Velocity question.

[sniperghost]

I have a few questions for you guys and every input it’s really appreciated. I’ve been reloading now for about 5 months but I never used a chronograph. Finally few weeks back I got a chronograph (CED M2) from MidwayUsa so today I went to the range and I got a chance to use it. I have a 308 R&D Precision rifle with 26" Schneider 5P 1:11 Twist barrel.
I loaded 30 bullets (308) using 155 A-Max, IMR-4064, 210 M Primers and Win Brass trimmed to 2.012”. OAL 2,813”.

I loaded the first 5 with 42Gr, and I got an average of 2756 L: 2713 -H: 2778
Second 5 bullets with 42.5 and average of 2776 L: 2758 -H: 2797
Third 5 bullets with 43 and average of 2834 L: 2816 -H: 2874
Fourth 5 bullets with 43.5 and average of 2864 L: 2837 -H: 2900
Fifth 5 bullets with 44 and average of 2901 L: 2883 -H: 2915

I use the Hornady reloading manual as a reference and in that book it shows the table for 155 A-Max under IMR-4064 2600 at 43.3 gr. and 2700 at 44.9 gr.
My question is why I get such of big differences than the book shows? And the second question is, is it OK to shoot at 2900 or I should go down on velocity?

Thanks,
Christian

 

[desertHK]

Re: Velocity question.

You also need to look at the twist rate of the barrel in the manual. You probably have a faster twist rate than them.
There is nothing wrong with 2900 fps. In fact, my 155 scenars is pushed at about 3000 fps.

 

[Grumulkin]

Re: Velocity question.

It's pretty common for "book velocity" to be different than what you get. If your gun is shooting accurately without signs of excess pressure, don't worry about it.

I started reloading several decades ago and I still don't use a chronograph to work up loads. To think that if you attain some certain velocity the pressure is safe or unsafe is erroneous since velocity is an indirect sign of pressure. In fact, I never even had a chronograph until 3 or 4 years ago. I work up a load for accuracy and acceptable pressure and then, when I feel like fiddling around I'll get the chronograph out to satisfy my curiosity as to how fast the bullets are going.

 

[308sako]

Re: Velocity question.

.

 

[DRAM40A1]

Re: Velocity question.

According to the manual, their test rifle was a Winchester Model 70 with a 22 inch barrel. You're using 26" Schneider 5P. Huge difference. Note also your ES is shrinking as you increase the charge.

 

[sniperghost]

Re: Velocity question.

Here are the results, but first I want to thank everyone for your comment. I was scared when I got 2900 f/s I thought that my loads are really hot, and I did some reading and they are saying that when your running hot loads you can mess up the barrel.

I shoot the exact same loads a few weeks apart but this time I had a chronograph. Looks like I was shooting better a few weeks back than I did yesterday, these are exact the same loads.

These are the results from a few weeks back.

And this are the results from yesterday, now yesterday when I got at the shooting range it was a little cold and I was shaking a little, it must have been 60 degrees and I also had my trigger changed, with a jewel trigger, so I’m still trying to get used to it.

Thanks everyone,
Christian

 

[josephberry]

Re: Velocity question.

nice shooting, are you in or out of the lands?

 

[josephberry]

Re: Velocity question.

nice shooting, are you in or out of the lands?

 

[Victor N TN]

Re: Velocity question.

Top left target looks like more of a wind report than a bad group.

 

[sniperghost]

Re: Velocity question.

Hi guys, I’m out of the lands .10. I’m going to try the RE-15 next time to see if there it’s going to be any differences, and also the IMR-4895. I would like to get these groups tighter if I can.

Christian

 

[BLAWTON]

Re: Velocity question.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperghost</div><div class="ubbcode-body">Hi guys, I’m out of the lands .10. I’m going to try the RE-15 next time to see if there it’s going to be any differences, and also the IMR-4895. I would like to get these groups tighter if I can.

Christian
</div></div>

Going through different powder trying to stumble onto the perfect load is gonna be difficult. You look like you have a great start i would take the best loads of of these tests and push the bullet into the lands up to .015 and then back it off to .04 off in .005 increments until you see them tighten up they way you want. You just cant mess with powder charges and get the perfect load for your gun without changing your seating depths. If anything i always start with a hogdgon extreme powder becuase you will send you head spinning trying to figure out why everything is changing when its a different temp outside.

 

[sniperghost]

Re: Velocity question.

Thanks for the advice, I really appreciated it. I will defiantly try what you have mentioned. I just got some Lapua brass for my next reloads.

Cristian

 

[Sig685]

Re: Velocity question.

Cristian, what is your ultimate goal? Are you searching for the tighest group at 100 yards with a 155gr bullet or are you looking at shooting at longer distances? If so, what kind of distances and what venue, hunting, plinking, competition?

 

[sniperghost]

Re: Velocity question.

Hi Sig685, I would like to shoot at longer distances, but now I’m searching for a good load to get the groups tighter at 100Yds with 155 gr, and based on that, to move to longer distances, probably 1000Yds. My goal is, one day to shoot in competition, but now I’m trying to learn as much as I can.

Cristian

 

[Sig685]

Re: Velocity question.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperghost</div><div class="ubbcode-body">Hi Sig685, I would like to shoot at longer distances, but now I’m searching for a good load to get the groups tighter at 100Yds with 155 gr, and based on that, to move to longer distances, probably 1000Yds. My goal is, one day to shoot in competition, but now I’m trying to learn as much as I can.

Cristian
</div></div>

Ok. Take what follows for what I intend it and that is to help you get to long range as quick as possible.

Unless you are going to shoot in pure Palma matches, stop dicking around with the 155gr bullet. That bullet is what I love to see in my competitors' rifles. It's a waste of time, components, and barrel life to develop anything for that bullet. Pick a 175-190 grain bullet and stick with it. Your 1:11 twist is perfect for that range.

Next spend some time at JBM calculating the muzzle velocity that you need to have in order to get that bullet solidly supersonic at 1000 yards. Discount the claimed BC by a few points or use the Litz values at JBM. Do not be satisfied with just barely above Mach 1, look for as much as possible above that.

Next, peruse the powder manufacturers website and see which load of their powder can give you that MV without going over max. When you have it, then you can start developing a load with a goal to find an accuracy node above that minimum MV, using your chronograph.

Get as accurate as possible at 100 yards, then you will be ready for the long range and you will have saved lots of time, components and especially barrel life.

Find a match in your area, add the come ups that JBM will give you for your load using your chronographed velocities (around 30MOA) and go shoot it. That's the only way to learn.

 

[sniperghost]

Re: Velocity question.

That’s a lot of good information, thanks a lot. I will get a few boxes of 175, and 190gr, and I will give that theory a try. It never crossed my mind to try the 175 and 190gr bullet in 308 Cal, I always thought that 155gr bullet it’s the best way to get to 1000yds, and that’s because I read a lot about how the competitors in competition prefer the 155gr.
Do you have any suggestion as far as powder goes? I do have IMR-4064,, IMR-4895,, and the RE-15.

Thanks,
Cristian

 

[Sig685]

Re: Velocity question.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperghost</div><div class="ubbcode-body">That’s a lot of good information, thanks a lot. I will get a few boxes of 175, and 190gr, and I will give that theory a try. It never crossed my mind to try the 175 and 190gr bullet in 308 Cal, I always thought that 155gr bullet it’s the best way to get to 1000yds, and that’s because I read a lot about how the competitors in competition prefer the 155gr.
Do you have any suggestion as far as powder goes? I do have IMR-4064,, IMR-4895,, and the RE-15.

Thanks,
Cristian
</div></div>

As I said, the 155 is the worst of the 1000 yard capable bullets. If you have to use it, it's good to know that everyone else has the same handicap (Palma.) If you don't have to use it, leave it alone and use something else, anything is better than that bullet.

I'm a Varget guy and that's all I use anymore. I buy it by the pair of 8 pound kegs. But from the powders you listed, any of them are fine for .308; pick one and work with it, and forget the 155gr, just hope that your future competitors are using it in their rifles.

By the way, it's not a theory, it's just a sane, effective and highly efficient manner to quickly develop a great 1000 yard load. Set up your parameters and goals and then go do it.

 

[sniperghost]

Re: Velocity question.

Thanks Sig for your help. I’m retiring the 155gr and next week I should get the 190gr.

Cristian