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  1. #1

    Default .303 accuracy improvement

    Morning guys and gals, I have a no1 mk 3 .303 sporterised, that I have had for a good 15 years already, and would like to know if there are ways and means within a normal persons ability to make it more accurate and reliable. I have free floated the barrel as the front sling screw was pressing against the underside of the barrel as well as the barrel touching the stock at odd intervals.

  2. #2
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    I seem to recall that correctly measuring the barrel (Slugging it?) and then ensuring you are using the right diameter bullets can do wonders.

    With .303 you can get .311 or .312 bullets off the shelf easily enough, but if your barrel is larger you'd have to do some homework to get the right diameter bullets.

    Apparently barrel diameter from new was acceptable at between .310 and .316 if my memory serves.

    I can't remember all the details but apparently amazing improvements can be had by paying attention to this.

  3. #3
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    Default Re: .303 accuracy improvement

    (Nope, nothing you can do, have to sell it me for R5!) How does yours group? 5cm@100m seems to be doable with a .303 and 2-3cm is considered exceptional if memory serves me correct. Contact Daan on the forum - he seems to know a lot about .303's, helped me out once. Or contact the collectors club - they have some real guru's there.

  4. #4

    Default Re: .303 accuracy improvement

    SMLE's are notoriously "iffy" in the accuracy department. Remember that they were all made for military use. The variance in bore and groove diameter is undoubtedly a factor. I had info the groove could vary 309-317 but I will cheerfully accept 310-316. Its all very well to say fit the bullet to the groove but where will you get a bullet bigger than 312 ? I'll return to this later.

    Some are very accurate. I know a No1 that groups in one inch at 100 yards. The No4T sniper rifles of WW2 were selected from the production line and accurised by H&H. I have no idea how they identified a good candidate for accurising or how H&H accurised them, but I'd love to know both.

    The other big problem is the two piece stock. It is very difficult to accurise two piece stocks, first because there is nowhere to bed the action (the SMLE is worse because of that huge mag well) and second because the forend wood hangs off the barrel. I know that there is supposedly a technique of floating the barrel, but I don't see how it can be done satisfactorily given the basic design.

    I worked on quite a few of them, but never tried to accurise one, so I can't offer much about that, except my scepticism that it can be done, realistically.

    I slugged quite a few. Can't remember how many, probably a dozen or so. I never found one as small as 310, or even 311. The biggest was 314 if memory serves. There were more 313 than any other diameter. The only practical answer to bullet diameter is cast bullets. Even then, it may be necessary to lap out the pilot portion of the mould if it casts smaller than bore diameter. But that's not all - the throat diameter is 313, and if the bullet has to be sized 314 to suit a 313 groove, it will be too big for the throat and will get shaved. That will negate any benefit of sizing to suit the groove.

    I have been asked to supply gas checked bullets to a group of 303 users. My only mould is an oversize 30 cal which has shot respectably in my SMLE. I have ordered the Lee 185 grain 303 mould from Titan Reloading in the US, to cast a batch for initial trial. But I suspect that it will not fit all the rifles, so there will be a lot of fine tuning. I say "initial trial" because the guys really want a heavier bullet, something like 215 grains. I can only get that from a custom mould maker, but I don't want to do that until the practicality has been proved by the less expensive Lee mould. Unless the barrels are all similar, I might need more than one mould. If so, it won't be economically viable, as I'll never sell enough bullets to be worth the cost.

    This shows the difficulties of the SMLE. You might get lucky, or you might not.

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    Dick your knowledge on this subject far outweighs mine. I was quoting figures from memory and, as a result I'd prefer to go with your figures.

    As always a very informative and valuable post from you. Appreciated!

  6. #6

    Default Re: .303 accuracy improvement

    Thanks so much, I have started by loading to maximum col 78mm, that she seems to like. I have also played with the loads and bullet heads and found what she likes there too. The big thing being PMP is $#×% €&£¥₩€ umm rubbish. I now load sierra pro hunter. She shoots touching groups most of the time, but sometimes they open up, to about 4 inch max, which I am not sure is because I pulled the shot or because of something else. I know this is very good, but am really trying to work out why the group opens up.

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    Default Re: .303 accuracy improvement

    I went through 18 different loads before my 303 and a friends hit the sweet spot of every round touching at 100 meters, obviously with the odd flier. I found that the col made the biggest difference and went all the way from 73mm to 78mm and found the sweet spot at 75mm. I also found S341 to be the best powder choice, before then I was lucky with a grouping of an A4 page. Patience is the key

  8. #8
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    Default Re: .303 accuracy improvement

    My sporterised 303 used to group slightly over 1moa @ 100m.
    It's been glass bedded. The thing is, most of these rifles come from 1912(ish). These barrels are getting pretty old.
    We've made the stock very heavy! This helps when taking a standing shot out of the shoulder.
    My last grouping was 10cm :-(. I would blame that on crappy ammo for now. (Do not really want to mention that I have not shot for 6 years prior to that)

    There is hope for 303. But as a plinker. Many hunting farms do not allow them any more. simply for the fact that they are getting old, and does not group sub 1moa any more.

    I've been thinking of changing mine into a 270, or some variation of 6mm type thing. Need LOTS of research first. The Lee Enfield actions is not know for high pressure ability.

  9. #9

    Default Re: .303 accuracy improvement

    Quote Originally Posted by gmmcdonald View Post
    Dick your knowledge on this subject far outweighs mine. I was quoting figures from memory and, as a result I'd prefer to go with your figures.

    As always a very informative and valuable post from you. Appreciated!
    That's very kind, gm, but the truth is that I have fair knowledge of some things because I worked with them. But not about others, and I'm very careful not to claim that I know what I don't. There are some very knowledgeable people, and I learn more than I give.

    Bulbar and Crafty's posts show that good accuracy can be gotten with SMLEs, its just more difficult and more a matter of luck than with most other rifles.

    Crafty is being very wise in exercising caution about converting an SMLE to another calibre. Its true that there are pressure limits. Selected No4s are OK for 7.62 NATO, as the British sniper rifle in use until quite recently shows. But the No1 action is thinner and not recommended above 45000 psi. Possibly the best known conversion was the 6mm Musgrave which was the 303 case necked to 243. Nice and simple. But there's no reason why other bullet diameters can't be used. There's a guy in the US who developed a series of cartridges bases on the 303 case. "Sabre" I think he called them. I had some info on that but I've lost track and don't recall the details. I also know that SMLE's have been converted to calibres like 444 Marlin and short 458 in the US and Canada. Those work well because their head diameters are quite similar to the SMLE. In the 1960s the Lithgow factory in Australia made a batch of 22 Hornet rifles on No1 actions for the Slazenger brand name. The action mods were extensive as you can imagine.

    Necking the 303 case up or down is one thing, cases with significantly smaller heads are another. The Ishapore factory in India still makes No1 rifles in 7.62. Apparently they have gotten around the pressure constraint by better metallurgy. The bolt head is not changed - they have handled the smaller case head by fitting an extractor with a longer claw. That can work but only to a point, and I am reliably informed that extraction is not as reliable as the 303. That would be the main problem with calibre conversion.

    There has been an interesting development in Australia recently. The Aussies liked their military rifles but semi autos were banned after the Port Arthur massacre. So they dusted off their SMLE's and faced with high cost and iffy availability of 303 ammo and components they converted them to other calibres, mostly 5.56 and 7.62 x 39. It was mostly the stronger No4s converted to 5.56. The rifle is rebareled with a 5.56 barrel the same profile as the original. A 5.56 mag is installed inside the 303 mag. All to preserve the original appearance of the rifle, although the bayonet lugs are lost. A machined ring is silver soldered to the bolt head to create a recessed bolt head suitable for the smaller case head, a different extractor is fitted, and a plunger type ejector is installed in the bolt head. It is reported to be a very successful conversion.

    It is felt that the No1 should be limited to the 7.62 x 39. It is also cheaper because it doesn't need a new barrel. However, the very interesting point emerged that the limiting factor is not chamber pressure but back thrust on the bolt. That is related to various factors, the main one, it seems, being case head diameter (bigger area = more back thrust). I seem to recall that backthrust of the 5.56 is only two thirds that of the 303, so the 5.56 would be OK in the No1 action.

    Ain't gunsmithing fascinating ? I'd LOVE to get back into it, but at our age it wouldn't be fair to my wife to be missing five days a week. Well, I do work, because I like to, but its mostly in my home office with only the occasional visit outside.

  10. #10

    Default Re: .303 accuracy improvement

    Quote Originally Posted by Dick View Post
    I have been asked to supply gas checked bullets to a group of 303 users. My only mould is an oversize 30 cal which has shot respectably in my SMLE. I have ordered the Lee 185 grain 303 mould from Titan Reloading in the US, to cast a batch for initial trial. But I suspect that it will not fit all the rifles, so there will be a lot of fine tuning. I say "initial trial" because the guys really want a heavier bullet, something like 215 grains. I can only get that from a custom mould maker, but I don't want to do that until the practicality has been proved by the less expensive Lee mould. Unless the barrels are all similar, I might need more than one mould. If so, it won't be economically viable, as I'll never sell enough bullets to be worth the cost.
    There has been an interesting development. For me and others who may be interested in cast bullets, at least. I received the Lee mould. It is grossly undersize. Perhaps this is as good a place as any to describe the requirements of cast rifle bullets. If I have done so in another thread, I hope I may be excused for repeating it here. Handgun bullets are simple because they have a single diameter. Because of manufacturing tolerances, it is near impossible to make moulds that cast to the exact desired diameter. Therefore, they are made slightly oversize, and the bullet is then reduced to diameter in the sizing die. Thus a 9mm bullet will typically cast 358 - 359, and is sized to 356 in the sizing die, and lubricated at the same time.

    Rifle bullets are more difficult. The bore riding style is the most popular these days. It has two diameters. As there seems to be no fixed nomenclature, let us call the major diameter the shank (that's the part with the lube grooves) and the smaller diameter nose portion the pilot (also known as the bore riding portion). The principle is that the shank is sized to one thousandth over groove diameter like handgun bullets, to engage the grooves, and the pilot is supposed to be exactly bore diameter, to ride on, and be guided by the lands. If the pilot is too small, the shank is not long enough to keep the bullet straight in the barrel and accuracy will be poor. Thus a 30 cal bullet will cast at about 311-312 for sizing to 309, while the pilot will cast exactly 300 to fit the bore.

    The catch is getting the pilot to cast exactly to size, because of the aforementioned difficulty of making moulds so precisely as to cast to the exact desired size. Both diameters of this new mould are undersize. The shank casts 313 and the pilot 299. It has already been said in this thread that SMLE barrels tend to be bigger than nominal size. The SMLE has always been popular in Australia and was manufactured in the government arsenal at Lithgow. Australia also has a custom mould maker, Cast Bullet Engineering. In the CBE website I found a report by CBE's owner Jim Allison, in which he said that bore diameter tends to be consistent at 303, but groove is mostly 312 - 314. That confirms my experience that there are more 313 than any other.

    As bores are drilled and reamed its not surprising that bores are a consistent 303, as there'd be no reason to make the reamers bigger, and as a reamer is sharpened several times it would be more likely to cut tight. But at that time the rifling was cut with a Pratt & Whitney sine bar machine, in which the rifling cutter reciprocated back and forth through the bore. It had a single cutting tooth that adjusted automatically to cut slightly deeper with each pass. Typically, the machine would complete the rifling in about thirty minutes. Therefore, the longer the machine was allowed to run, the deeper the grooves would get. It would be human nature, with the pressure of wartime production, to let the grooves be slightly big for insurance, and would explain why so few are undersize and so many over.

    It may also answer my question as to how rifles were selected as sniper rifles - it would undoubtedly have been the groove diameter, because there was no special sniper ammo in either war, standard issue ammo was used with a 311 bullet.

    Jim Allison recommended a minimum sizing diameter of 313 with 314 often a better choice. I would agree with that. This Lee mould won't let me size above 313, and even that will not be sizing, it will be lubricating a 313 bullet in a 313 die. But, as most SMLE's seem to have 313 grooves, 314 would be a better choice. That means at least a 315 casting and preferably 316.

    As for the pilot, I can't confirm Allison's consistent 303 but I'm happy to believe him as he obviously measured a lot of them. As matters are, I have a useless R400 mould. I could lap out the pilot, I've done it before, but its a slow and painstaking procedure, not without risk of causing ovality and taper. Lapping a pilot from 299 to 300 (as I had to do for a Lee 30 cal mould) is not too onerous because of the small amount of metal removal (half a thou or 12.5 microns all round) and the risk of ovality is minimal. But four thousandths (100 microns) is a very different matter. Not to mention enlarging the shank to 315.

    I had intended to use this bullet to see whether the customers would be prepared for the different loading techniques before ordering the more expensive mould I really need. I should have saved the R400 and ordered the custom mould from the word go. The lesson is clear enough, I hope. Custom moulds are not cheap, but only Lee are relatively inexpensive. RCBS and Lyman are of a price that makes the price of a custom mould easier to swallow. Why would a custom mould be better ? The custom mould makers cut them on CNC lathes. There is some tolerance but they cut them more accurately than the mass producers. That's why they are more expensive, among other things. But Lee CNC lathe bores them, the only mass producer to do so. A CNC machine can cut consistently within 25 microns, and the several Lee 30 cal moulds I have used have all had pilots in the 299-300 range. If this 303 mould had been 302 or even 304 I wouldn't complain, but Lee has been careless in setting its machines. Why don't I return the mould ? It will cost me at least half as much in postage as I paid for the mould, with no guarantee of getting a better one. Not worth the bother.

    As a final point, I had a look at the chamber throat dimensions of the 303 British. They are generous and favour a heavy bullet. The standard military load from 1907 was the Mk7 ball. But the earlier Mk6 was a 215 grain round nose. I have no idea what the early throat dimensions were but I suspect that they were not changed from the Mk6 cartridge, hence the very generous freebore. Bullets up to 220 grains are OK, in fact CBE offers a 240 grain mould. I have said in the past that the throat entry is 313, which would shave cast bullets bigger than 312 or 313. But I had another look at a chamber slug of my own 303 with 313 grooves. A chamber slug is like a chamber cast but lead. 313 Groove with 313 throat means that the rifling would extend to the start of the throat. But it extends only half way, which means that the throat is bigger than 313. And, of course, don't forget that SAAMI chamber specs are permissible minimum. Jim Allison's recommended sizing diameter of 314 confirms that. Therefore, unless you have an unusually tight 303, it is probably safe to assume that bullets as big as 314 and as heavy as 220 grains are OK.

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