My bet is you'll have poi shift, and group sizes would be a crap shoot. Grouping comes from a consistent loading that is tailored to the rifle, so the case can change velocity and therefore can swing in or out of an accuracy node. The poi will change because the cases will have different capacity which will change pressure and burn rate which affects velocity. You can probably work up equivalent accuracy loads for each case, but they will be slightly different. Have fun and post results!
Does using different brass matter?
- Thread starter Big k
- Start date
X2
You would think that all makers of brass would have super tight tolerances, but apparently not. If you do very careful water volume tests you will see that all makes will vary, not much, but they will. And because the interior case volume is slightly different the pressures will also be, but again, not by much. The difference in all my loads is not to worry about. For a benchrest shooter, everything comes into play and I am sure water volumes are matched as close as possible ! IMO
You would think that all makers of brass would have super tight tolerances, but apparently not. If you do very careful water volume tests you will see that all makes will vary, not much, but they will. And because the interior case volume is slightly different the pressures will also be, but again, not by much. The difference in all my loads is not to worry about. For a benchrest shooter, everything comes into play and I am sure water volumes are matched as close as possible ! IMO
boltonscouter
CGN frequent flyer
- Location
- parts unknown
tagged for interest!
Ok so I went to the range this afternoon. It was cold, snowing heavy, and visibility was poor. I did the test at 300M. The results were surprising. All groups were about 3 to 3 1/2 inches or about 1 MOA. Not my best shooting at all.
No noticeable differences in group sizes.
No noticeable differences in point of impact.
So I would still sort my brass by type. But it appears that there is no noticeable difference at that distance and at my level of shooting.
No noticeable differences in group sizes.
No noticeable differences in point of impact.
So I would still sort my brass by type. But it appears that there is no noticeable difference at that distance and at my level of shooting.
You aren't telling us if you have an off the shelf commercial rifle or a custom match rifle.
If you have a custom match rifle then things change a lot. If it is an off the shelf commercial rifle then you just may have to dial in where your scope settings match the point of impacts.
First, prepare the case by swaging through your dies, with the decapping pin removed from the stem. Size the brass and trim all cases to the same length.
Next, weigh each case and record then fill the case with water so the meniscus is on the edges of the case mouth and figure out the average volumes for each set of different brass. You will likely find that the heavier the case the less water it holds. If there is only a grain or less difference between the case volumes you will likely be able to mix and match without issues.
If you are using range pick up brass, then you will need to separate them into their individual makers and then weigh each piece to see which are the lightest and heaviest. I try to keep different piles within around .2 grains. If the cases are for a match rifle only the cases in one pile will be used. If it is a commercial rifle, cases within less than one grain weight difference (plus or minus .5 grain) will work just fine. Depending on the range you plan on shooting, the variable can be twice that amount and not show a lot of difference as far as point of impact and group size goes.
If you are getting that picky, you have to deduce whether your rifle is accurate or consistent enough to show the difference. Of course, everything will go to hell as soon as you get different lots of components, such as primers/powder/bullets, even if they come from the same manufacturer.
Sadly, accuracy is seldom simple
If you have a custom match rifle then things change a lot. If it is an off the shelf commercial rifle then you just may have to dial in where your scope settings match the point of impacts.
First, prepare the case by swaging through your dies, with the decapping pin removed from the stem. Size the brass and trim all cases to the same length.
Next, weigh each case and record then fill the case with water so the meniscus is on the edges of the case mouth and figure out the average volumes for each set of different brass. You will likely find that the heavier the case the less water it holds. If there is only a grain or less difference between the case volumes you will likely be able to mix and match without issues.
If you are using range pick up brass, then you will need to separate them into their individual makers and then weigh each piece to see which are the lightest and heaviest. I try to keep different piles within around .2 grains. If the cases are for a match rifle only the cases in one pile will be used. If it is a commercial rifle, cases within less than one grain weight difference (plus or minus .5 grain) will work just fine. Depending on the range you plan on shooting, the variable can be twice that amount and not show a lot of difference as far as point of impact and group size goes.
If you are getting that picky, you have to deduce whether your rifle is accurate or consistent enough to show the difference. Of course, everything will go to hell as soon as you get different lots of components, such as primers/powder/bullets, even if they come from the same manufacturer.
Sadly, accuracy is seldom simple
Wait for a day with better shooting conditions, and shoot some groups using one of each brand of brass per group and then shoot some groups each using only one brand of brass for each group.
yes he did. see post 11. not your average hunting rig.
Funny... for a guy that wrote such a long post... he didn't read much of the thread. I thought it was pretty evident that the OP wasn't looking for advice on how to best sort brass. The OP is experienced enough, and he's conducting his own experiment.
OP... I'm still interested in results when you're shooting more at your level. The uncertainty of the brass is certainly being lost at the 1 moa level. Down to your regular .5 or even .3 moa, and I think there's a chance we can see some shifting.
Thanks, I missed that.
OP, with a rifle like that you need to look at some of the books by fellows like David Tubb. Depending on the accuracy you are looking for, following match procedures for preparing brass and loads is a good idea. There is a very good reason match shooters get anal about brass preparation. One other thing, there is a lot more to it than brass and its preparation. You need to be extremely careful with the trueness to center of your dies to eliminate run out.
Huge learning curve coming up.
Chinbullco
Regular
- Location
- NW Alberta
Recently I switched out 100 rounds of IVI Match 222 Rem. Replaced IVI with Lapua. Dropped charge to starting loads with Lapua brass. Barrel was not cleaned prior to this test. First shot indicated "warm load". Second shot blanked primer, wrecking Jewell trigger. This is an extreme example and I doubt a 308 would cause the same issues.
BTW: IMR 4895 powder used in the deuce. If IMR 4198 was used it might of done more damage.
When people talk of different brass giving different pressures, they are talking about the powder capacity of the brass. The sizing die makes the cases all the same size on the out side, so a heavier case has more brass in it than does a lighter case.
With it the same size on the out side, more brass means less room for powder, or air, or water, or anything else. It's as simple as that. If there is a big difference in weight, the heavier brass will raise more pressure with the same load, than will the lighter brass.
I wanted to see if there was any, or much difference with normal brass that was a few grains different in weight.
I have a bolt action 243 with a rather tight chamber, meaning I full length resize every case, to ensure they enter the chamber without any problem.
I have empty fired WW cases that weigh 168 grains and fired Federal cases that weigh 180 grains, 12 grains heavier than the WW.
I loaded five WW cases weighing 168 grains each, with 46 grains of H414 powder and seated a 75 grain Sierra bullet in them.
I then loaded the same charge, 46 grains of H414 and seated the same 75 grain Sierra bullets in the five Federal cases, which weighed 180 grains each.
I fired the five lighter WW cases over a chronograph and they came out at an average speed of 3491 fps.
I then fired the five heavier Federal cases over the chronograph. According to the theory the heavier cases should have raised more pressure and thus more velocity.
However, the five Federal cases, which were 12 grains heavier, averaged 3468 fps!
Thus, as far as I'm concerned, minor differences in case weight can be ignored, as it can't be proven to change anything.
With it the same size on the out side, more brass means less room for powder, or air, or water, or anything else. It's as simple as that. If there is a big difference in weight, the heavier brass will raise more pressure with the same load, than will the lighter brass.
I wanted to see if there was any, or much difference with normal brass that was a few grains different in weight.
I have a bolt action 243 with a rather tight chamber, meaning I full length resize every case, to ensure they enter the chamber without any problem.
I have empty fired WW cases that weigh 168 grains and fired Federal cases that weigh 180 grains, 12 grains heavier than the WW.
I loaded five WW cases weighing 168 grains each, with 46 grains of H414 powder and seated a 75 grain Sierra bullet in them.
I then loaded the same charge, 46 grains of H414 and seated the same 75 grain Sierra bullets in the five Federal cases, which weighed 180 grains each.
I fired the five lighter WW cases over a chronograph and they came out at an average speed of 3491 fps.
I then fired the five heavier Federal cases over the chronograph. According to the theory the heavier cases should have raised more pressure and thus more velocity.
However, the five Federal cases, which were 12 grains heavier, averaged 3468 fps!
Thus, as far as I'm concerned, minor differences in case weight can be ignored, as it can't be proven to change anything.
- Location
- Nova Scotia
I tried something similar to what you are about to try out of a Savage 308 at 200 yards and I had big differences on the paper. Please let us know what happens on the paper
