Anybody have any ideas?

[johnnymac]

I started reloading about 6 months ago and i am still finding myself very frustrated and confused with my results so far. First let me explain the process i go through when loading:

I am using Federal Gold Medal Brass and CCI BR Primers for all loads.

1. Full length size brass
2. Tumble brass overnight
3. Trim Brass
4. Debur flash hole, and case mouth. Chamfer inside
5. Prime with RCBS hand primer
6. Powder charge
7. Seat bullet

I first load groups of 3 at different powder charges increasing by 0.3 increments. All loads are seated at the same depth.

I shoot all loads through chronograph to determine which load has the most consistent velocities.

Once the most consistent(velocity) load is determined i then load groups of three with that same powder charge at different seating depths getting progressively closer to the lands.

I then shoot these to determine which one groups the best.

So now for the problem: Today i was testing some different loads. I was using Varget and 168 gr Hornady AMAX. These were shot out of a remington 700 5r .308. I had one group measuring 0.24 and another measuring 0.38. Other groups were from 0.75 to 1.00. Later in the afternoon i duplicated the same two loads that shot well and could not get a group under an inch. This seems to be the way it goes for every gun/bullet/powder i try. I have tried 168 gr Sierra MK's as well as the 175's and have the same problem every time.

Sorry this is so long, just wanted to explain as much as possible. Any help would be appreciated.

Thanks, John

 

[AJ Peacock]

How often are you cleaning your barrel?

AJ

 

[johnnymac]

After every 20 rounds or so

 

[AJ Peacock]

Every 20 rounds is pretty often. It probably takes 3-5 rounds to correctly foul the barrel. I clean mine when the accuracy falls off (or I can't take it any more) maybe 100-200 rounds on some of my rifles.

Did the better groups come right after cleaning, or after a couple groups?

AJ

 

[jmason]

John- when you found the charge weight that worked good for consistency you changed the seating depth. That changes the pressure. You'll now need to find the charge weight that works with the seating depth you chose. You'll need to back down a bit on the powder and shoot some more 3 shot strings over your chrony again to find the powder charge for velocity consistency at that depth. Basically start over. If you depth was a good selection you should (in theory) end up with a better grouping load for your troubles.

Keep us posted!

 

[jmason]

holy crap you guys are quick. 4 posts from the time I read the first post to my 1st reply!

 

[johnnymac]

some of the good groups are fresh off a clean barrel and others are the last group of the day. Im confused with how a particular load will shoot very well but when i load it again it shoots very poor everytime after that. the groups arent even close in size. one will be under a quarter inch and then 4 groups in a row will be close to and inch and a half.

 

[learning]

How many rounds through the barrel total?

 

[johnnymac]

No more than 5 or 6 hundred

 

[Katbird]

Averaging three 5 shot groups is what most use to determine the rifle's accuracy potential. Statistically, that really isn't enough of a sample, but it is probably the most practical.

Unfortunately, it is possible that your groups may not really be all over the place. Get your barrel down to a clean bore using a good copper solvent after you scrub out all of the carbon. Fire 3 or 4 sighters to foul the bore and then try a ten shot group. Allow plenty of time for the barrel to cool between shots. That will tell you how the rifle actually shoots. You probably won't like the fact that some of those fliers are not really fliers at all, but simply part of the group.

You may find that your load is not up to snuff, regardless of the fact that velocities are consistent. You need to find the best bullet/powder combination before you worry about tightening up velocities. It doesn't matter what bullet or powder everybody else's rifle likes. It only matters what your rifle likes.

Work up your loads using bullets of the same weight from two different bullet makers. Pick two bullets that you could be happy with and disregard your preconceived preference. Let your rifle dictate which one it likes.

From the wealth of reloading data available today, you will find that are usually two powders that stand out from the crowd. Try the two powders that are most frequently cited as the the most accurate or the best hunting load from various sources and load rounds for each bullet with both powders.

Once you find which bullet and powder combination your rifle likes, you can move on to tuning your load. The ladder method (several variations) works fine.

 

[Willys46]

I know your frustration. You think you found the sweet sot, then BOOM! It goes to hell.

I hate to say this, but it might not be a loading issue, it may be a gun issue. It says you're shooting a 308.

This is how I would approach it:
1. Buy some Federal Gold Match in 175's or 168 and shoot some factory ammo. Most 308's will shoot FGM as good as most hand loads. This would be to determine a base line. Shoot all 20 over the chronograph.

The .25 moa groups might just be flukes. .25 MOA groups do not grow on trees. If I were to guess the 5r is a .7 to .85 MOA gun.

2. Then start loading form there. After you shoot your 3 shot groups and find the best group. Try loading some .1 and .2 over and under that load to fine tune.

Are you shooting single feed or Mag length. Most 308 mag will only hold a 2.800 OAL. I would tune a powder charge instead of a seating depth. The 308 and SMK handle a jump just fine.

What powder. Most find 43-45grs of Varget behind a 175 SMK seated at 2.800 to be satisfactory for a 308.

Also check out snipershide.com in the reloading section. They have a great 308 load section.

 

[boomtube]

"one will be under a quarter inch and then 4 groups in a row will be close to and inch and a half."

Actually, it isn't "magic" working against you. The close shooting groups are just the laws of chance or, as the math gurus call it, "a statistical anomally." Meaning your "great groups" are likely just the result of chance and is NOT representitive of the grouping qualities of that load.

Toss a handfull of rocks at a wall. Note that somewhere on the wall the you can easily find several impacts quite close together but that means nothing to do with the overall pattern.

Some of your groups will show that same kind of random chance as well. By pure chance, any 3 or 5 rounds may cluster together but the real accuracy is displayed by the widest shots in the total number fired. Thus, larger groups are usually showing what our rifle is doing with that load, not an occasional small group.

This is especially true if we are test firing a sequence of loads for groups. If the charge (or seating) steps are small, large groups are unlikely to suddenly shrink tremendously and then get much larger immediatly after any one test load. Only groups tending to shrink as we approach a good point and then tapering back out as the charge is increases is likely to "prove" anything. I prefer to test 3 shot groups in no more than .3 gr. steps to show the group progression better. Even then, I'm not surprised to later find some small groups aren't repeatable.

I consider the size target I can hit - everytime - is my true accruacy. Averaging serves to smooth out the effects of the wider shots and merge them into a smaller mathmatical composite. IMHO, that's not a really good thing to do, I can't hit anything with math, I have to use my rifle. So, for me, averaging becomes a means of happy-side self delusion.

 

[Kevin Thomas]

Gotta agree with Boomtube here. Few shooters really do what the beancounters refer to as statistically significant analysis of their loads. This can involve LOTS of shooting, if you really want to verify something like this. Fortunatley, most of us don't need to. A good load, one that shoots reliably well (but may not be the "true" best load) is perfectly fine. For what it's worth, Lake City Army Ammunition Plant used to require six 14-shot groups @ 200 yards for a certification of a given lot of bullets. This was later modified to ten 10-shot groups @ 300 meters, and this is what is used today. A bit more trouble than most of us want to go through. For my own stuff, I'm willing to take whatever time I need to eliminate those loads which give funky anomolies and deliver whatever level of accuracy I need for that particular application, Beyond that, hey, you can easily shoot out a barrel looking for the ultimate load, without ever having tested all the variables involved. Life's too short. Develop a good load, and run with it!

Kevin

 

[johnnymac]

Thanks for all of the help. Im beginning to think i might have just gotten lucky on those few small groups.