Not sure where to post this as it is not Gunsmithing nor is it Reloading. A couple of months ago I began loading for a 6.5x06 that I inherited when my son died. I do not want to name the barrel, but it is well known and was essentially new. I went through a few iterations of different bullets and loads with all the shooting at 100 or 200 yards. When I settled on a 140 grain load I shot at 400 yards and the POI was way low to projection. I then choreographed the load and it averaged 302 feet slower than the Nosler Manual indicates for that combination. Barrel lengths were essentially the same. I wondered about the chrono, but the trajectory curve is a perfect match for the chronograph velocity. I changed powders and went to a 130 grain bullet and the load averaged 173 slow vs. the Nosler manual. I have run into fast barrels and slow barrels but nothing like this. Any ideas? Remember guys, this is not a small variance.

Your throat condition and length have a huge bearing on velocity. Check them.
Lots of factors involved and I always suspect the actual bore, lastly.
Make sure you don't have a Weatherby type throat. Meaning long. Or burned out, long.

Thanks dpcd. It is not burned out unless made of butter, as it only has 114 rounds down the tube, all slow fire. I have been seating bullets as long as the magazine will allow, but I will check for freebore.

Remember that every barrel is a law unto itself to some extent. Some barrels shoot faster than others and vice-versa. Also, a reloading data guide is just that, a guide, and was not written under the full inspiration of God. Some rifles can never reach the manual max load without going into dangerous pressure territory, while others I have seen that will let you put more powder in them and still have a safe load. The velocity listed in the manuals don't mean squat to me, only what my rifle and loads will do.

A long chamber doesn't necessarily mean a slow or inaccurate barrel but do sometimes require more trial and error finding one that will work. I do prefer a chamber short enough that I can seat bullets close to the lands, but sometimes I have to work with what is there.

True, except that a long throat does, in fact, result in slower velocities.
All else being equal. That is why we gauge our tank cannon barrels only at the breech; as the throat advances, it results in slower velocities. Then the ballistic computer can't give a correct super elevation on the gun. It only knows range, not velocity.
Then you miss. Which is bad.

quote:

Originally posted by dpcd:
True, except that a long throat does, in fact, result in slower velocities.
All else being equal. That is why we gauge our tank cannon barrels only at the breech; as the throat advances, it results in slower velocities. Then the ballistic computer can't give a correct super elevation on the gun. It only knows range, not velocity.
Then you miss. Which is bad.

Geeze Looouise......

All the have to do is seat the projectile closer to the lands......

Who is Louise?
Read the part that says; "All else being equal". If the OP has a long throat, (for which he has not checked), and is seating shallowly, then he will have low velocities. You know that.
Certainly, what you say could possibly be the cure, but we are still looking for the disease.

FYI the rifle is built on a pre-64 model 70. As I previously stated I am bumping up against magazine length at 3.390"COAL. There ain't going to be any chasing the throat out of the magazine!

I have had two identical barrels chambered with the same reamer have over 100 fps difference with the same load.

300 fps is a lot of difference. That over 10% for most cartridges, I would expect 3% - 5%

quote:

Originally posted by dpcd:
Who is Louise?
Read the part that says; "All else being equal". If the OP has a long throat, (for which he has not checked), and is seating shallowly, then he will have low velocities. You know that.
Certainly, what you say could possibly be the cure, but we are still looking for the disease.

I am talking about the tank barrel. Not EVERYTHING needs to be so serious......

If I have to be serious, 170-300 fps slow seems like a lot. If the barrel and chamber are in good shape, you ought to be able to get published velocities with exceeding pressure by adding more powder. However, if the slow velocity is due to a rough bore then adding adding powder is unsafe.

Which brings back to what most say, and that is each barrel is indeed unique and the published velocity is only a guide. You have to start low and carefully work up, always looking for signs of pressure and then backing off if you see any signs of pressure.

If the barrel is chambered okay and the bore isn’t rough, then my guess is one more of the following:

1. The chamber might be a tad large
2. The throat long
3. The groove size might be on the larger side

dpcd, the throat is approximately .200" longer than the magazine length. I do not have a borescope, but have no reason to be suspect of the chamber. I am with Fjold on this, plus or minus 100 FPS would not even get my attention, but 300 feet sure did! As I stated in the OP I inherited the rifle. It had been fired 12 times. I do not know who did the chamber work or whose reamer was used.

What is accuracy like?

I just threw in the tank barrel thing since I spent so much time with them both shooting them and on the logistics end. Can't help it.
Yes, 300 fps is a lot. But .2 inch of freebore means that you can use more powder; that is how Weatherbys work.
For reference, a 260 Rem has .135 free bore.
Do what INTJ said.
Some things have no rational explanation.
Or could set the barrel back and re chamber and hope for different results.
Or get a new barrel. Or sell the rifle. Or use it as is. Lots of options.

it ain't that hard to do a pound slug of the throat/neck area of the rifle and a slug of the barrel.
then you'd have exact measurements in hand, and not be guessing at what's going on.

they make cerrosafe for a reason.
It ain't as good but it gets you within a couple thousands of the diameter.

I would call the accuracy not great, but pretty good. It averages about 5/8 MOA with the most accurate combination I have come up with.

You could run a brush wrapped with 0000 steel wool around it through the bore a few times to confirm or rule out any embedded metal flakes.
I have a .270 with a cryoed Douglas barrel that had 2 flat mica-like flakes in the barrel that when removed improved groups by 1/2 MOA. Might help your velocity issue with little risk. 10 dry passes back and forth will snag what regular cleaning might miss.

All things not being equal. I will preface my response that I am not expert. Been reloading about 10 years and use Lyman, Sierra, and Nosler reloading manuals.

In most cases, I can rarely duplicate Nosler velocities. Remember the book loads are shot under ideal conditions, temp, elevation, humidity etc. I have found Sierra manual to be pretty close to my loads.

That being said 170 FPS is still a tad more than I have seen in my experience. Usually my loads are 75 sometimes 100 FPS slower than Nosler lists.

I live at a 4000 foot elevation and usually shoot with ambient temps between 50F and 70F.

I have also seen a difference in Chronographs. I do not remember the brand of mine, but it is not a high dollar one. My buddy has a Caldwell and his will show my loads going slower than mine does. Just a guess, maybe with all those factors you are getting those results.

But like I said, not an expert and I would definitely look at the throat and barrel first.

I am pretty familiar with the "neighborhood" of cartridges. My 25-06 is on its forth barrel, I have owned more than a dozen .270 Winchesters and I have a 6.5x.284. I do not think 2850-2900FPS with a 140 grain bullet is asking too much out of a 6.5x06. 2600fps tells me one or more things are off. That is what this whole discussion has been about. The cheapest experiment will be to carefully increase the load until some pressure signs are noted and see how it effects velocity and accuracy. I must say I am a little skeptical that there is 200 or 300 feet to be gained safely.

Please post your results. I think most of us are wondering if 200-300 fps is safely achievable.

quote:

Originally posted by squeezenhope:
I am pretty familiar with the "neighborhood" of cartridges. My 25-06 is on its forth barrel, I have owned more than a dozen .270 Winchesters and I have a 6.5x.284. I do not think 2850-2900FPS with a 140 grain bullet is asking too much out of a 6.5x06. 2600fps tells me one or more things are off. That is what this whole discussion has been about. The cheapest experiment will be to carefully increase the load until some pressure signs are noted and see how it effects velocity and accuracy. I must say I am a little skeptical that there is 200 or 300 feet to be gained safely.

What are the loads that you are shooting that are slow, what powder and quantity.?

The load that I have shot the most is 48.5gr. of RL19 with a 140 Berger VLD hunting bullet, Federal 210's. Barrel is 24 1/2 inches. That load clocks 2600 fps. Another load I chronographed was 53.0 Vit 560, Nosler 130 gr. Accubond, Fed 210. I do not remember the velocity off the top of my head, but it was 173 feet slow to the Nosler Manual.

I have been on the road about 10 days but hope to get back on this soon.

Questions will remain, because I took the easy way out and pulled the barrel. Probably use it for a tomato stake. The one thing I know for certain it did have a long throat. With a Hornady O.A.L gauge it would push the bullet right out of the neck before engaging the lands.

What is the altitude difference and is that enough to make the difference?

Then I think you have your answer; if a bullet can be breech seated and not even touch the case then that free bore will give you the lower velocity. You might not have a slow barrel after all and a re thread and chamber job will restore it.

dpcd, I thought the same thing, but like I said I took the easy way out. I guess the main driver was I have no particular need for a 6.5x06, but I can always use an action.

6.5 Creedmoor. Everyone wants one nowadays; that's all I get asked for.

It wouldn't be much work to set the barrel back three or four threads.

I actually thought about one of the short 6.5's, but it is a pre-64 Model 70 action and would not be my first choice.

I have a batch of rl 19 that is much slower than it should be. I swear it is rl 22. Shooting it in a 30-06 it was 250 fps off the book iirc.
Try a faster powder like h4350 or imr 4350.

Could be a combination of an extra long throat and RL 19 producing slow velocity??? As stated I did try Vit 560 and it was also slow, but not like RL 19.