Rifle reloading confusion...

[maseh2os]

Hey all,

Got a couple of questions for ya. Apologizing ahead of time as this will be a bit lengthy.

First a bit of background. My friend and I recently completed our first rifle builds. We built pretty much identical rifles, chambered in 6.5 Creedmoor, Savage action, Criterion 26" barrel. While our chambers certainly seem identical (as evidenced by measuring cases from both after several firings), we seem to have slightly different throating, his consistently measuring .026" shallower when measured with the Hornady OAL gauge.

We have been working on load development, and run into a few confusing bits of data. We are using 140gr Berger VLD's, H4350 powder, RCBS Charge Master, Wilson neck and seating dies, and Sinclair comparator for seating depth measurement.

First, his rifle seems to shoot slower than mine and I can't figure out why. On average, about 20fps less than mine with the same exact load. We are both seating .010" into the lands, his OAL obviously being .026" shorter than mine due to difference in distance to lands. Because of this, I would have thought that his would shoot a bit faster, due to the decreased case capacity from slightly more bullet intrusion, thus raising his pressure a tad above mine. Am I missing something here?

Second, we shot several groups today, 30 shots each total. All the same powder charge and at our normal seating depths. However, the first 15 shots for each of us was loaded in once fired brass, having only had a factory load in it before today. The second sets of 15 were from twice fired brass, once from factory, once reloaded. Not only did we have our usual 20fps average difference between his and mine, but we both had about a 25fps increase in velocity when going from the once fired to the twice fired! The consistency and ES got quite a bit better in the second set as well.

I am at a loss as to why this might be. I would think the once fired brass would be just as formed to our chambers, or really darn close, as the twice fired.

This really has me worried now, because now I'm figuring we are going to have velocity issues every time we get new brass, needing to fire it twice just to get better consistency and back to expected velocities. Not only that, if I'm guessing right we'll have similar problems whenever we go to FL size and bump the shoulder! Anybody else have this happen? Causes? Remedies?

Any help you guys can give would be much appreciated! Thanks in advance,

maseh2os

 

[USSR]

Every barrel is a world unto it's own. I have 2 rifles, both with 26" match barrels, and with the same load they average 75fps difference in velocity. You're worrying about things that are of no real consquence. Find the loads that the pair of 6.5 Creedmoors like and enjoy it.

Don

 

[RevDerb]

A difference of 25 fps is virtually the same velocity.

 

[Hondo 60]

Both answers above are spot on ^^^^^

 

[maseh2os]

Ok, having read your replies and doing a bit more research, I see I have been overly concerned with the side by side performance of these rifles.

I get why people aren't concerned about the 25fps swing in our ammo, as it really doesn't make a huge difference down range. I plugged the numbers into a ballistics program, and it only showed a +/-1.5" change in drop at 600yds with and increase or decrease of 25fps off our target velocity. Is this considered "close enough"?? We are hoping to hunt with these rifles, potentially at longer ranges, but we don't intend to take ANY shot the we aren't confident in where the bullet will hit. Do you guys think we can do that with the results we are currently getting?

 

[gamestalker]

20 fps isn't considered a variance. I have a couple of 7mm RM's, both are 700 actions, same barrel's and one shoots over 100 fps faster than the other. The only reasonable cause for such variation, is that no two barrel's or chambers are the same.
I wish the variance I'm experiencing was only 20 fps, because that is a variance that will make absolutely no noticable difference at any shooting distance.

 

[noylj]

Is this your first time reloading and you are already trying to load ultra-precision rounds for long-distance shooting? Have you got a background with prior rifles in this type of accuracy? Have you even measured any groups yet or are you just into velocity?
People loaded for decades without a chrony and most of us still do. It would have been a very rare benchrest shooter who ever worried about velocity. Long range shooters need to know, but they don't worry about the absolute number, just what the velocity is so they can set the estimated drop.
Worry about your targets and practice. How did the factory ammo do? Any targets we could see?
There is nothing to worry about when comparing guns and velocity. Every barrel is different--some are fast and some are slow, but they all can be very accurate.
Trigger time will get you the biggest improvement in group size.

 

[maseh2os]

Thanks for the replies everyone, this has been a lot of help already!

Is this your first time reloading and you are already trying to load ultra-precision rounds for long-distance shooting? Have you got a background with prior rifles in this type of accuracy?

Not first time reloading, but certainly first time trying to get as much precision and consistency as we are currently aiming for. This is our first foray into longer range shooting, but we have done a fair amount of shooting and reloading in the past. I know we aren't doing EVERYTHING to obtain the best accuracy, or even everything right, but we're trying to do the best we can with the tools we currently have.

To let you know what we are currently doing: Sorting brass by number of firings, neck sizing with Wilson neck dies (haven't seen a need to bump shoulders back yet, but do have a Redding body die for that purpose when the time comes), trimming cases to uniform length, throwing powder with RCBS Chargemaster, hand seating WLR primers, uniforming/deburring primer flash holes, seating with Wilson seater, measuring seating depth with stoney point OAL gauge, and checking cartridge concentricity (removing and load with greater than .002" of runout).

We still aren't: sorting bullets by weight or ogive length, weighing brass, turning necks, reaming necks, tracking powder lots, using bench rest primers, etc, etc.

Have you even measured any groups yet or are you just into velocity?

So far with our hand loads, we have been sub 1/2 MOA at 100 and comfortably sub MOA out to 300yds. I would attribute any accuracy issues thus far to our own pulling of shots. Like you said, trigger time will surely shrink our groups more than any of this other stuff. I guess to be honest, I don't know what kind of accuracy I should be hoping for! Should I be disappointed with sub MOA? Or should we be pushing harder for 1/2 MOA?

We were getting the same out of factory loads, which Hornady says is "match grade".

No pictures of targets just yet, will try to take some on our next outing.

I know we may be expecting too much too soon. Perhaps expecting too much bench rest precision out of rifles made for hunting is part of the problem.

 

[USSR]

Not first time reloading, but certainly first time trying to get as much precision and consistency as we are currently aiming for. This is our first foray into longer range shooting, but we have done a fair amount of shooting and reloading in the past. I know we aren't doing EVERYTHING to obtain the best accuracy, or even everything right, but we're trying to do the best we can with the tools we currently have.

To let you know what we are currently doing: Sorting brass by number of firings, neck sizing with Wilson neck dies (haven't seen a need to bump shoulders back yet, but do have a Redding body die for that purpose when the time comes), trimming cases to uniform length, throwing powder with RCBS Chargemaster, hand seating WLR primers, uniforming/deburring primer flash holes, seating with Wilson seater, measuring seating depth with stoney point OAL gauge, and checking cartridge concentricity (removing and load with greater than .002" of runout).

maseh2os,

You're doing a lot of the right things. Don't sweat the difference in velocity between the 2 rifle, but try to find loads that produce ES's of 20 or less and SD's of 5 or less for each of the rifles. Having shot in 1k competition for 7 years, I can tell you having quality brass (Lapua) is the place to start. No sense in weighing bullets, as you will find little variance there with match bullets, but sorting them by ogive-to-base length may be beneficial, especially with Sierra MatchKings. Also, you might want to try a milder primer than the WLR's. I have been using the Russian primers in my 6.5x55. Hope that helps.

Don

 

[243winxb]

For precision and consistency full length resize each loading with custom dies,no expander, neck turned. Control shoulder bump. When neck sizing only, the brass will expand less each firing till you have to bump the shoulder back.This means the brass is expanding differently each firing, with different pressures. The first loading of factory new 243win. (rem & win) brass has been less accurate for me. Only size 1/2 of the neck with a bushing die. This lets the round center in the chamber(if not seating into the lands) as the unsized part of the neck expands to the chamber, takes 3 firings. Brass must be fire formed, at least in my factory chambered Rem. 40X. Weight and sort brass by .1gr.

We are both seating .010" into the lands, using 140gr Berger VLD's,

VLD bullet can be jumped to the lands, have you tried different seating depths as said by Eric Stecker from Berger Bullets?

So far with our hand loads, we have been sub 1/2 MOA at 100 and comfortably sub MOA out to 300yds.

This is about as good as it gets for most of us. Many would hope for this kind of accuracy.

 

[howlnmad]

I love your enthusiasm and appreciate your labor. But you are going way to far for a hunting rifle. I'm anal about my rounds as-well but would never worry about a 25 fps dif between two rifles. Actually, unless I'm using it, I wouldn't care what anothers performance is. As far as speed goes... doesn't matter as long as the bullet is on the mark and has the energy to do the job. You say you built these rifles to hunt with but it sure seems like you'd want to match shoot with them. Just my .02 worth.