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Senior Member
Join Date: May 27, 2007
Posts: 5,261
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This is an excellent post and pay heed to the admonition about sensitive primers.
http://www.thehighroad.org/archive/i.../t-665024.html
mackg
June 26, 2012, 08:17 PM
http://web.archive.org/web/200605060...ch/sainfo.html
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Quote:
These articles were available on-line, but the links are dead, so I copied
my post from an other board (two posts here as we are limited to 20000 characters):
Disclaimer: This article contains information that may not be appropriate for your particular firearm. Consult your gunsmith in regards to the safety of firing your particular firearm. Consult your reloading manuals for all safety procedures when reloading ammunition. We are not responsible for typographic errors. Your mileage may vary.
What follows is a reproduction of an article from Handloading Magazine on the 7.5x54 MAS, prefaced with comments by myself, updating the magazine article with considerations for the MAS semi-auto rifles.
Update: Reloading the 7.5x54 MAS.
By Paul Pelfrey
While the reprinted article that follows is essentially accurate, the author did not take into consideration the availability of the various semi-auto French rifles that would later be on the market at an affordable price. This article should be applicable to the MAS-44, MAS-49 and the recently imported MAS-49/56 rifles. With the data in table II of the article below, I didn?t need to reinvent the wheel to start my experimentation. My load was the 150 grain Sierra FMJ spitzer, loaded on Norma brass, with Winchester WLR primers, packed with 44 grains of AA-2520 powder. I had had a good experience with this load through my MAS-36 bolt action rifle and decided to give it a go in the MAS-49/56. The MAS-49/56 I had acquired came from SOG and was still in the arsenal wrapping when I received it. After a thorough cleaning I took it and 50 rounds of my handloads. I first test fired the rifle with some surplus Syrian ammo I had. I was disappointed. The Syrian ammo was rife with
hangfires and dead primers, and those rounds that did fire would not actuate the bolt properly. Most of the rounds stovepiped none ejected fully. I then took my handloads, loading a single round in the magazine at a time and easing the bolt forward. To my delight, the rounds were rather accurate, keeping inside 1.5 inches at 50 yards, and the brass ejected cleanly. After 10 shots loaded one at a time I loaded two rounds. This time, I let the bolt fly forward on it's own to chamber the first round. The round immediately slamfired as the bolt closed, and the second round chambered. My finger had been outside the trigger guard. I unloaded the gun, then reloaded two rounds. This time, the round did not fire when chambered. However, when I pulled the trigger, the rifle fired both rounds in rapid succession. My first thought was that this was a repeat of a phenomenon that I had experienced with an SKS carbine. In that case, the modern lube I had used on the SKS was too slippery and
allowed the firing pin to travel forward with the bolt actuation with sufficient inertia to impact and detonate the primer. In that case, removal of the lubrication solved the problem. I disassembled the MAS rifle and dried the components completely and reassembled it. The slamfire problem persisted. My attention turned to the handloads. Checking the primer seating depth and dimensions of the case turned up nothing out of spec (except the smaller rim diameter, per the Handloader article). I then chambered a Syrian round and then removed it. Examining the Syrian round showed a slight indentation on the primer. I then left the range to ponder my next move.
Next weekend I returned with more handloads, this time using CCI regular and match primers, and Remington primers. During this session my handloads still suffered from slamfires while the military French and Syrian ammo did not. Conclusion: Commercial primers are too thin to operate safely in the French MAS semi-auto rifles.
Solution: CCI, under the name of their parent company, Blount, manufactures a military spec primer. I found a brick at a gunshow in a plain white box. The label read "1000 M-34 Primer for 7.62mm Cartridge". Loading 50 more rounds with these primers solved the problem. Not a single slamfire. Most distributors do not carry this primer, and will only order and sell it in a case lot (5000 primers). The good news is that these primers sell for only about $6-$9 more than the same quantity of regular primers. I would recommend their use in any round that might be loaded in a semi-auto rifle, just for an added margin of safety.
Reloading this round has become much cheaper since the publication of the Handloader article. Lee now makes the dies for this round, and I have seen a retail store price on them for $29.99 (half of RCBS). After talking to the techs at Lee, they are willing to make a tapered expander for necking up the Swedish brass for $15, and if you send them a formed cased with a bullet (no primer, no powder) they will make one of their Factory Crimp Dies for it for $25. I recommend this, inasmuch as a few of my handloads had a problem with the bullets being pushed back into the case upon chambering. This can lead to overpressure and possible injury. Brass is more plentiful now as well. I find Remington 6.5 Swedish at shows for $27/100 and Kengs in Georgia also stocks Lapua 6.5 Swedish for a similar price.
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The original article:
Americanizing the 7.5x54
By Al Miller
Modern French arms have always been rare this side of the Atlantic. As a result, that nation's cartridges never developed much of a following among American shooters. The landmark 8x50R Lebel is a case in point: Not only was it the very first smallbore service cartridge ever developed but it was the French military round from 1886 to 1936. If that wasn't enough to gain it a niche in the American handloader's pantheon, Remington manufactured Lebel rifles and ammunition during World War I.
Following the Armistice, both arms and ammo were sold to Americans at bargain prices. For a follow-up, Remington produced a sporting version of the cartridge and listed it in their catalogs for years afterward. Nevertheless, anyone who begins digging around for some published loading data for the fat, rimmed round is in for an Excedrin-sized disappointment.
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mackg
June 26, 2012, 08:19 PM
part 2:
As far as the more recent 7.5x54mm is concerned, the situation is just as frustrating. Except for two or three suggested loads in Barnes' Cartridges of the World, the 7.5 has been largely ignored in the U.S. Too bad, for it's an interesting round, surprisingly modern and blessed with a useful potential. In fact, from the vantage point offered by hindsight, it's easy to see that the 7.5 was 25 years ahead of its time when it was adopted back in 1929.
The 7.5x54 is the cartridge the French wished they'd had to fight World War I - but didn't. When the Kaiser's army bulldozed its way through the Belgian borders in August 1914, the French - and everyone else, for that matter - were unprepared for how the war would be fought. As effective as the 8mm Lebel was, it was ill-suited for automatic weapons - and the 1914-1918 war was a machine-gunner's fracas, especially on the Western Front. By the time the Germans finally tossed in the towel, French ordnance experts knew what they had to do and lost little time in getting down to work.
In 1924, the fruit of their labors was unveiled: a rimless, bottlenecked cartridge of 7.5 caliber (around .3075 inch, give or take a few ten-thousandths), which had been designed for use in autoloaders. For some obscure reason, the M1924 cartridge proved unsatisfactory and was replaced by a slightly shorter version in 1929, the 7.5x54mm or 7.5 M1929C, as French manuals prefer. That "C" designation, by the way, identifies the cartridge featuring a 139-grain full-patched spitzer; the basic service round. Balle D cartridges carried a 190-grain boat-tailed spitzer.
After the new cartridge had been in use two or three years, it occurred to somebody that it should perform admirably in rifles as well - at least, it would be worthwhile to find out. As a result, some Mannlicher Berthier Model 16s were converted from 8mm to 7.5 in 1934. That was followed by the introduction of the MAS (Manufacture d'Armes de Sainte Etienne) Model 1936, which was to be the last bolt-actioned rifle adopted by France. With that, the 7.5 became the primary service round of the French armed forces. At first glance, the 7.5x54 looks like a slightly oversized .308 Winchester. When bullets are seated to the same depths, the French case will hold three to four more grains of powder than the NATO round - even more than that, with the assistance of a drop tube.
Military specifications of the Balle C round call for the 139-grain spitzer to be driven close to 2,700 fps from the MAS rifle's 22.6-inch barrel. Chamber pressures are supposed to be down around 40,000 psi. The only ammunition I could get my hands on was a batch with Syrian markings supplied by Century Arms (S Federal Street, St. Albans VT 05478). Fired from the Model 36, velocities averaged 2.655 fps 15 feet from the muzzle. Groups ranged from 2.5 to three inches at 100 yards. benchrest - using the issue sights, of course.
When a few rounds were broken down, bullet weights averaged 138.7 grains, miked .3075 inch in front of their cannelures and .3078 at their bases. The cases were stuffed with 47.5 grains of a powder resembling IMR-3031.
To the best of my knowledge. the 7.5x54 is strictly a military round. Nobody has ever offered sporting cartridges in that caliber. At the moment, surplus ammo, all Berdan-primed, is plentiful and not too expensive (note, this was published in May, 1990). Although re-priming Berdan cases isn't the problem it used to be, my gut feeling is that those excess military cases are sparked by corrosive primers. I can't swear to that, of course, but the possibility of a case giving away a few inches from my face always makes me a bit cautious. Rather than chancing do~it~yourself facelift, I'd rather depend on fresh, Boxer-primed brass for any reloads.
Dimensions of the 7.5 case vary from one reference to another. Take the diameter of the head, for instance: one source listed it as .480 inch; another specified .488; still another settled for .483. When the cited Syrian cases were miked, their head diameters ranged from .484 to .485 inch.
There's a significant lesson tucked away in all that confusion. A great many experienced handloaders lose sleep over disparities in specs like those. They forget that ammunition, both commercial and military, is mass-produced with certain necessary tolerances allowed. Precision is an admirable goal but it must be tempered with a realistic appreciation of production costs and schedules. That's why there is always a certain amount of built-in latitude to permit an acceptable amount of wear and tear before dies and other production machinery must be replaced. Rifles are manufactured the same way, with a specified degree of leeway permitted for each part. Were it otherwise, arms parts would seldom be interchangeable and ammunition would be prohibitively expensive.
On the flip side, it's obvious that the existence of realistic tolerances makes a handloader's life much easier - especially when confronted with the task of adapting one cartridge case to substitute for another. Were head diameters as critical as some would have us believe, there would be only one option for anyone wanting to handload the 7.5x54C: to follow the late John Donnelly's recommended procedure, as outlined in his Handloader's Manual of Cartridge Conversions. There, John's directions read as follows: (Taking a 7.62x54R Russian case) "Lathe-turn base to .480-inch diameter and rim to .482-inch diameter. Cut new extractor groove. Full-length size case in 7.5x53mm die. Trim and chamfer. Fireform in chamber." Undoubtedly, that will result in a fine, reloadable case - but is all cutting and turning and trimming really necessary? Not hardly. There's a much easier way. Why not let the rifle's bolt face decide what it will - and will not - accommodate? If nothing else,
that should broaden the choice of acceptable cases.
A glance at a table of case dimensions shows there are several which are reasonably close to the 7.5's - the 6.5x55, 7x57, .30-06 and 8x57, just to name a few. My first choice was the '06. It wasn't the closest, dimensionally - that honor belonged to the 6.5x55 - but the '06 has always been the wildcatter's delight because cases in that caliber are notoriously strong, adaptable and easily obtained. Whatever the objective, the '06 is seldom a bad choice.
SAAMI specs show the ex-government round's head diameters could range from .463 to .473 inch, a bit short of the 7.5's .480 to .485 inch. Measuring some GI' Match cases and a few others produced by Winchester revealed that head diameters of the issued hulls miked .469 to .470 inch, very uniform. Those of the Winchester cases ran from .467 to .470. Taking the bolt from the MAS 36,1 slipped the '06 case head behind the extractor, up against the counterbored face. The extractor maintained a good, strong grip on the head and even though there was a tiny gap a few thousandths inch wide between the edge of the case head and the bolt face's rim, the cartridge couldn't escape the extractor's clutches. Next, a 6.5x55 case was selected at random. Its head was slightly larger than the '06's. According to the SAAMI drawing, its diameter should fall somewhere between .469 and .479 inch. Those in my inventory miked .475 to .479.
Snugging the Norma case into the French bolt face showed it made a slightly tighter fit than the '06 hulls had. Even so, there was still a tiny bit of space between the head's edges and the perimeter of the bolt face counterbore. Of course, that proved to be true of the 7.5 cases as well, even though they fit tighter than the Swedish cases did. They didn't fill the bolt face completely, either.
Differences in fit between case makes were minuscule, of course. Once held captive by the extractor, the bolt was in complete control of case movement, whether the headstamp said 06, 6.5 or .a. Even so. all those cases would expand in the chamber when fired. The question was: How much expansion would the substitute brass tolerate - safely?
To get an idea of what I was dealing with. a box of once-fired Remington '06 hulls were decapped with a punch, then forced into an RCBS 7.5 sizing die after its decapping rod had been removed. The necks were shortened so case lengths were the specified 54mm, mouths were chamfered, Remington 9i~., primers seated and each empty was charged with 38 grains of IMR-3031 beneath a 130-grain Hornady Spire Point. That charge was a couple of grains lower than one of the recommended starting loads for the .308 in Speer Manual No. 11. I figured it would be safe enough in the 7.5. It was. Instrumental velocities averaged 2,415 fps and five-shot strings grouped from 1.7 to 2.2 inches at 100 yards. As expected. all rounds fed and extracted smoothly. Case heads expanded from .462 to .465 inch; pressure ring areas revealed the web had stretched from .472 to .475. Successively more powerful loads were fired but the cases seemed to have stabilized. Further expansion was practically nil.
Remington hulls are among the stoutest made and they probably would have withstood full charges without complaint - but why bother? Norma 6.5x55 brass is available once more from Federal dealers and since they are a better choice for converting to 7.5, there was 110 point in continuing the '06 brass experiments. In the future, however, should the supply of Swedish cases ever run out. I'd have no qualms about picking up where I left off with the '06 brass.
Thanks to RCBS. reforming 6.5x55 cases to 7.5x54 is simplicity itself. The Oroville firm will supply their 7.5 sizing die with a tapered expanding button on request. That allows the handloader to decap and expand the case mouths in one operation. All that's left to do after that is to shorten the hull a tinv bit and chamfer the mouth. Then it's time to prime, measure the powder charges and seat the bullets. No rim-turning. no extractor grooves to cut-just load and shoot.
Developing a load from scratch is not a new problem. Like most handloaders,I have faced it before. It used to be that whenever such a situation arose, out came the Powley Computer'. Unfortunately, mine is long gone. I loaned it to someone years ago and have never days, I'll have to replace it. In the meantime, when starting from point zero. it's my habit either to select starting charges from those recommended for some other cartridge with similar case dimensions, volumes and ballistics or to work backward, i.e., fill the case with a powder whose burning rate is obviously too slow. find out what kind of velocities it generates, then switch to slightly faster numbers until the round's preferences and limitations are understood better. Admittedly, it isn't a particularly scientific approach, but it works.
The next move was to determine the 7.5's usable case capacity. Most handloaders I know prefer to depend on water for that task but that never made a whole lot of sense to me. Granted, water - or any liquid, for that matter - will fill a case completely but no powder is that dense. Of greater significance is the fact that, when the time comes to empty a case and weigh the water, there are always a couple of non-cooperative drops left clinging to the metal inside the case. As a result, water doesn't always deliver as precise a measurement as some believe. Besides, I'm really not interested in knowing how much water a given case can hold, anyway. The question is: How much powder can it hold when a bullet is seated in its normal position? That, to my way of thinking, is a much more useful piece of information. Taking a fired military case, I sliced the neck off at its junction with the shoulder, then filled it with IMR-3031, tapping the case to settle the powder as much as
possible. After weighing the charge, the case was refilled four more times. The five charges varied less than .2 grain and averaged 47.5 grains. As far as my experiments were concerned, that would be the 7.5's working case volume.
With my brief experience with the '06 case in mind, it was apparent that .308 starting loads should be more than safe in the slightly larger .5 case. According to the Speer manual, 40 grains of IMR-3031 in a .308 hull should launch a 150-grain spitzer around 2,514 fps from a 22-inch barrel. Pressures and velocities should be lower in the French case, of course.
What about those .308 bullets? Since they were slightly oversized for the French bore, wouldn't they tend to boost pressures? Probably - but not a great deal. Certainly not enough to create any dangerous pressures. The difference between .308 and 7.5 was less than.001 inch - not enough to get excited about.
That .308 starting load was tried in the first batch of reformed Norma cases. Instrumental velocities averaged 2,465 fps - as anticipated, lower than the same recipe generated in the .308 case. Head and pressure rings were measured after that and all subsequent loads. As Table I reveals, the Swedish brass ccommodated combinations slightly hotter than military-equivalent loads without a whimper.
From the outset, it was my intent to work up a few loads which would duplicate, more or less, the French round's trajectory. I saw no reason to try to squeeze the maximum amount of performance out of the 7.5's case. I just wanted to shoot the rifle occasionally, not make a magnum out of it. Since no American 139-grain spitzers were on tap, I settled for 150-grainers, then decided to try some 180-grain soft points, too. Their longer bearing surfaces might encourage better accuracy. Although the MAS action is perfectly capable of handling much more pressure than the 7.5 generates (witness the sporting models chambered for such snappy performers as the fast-stepping 7.54 and potent 8x605), and those Norma cases are as sturdy asthey come, I saw no advantage in pushing my luck. Men might not get any smarter as they grow older, but most develop a healthy respect for high chamber pressures along the way. Any time a handloader depends on cases converted from some other caliber, he
can never afford to forget that the brass is the weak link in the chain, the load's limiting factor. Consequently, if anyone wants to add more powder to any of the loads in the accompanying table, they have my very best wishes but frankly, I see no particular advantage in doing so. On the contrary, there is bound to be an increasing amount of risk with each additional grain of powder. The listed loads were all safe in the test rifle but as always, everyone is urged to reduce them at least 10 percent and work up from there slowly and cautiously. As expected, the medium-burning powders, IMR-3031 through W-748, were the most efficient in the 7.5's case. Of course, whenever a handloader treads unknown territory, there are bound to be a few surprises. IMR-4064, for instance, racked up a whole series of disappointing groups, few of which were smaller than 3« inches. Velocities were consistent and extreme spreads were well within reason but for once, faithful old 4064 proved
stubbornly uncooperative. Odd. Reloder 7 turned out to be a real eyebrow-raiser. Beginning with a modest charge of 35 grains beneath a 150-grain Sierra spitzer, instrumental v~ocities averaged a sedate 2,255 fps and five-shot groups ranged from 2.1 to 2.3 inches. Charges were increased one grain at a time with all going well until the 40-grain level was reached. At that point, the extreme velocity spread, which had been fluctuating from 42 to 67 fps, sudde~y bounced to 256 fps and groups dissolved into patterns.
When charges were reduced one grain, velocities stabilized (2,535 fps) and extreme spreads shrank back to a reasonable 58 fps. Just why those pressure excursions occurred is anyone S guess but taking the hint, further trials with Reloder-7 were abandoned and I turned to other powders.IMR-4831 was much too slow for the 7.5's case as was H-380. On the other hand, two other members of the slow burning clan, IMR-4350 and W-760, not only churned up decent muzzle speeds but were responsible for some of the tightest groups recorded. Laurels for the best, most consistent accuracy, however, must go to Accurate Arms 2520. Not only did it deliver the smallest groups, but the vast majority of them were round, almost circular in shape. In addition, velocity spreads averaged under 40 fps.
After the range tests had been completed and I had a chance to study the targets, it was only too clear that my hypothesis about bullet accuracy had been 180 degrees off. Regardless of brand, the 150-grain bullets outshot the longer 180-grainers every time. At first, I thought that was just a matter of chance but the rifling's 10.6-inch rate of twist notwithstanding, the shortest bullets were always the best performers. Differences in group sizes weren't great, of course. They seldom exceeded .5 inch - but they were usually there. Case life was much better than anticipated. None of those in the first box even required trimming until all bad been fired three times. Admittedly, the initial loads were on the mild side and charge increases were small. Regardless, every case employed in the tests was reloaded at least 12 times before being discarded. Of greater import, only one displayed any evidence of an impending separation - and it had been reloaded 13 times. No split necks
were recorded and stretching was minimal. After the tenth reloading, there was a definite decrease in resistance when seating primers and after the twelfth, most primer pockets were noticeably worn.
As much use as possible was squeezed out of each case because I wanted to learn how much that converted brass would tolerate. In the beginning, I had wondered if the primer pockets would expand as case head diameters increased when the brass stretched to fill the chamber. There was never a hint of that. Even though its track record indicates that the quality of Norma brass is still as high as ever, it would be a prudent idea to discard cases after the tenth reloading - just as a precautionary measure.
Properly handloaded, the 7.5 could be turned into a superior sporting round. At this late date, however, few MAS rifles will ever be sporterized or carried afield during hunting season - there are too many other surplus rifles and cartridges available which offer the same or better potential. Still, for the military collector or the veteran who wants to pump a few rounds through his combat souvenir now and then but doesn't cotton to the idea of using surplus ammo with its suspect primers handloading makes a lot of sense.
Table I: Case Expansion.
Table II: 7.5x54 Load Data Table Bullet Powder Charge Velocity Remarks
150-gr Speer spitzer IMR-3031 45.5 2671** 2.5 inch groups
150-gr Sierra spitzer AAC-2520 48.0 2626* Most accurate load
150-gr Hornady Spire Pt. IMR-4350 54.0 2710*
150-gr Hornady Spire Pt. IMR-4895 46.0 2628* 2.5 inch groups
150=gr Hornady Spire Pt. W-760 53.0 2651* 2.5 inch groups
150=gr Hornady Spire Pt. AAC-3100 51.5 2400* Compressed load
150=gr Hornady Spire Pt. IMR-4831 54.0 2405* Compressed load
180-gr Speer spitzer IMR-3031 43.5 2426** 3 inch groups
180-gr Sierra spitzer IMR-4895 43.0 2370** 34fps extreme spread
180-gr Speer spitzer AAC-2520 45.0 2372** 3 inch groups
180-gr Sierra spitzer RL-15 45.0 2365** 51fps extreme spread
180-gr Sierra spitzer w-748 46.0 2490** 3 inch groups
180-gr Sierra spitzer IMR-4831 51.0 2247** compressed load
* Measured 15 feet from the muzzle by a PACT chronograph.
** Measured 15 feet from the muzzle by an Oehler Model 35P chronograph.
Norma brass and remington 91/2 primers used with all loads. Ambient
temperatures ranged from 50-75 degrees Fahrenheit. All groups fired
with issue sights.
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If I'm not shooting, I'm reloading.
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April 1, 2013, 07:53 PM
