I have question about increasing pressure in a 308 load
 

I was working up a load for my 308 I worked it up to 45.5 grains of varget and decided to stop I was happy with the velocity, But a few days later I decided to see what Kind of velocity I could hit workin it up a bit more. The max load is 46 grains, But when I fired one with 45.7 grains it considerably flatten the primer alot more then it does with 45.5 grains, but when I fired another this time with 46 grains the primer was only flattened like it did with the 45.5 grains. what does this mean??? why am I getting a good sign of pressure increase with 45.7 grains and not with 46 grains?? I'm am confused with this one

RE: I have question about increasing pressure in a 308 load
 

I would never use the look of a primer as a true pressure indacator. I read that it takes lots of pressure to flatten a rifle primer.
The ways I use and I am no expert at it , just what I have read .
On lifting the bolt handle ,dose it stich or any extra resistance ?
I mik. the case just in front of the web ,is it the same or less exspansion as factory ammo ?
What bullet and load data are you using ? I looked at my Hornady book and Varget with 150 gr bullets tops out at 44.9 gr

RE: I have question about increasing pressure in a 308 load
 

The bolt doesn't stick and no resistance at all, I tried using my micrometer to measure the case there on the web but I cant use factory ammo for reference since I use fire formed brass and only size the neck. I did use some of my once fired casings from the same batch as the now twice fired cases for reference and there was no difference if there is any variation its within .0005. My load data is:

Bullet: Sierra 165 grain BTHP gameking Case:winchester Primer: fed 210m Powder: 46 grains varget MAX

I used remington brass instead and a fed 210 primer also that is why I wanted to work up the load to be on the safe side since remington brass has a little less case capacity then winchester.

Asfar as the load data for a 150 grain bullet that you have 44.9 grains sounds like a start charge. All My data I have all shows 44 grains as a start charge for a 150 grain bullet with varget and shows 47 grains as MAX. that was both in Sierra rifle and pistol reloading data manual: 5th edition and Hodgdon's 2002 annual reloading manual.

Let me ask what would you do would you go ahead and use the max load or would you keep it backed off a bit? I was told by a friend here in arizona because it can be very dry and hot the max load isnt really the best idea because on hot days of shooting the barrel warms up faster and if I have nice hot barrel put a new cartridge in the gun and wait a few minutes before firing and the new cartridge with a max load warms up to the tempature of the barrel then you might have a problem and could blow the gun up when fired.

The chronograph I used in the begining to work up my load to the 45.5 grains wasnt very accurate half the time it would just read 0000 when shot through it, my buddy did tell me it was old and not very good. I'd like to think i was getting 2700+ fps with the 45.5 grain charge. Can anyone tell me that uses the same load as I do what charge they use and what kind of velocity they get from a better chronograph then the one i used. I know even with the same loads but different guns velocity can vary but I just need a general ball park idea. the velocity I want needs to be at the least 2700 fps.

RE: I have question about increasing pressure in a 308 load
 

Q:?
Did you use new brass on your first series of load workups, and then reload the brass by neck sizing it to do your later loads?

A neck sized piece of brass is going to fit the chamber of the rifle alot tighter than a new piece of brass. A new piece of brass is likely to leave a bit more headspace in the chamber where the brass needs to expand to fill it out. When this happens, the base of the case is pushed backward fairly hard and can flatten the primer. The force pushing back on the necksized cases isn't going to be quite as high as the headspace will be less, and you won't get the false-positive high pressure signs of the primer flattening.

This would be my best wild -ss scientific guess as to what might be happening.

RE: I have question about increasing pressure in a 308 load
 

That just showes the differance between load books and bullets Hornady 5 edition says 44gr with a 165 -168 gr bullet is Max . Have fun and be safe!

RE: I have question about increasing pressure in a 308 load
 

While performance is always a goal of reloaders, trying to beat (considerably) the velocity of factory loads is a futile exercise filled with the promise of future trouble. It's just not worth it.....even if you succeed in beating factory velocities by 150'/sec there still isn't any game animal in the world that will notice. Further doing so can be a very difficult task.....if you really need that additional velocity trade the gun for a .30-06 or a .300 Mag.....you have a very fine gun in a .308.....enjoy it "as is"!!!

RE: I have question about increasing pressure in a 308 load
 

I have an older Remington M700 mountain rifle in 308 win, A rare one I think its the only one I have ever seen chambered in .308 win.

The brass was factory ammo first, then I neck sized it and thats what I have for brass. I dont see any reason to buy brand new brass.

A factory load for a 165 grain bullet pushes right at or a little above 2700 fps from most data I have looked at. I am just wanting to hit factory velocity, what charge weight would give me factory velocity? the extra velocity is unimportant to me all i want is to be at or slightly above 2700 fps. My load data from hodgdon states the 46 grains of varget hits a velocity of 2773 fps from a 24 inch barrel, My rifle has a 22 inch barrel.

RE: I have question about increasing pressure in a 308 load
 

If its just factory velocity you want to match, don't bother worrying about it. Factory velocity ratings are based on on of their test rifles- comparing this to what it will do in your rifle is like comparing apples to oranges. Reloading manuals- pretty much the same deal, you can't accurately predict velocities unless you already have data for your personal rifle.

This is also the reason why you want to work up a load- in some rifles you load a little hotter than the maximum load, in others somewhat less to get to the point of high pressure signs.


If you just load for velocity- especially blindly without a good chonograph, you are ignoring the biggest virtue of the cartridge, which is accuracy. A .308 that shoots cloverleafs is alot more fun and useful than a .308 that shoots 100 fps faster and shoots 1.5" groups.;)

RE: I have question about increasing pressure in a 308 load
 

johnch,

that hornady load data you have what brass are they using in it?

Birman,

I'm not looking for more velocity i'm after accuracy thats why I am lookin to push the bullet at about 2700 fps. I think I'm just gonna stick with the 45.5 grains and call it good for now untill i get a good chrono. or if i can find some helpful info that might steer me i the direction im lookin for.

RE: I have question about increasing pressure in a 308 load
 

well i just found some info for the 165 grain bthp game king the info shows the best accuracy for a 20 inch barrel with 1 in 10 twist nearly the same as what my rifle has (22 inch barrel 1 in 10 twist) is a charge weight between 44 and 45 grains those charges in a 20 inch barrel produce between 2600 and 2670 fps. So i think I will back off my charge to 45 grains and give it a try id imagine in my barrel with 2 inches more barrel should produce a little closer to 2700 i'm guessimating 2,680 fps. which is about the velocity for a factory match loading. Thanks guys for giving a little more to think about if you have anything else to share you are most welcome I would love to read more ideas that might help.

RE: I have question about increasing pressure in a 308 load
 

I'm trying to analyze why 2700 is a magic number for you...

Do the factory loads give you outstanding accuracy? If this is the case, then it might make some sense to try to get the velocity somewhat close. in alot of cases, a velocity for a given powder will give you similar accuracy for the same velocity load with with a different powder- or at least give you a starting point for finding an accurate load. Without a chronograph checking your loads and factory loads, you won't be able to find your proverbial rear end with a flashlight, mirror, two hands, and a funnel.

Remember- comparing book values to factory values is still comparing apples to oranges. I have different manuals that list significantly different velocities for the same loads.


I think you are overthinking this. If you start a few grains below the max load and load 3-5 rounds for each increment of .5 gr, I have no doubt you will find a good accurate load for your .308 so long as there is nothing wrong with the rifle. When you find a good accurate load, you can go back to your starting point and work the load down in .5 gr increments also for some low recoil practice/targtet loads.

RE: I have question about increasing pressure in a 308 load
 

This does't make sense to me. I have yet to see .2gr make that huge of a pressure difference. I know its a steep waterfall curve with pressure after you lock up brass in the chamber, but I think .2gr is picking pepper out of fly crap if you not using this rifle for competition. I mean the .2gr pressure difference could be alot of things like a fouled barrel. I would try the same workup shooting the 45.7gr first, and then the 45.5gr.

In all my years I have never worked up a load with such fine granularity. Most hunting rifles and weather varible will not let you see the difference in groups. At most I will find out that I have great accuracy between 45 and 46gr and maybe next time I go, I will try 45.5gr and see the difference. If none out of 4 3shot groups, then I always go with the 46gr. But there is too many varibles in even that. A good dynamic load shouldn't matter so much as 45gr and 46gr. Especially with a 308win. A sensitive load maybe.

RE: I have question about increasing pressure in a 308 load
 

I am wondering the same thing. I have used the 308 with 165gr gamekings for years on deer at close to 2800fps with no problems.

RE: I have question about increasing pressure in a 308 load
 

I think you are right I've been driving my self crazy with this LOL last night I hardly slept thinkin about it. 2700 fps is kinda the magic velocity to me since the factory ammo I shot forever was remington 165 grain BTSP's they had, well according to the packaging muzzle veloc. of 2700 fps but for factory ammo at 100 yards they shot awesome the groups looked like one ragged hole. just at 17 dollars for 20 shots was getting rediculous especially as much as I want to shoot reloading was the only answer. I suppose I am trying base my reloads on the accuracy I experienced with those, and yes I am thinking about it tomuch. what I am gonna do just stick with th 45 grains play with the bullet seating depth see what I get, if nothing I will try something else. My biggest problem I think I am doing is I know in reloading asfar as accuracy is concerned there is alot of trial and error to be worked out before you have a good load, I am trying to work out the problems in my head and its not working.

RE: I have question about increasing pressure in a 308 load
 

yeah I know seemed like pickin pepper from fly crap to me too but I was just following 1mile50's recommendation on working up a load. after doing it his way I figured out it was completely pointless, my deal now is im just trying to find a good powder charge to work with.

RE: I have question about increasing pressure in a 308 load
 

i feel 45 grains is what im gonna use i figure its a good starting point i can go either way back down to 44 or back up to 46. Basically from what I am gathering from you guys is that Ill never know untill I atleast try it. perhaps I was giving it tomuch thought thinking I could create a hunting load with competition precision. get the best of both worlds.

RE: I have question about increasing pressure in a 308 load
 

Not to throw another fly in the ointment, but I have had greatluck with BL-C2 lately. Also been shooting alot with 4064 with TSX's. I also can't leave much alone.

RE: I have question about increasing pressure in a 308 load
 

[quote][Also been shooting alot with 4064 with TSX's/quote]

Yup 4064 and 4895 work really well with the .308 also.

RE: I have question about increasing pressure in a 308 load
 

Are those spherical powders?? I was thinking about trying a spherical powder, i was told they meter better then extruded type powders like varget. is that ture?

alright since the powder charge cat is about killed, I have another question about adjusting bullet seat depth. in the past all I ever loaded was canilured type bullets Id seat it so the canilure was just barely exposed from the mouth then I would use a slight crimp. but now with sierra's Im using no crimp but need to figure out a good seating depth. My starting col will be 2.750 and will work it up to 2.800 what kind of increments should I use? should I go by 100ths or thousandths?

RE: I have question about increasing pressure in a 308 load
 

4895 and 4064 are extruded powders. The IMR versions which I use aren't the easiest to meter, though with practice they aren't a problem. I believe Hodgdon 4064 and 4895 have shorter powder grains and should be easier to meter, but I don't use them.

For COL, you need to measure to see if the bullet comes close to the lands. There are a few different ways to do this, but I won't go into the details- try seating a bullet in a resized (empty) case so that the base of the bullet is .300" deep. chamber the round, if you feel resistance from the bullet hitting the lands in the barrel, reseat the bullet so that it is .308" deep, and try again.

If the bullet touches the lands at either point, you will want to measure how far you can seat the bullet out before it hits- reason to start at .300 is to make sure you have some safety margin instead of starting with a .308 depth. If it still touches with a .308 depth, you can adjust the bullet seating depth so its closer to the lands, though I wouldn't go any closer than .020" unless you have a high qulaity barrel on it that was carefully installed and the chamber was cut very carefully and the freebore in front of the chamber was cut very uniform and square.

If the bullet doesn't touch at either point- seat your bullets to .308" deep, or whatever is the maximum length that will function in your magazine- whichever gives a shorter COL.

Seating bullets shallower than its diameter to get you closer to the rifling won't give you any better results- the possibility of the bullet being knocked off center easily and a lack of neck tension more than destroy any potential accuracy gains.

RE: I have question about increasing pressure in a 308 load
 

Too add- seating depths aren't all that important, so long as you don't go too short, or too long- longer COL's will lower pressures a bit, but if you get too close to the rifling, the pressures can increase very dramatically.

RE: I have question about increasing pressure in a 308 load
 

Something I read is that bullet seating depth is kinda like setting the timing on a engine, different bullet seat depths allows you adjust when the bullet leaves the barrel at certain harmonic fluctuations in the steel of the barrel, So basically setting your bullet .020 from the lands will not neccisarily give you the best accuracy and a bullet set even a 1/16 of an inch from the lands could possibly give you the best accuracy. I am gonna play with the SAAMI specs of bullet seating staying within the printed minimum and maximum and see what I come up with.

RE: I have question about increasing pressure in a 308 load
 

Yes, adjusting the seating depth is something you do once you find an accurate load.

Its done more to reduce the jump the bullet has to make to engage the rifling, so that the bullet has a better chance of starting down the barrel with good alignment. When you get to the point of where you are adjusting in increments of +/- .010" you are just trying to squeeze the last 1/4" reduction in your group sizes. If youwant to use the engine analogy, adjusting seating depths before getting a good load is like setting your timing before installing a distributor.

RE: I have question about increasing pressure in a 308 load
 

Ok that makes perfect sense, before it was a little confusing. I totally get in now. thank you. so it would be the best idea to start with a minimum COL?

RE: I have question about increasing pressure in a 308 load
 

Best Sphical powder for a 308 is BL-C2. Meters so very nice. And a tad higher velocity than Varget.

RE: I have question about increasing pressure in a 308 load
 

Seating depths is not that important for alot of bullets but find it very important for solid shank bullets like failsafe, Barnes, and even TBBC.