Thread: Lower than expected velocities

Hi,
First time with garmin chrony.

25-06 near top of load data.
100gr hot cor instead of 100gr partition in load data.
Bullet seated about diameter of bullet into case.

Recorded velocity 3013fps Data velocity 3300fps

I appreciate that it's a different bullet that I have seated quite far out. 22inch barrel.

Questions. Would seating the bullet in further generate much more pressure/velocity?

Should I increase the charge beyond data to achieve something like 3300fps?

I have the same story going on with a 6.5 x 55.20inch barrel.
Also a 250savage that is recording velocities as expected.

Don't believe everything you read. There are so many variables, barrel length, bullet bearing area, barrel wear, batch lot of powder, temperature etc. Chasing 3300 isn't the best way of doing load development

Yeah, kind of what I was thinking. I wouldn't have thought the variables would amount to a 300fps difference though.

Is it accurate????

Welcome to the world of theory vs reality.

Some barrels are just slow, different bullets can make a significant different as can Coal.

Greetings,
I would expect the Speer to give less velocity. I recorded a difference of 100 fps between the Hornady 129 grain and the Nosler 129 grain LRAB in a 6.5-06 with everything else the same. What was the source of your data? Just checking a couple of sources don't show anywhere near 3,300 fps with the 100 grain partition. I can probably help with the 6.5x55 if you would like to share or PM the details.
Regards Grandpamac.

I hear you on this one, my .308win is doing this too. For some reason it's way down on velocity and I've basically checked everything mechanical with it to ensure I'm not getting sucked into porkies somehow. Effectively the only thing that it can be that I can't eliminate is for some reason the barrel isn't hanging onto the pill long enough to generate enough kick to get the speed that it should.

Options are reloading with a faster powder, and seeing what that does as 2208 is rather disappointing and some factory loads are producing wildly different results. Win 150g powerpoint is on the box drops at 100 and 200m, but off at 50 and 150 and the bullet is rolling along the range floor at 275m (almost off the bottom of the 300m target backer). An old box of PMC is shooting a lot lower but flatter, I'd be happy to run with that but can't replace it - no longer imported. If I could get a small box of the Sako I'd try that, as I always like having an off-the-shelf backup even if I go for reloading for this one. Some of the upper end ammo shoots minute of barn door, it's not the rifle as such as subsonics are three-shots-touching at 50m and a nice regular less than 1" cloverleaf at 100m all day.

Just for whatever reason I can't get the expensive premium crap to run on a node on that rifle... I need to find a slightly faster powder than 2208 and some fancy pills and see what I can come up with for it.

As far as seating out, I would expect a few fps difference but not 300fps. That in itself would look to me that if the groups are either variable or unacceptably large that a change of powder is in order, or a change in pill. If you aren't planning on using the load at long range it's possibly fine as is depending on if the groups are OK, but like my experience with the .308 if you are finding the trajectory is more like a parabolic bell curve then it's just not worth fighting with the load as the drops aren't acceptable past about 300-350m.

Originally Posted by No.3

I hear you on this one, my .308win is doing this too. For some reason it's way down on velocity and I've basically checked everything mechanical with it to ensure I'm not getting sucked into porkies somehow. Effectively the only thing that it can be that I can't eliminate is for some reason the barrel isn't hanging onto the pill long enough to generate enough kick to get the speed that it should.

Options are reloading with a faster powder, and seeing what that does as 2208 is rather disappointing and some factory loads are producing wildly different results. Win 150g powerpoint is on the box drops at 100 and 200m, but off at 50 and 150 and the bullet is rolling along the range floor at 275m (almost off the bottom of the 300m target backer). An old box of PMC is shooting a lot lower but flatter, I'd be happy to run with that but can't replace it - no longer imported. If I could get a small box of the Sako I'd try that, as I always like having an off-the-shelf backup even if I go for reloading for this one. Some of the upper end ammo shoots minute of barn door, it's not the rifle as such as subsonics are three-shots-touching at 50m and a nice regular less than 1" cloverleaf at 100m all day.

Just for whatever reason I can't get the expensive premium crap to run on a node on that rifle... I need to find a slightly faster powder than 2208 and some fancy pills and see what I can come up with for it.

Greetings,
I have had disappointing results with AR2208 in the .308 as well and have mostly used AR2206H for some years. I chronographed some comparison loads recently in a 24" barrel. AR2206H gave a little more than book velocity and AR2208 somewhat less.
GPM.

Originally Posted by Longrun

Hi,
First time with garmin chrony.

25-06 near top of load data.
100gr hot cor instead of 100gr partition in load data.
Bullet seated about diameter of bullet into case.

Recorded velocity 3013fps Data velocity 3300fps

I appreciate that it's a different bullet that I have seated quite far out. 22inch barrel.

Questions. Would seating the bullet in further generate much more pressure/velocity?

Should I increase the charge beyond data to achieve something like 3300fps?

I have the same story going on with a 6.5 x 55.20inch barrel.
Also a 250savage that is recording velocities as expected.

ADI is giving a maximum of 3212fps with 24" barrel for 100gr in 25.06. Some powders much lower.

This was hogdon load data and stabal 6.5 powder.




Load is accurate but I'm shooting 25-06 for its mpbr

Originally Posted by grandpamac

Greetings,
I would expect the Speer to give less velocity. I recorded a difference of 100 fps between the Hornady 129 grain and the Nosler 129 grain LRAB in a 6.5-06 with everything else the same. What was the source of your data? Just checking a couple of sources don't show anywhere near 3,300 fps with the 100 grain partition. I can probably help with the 6.5x55 if you would like to share or PM the details.
Regards Grandpamac.

The swede is shooting 120gr gold dots 2750fps with 47gr of w760

Greetings @Longrun and all,
I have found some significant differences from published data in the 6.5-06 and I expect that the .25-06 is much the same. A new pressure barrel which is made to tight tolerances is always going to deliver higher velocity and pressure than one which has had considerable use. I always look around the various data sources and use the one that is closest to the chronographed results I am getting. Stabal won't have the range of data being so new.
With the 6.5x55 there is plenty of data for W760. 47 grains is right at the top of the data I have looked at although the 6.5 is loaded to a lower pressure than other cartridges. Some years ago I worked up to a velocity of 2,923 fps with the 120 grain in my M38 6.5 with a 24" barrel. you would lose 100 fps or so in your 20" tube. My load which will not be divulged or repeated is well above current max loads as is your load of 47 grains of W760. Nosler list 45.5 grains and Hodgdon 44.5. As mentioned these are for the M38 Swede rifles and you don't mention what your rifle is. In a 20 inch barrel 2,750 fps is probably about right.
Regards Grandpamac.

Yeah m96 Mauser data is more or less the start load for a modern rifle.

I might sneak up to about another .5gr on both loads and see where it's at.

Alternatively I might load singles progressively up till I find excess pressure signs and back off a bit from there for a load.

The swede is not far off. I'd be happy with 2800. The 25-06 I'd like to see around 3150 from it all considered

Your most accurate load will not likely be the fastest.

Minute of deer doesnt need max velocity - just accuracy.

Yeah, it's nice to use cartridges to their potential though.