.280 Enfield...Ahead of its time

[Tony Williams]

You need to be careful where the performance of the 7mm British/Belgian rounds are concerned - they came with different loadings and case lengths.

The .280's initial loading was a 130 grain bullet at 2,450 fps (the same MV as the .303 Mk VII ball).

By November 1948 (after the switch to the .280/30 case in April), attention switched to 140 grain bullets to obtain the required steel helmet penetration at 2,000 yards. Muzzle velocity was 2,415 fps.

In the 1950 NATO trials held in the USA the steep trajectory was criticised so the MV was raised to 2,530 fps.

The final loading adopted in 1951 as the "7mm Mk 1 Z" was a 140 grain lead-cored FN bullet at 2,550 fps.

Other loadings (all using 140 grain bullet) were:

7mm Optimum: same case and bullet as Mk 1 Z but with bullet seated further out to leave more room for propellant and give the potential for higher velocities as required.

7mm High Velocity: cartridge case extended from 43.3mm to 49.5mm, MV 2,750 fps

7mm Compromise: cartridge case basically the US T60 .30 necked down; case length 51mm, MV 2,800 fps

7mm Second Optimum: based on Belgian 7mm Medium 2 (the only one to enter service - with Venezuela); case length 49.15mm, MV 2,755 fps.

[JASmith]

The AR10 is much easier to manufacture than a Garand, M14, or other steel receiver rifles, since the machining is done on aircraft-grade aluminum receivers, cutting tool time and increasing tool head life, then hardening through anodizing after they have been machined.

I will admit that I was about 10 years old when the M14 was going through final design and competition. But our family interest in firearms and my father being in the steel fabrication business brings couple of impressions strongly to mind: First, "only cheap and unreliable firearms used aluminum." and second, aluminum had not yet become popular outside the aircraft industry. Indeed, aluminum was only coming into popularity as a roofing material during that period.

At that time, accepting a firearm that employed an aluminum receiver would have been a serious break from tradition, representing a serious gamble on reliability and safety. Add to that we know that very few institutions evolve more slowly than the military firearms community, one can readily understand the reluctance to go with the new-fangled weapon. (Recall that the adoption of the M16 was viewed as a revolutionary step imposed from the outside.)

To be sure, other parts of the military R&D establishment were rather dynamic in trying new things. Even there, however, there were significant pockets of technological inertia in many areas, including some that I spent a significant part of my career working in.

Bottom line is that reluctance to adopt the AR10 in the mid-1950s would have been seen as a reasonable move by most of the folks that had even a rudimentary understanding of the business.

[LRRPF52]

You need to be careful where the performance of the 7mm British/Belgian rounds are concerned - they came with different loadings and case lengths.

The .280's initial loading was a 130 grain bullet at 2,450 fps (the same MV as the .303 Mk VII ball).

By November 1948 (after the switch to the .280/30 case in April), attention switched to 140 grain bullets to obtain the required steel helmet penetration at 2,000 yards. Muzzle velocity was 2,415 fps.

In the 1950 NATO trials held in the USA the steep trajectory was criticised so the MV was raised to 2,530 fps.

The final loading adopted in 1951 as the "7mm Mk 1 Z" was a 140 grain lead-cored FN bullet at 2,550 fps.

Other loadings (all using 140 grain bullet) were:

7mm Optimum: same case and bullet as Mk 1 Z but with bullet seated further out to leave more room for propellant and give the potential for higher velocities as required.

7mm High Velocity: cartridge case extended from 43.3mm to 49.5mm, MV 2,750 fps

7mm Compromise: cartridge case basically the US T60 .30 necked down; case length 51mm, MV 2,800 fps

7mm Second Optimum: based on Belgian 7mm Medium 2 (the only one to enter service - with Venezuela); case length 49.15mm, MV 2,755 fps.

Yes I've been reading up on all the variations of the British 7mm. If we're talking about a case based on a .458" rim diameter, that seems to be geared towards the intermediate cartridge concept more than a full-power cartridge like the 7.62x51, and would be limited in muzzle velocity with 7mm projectiles of weight in the 130gr plus range. If we're talking about the 7mm High Velocity, Compromise, and Second Optimum, we're basically looking at something very close to a 7mm-08, which would use the same receiver and magazines as an AR10, FAL, or M14. It's still too big for a service rifle for mission endurance, but viable for GPMG's, sniper rifles, and vehicle-mounted weapons, with measurable advantages over the 7.62 NATO.

[stanc]

The .280 pushing a 7mm 168 VLD type bullet versus the 7.62 pushing a M118 173gr Special Ball leans in favor of the 7mm, and makes it a true 800m cartridge. That is with the 7mm 168 VLD starting 100fps slower at 2400fps and the M118 at 2500fps, which is book value for the M24 Sniper Rifle.

With the .280/30, we are looking at faster velocities that make the 7.62 NATO not worth looking at, and you have bullets of similar weights, similar velocities, with the sectional density and aerodynamic advantage clearly in the 7mm's favor. I just ran the numbers side-by-side with the G7 BC values for a 168 7mm VLD at .313, and the M118's .240 G7 BC. The 7mm retains 911 joules at 800m, while the 7.62 M118 only retains 692 joules at that range, having started 100fps faster at the muzzle.

Unfair comparison. AFAIK, the US and UK have never used VLD bullets in infantry rifle calibers.

Try 7mm 168gr FMJ (w/tangent ogive) against M118SB.

(And your 2400fps MV seems a trifle optimistic, seeing as how the long, 168gr bullet would reduce powder volume.)

[LRRPF52]

Unfair comparison. AFAIK, the US and UK have never used VLD bullets in infantry rifle calibers.

Try 7mm 168gr FMJ (w/tangent ogive) against M118SB.

(And your 2400fps MV seems a trifle optimistic, seeing as how the long, 168gr bullet would reduce powder volume.)

I was actually comparing sniper rifles to sniper rifles, and appropriate projectiles for each. Even the hunting 7mm bullets with exposed lead tips have higher average BC's than the BTHP match .30 cal pills in the 150-175 weight ranges. A flat-based 139gr 7mm still has a G1 BC of .392, and since boat tail projectiles were adopted for the 7.62 NATO across the board, one can deduce that a 7mm FMJ with a boat tail would have been used then as well. Once you boat tail the 7mm, bullets almost 30gr lighter have the same or higher BC as their .30 cal BTHP match counterparts.

2400 fps is about 200-400fps mild when looking at the 7mm/.30 and other 7mm cartridges based on the .473" rimmed US cases, so I purposely handicapped the 7mm to show that it still has an advantage. The original .280 Enfield produced velocities in the 2530fps range with a 139gr projectile. With further powder development specifically for the .280 in any form, the US would most likely have developed loads with faster velocities using mixed powders, although the 7mm still smokes the .30 cals no matter how you look at it.

The .30 cal was a mistake in my opinion. Barrel availability isn't a limiting factor since entirely new barrels were made for the M14, FAL, AR10, and G3. The 7mm from a .473" rimmed case also enjoys about the same barrel life for accuracy as a 7.62 NATO, so there isn't a trade-off there either. It just made too much sense for big green pickle machine, so it wasn't adopted. That's my take on it. You can't fix the mindset of big Army brass. Stupidity is an eternal disease, I've concluded. It can't be helped, assisted, or corrected...only steered, and corrupt + stubborn + stupid makes a problematic mule.

[Buck2732]

Ok I need to confess I would like a rifle in this cal I have put in some time reading alot about it. So I offer this as some light reading.

http://www.quarry.nildram.co.uk/256brit.htm

Buck2732

[jbob208]

i aggree with the comments about aluminum, in that period most aluminum was being sand cast the alloys were simply not available at the time to make the high strength forgings. At the time aluminum was just highly refined dirt,(buaxite ore) to make it strong it had to be thick. Remember we were using a slide rule for caculations and adding a fudge factor in essence overbuilding everything. Now we have finiate element software that allows us to precisly determine a safety factor.

[LRRPF52]

For making conventional civilian market products, aluminum might have been viewed as weak, but for aviation, it was not cast. Aircraft-grade aluminum from WWII era is where Stoner really pushed things, even though the original rifle designs he was working with used steel stampings for the receivers.

The jump to aircraft aluminum made not only lightweight and strength a possibility, but dimensional uniformity under vast temperature ranges-something steel does not enjoy.

I'd still like to see a 7mm AR10 built in the original Armalite or Dutch pattern from the late 1950's. Those are great guns:

[Bambibasher]

Well so much to read

and so much to comment/correct. There has been one sporting rifle in the British 7MM round, it was a Ruger No1 owned by a senior chap at Shrivenham and when he retired he offered it for sale with dies and brass. Sadly before I was aware of its significance.
The use of boat tail bullets in an infantry calibre rifle goes back to the use of the .303 streamlined for long range match competitions. I have one box of kynoch 1960 dated manufacture .303 SL with the hald black adonised cases still. The ammo was developed in the interwar period and i may have the ICI notes on its development still.
The lack of a boat tail on the 7mm British is possibly solely down the batch produced for the trials and the spec issued for the trials, if the spec had called for boat tail bullets then they would have been used. Who knows? Without the committee notes to hand I cant say!

[Steyr94]

I would love to have seen the AR10 in this caliber.

I second that motion.

[Tony Williams]

The use of boat tail bullets in an infantry calibre rifle goes back to the use of the .303 streamlined for long range match competitions. I have one box of kynoch 1960 dated manufacture .303 SL with the hald black adonised cases still. The ammo was developed in the interwar period and i may have the ICI notes on its development still.

Actually the use of boat-tailed bullets in an infantry calibre goes back to the 8mm Lebel "Balle D", whch was machined from solid brass and was I think the first spitzer as well as boat-tailed bullet in military service. It was adopted by the French army in 1898.

In 1911 the Swiss army adopted the 7.5mm GP11 cartridge which had a more conventional lead-cored FMJ bullet which was also pointed and boat tailed. This is still in service today. It had quite an impact on British thinking throughout the interwar period.

The first official British experiments into boat-tailed .303 bullets commenced in 1922, the starting point for these being some work Vickers were doing with boat-tailed .5 inch bullets, so it was decided to try them in .303 calibre. In parallel with this, Kynoch was developing boat-tailed bullets for commercial sale as match ammunition, so 45,000 rounds of ammunition loaded with their 1927 pattern BT bullet were purchased in 1932 and added to the trials. Another 240,000 rounds were purchased in 1936-7. The ultimate outcome of the trials was the .303 Ball Mk VIII adopted for Vickers MGs in 1938. This was the first British service cartridge with a boat-tailed bullet.

[adamjp]

Odd that you don't mention some other relevant matters at the time.

The AR10 was not a true competitor in the competition that resulted in the M14 being selected as they were more concept demonstrators than pre-production rifles.
At the time NATO was seeking to standardise on ONE rifle and ONE cartridge. The US, UK and France had very different ideas about the nature of future war and the soldiers role in it. The 'other' rifle the M14 competed against was the Belgian FN-FAL which was subsequently adopted by pretty much everbody else (except the frogs and the swiss). The US Army competition was really won on the basis that the M14 did not require significant retooling of the factory and could therefore be made 'cheaper'. History tells us that those assertions were not true and the factory was significantly rebuilt to manufacture the M14 which arrived so many years late and over budget. Truth of the matter is that it was an obsolete design when the competition was run, the FAL was a better design for a battle rifle, just as the SR25 type rifle is the next generation after that (although the design needs a gas piston IMHO). The FN SCAR is the most recent design.

The FAL was actually designed around smaller rounds, the 280 Brit cartridge was a stretch, the 7.62x51 took the design to the limits.

I've used the AR10, the FAL an M1A and a G3 enough to be quite familiar with them all. I feel that the FAL was by far the best battle rifle, but the M1A was a better rifle for punching paper. Real experience from the 1960s to the 1990s suggests that the FAL was the best rifle for a soldier across the world, probably why it has been nicknamed the "right arm of freedom". Interestingly I noted several of them in the footage from Libya last year. Early AR10s didn't work that well at all, particularly after a few days in the field. The SR25 type rifles borrow alot of the developmental changes that went into the AR15 and are both similar and very different to the original AR10.

It is a pity the US went with the M14 as that choice certainly created an opportunity for the 5.56 cartridge and we have been cursed with it ever since.

[LRRPF52]

Odd that you don't mention some other relevant matters at the time.

The AR10 was not a true competitor in the competition that resulted in the M14 being selected as they were more concept demonstrators than pre-production rifles.

Agreed: The AR10 was in fact not mature during the trials, and they even experienced an aluminum-sleeved 9130 steel bore alloy barrel that burst during the tests. Stoner had warned them against such a barrel IIRC.


At the time NATO was seeking to standardise on ONE rifle and ONE cartridge. The US, UK and France had very different ideas about the nature of future war and the soldiers role in it. The 'other' rifle the M14 competed against was the Belgian FN-FAL which was subsequently adopted by pretty much everbody else (except the frogs and the swiss). The US Army competition was really won on the basis that the M14 did not require significant retooling of the factory and could therefore be made 'cheaper'. History tells us that those assertions were not true and the factory was significantly rebuilt to manufacture the M14 which arrived so many years late and over budget. Truth of the matter is that it was an obsolete design when the competition was run, the FAL was a better design for a battle rifle, just as the SR25 type rifle is the next generation after that (although the design needs a gas piston IMHO). If you mean an op-rod, then I couldn't disagree more. That's the last thing the AR10 needs, for the same reasons why it doesn't belong on an AR15. The FN SCAR is the most recent design.

The FAL was actually designed around smaller rounds, the 280 Brit cartridge was a stretch, the 7.62x51 took the design to the limits. Yes, this is a matter of history. I would also mention that the FAL that was part of the service rifle trials was named the T48, and some differences than the Belgian FAL.

I've used the AR10, the FAL an M1A and a G3 enough to be quite familiar with them all. I feel that the FAL was by far the best battle rifle, but the M1A was a better rifle for punching paper. Real experience from the 1960s to the 1990s suggests that the FAL was the best rifle for a soldier across the world, probably why it has been nicknamed the "right arm of freedom". Interestingly I noted several of them in the footage from Libya last year.

If we base the popularity of the FAL on production numbers, and how many countries adopted it, it can be said that it was the most successful battle rifle design out of the 4. I prefer the AR10 to it, and would rate the other 3 on their individual merits and handicaps depending on the intended use, but the AR10 really has the best of all of them, minus the FAL's adjustable gas block.

Lightweight/balance: AR10, FAL, M14, G3
Soldier's Load: AR10, G3/FAL if Aluminum mags are used, M14
Accuracy potential: AR10, G3, FAL, M14
Reliability: They're all pretty close, but you can tune the FAL to the conditions
Ergonomics: AR10, FAL, G3, M14
Logistics ease of support: AR10, G3, FAL, M14

Early AR10s didn't work that well at all, particularly after a few days in the field. The SR25 type rifles borrow alot of the developmental changes that went into the AR15 and are both similar and very different to the original AR10.

It is a pity the US went with the M14 as that choice certainly created an opportunity for the 5.56 cartridge and we have been cursed with it ever since.

It's a pity the US tried to adopt a universal caliber system with the 7.62 NATO/M14/M60. It was inevitable that a proper assault rifle caliber would be necessary, since the battle rifle was proven obsolete by maneuver warfare during WWII.

The 5.56 is not a curse, but one of the best calibers ever adopted by the US military. It does what it was intended to do, and does it extremely well. There are other threads here where we have elaborated on that back and forth, since the Grendel offers a very attractive universal caliber system. I'm in the 5.56 camp, but am an advocate for a Grendel Multi-role LMG, which is where small arms development is needed the most, since the individual service weapon is quite ideal with the 5.56 M4 SOPMOD Block II.

..

[Tony Williams]

At the time NATO was seeking to standardise on ONE rifle and ONE cartridge.

That is true, but the competition took place in two separate phases:

1. A NATO-wide competition for one standard rifle/MG cartridge. This was "won" by the 7.62x51 (even though the US Army's own testers at Fort Benning recommended that the .280/30 was a better basis for development).

2. After the calibre had been settled, there was a follow on competition for the rifle to fire it. This was effectively run by and for the US Army - the result was not binding on the rest of NATO. This was initially won by the FN FAL but the Army kept modifying the M14 and rerunning the tests until they decided that they could declare the M14 the victor. No-one else in NATO took any notice of this and nearly everyone chose the FAL, with the exception of Germany (and subsequently a few others) who chose the G3 instead. Actually, Germany would have chosen the FAL too but Belgium wouldn't permit them a manufacturing licence - a costly mistake!

The selection of the 7.62x51 was stupid and pointless. If they wanted a full-power cartridge they should have kept the .30-06 (which the UK had provisionally selected as its future cartridge before the cartridge competition issue was raised). That would have left them room to introduce a new, shorter-range round suitable for assault rifles. This is exactly what Germany had done in WW2, and the USSR immediately afterwards.

I have to laugh at the current fuss some people are making about the AAC 300 Blackout, touting it as a 5.56mm replacement. The joke is that the ballistics of the standard supersonic loading for this round are an exact match for the 7.62x39 introduced in the AK over 60 years ago! Back to the future...

[adamjp]

Germany did field the FN-FAL for many years before they adopted the G3. The used over 100,000 of them! Probably sold them off to someone when they bought the G3 into service.

The G3 seems like a cool rifle, it certainly is accurate, but I found that when it gets dirty it can become unreliable in extraction. Never had that problem with the FAL no matter how filthy it became.

LRRPF52, I going to continue to disagree with you over the 5.56.

I do agree that the 7.62x51 is too powerful for a standard infantry round and even at the time open minded participants would have realised that they had missed the objective. If the M14 had been a better rifle, and the cartridge had been something closer to the 280 Brit, then it is quite likely the combination would have lasted longer (probably the late 1970s - after Vietnam) and the 5.56 would never have been. Both the 7.62x51 and the 5.56x45 are purely American in their conception and to me they are examples of tunnel vision. They really could have done with a red team review - are the requirements correct, are we designing something that meets the need, are we about to build the solution - or another problem?

They are not the first, and probably won't be the last.