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Discussion Starter · #1 ·
Note:This info is for shooting a either a .308 or .311 or .312 bullet form a bore that is .311 or bigger.

I contacted Lapua about their load data for 7.62x43R and if its for .308 or .311 and got a reply:

"The data shown in our manual is for the 7.62x53R, and was developed with .308” diameter bullets. Bullet diameter, incidentally, is the sole difference between this cartridge and the original 7.62x54R. This is also what accounts for the different nomenclature of each, as CIP rules require such changes to be indicated to avoid confusion of similar cartridges. Large numbers of the Finnish M/91 Mosin-Nagant rifles were rebarreled with the .308” grooved barrels, and it became the standard for much of their ammunition."

I see there is load data for .308 and .311/.312 bullets. Is there much of a difference in pressure between the a .308 and .311 bullet loaded with same load data? If so is it enough to worry about?
Hodgdon data for 7.62x54R is for .308 bullets, shouldn't it be called 7.62x53R? I guess not as USA is not a CIP member.

Accurate Powder data is for a bullet .312.

Not sure if Sierra has data for 7.62x54R or what diameter they use.
 

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It depends upon how you load.
If you reload on the mild side, the switch from .308 diameter projectiles to .310, .311, .312 or .313 diameter projectiles will not boost pressures above acceptable levels.
But if you have the habit of loading everything to "Maximum" load, you could push a the load with a 308 projectile into the proof round pressures using a .311 diameter projectile.
Other issues also come into play, that many people tend to ignore, rifling bearing length plays a big part in pressures.
Projectiles with long bearing lengths (round nose projectiles) will generate higher pressures than will a projectile of the same diameter and weight that has a shorter bearing length.
Gregg
 

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The Hornady 9th Edition has .312 bullet loads for 762x54R. Highly recommend that as a reference if you hand load for 91/30, PU sniper or any 762x54R caliber rifle.

Pushing a .312 bullet down a .308 bore ?? .....This is not safe. If in doubt, slug your bore and measure it , use proper bullets.

Don't really understand LandToys concerns, he has been telling us he shoots 308 down a .315 size bore so we know he measures bores . I may have misunderstood his focus / point of view.
 

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I am somewhat confused by the reply from Lapua the OP quoted. I reload for the Finn M39 using Vihta Vuori manual data. I am using the charge for N140 with the Lapua D166. which is described as .310" although mine mike to somewhat under that.
 

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Leon, with no disrespect intended, I have been scratching my watch and winding my a$$ trying to figure out how Landtoy shoots 308 in a 315 bore and gets any accuracy as he reports. I suspect its a set of calipers that are out of calibration and measuring wrong.

However..NEVER SAY Never
 

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Leon you need to slug the bore .. some of the Early Finns were .308 in the groove .300 on the lands.. Russian were more like .311 in the groove up to the .315 mentioned and .303. up to .307 in the lands ..
I can see a .308 bullet getting some land and some spin in a .315 groove .306ish land bore and shooting with decent accuracy.

Using the .310-311 bullets could give you pressure issues in a true 308G- .300L bore it gave the Finns pressure issues which is why they modified the throat and marked the rifles with the modified throat with a "D" as you usually find on the M39's so they could use the Russian ammo safely .. should find it on most Finns.. The main pressure issue comes from the .311 bullet sitting up against the lands on a tight .308 bore and an unmodified throat. You will also notice that the D-166 and the D-47 bullets have a longer secant ( are more pointy than you average bullet) this also changes the interface in the throat between the bullet and the lands.

The rule with reloading is you start down 10% and work up for reasons just like this. You can't really go by any of the reloading books except for starting data unless you happen to have the same model rifle they developed the reloading charts on and in approximately the same condition. think about it, any pressure or velocity data can't be the same for a M44 length barrel as a 91/30 length a M91 length, or a M39 length from any particular recipe. And yes.. you are right about load books being very casual about the .308 V .311 difference between 53r and 54r .. but that too is all covered by starting 10% and working up looking for pressure signs.
 

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I don't know Milprileb.. what does the guy say he is getting? A lot has to do with the bullet.. folks have been milking reasonable accuracy out of shot out Enfield's for years. Your argument isn't with me.. it is with the guy making the claims.. all I am saying is it seems possible to me.. everybody so far has been talking about groove diameters like lands don't exist, and lands do exist and .303-.307 land will engage a .308 bullet .. On a new barrel for 7.62x 54 or Brit. 303 we are talking lands around .303 and using .308 bullets and grooves around .311 .. flat based bullets would work better than boat tails and those long straight sided round nosed like these http://www.midwayusa.com/product/16...ter-170-grain-soft-point?cm_vc=ProductFinding better yet.

not saying proper .311's +/- .001 wouldn't work better or even some of the .314's that were available out of Canada a few years back wouldn't be better still in an oversized or shot out nominal .311 now .315 .

All I am saying is if the lands are cutting the bullet and the bullet is spinning it's possible IMHO for what the guy making the claim is saying to be true. You want to argue with my opinion fine, but I think your "fight" would be with the guy making the claim.. I just think it is possible and folks have been getting reasonable accuracy out of oversized barrel for decades using bullets sized for new in spec to tolerance bores. I think it would take more hard data and specifics before it would be reasonable to come so close to just calling somebody a liar.. but that's the internet these days.

Are you mad at me for bringing up the "land's" dimensions?
 

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Discussion Starter · #9 · (Edited)
I dont know how this turned into an accuracy post. I just asked about pressure issues of .311/.312 bullets with 7.62x54r load data .308. When I do find some .311/.312 bullets I wanted to know what data to use.

I do find that .311/.312 bullets do better than .308 bullets in my .315 bore but as I dont have any more .311/.312 bullets (less what I loaded) as does most gun store, I am left with shooting .308 bullets.

Now if you measured pressure in a .308 barrel with a .308 bullet and measured pressure in a .311 barrel with a .311 bullet, using the same load data, would there be much of a pressure difference?

Being that I have an over size bore, I am assuming that my pressures should be less due to blow-by.

I had my slug measured my a cast bullet maker, by me with caliper and micrometer and even slugged it a second time for good measure and its always .315.

For me, plinking with .308 bullets will work fine.



The left if a .311 and right is a .308 bullet.
 

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Discussion Starter · #11 ·
Are those FMJ (looks like it) pulled (i think so as it says "no marks")?
Are they steel core? Dont want steel core as range doesnt like us shooting steel targets with steel core bullets plus its a fire hazard out here in the dry west. I get board real fast shooting paper and switch to steel gongs and rocks.

Thanks for the link.
 

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Yep.. pulled 7.62x54r bullets
 

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I think it would take more hard data and specifics before it would be reasonable to come so close to just calling somebody a liar.. but that's the internet these days. Are you mad at me for bringing up the "land's" dimensions?
Nope and Nope. Not calling anyone a liar and not mad at anyone. I am asking for understanding how this can be happening.
 

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Leon you need to slug the bore .. some of the Early Finns were .308 in the groove .300 on the lands.. Russian were more like .311 in the groove up to the .315 mentioned and .303. up to .307 in the lands .. I can see a .308 bullet getting some land and some spin in a .315 groove .306ish land bore and shooting with decent accuracy...
My three 44 M39's are definitely .310" and with the D166 over 40 gr Vihta Vuori N140 shoot precisely as the range calibrations indicate. They also shoot Serb M30 splendidly, but high. I have a M28/30 and this is the only Finn with a true .308" bore. With this rifle I load Lapua D46's - 185 gr .308". I had until recently a M38 with a rough sewer pipe bore. Any size boat tail bullet fell to the ground before reaching a 200 yd target. The only bullets that could actually reach the target and group were the flat base 174 gr FMJ used in Brown Bear "match" ammo - now sadly no longer available - and the .312" flat base RN Hornady. It's a pity the Brown Bear 174 gr flat base FMJ bullet is not available separately. It does well also in the .303 No 4 since it is very similar to the Mk VII bullet.
 

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Discussion Starter · #15 · (Edited)
The groove is .315 and lands are .3015 on my rifle.

I did try some 100g, 130g and 150 plated bullets and most of them didn't even hit the 50y target, not sure where they ended up.

Here is one that patterned like a shotgun .308.


All .311/.312 Left, all same bullet/data, right 2 shot groups, 100 yrds


Next time out I will use a bigger target as some loads hit very high and others hit very low. I just want to see how much bullet shape, weight, and diameter change where the bullet hits using the same point of aim. There is about an 18" difference in where the bullet hits.
 

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Nope and Nope. Not calling anyone a liar and not mad at anyone. I am asking for understanding how this can be happening.
That is why I mentioned the lands still being tight enough to engage and cut the bullet and make it spin, the reason I think some accuracy is likely.
 

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The groove is .315 and lands are .3015 on my rifle. I did try some 100g, 130g and 150 plated bullets and most of them didn't even hit the 50y target, not sure where they ended up. Here is one that patterned like a shotgun .308. All .311/.312 Left, all same bullet/data, right 2 shot groups, 100 yrds Next time out I will use a bigger target as some loads hit very high and others hit very low. I just want to see how much bullet shape, weight, and diameter change where the bullet hits using the same point of aim. There is about an 18" difference in where the bullet hits.
What is a "plated" bullet? Do you mean jacketed? Are these bullets FMJ, i.e. with the jacket material open at the base exposing the core? Or are these bullets hollow point with the jacket entirely enclosing the core at the base? It is no wonder these bullets did not hit a target at 50 yards. They fell to ground because of blowby. The blowby results from "windage" in its original muzzle loading era meaning: the difference between the diameter of the projectile and the diameter of the bore. With very high lands, the soft bullet jacket may be squeezed down and the displaced jacket and core material expand into the available free space, providing some mechanical sealing in the bore.
 

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Discussion Starter · #18 ·
Berry's bullets are copper plated lead bullets. Its a thin soft copper plating. They load with cast or very low jacketed bullets. The 30-30 version can go up tp 1700 fps. They are in between cast and jacketed bullets.

The others were very short 100g to 130g jacketed bullets so I am sure they never stabilized in the bore.

I really need to get some longer bullets and see how they work. Was told that Barns copper bullets are longer than same weight jacketed bullets. When the economy gets better ( ie, I work more hours) I will do more experemnets with different bullets, that is if there are bullets to be had...hoarders...
 
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