velocity nt increasing... how come??

[Mc85]

Ok so im working up some loads or my savage 10fcp. Im using win brass, and trying out lapua 155 scenars. Im using Varget for my powder.
I started out with 45 grains and seated the bullets about .008 away from the lands. I got an avg velocity of 2865 with the chrono sitting 17ft away.
I bumped up to 45.3 and tested again today. It was slightly warmer out today, but temps where within 5 degrees or so.
Today using the same brass I did last time I got 2840 or so.
then I bumped up to 45.5 and got a avg for 5 rounds at 2835.

45 grains gave me great accuracy. 45.3 was not as good and 45.5 was worse yet though the sd was very good. Primers were starting to get on the flat side too btw on the 45.5 loads. Though bold still felt good and I didn't notice any marks on the case heads.

So does anyone have any ideas why I didn't see any real increase but rather about the same to slightly less velocity?


thanks for the help.

 

[308sako]

Re: velocity nt increasing... how come??

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[Mc85]

Re: velocity nt increasing... how come??

I've had that too when switching lots of varget, but right now Im using a 8 pound lot of it.
U said when you were op u had that type of results..
my sd were good but I wonder if I could be getting up there close to the op range and thats why?

 

[308sako]

Re: velocity nt increasing... how come??

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[Dustin Morris]

Re: velocity nt increasing... how come??

Overpressure, Period. Back down to load that shot the best, dont get all hung up on how much powder is in there. I woould go with 45 grains and try different seatings depths to get best accuracy.
Just my opinion

 

[Mc85]

Re: velocity nt increasing... how come??

bolt lift still felt good on mine. sd for me and my current loads is normally between 10-15 fps. 5-10 is good for me.
primers looked decently flat but a little radius still remained and only the normal bolt face marks were present and not any more pronounced than is normal for my rifle.

Im really at a loss so far.

 

[bohem]

Re: velocity nt increasing... how come??

You're over the OCW, with my 30-06 I noticed the identical trend for medium and heavy bullets with H4350 and RL22.

A single example for me was:

208 Amax, starting at 58gr of RL-22

I stepped up the powder like this:

58gr: 2775 fps - decent accuracy
59gr: 2825 fps - better accuracy
60gr: 2840 fps - accuracy about the same as 59gr
60.5: 2800 fps - OK accuracy, but not as good as 59 or 60

60.5gr also backed out the primers, 60 was HOT, 59 was not a problem.

I was working from information from another rifle and other brass that said I should be able to shoot 62gr of powder without issue, hence the big steps.

I ran a second test at

59gr: Same velocity and accuracy
59.5gr: 2885 fps on 20ft chrono, ~ 2900 at the muzzle and the best accuracy yet
60.0gr same previous results.

Verdict? I missed the node on the first test being in a rush, hit it on the second one.

I think you should run a test starting at 44.0gr with that load and work to no more than 45.3gr

Keep the seating depth constant, check the results. Once you get the finalized powder charge, mess with the depth.

 

[RL15]

Re: velocity nt increasing... how come??

I would advise you to stop at that point where it did not increase and play with the seating deapth.
Did you shoot that ammo in 95- 100 degree weather?

 

[308sako]

Re: velocity nt increasing... how come??

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[Mc85]

Re: velocity nt increasing... how come??

I was shooting in about 70 degrees the first time. the next day it was about 75 though more humid out.

 

[Grump]

Re: velocity nt increasing... how come??

I've seen some reports that Varget would shoot minimally slower velocities at higher temperatures. The internal ballistics and chemistry needed to overcome ideal gas behavior has GOT to be something special.

OTOH, the gross differences reported between same-charge velocities on different days, as well as yours (on the order of 25 fps), are such small percentage of the total value, they are at the outer limits of normal statistical variation or "noise" in the data.

Finally, increasing powder charges without increasing bullet speeds is a sign of hitting the law of diminishing returns and usually happens somewhere above the max pressure specs. 20 years ago, I saw firsthand some testing with slightly fast powder in a 7.62x39 SKS using quality brass and bullets, and the velocity curve went FLAT at the very top end, while the only change in the brass and primers were classic 65-75KPSI (?) pressure signs of primer cratering, machining marks in the casewalls, and eventually extractor cut marks in the caseheads.

 

[Mc85]

Re: velocity nt increasing... how come??

ok so I backed down to 44.8 and accuracy came back cept for a stupid flier..... # shots including cb shot in .36 moa and then one stupid shot making it spread out to .8 moa .... DOH!!!

anyways vel is down to 2808 avg. Im gonna try 45 one more time and see if the sd comes down any and if accuracy goes up anymore.

Thanks for the help.
Learn something new everyday.

 

[Grump]

Re: velocity nt increasing... how come??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mc</div><div class="ubbcode-body">ok so I backed down to 44.8 and accuracy came back cept for a stupid flier..... #</div></div>

If, with total and brutal honesty to one's self, and IF you have a consistent record of being able to call your shots, a called flyer that's ON CALL in both direction and distance can be safely discounted.

Hope this means your day is just getting better and better. Chasing the difference between .4 and .8 MOA is really getting to the limits of mechanical accuracy for most of us.

 

[Mc85]

Re: velocity nt increasing... how come??

With all honestly I wasn't able to call how far off, but as the trigger broke I felt me self move off target up high and right which is where the bum shot landed. Typically with a good load and me shooting to my potential at 100yds off a harris and sand sock I am capable of shooting .5's-.6's on avg. I do get the occasional WTF how did that happen shot where 4 are between .4-.6 and one reaches out to expand the group to alomst 1 moa.
then there was a day like the other day that I was eqaully surprised when I slapped my target on the scanner and OnTarget came up with .115 moa for 3 shots. I was blown away. HA Ha of only I could repeat that LOL .

Thanks again for you input and helping me figure this out.

 

[Evilaviator]

Re: velocity nt increasing... how come??

I can never understand why someone settles on a load where .2gr is going to make or break a load? If your loading for accuracy, shouldn't you be looking for that sweet spot charge? A charge where temperature fluctuations or over/under throws won't distort accuracy? Seems like a lot of people on this board are trying to find a charge rounded to 8th decimal place.

 

[Mc85]

Re: velocity nt increasing... how come??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Evilaviator</div><div class="ubbcode-body">I can never understand why someone settles on a load where .2gr is going to make or break a load? If your loading for accuracy, shouldn't you be looking for that sweet spot charge? A charge where temperature fluctuations or over/under throws won't distort accuracy? Seems like a lot of people on this board are trying to find a charge rounded to 8th decimal place. </div></div>

I get what you're saying. Understand the point 2. I settled on 44.8 grains today and went out to 700yds and shot the best I have yet. The load worked great. Would it work in 100+ degrees IDK??? Varget is supposed to be temp insensitive but i haven't tested it. I plan on continuing to experiment. 45 grains shot great and I didn't see any signs of being past the OCW or over pressure. Though moving up as little more seemed to show I was right on the border. I am gonna try a couple loads backed off a little more and see how it does so I do have a little head room to account for temp variations and what not. Anyways 44.8 was great and 4 today in these temps I knew it would be fine and seeing as I was leaving for the range early in the morning it was the only "good" load I had available to test the new to me lapua scenar bullet in my gun with at decent range.