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Finally, light at the end of the tunnel for the non-reloading shooter of 7.62 NATO chambered Mil-Surp rifles |
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| Article written by: Mark Trope | |||||||||
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Federal 308 Winchester Low Recoil Power Shock round on left South African 7.62 NATO Mil-Surp on right |
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The Story Behind The Story |
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The following paragraph is a quote from a previous article published at Surplusrifle:
“Here at Surplusrifle.com, we recommend in the strongest possible terms that you do not fire .308 Winchester ammunition in any Mil-Surp rifle chambered for the 7.62 NATO round.” It recently came to the attention of Surplusrifle.com that there may be ONE exception to the above statement. Federal Cartridge Corporation has introduced a “low pressure” loading in .308 Winchester! Federal
Cartridge Company Mr. Jason Nash, Group Leader at ATK Products Group (the parent company of Federal Cartridge Corporation), http://www.federalpremium.com was contacted. I requested information on the new load (Federal’s 308LR Power Shock). Jason took time out of his busy schedule and had this to say in response to our query as to the pressure of Federal’s 308LR Power Shock load: “The max pressure spec for that load is 43,000 psi. Our loads typically fall well below that.”
We wish to thank Jason Nash & Tim Brandt at AKT Products Group / Federal Cartridge Corp, both these gentlemen expressed great interest in Surplusrifle’s investigation of safe ammunition use in Mil-Surp arms; and graciously supported our efforts with samples of Federal 308LR Power Shock ammunition for this article. AKT Products Group / Federal is deeply committed to customer safety and satisfaction. Let’s take a look at the Federal 308LR Power Shock load. |
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Federal’s 308LR Power Shock |
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How did Federal do it? By combining a thinly jacketed 170-grain bullet designed for the 30/30, and a low-pressure powder charge, Federal’s 308LR Power Shock load is designed for hunting medium game. Medium game often shot at relatively close ranges; does not requiring a full power .308 Winchester load. Consider how many deer are harvested every year with a 30/30-lever gun. Federal’s 308LR Power Shock load fairly well duplicates the performance of the 30/30. |
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Federal’s 308LR Power Shock Load contained 40.3 grains of a long-cut stick powder |
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Federal 308LR Power Shock Load, length overall |
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Federal’s unfired case length is 2.009 |
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Federal’s bullet diameter was .308 on the dot. Weight was 170.3 grains |
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Federal unfired case, distance from case head to .400 diameter on case shoulder (Stoney Point Gauge) (Caliper is accurate to +/- .0005) |
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For decades handloaders have tailored loads for the game animal, and conditions under which hunting will occur. The non-handloading hunter’s choices were strictly limited to different bullet weights. Regardless of which bullet weight was selected, factory ammunition was always at, or near the top of pressure and velocity limits. Federal’s 308LR Power Shock load changes all that. Now a hunter wishing to hunt medium game in close cover, but use a .308 Winchester chambered rifle, has a lower power, and low-pressure factory load. This is a literal boon to the non- reloading fellow owning a Mil-Surp chambered in 7.62 NATO. Rifles chambered in 7.62 NATO should be able to be kept on a steady diet of Federal 308LR Power Shock ammunition with no ill effects to the rifle, and a much easier push on the shooter’s shoulder. Let’s quickly review a few of the Mil-Surp’s concerned with the 7.62 NATO round. |
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Spanish FR-8 A model 98-type action rebarreled in the 50’s to 7.62 NATO |
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Spain bought, and later produced many M1916 and M93 long rifles in 7X57 Mauser. Many South American Contract Mauser’s were also chambered in 7X57. The chamber pressure of the 7X57 is 45,000-PSI. In the 50’s & 60’s, Spain and many of the South American countries rebarreled many of these rifles to 7.62 NATO, which has a chamber pressure of 50,000 PSI. Spain also converted many of their rifles to Model FR-7 and Model FR-8; they too were chambered in 7.62 NATO. |
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Indian Rifle 2A-1 An SMLE type, but designed exclusively for the 7.62 NATO |
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There are other 7.62 NATO Mil-Surp rifles too. Many model 98-type rifles were rebarreled to 7.62 NATO and served in Israel. In the 60’s and early 70’s India built new SMLE Rifles, Models 2A & 2A1’s, that were made exclusively for the7.62NATO round (Note.1). All Mil-Surp guns chambered in 7.62 NATO have a maximum pressure limit of 50,000 PSI. The.308 Winchester’s pressure limit (regular pressure ammo, NOT Federal’s 308LR Power Shock load) exceeds the pressure of the 7.62 NATO. |
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South African 7.62 NATO ammunition |
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South African surplus ammo contained 43 grains of a short-cut stick powder |
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South African surplus ammo, length overall |
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South African surplus ammo, unfired case length is also 2.009 |
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South African bullet diameter was .308 inch. Bullet weight was 143 grains |
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South African unfired case, distance from case head to .400 diameter on case shoulder (Stoney Point Gauge) (Caliper is accurate to +/- .0005) |
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I was almost ready for the range, and then realized I would need some 7.62 NATO Mil-Surp ammunition for “felt recoil” (shoulder bumping) comparison purposes. Randy Ward, proprietor of WEST TEXAS MILITARY SURPLUS, 2413-34th St, Lubbock, Texas 79411, 1-(806)-785-4867, www.gunsandblades.com supported this article by furnishing some South African 7.62 NATO Mil-Surp ammunition. Check out his store, Randy is another one of the “good guys”! |
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Part II The Story Continues: Range Time & Data Collection |
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OK, we have ammunition, now to the gun locker and select 7.62 NATO chambered Mil-Surp’s for the range. Let’s see, grab the FR-8 and the Indian 2A-1. The FR-8 has an 18.5-inch barrel, and the 2A-1 has a 25.2-inch barrel. These rifles represent both the long and short end of barrel extremes in 7.62NATO chambered arms. Chronograph results will be listed for both rifles. |
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Spotting scope, chronograph and FR-8 |
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First the FR-8 was fired with South African 7.62NATO ammunition. I wanted my shoulder conditioned to firing surplus ammunition before moving on the Federal ammunition. Recoil (shoulder push and muzzle flip) was fairly stout with surplus ammunition in this short carbine. Even wearing earmuffs, muzzle blast was authoritative. The normal amount of energy was required to unlock and lift the bolt, empties extracted and ejected normally.
The pointy South African 7.62NATO ammunition fed and extracted without a hitch. The velocity figures for the South African 7.62NATO ammunition are for comparison purposes only. What we are concerned with is pressure, not velocity! |
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South African 7.62 NATO Ammunition / FR-8 Spanish Carbine |
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Next Federal’s Low recoil ammunition was tested. When fed thru the “controlled feed” 98-type action, the short, blunt bullet ammunition fed with 100% reliability, however the bolt handle required a bit more push to get the rounds started out of the magazine. Once started into the chamber, they glided home. Upon firing, the first thing I noticed was recoil (shoulder push and muzzle flip) was greatly reduced with Federal’s Low Recoil ammunition in this short carbine. Muzzle blast was nowhere near as loud with the Federal load. Federal’s ammunition lives up to the name “Low Recoil”. The recoil difference between surplus ammunition and Federal’s Low Recoil can really be felt. Additionally, I could lift the bolt handle with my pinky to extract and eject fired cases.
Federal’s published velocity figures for this ammunition is 2000 FPS from a 24-inch test barrel. It was no surprise that the average velocity in the 18.5 inch barreled carbine is 1930 FPS . |
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Federal Low Recoil .308 Winchester Ammunition / FR-8 Spanish Carbine |
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Indian Rifle 2A-1, this SMLE type was designed for the 7.62 NATO |
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Next, the Indian Rifle 2A-1 rifle was fired with South African 7.62NATO ammunition. Recoil (shoulder push and muzzle flip) was not as pronounced with surplus ammunition in the 2A-1 as it was in the FR-8. Muzzle blast was not as loud either. With a 25.2 inch barrel and greater weight, I expected this. The normal amount of energy was required to unlock and lift the bolt, empties extracted and ejected normally.
The pointy South African 7.62NATO ammunition fed and extracted without a hitch. The 25.2 inch barrel of the 2A-1 turned in higher velocity also. |
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South African 7.62 NATO Ammunition / Indian Rifle 2A-1 |
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Next, Federal’s Low Recoil ammunition was tested in the Indian Rifle 2A-1. The SMLE design fed the short, blunt bullet ammunition just as easily and smooth as it fed the pointy surplus. Upon firing, the first thing I noticed was recoil (shoulder push and muzzle flip) was downright tame. Muzzle blast was reduced in the extreme. Again, I could lift the bolt handle with my pinky to extract and eject fired cases. Notice the 25.2 inch barrel of the Rifle 2A-1 turned in velocity figures very close to the figures Federal got in their 24-inch test barrel. |
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Federal Low Recoil .308 Winchester Ammunition / Indian Rifle 2A-1 |
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Part III A picture is worth a 1000 words, and also displays pressure signs, or lack thereof! |
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A piece of surplus brass fired in the FR-8, it grew .0015 thousands (The result of normal 7.62 NATO pressure) |
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A piece of Federal brass fired in the FR-8, it shrank .0015 thousands (The result of low (below 7.62 NATO) pressure) |
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A piece of surplus brass fired in the 2A-1, it grew .004 thousands (The result of normal 7.62 NATO pressure) |
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A piece of Federal brass fired in the 2A-1, it shrank .003 thousands (The result of low (below 7.62 NATO) pressure) |
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“What’s that you say, the Federal Low Recoil .308 brass cases shrunk...what the heck!!??”
It’s pretty easy to understand if we just think about it. Let’s review the firing process. When the trigger is pressed, the firing pin drives the case forward until forward motion is arrested by either the flanged rim, as in the case of the 303 British, or, in the case of a rimless cartridge such as the 7.62 NATO; when the case shoulder is stopped by the matching area in the rifle’s chamber. When the case shoulder strikes the matching area in the rifle chamber, the case shoulder is actually pushed back a bit. So far so good…
When forward case motion is arrested, the firing pin indents the primer, setting off the round. Since pressure is applied equally, and in all directions, the bullet must move forward down the barrel. The primer, being much lighter then the brass case, actually moves backward before the brass case does! The primer backs out of the primer pocket slightly. The brass cartridge case then moves backwards and reseats the primer as the end of the brass case strikes the bolt face.
In a cartridge loaded to industry standard pressure, the brass case tightly grips the walls of the chamber. Now, the only unsupported portion of the brass case is the shoulder. Pressure will cause the shoulder to move forward until the matching area in the rifle chamber once again arrests it (Note.2). Such a brass case will be slightly larger then it was before firing (as can be seen by the 7.62 NATO cases fired in both rifles).
“OK, so how and why did the Federal Low Recoil .308 brass cases shrink?”
With Federal Low Recoil .308 ammunition, when the trigger is pressed, the firing pin drives the case forward until forward motion is arrested when the case shoulder is stopped by striking the matching area in the rifles chamber. When the case shoulder strikes the matching area in the rifle chamber, the case shoulder is pushed back a bit.
When forward case motion is arrested, the firing pin indents the primer, setting off the round. Since pressure (much lower in the case of federal Low Recoil .308) is applied equally, and in all directions, the bullet moves forward. The primer, being much lighter then the brass case, moves backward before the brass case does. The primer backs out of the primer pocket slightly. The brass cartridge case then moves backwards. But, with a low pressure round, things are a bit different.
Since the pressure is quite a bit lower, the brass cartridge case may not move backwards with enough force to completely reseat the primer. Not only may the primer stand up in the pocket by 1 or 2 thousands, but also, there will not be enough pressure to cause the brass case to grip the sidewalls of the chamber, and move the case’s shoulder forward. So, the case is slightly “shrunk”. That’s exactly what happened with Federal’s Low Recoil .308 ammunition in both test Mil-Surp rifles, and proves conclusively, beyond all doubt, that Federal Low Recoil .308 ammunition is safe to fire in 7.62 NATO chambered Mil-Surp rifles. The pressure is lower. |
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Part IV Epilog: Several Learned Conclusions |
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► Federal Low Recoil .308 Winchester ammunition has pressure well below regular .308 Winchester ammunition, and pressure below that of 7.62 NATO ammunition. It is the only factory .308 Winchester cartridge that is totally safe to fire in a properly functioning Mil-Surp arm chambered for the 7.62 NATO cartridge. ► Owing to the decreased recoil and muzzle blast, Federal Low Recoil .308 Winchester ammunition is a pleasure to shoot. It will strain nether the old Mil-Surp rifle, or the old shooters shoulder! ► The 170 grain bullet in Federal Low Recoil .308 Winchester ammunition is an excellent choice for medium game (such as deer) taken in close cover. It is also an excellent choice for target shooting. Less recoil translates into less shooter fatigue. ► Federal Low Recoil .308 Winchester ammunition feeds well thru “controlled feed” Mauser style actions, which includes all Spanish, South American and Israeli arms. It literally glides thru Indian Rifle 2A-1 (including Rifle 2A) SMLE type arms. ► Federal Low Recoil .308 Winchester ammunition is of course a commercial product loaded with non-corrosive primers. While we always recommend the cleaning rifles after shooting, it isn’t a “rush job” with non-corrosive primed ammunition. Much Mil-Surp ammunition is corrosive primed, requiring a prompt cleaning with water based cleanser to remove the Potassium Chlorate coating that would attract moisture and rust the barrel. ► For the non-handloading shooter of Mil-Surp arms; Federal’s Low Recoil .308 Winchester ammunition is the ONLY SAFE alternative to Mil-Surp ammunition.
I’ll say it again. Federal’s 308LR Power Shock load, with its 43,000-PSI max chamber pressure, is the one, single, safe; factory .308 Winchester load that is perfectly acceptable and proper to fire in these 7.62 NATO chambered Mil-Surp rifles. (Note. 3) |
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| Article written by: Mark Trope |
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