time of the development of the SVT38, which is the primary reason they incorporated the gas regulator in the design... and carried forward to the SVT40... so the end user could adjust his rifle to shoot either heavy (185 grain) or light ball..

By adjusting the regulator, one can accommodate many varieties of propellant and port pressures.

Thanks for the heads up on the short throat issue. I will utilize time tested, tried, and true, techniques to ascertain the origin of the rifling.

Thanks guys for the input.
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Old September 22, 2013, 11:21 AM   #6
Mueller
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The Russian forces switched over to light ball L (147) in 1908 due to experiences with the original 210 grain FMJRN Jager loading in the Russo-Japanese war.

The L Ball (147gr) was the standard for Russian/Soviet forces with the Heavy ball having been designed/fielded for machine guns, which featured a 182 - 185 gr bullet in several variations.

The Finnish forces began producing/used light ball designated the Type S (1920's) and developed the D166 (1930's) and used both during the Winter and Continuation wars.

The SVT 40 was employed by Finnish forces and did suffer breakages due to Finnish D166 ammunition and improper gas system adjustment, I have talked with several Finnish soldiers who had a chance to use these rifles against Soviet forces and general consensus was they were not made to handle the D166. This was pre internet when information on Finnish D166 was hard to find.

The reason a gas regulator was incorporated in the design was to accommodate changes in the quality of ammunition and weather conditions and during long engagements where there might not be time to clean the rifle for it to continue functioneing, not to allow use of non standard ammunition.

Heavy ball for use in machine guns had a tendency to be loaded to the upper ends of the pressure curves as has been seen in loads intended for use in aircraft machine guns which have to operate under extremes not encountered on the ground and to extend range and this can lead to unexpected consequences when fired out of infantry small arms

I have reloaded and have consulted with collectors who had to resort to reloading to be able to shoot some of the period pieces in their collections and have seen several weapons destroyed or damaged due to the use of ammunition that fell outside the original specs and at the time, considering the scarcity of many of these arms, they were extremely valuable, so extreme care was being used during load development.

My information comes from my own notes generated over years of research and consultation with arms designers,ballisticians,veterans and advanced collectors.

Just be careful, if you do decide to go ahead with using the SVT 40 and the D166 load, would hate to hear about a rifle being destroyed.

Have fun.
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Old September 22, 2013, 04:40 PM   #7
stubbicatt
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Well. There you have it!

Not sure what to do next. The rifle itself is pretty accurate for the first 10 rounds, but after that, the rounds go vertical. I appreciate your input, and am rethinking this project altogether.
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Old September 22, 2013, 05:06 PM   #8
Mueller
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The vertical stringing can be linked to the rather loose fit of the stock around the receiver and it can be addressed by using thin shims to prevent the action from moving within the stock, a common occurence for the SVT 40's that were intended to be sniper rifles, one of the reasons leading to them not replacing the PU, PE/PEM sniper rifles.

I have heard about some shooters (Finnish) who have built up the stocks by judiciously glass bedding certain area's but have never encountered one that I could examine and measure to give you an idea of where and how.

Glad that I could be of help.
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