.311 bullets in a .308

SwampYankee · December 6, 2009, 10:14 PM

I've got a bunch of 150 gr .311 bullets that I've used for my Enfields. My guns seem to like the .312 bullets much better, however, so I would like to find a better use for the .311's. Can .311 FMJ bullets be used in a .308 rifle? My suspicion is that it will cause a dangerous pressure spike, especially loaded anywhere near max. While this is certainly not a good thing, I also wonder if this may cause excessive wear on the bore?

I assume that accuracy would probably also be in the toilet.

Has anyone ever attempted this?

IllinoisCoyoteHunter · December 6, 2009, 10:19 PM

Have you slugged your bore? This would be a good first step to take. After you get this measurement, you may be able to get more accurate answers. I don't own a .308, so I am not sure how much variation there is from manufacturer to maufacturer. Take for example 9mm. I have had nines slug as low as .354" and my Sig slugs at .357. Let us know! Good luck!

Old Grump · December 7, 2009, 04:36 AM

Please don't do that, if you don't want to use them in your 303 then sell them to somebody who will but don't mess up a perfectly good .308 with over size bullets. If nothing else you can probably find a buyer for them right here on this site.

SwampYankee · December 7, 2009, 07:55 AM

Quote:

don't mess up a perfectly good .308 with over size bullets

OK, so, going back to my original post: How will this screw up my FR8?

Frankly, it is not something I plan on attempting because it sounds like a bad idea when I try and reason it to its conclusion. But I'm not the kind of guy that believes everything he is told, reads or thinks he knows. I want to UNDERSTAND why this is a bad idea.

I knew I was going to get the "just sell them responses". I should have indicated in the original post that I know how to sell something and that is not a helpful answer.

I have not slugged the bore but it is an FR8 with little use and I have found no information that would lead me to believe that the bore is seriously out of whack. With my Enfields this is always a good idea, they can have a bore as large a .314. I may try locate some slugs anyway.

Rangefinder · December 7, 2009, 01:19 PM

Quote:

OK, so, going back to my original post: How will this screw up my FR8?

Well, the first thing to do, as already suggested, is slug your bore. If your bore does come out to a true .308, then running .311 through it WILL over-pressure badly. Now, if your bore comes out to an actual .310, then you're going to probably wish you'd checked sooner. It will probably love the .311's. But SLUG YOUR BORE FIRST. Don't just shrug and try one through it.

**Unclenick** · December 7, 2009, 03:02 PM

The U.S. military spec for .30 caliber bore groove diameters is .3065" to .3095", a spread of 0.003". Bullets are allowed up to 0.309". So it is expected that up to 0.0025" over-size bullets will work with standard loads. Bigger than that, and it would be advisable to reduce the load.

Please note that while the U.S. military bores may be undersize for some bullets, the chambers, freebores, and throats in them are not. This is going to be the bigger issue. Is the diameter of your chamber's neck wide enough to accept a case with the fatter bullet in it and still let the case open up to release the bullet normally? Three extra thousandths is within chamber neck tolerances. Take a case that was fired in your chamber, but not resized. Trim the inward curled lip off the mouth, chamfer it, then see if one of these oversize bullets will slip into it freely? If not, you will have to outside turn up to .0015" off the necks of cases for shooting these bullets. Then you need to make sure, in subsequent loading, that none of the wide bullets ever gets into brass that has not been turned that way.

Also check that any freebore in your chamber is wide enough for these bullets. A chamber cast would be a good idea for checking both these factors definitively. Otherwise, try coating a fat bullet with Magic Marker and drop it nose-first into the chamber and use a dowel to tap it lightly on the base. Then use a cleaning rod to push it back out. Look for rifling marks and a ring where the freebore starts (unless it is a ball throat; unlikely, but I don't know that particular gun, so I can't say). If there are rifling marks and no pronounced ring, the freebore is big enough. If you have a ring and little or no rifling mark, the bullet hung up in the mouth of the freebore and these bullets are not candidates for shooting in this rifle, as they will be shaved going into the freebore, creating extra pressure, poor bullet uniformity, and fouling that may interfere with the next round if it isn't blown out completely.

If you've checked the chamber, freebore and throat, and all are OK for the fat bullets, then I would start with a load about 15% below normal and work up slowly, watching for pressure signs. I think I would stay at least 5% below a normal load, for insurance, but that is your call based on the pressure signs.

BTW, you could also open the breech end of the bore up half a thousandth by firelapping. That makes a gun far easier to clean and makes the bore great for shooting lead bullets, so it's a beneficial step to take anyway, in this situation.

Hey_Allen · December 7, 2009, 04:37 PM

If after all the slugging is done, you find you actually are at ~.308, you could probably find someone who'd be willing to trade for the .311 bullets for their rifle loads.

In my case, I've often gone looking far and wide trying to find .311 bullets to load for a .303 Enfield, as well as my two 7.62x54R rifles.

Old Grump · December 7, 2009, 05:22 PM

Quote:

OK, so, going back to my original post: How will this screw up my FR8?

High pressure and copper fouling at the very least, accuracy goes out the window and your action takes a pounding. Short life for your brass but that isn't as important as possibly ruining your barrel. A lot of people shoot 303's and would be happy to buy your bullets. Shooting them up is a false economy that could cost you more than a box of .308 bullets.

My favorite centerfire rifle is my 308 so maybe I am a little over protective but I have seen a few rifles goobered up for no good reason and it just doesn't make any sense. You can always have it reamed out to a 303 but now you have a one of a kind gun and you have to reload all of your ammo. I don't think I would do that if its a good shooter now. Shoot the .311 in it and the good shooter part goes bye-bye.

mkl · December 8, 2009, 10:50 AM

Does anyone have any actual test data that shows shooting slightly oversize bullets increase pressure?

I seem to recall that Ackley ran an experiment where he shot 8mm (.323") in a .308 barrel and found NO increase in pressure.

I would think that at the pressures we are talking about in a modern rifle cartridge, the lead/copper bullet would display the same characteristics as if it were made of silly putty.

Just wondering if anyone has references to any actual tests showing that an increase of a few thousandths causes a pressure rise.

Old Grump · December 8, 2009, 04:43 PM

Quote:

Does anyone have any actual test data that shows shooting slightly oversize bullets increase pressure?

I seem to recall that Ackley ran an experiment where he shot 8mm (.323") in a .308 barrel and found NO increase in pressure.

I would think that at the pressures we are talking about in a modern rifle cartridge, the lead/copper bullet would display the same characteristics as if it were made of silly putty.

Just wondering if anyone has references to any actual tests showing that an increase of a few thousandths causes a pressure rise.

I would like to see that Ackley test and I want to know what kind of bullets he used. we are talking about FMJ .311 bullets here and SAAMI specifically rules out using .311 bullets in a .308 barrel.

You might like to read this test using undersized barrels with .308 bullets.
http://www.triplej.com.au/pdfpages/pressure_factors.pdf

Slamfire · December 8, 2009, 05:43 PM

Measure the inside neck diameter from a fired case. If the inside expansion is less than .311, don't shoot .311 bullets in that rifle. It would be a dangerous practice.

The case neck must be able to expand and release the bullet. If the case neck is pinched in anyway, pressures will climb dangerously. No joke.

If you have plently of expansion space, you can fire the slightly larger bullet with reduced loads.

Why not trade your 311 bullets with someone who has 308 bullets?

mkl · December 8, 2009, 06:15 PM

Quote:

I would like to see that Ackley test and I want to know what kind of bullets he used. we are talking about FMJ .311 bullets here and SAAMI specifically rules out using .311 bullets in a .308 barrel.

I found the reference. It came from P. O. Ackley's Handbook For Shooters & Reloaders, Volume II.

I am attaching scans of the two pages on which he discusses firing an 8mm bullet down a .308 barrel.

mkl · December 8, 2009, 07:57 PM

Quote:

You might like to read this test using undersized barrels with .308 bullets.
http://www.triplej.com.au/pdfpages/pressure_factors.pdf

I read the article, and have a problem with their test methodology. Their implicit assumption is that all five barrels had identical characteristics with the exception of throat and barrel diameter. This is seldom, if ever, the case.

We have all seen questions on these forms from members asking why they get different velocities among identical guns using the same load. Some barrels are just "faster" than others, even those from the same manufacturer.

I would think a more valid test would be similar to Ackley's, where they used the same barrel, and varied the projectile diameter. That eliminates differences between barrels.

I don't mean to start an argument; I just wanted to point out that at least one very respected authority (Ackley) had run tests and found results that were quite different from what one would intuitively expect.

James K · December 8, 2009, 08:03 PM

Listen to Uncle Nick and Slamfire1! The oversize bullet is no big deal, but if the case neck can't expand you will have a real problem.

Jim

Old Grump · December 8, 2009, 08:12 PM

Thank you for the link.

I will only point out that Ackley bored out the throat of a 30-06 to fit the ammunition eliminating the main problem and it was a test barrel. Making any bets what the inside of that bore looked like when he was done shooting or what the accuracy would be. That is a lot different from just loading up .311 bullets and shooting it in a 308 chambered for .308, that is where my problem is. He will have a high pressure jump at the very least, leakage of gas feed back and a hot tight load screaming down the barrel. To many shooters out there who would gladly swap bullets or buy his so he can buy the right bullets unless you think he should ream out his chamber and make it fit only for .311 from now on. I would think of that to make it a 8MM but I would make the rifling to match but if the .308 is a good shooter I wouldn't want to mess it up like that.

Stumper · December 8, 2009, 08:33 PM

Unclenick,Slamfire1 and Jim Keenan have a good grasp of the issues of real concern. If the chamber and throat can accomodate.311 bullets things should be okay.......you just have to check.

SwampYankee · December 8, 2009, 09:01 PM

Unclenick and the rest, thanks for all the information! The size of the throat diameter never occurred to me. It might be interesting to play with the rifle, just to see what the diameters are. I learn something new everyday.

284 Win · December 8, 2009, 09:10 PM

Ok first off I can tell you fellas from experience that shooting .311 diameter projectiles in a .308 bore is possible. All you have to do is check out the Ruger Mini 30. American ammo in 7.62 X 39 Russian is .308 but the Com Block ammo runs anywhere from .310 to .312 thous of an inch and both ammo is fired from the Ruger Mini 30 with no problems. If it will chamber without forcing it in the chamber it should work without a hitch. Now to further enforce that point, I have fired Hornady 123 grain .310 PSP meant for the 7.62 X 39 Russian round in my 30-06 SPRG and my 308 Win. with starting loads in both Mod 70 Winchesters with no signs of excessively high pressure. I have also shot .312 diameter 180 grain RN projectiles in a Remington 760 in 30-06 Sprg that I was having accuracy issues with when I used .308 projectiles and the accuracy was no longer an issue from then on. so I doubt if an extra .003 Thousanth of an inch will make a whole lot of difference when you take into account that a human hair is around .003 thous of an inch. BTW the 123 grainers are devastating on whitetail deer. I have been reloading since 1973 so I have a bit of experience in reloading.

284 Win

Slamfire · December 8, 2009, 09:38 PM

284 reminded me of the thousands of 7.62X54R ball I have shot in my collection of Finnish Mosin Nagants.

Some of these Finnish rifles have 308 barrels. Some have 310. I shot spam cans of Chinese ball, Russian ball, Yugo ball, through these rifles.

No ill effects, but the throats were huge. If the throats were not large enough, bad things would have happened.

Jim243 · December 8, 2009, 10:19 PM

284 Win - ALL Mini-30s manufactured after 1986 are .310-.311 barrels (thats directly from Ruger). I would say your Remington 760 has it's barrel burnt out and needs to be replaced, I have the same gun as a 7600 in 30-06 with no accuracy problems shooting .308s.

Jim

radom · December 10, 2009, 05:13 AM

I would be trading them for some .308 slugs and save some hassle. The gun may like the .311s and it may not on groups. Just keep in mind that US 8mm ammo uses a .323 diamater slug and is designed to be shot in the older .318 bore guns safely and thats a much wider differance from .308 to .311. If the things are not tight in the neck and you back the loads off a bit they will be totaly safe, may not group under a inch but it wont hurt the gun.

bamaranger · December 11, 2009, 02:27 AM

+1 on the Ruger bore dia's. And I've read the early mini's , though bored .308, had a "long" throat and chamber dimensions to allow .311 ammo, though the manuals advised against it.

I have gone the other way, and shot .308 from my .311 PSL, and gotten GREAT improvement in accuracy over Wolfe and surplus x54r ammo, contrary to what one might think.

December 6, 2009, 10:14 PM	#1
SwampYankee Registration in progress Join Date: November 1, 2008 Location: I can be found on a number of other forums. Posts: 1,333	.311 bullets in a .308 I've got a bunch of 150 gr .311 bullets that I've used for my Enfields. My guns seem to like the .312 bullets much better, however, so I would like to find a better use for the .311's. Can .311 FMJ bullets be used in a .308 rifle? My suspicion is that it will cause a dangerous pressure spike, especially loaded anywhere near max. While this is certainly not a good thing, I also wonder if this may cause excessive wear on the bore? I assume that accuracy would probably also be in the toilet. Has anyone ever attempted this?

December 6, 2009, 10:19 PM	#2
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	Have you slugged your bore? This would be a good first step to take. After you get this measurement, you may be able to get more accurate answers. I don't own a .308, so I am not sure how much variation there is from manufacturer to maufacturer. Take for example 9mm. I have had nines slug as low as .354" and my Sig slugs at .357. Let us know! Good luck! __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

December 7, 2009, 04:36 AM	#3
Old Grump Member in memoriam Join Date: April 9, 2009 Location: Blue River Wisconsin, in Posts: 3,144	Please don't do that, if you don't want to use them in your 303 then sell them to somebody who will but don't mess up a perfectly good .308 with over size bullets. If nothing else you can probably find a buyer for them right here on this site. __________________ Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters. --Daniel Webster--

December 7, 2009, 03:02 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	The U.S. military spec for .30 caliber bore groove diameters is .3065" to .3095", a spread of 0.003". Bullets are allowed up to 0.309". So it is expected that up to 0.0025" over-size bullets will work with standard loads. Bigger than that, and it would be advisable to reduce the load. Please note that while the U.S. military bores may be undersize for some bullets, the chambers, freebores, and throats in them are not. This is going to be the bigger issue. Is the diameter of your chamber's neck wide enough to accept a case with the fatter bullet in it and still let the case open up to release the bullet normally? Three extra thousandths is within chamber neck tolerances. Take a case that was fired in your chamber, but not resized. Trim the inward curled lip off the mouth, chamfer it, then see if one of these oversize bullets will slip into it freely? If not, you will have to outside turn up to .0015" off the necks of cases for shooting these bullets. Then you need to make sure, in subsequent loading, that none of the wide bullets ever gets into brass that has not been turned that way. Also check that any freebore in your chamber is wide enough for these bullets. A chamber cast would be a good idea for checking both these factors definitively. Otherwise, try coating a fat bullet with Magic Marker and drop it nose-first into the chamber and use a dowel to tap it lightly on the base. Then use a cleaning rod to push it back out. Look for rifling marks and a ring where the freebore starts (unless it is a ball throat; unlikely, but I don't know that particular gun, so I can't say). If there are rifling marks and no pronounced ring, the freebore is big enough. If you have a ring and little or no rifling mark, the bullet hung up in the mouth of the freebore and these bullets are not candidates for shooting in this rifle, as they will be shaved going into the freebore, creating extra pressure, poor bullet uniformity, and fouling that may interfere with the next round if it isn't blown out completely. If you've checked the chamber, freebore and throat, and all are OK for the fat bullets, then I would start with a load about 15% below normal and work up slowly, watching for pressure signs. I think I would stay at least 5% below a normal load, for insurance, but that is your call based on the pressure signs. BTW, you could also open the breech end of the bore up half a thousandth by firelapping. That makes a gun far easier to clean and makes the bore great for shooting lead bullets, so it's a beneficial step to take anyway, in this situation. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; December 7, 2009 at 03:09 PM.

December 8, 2009, 08:12 PM	#15
Old Grump Member in memoriam Join Date: April 9, 2009 Location: Blue River Wisconsin, in Posts: 3,144	Thank you for the link. I will only point out that Ackley bored out the throat of a 30-06 to fit the ammunition eliminating the main problem and it was a test barrel. Making any bets what the inside of that bore looked like when he was done shooting or what the accuracy would be. That is a lot different from just loading up .311 bullets and shooting it in a 308 chambered for .308, that is where my problem is. He will have a high pressure jump at the very least, leakage of gas feed back and a hot tight load screaming down the barrel. To many shooters out there who would gladly swap bullets or buy his so he can buy the right bullets unless you think he should ream out his chamber and make it fit only for .311 from now on. I would think of that to make it a 8MM but I would make the rifling to match but if the .308 is a good shooter I wouldn't want to mess it up like that. __________________ Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters. --Daniel Webster--

December 7, 2009, 04:37 PM	#7
Hey_Allen Member Join Date: October 14, 2008 Location: NW Washington Posts: 39	If after all the slugging is done, you find you actually are at ~.308, you could probably find someone who'd be willing to trade for the .311 bullets for their rifle loads. In my case, I've often gone looking far and wide trying to find .311 bullets to load for a .303 Enfield, as well as my two 7.62x54R rifles.

December 8, 2009, 10:50 AM	#9
mkl Senior Member Join Date: April 25, 2008 Location: DFW area, Texas Posts: 494	Does anyone have any actual test data that shows shooting slightly oversize bullets increase pressure? I seem to recall that Ackley ran an experiment where he shot 8mm (.323") in a .308 barrel and found NO increase in pressure. I would think that at the pressures we are talking about in a modern rifle cartridge, the lead/copper bullet would display the same characteristics as if it were made of silly putty. Just wondering if anyone has references to any actual tests showing that an increase of a few thousandths causes a pressure rise.

December 8, 2009, 05:43 PM	#11
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Measure the inside neck diameter from a fired case. If the inside expansion is less than .311, don't shoot .311 bullets in that rifle. It would be a dangerous practice. The case neck must be able to expand and release the bullet. If the case neck is pinched in anyway, pressures will climb dangerously. No joke. If you have plently of expansion space, you can fire the slightly larger bullet with reduced loads. Why not trade your 311 bullets with someone who has 308 bullets?

December 8, 2009, 08:03 PM	#14
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Listen to Uncle Nick and Slamfire1! The oversize bullet is no big deal, but if the case neck can't expand you will have a real problem. Jim

December 8, 2009, 08:33 PM	#16
Stumper Senior Member Join Date: June 15, 2008 Location: Colorado Posts: 438	Unclenick,Slamfire1 and Jim Keenan have a good grasp of the issues of real concern. If the chamber and throat can accomodate.311 bullets things should be okay.......you just have to check. __________________ "Let us speak courteously, deal fairly, and keep ourselves armed and ready." Theodore Roosevelt "If only God has magic, how does Santa get down the chimney?" Natalie Peters age 4

December 8, 2009, 09:01 PM	#17
SwampYankee Registration in progress Join Date: November 1, 2008 Location: I can be found on a number of other forums. Posts: 1,333	Unclenick and the rest, thanks for all the information! The size of the throat diameter never occurred to me. It might be interesting to play with the rifle, just to see what the diameters are. I learn something new everyday.

December 8, 2009, 09:10 PM	#18
284 Win Junior Member Join Date: November 29, 2009 Location: Northern Ontario Canada Posts: 10	.311 bullets ia a .308 Ok first off I can tell you fellas from experience that shooting .311 diameter projectiles in a .308 bore is possible. All you have to do is check out the Ruger Mini 30. American ammo in 7.62 X 39 Russian is .308 but the Com Block ammo runs anywhere from .310 to .312 thous of an inch and both ammo is fired from the Ruger Mini 30 with no problems. If it will chamber without forcing it in the chamber it should work without a hitch. Now to further enforce that point, I have fired Hornady 123 grain .310 PSP meant for the 7.62 X 39 Russian round in my 30-06 SPRG and my 308 Win. with starting loads in both Mod 70 Winchesters with no signs of excessively high pressure. I have also shot .312 diameter 180 grain RN projectiles in a Remington 760 in 30-06 Sprg that I was having accuracy issues with when I used .308 projectiles and the accuracy was no longer an issue from then on. so I doubt if an extra .003 Thousanth of an inch will make a whole lot of difference when you take into account that a human hair is around .003 thous of an inch. BTW the 123 grainers are devastating on whitetail deer. I have been reloading since 1973 so I have a bit of experience in reloading. 284 Win

December 8, 2009, 09:38 PM	#19
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	284 reminded me of the thousands of 7.62X54R ball I have shot in my collection of Finnish Mosin Nagants. Some of these Finnish rifles have 308 barrels. Some have 310. I shot spam cans of Chinese ball, Russian ball, Yugo ball, through these rifles. No ill effects, but the throats were huge. If the throats were not large enough, bad things would have happened.

December 8, 2009, 10:19 PM	#20
Jim243 Senior Member Join Date: January 5, 2009 Location: Just off Route 66 Posts: 5,067	284 Win - ALL Mini-30s manufactured after 1986 are .310-.311 barrels (thats directly from Ruger). I would say your Remington 760 has it's barrel burnt out and needs to be replaced, I have the same gun as a 7600 in 30-06 with no accuracy problems shooting .308s. Jim

December 10, 2009, 05:13 AM	#21
radom Senior Member Join Date: January 21, 2000 Posts: 1,357	I would be trading them for some .308 slugs and save some hassle. The gun may like the .311s and it may not on groups. Just keep in mind that US 8mm ammo uses a .323 diamater slug and is designed to be shot in the older .318 bore guns safely and thats a much wider differance from .308 to .311. If the things are not tight in the neck and you back the loads off a bit they will be totaly safe, may not group under a inch but it wont hurt the gun.

December 11, 2009, 02:27 AM	#22
bamaranger Senior Member Join Date: October 9, 2009 Location: North Alabama Posts: 8,309	mini bores +1 on the Ruger bore dia's. And I've read the early mini's , though bored .308, had a "long" throat and chamber dimensions to allow .311 ammo, though the manuals advised against it. I have gone the other way, and shot .308 from my .311 PSL, and gotten GREAT improvement in accuracy over Wolfe and surplus x54r ammo, contrary to what one might think.