Need help with 6.5x284

[demarpaint]

Hi and thanks in advance,

I had my 6.5x284 to the range today in preparation for 1K F-Class. It has a 30" 5C Broughton Barrel 8 twist. It is amazingly accurate. I am shooting Danzec Coated 142 gr SMK bullets using 51.5 gr of 4831 SC.

My velocity is averaging 2780 fps, which is a little slow. Reading here I see that 2950 seems to be the magic number for 1000 yards. I was going to try 53 grains and check for pressure signs and work up to 2950 from there. There are no signs of pressure with the current load and at 100 yards it is amazingly accurate.

Any information is greatly appreciated!

Thanks
FD

 

[Dubya]

Hey FD,
About all that I can tell you, is that I'm using the same barrel
but different powder,H4350 48.8 gr.)and I'm getting 2980 fps out of it. With 51.5 of H4831 you should also be in that area.
Try seating a little deeper and try a different primer,I'm using
CCI-BR2s)

Good luck & good shooting.
Gary.

 

[Spotcheck_Billy]

Your coated bullets will need more powder than an uncoated bullet to reach equal velocities. You'll see lower chamber pressures when using coated bullets vs uncoated.

I'm using a new 30" Bartlein 5R 1/8.5" twist barrel in 6.5-284 and am getting the following velocities -

142SMK naked, 51.5gr H4831SC Lapua brass BR-2 primers - 2898 MV

142SMK naked, 48.5gr H4350 Lapua brass, BR-2 primers - 2989 MV

You can probably increase your loads by 1 to 1.5 grs. with coated bullets.

 

[demarpaint]

Thanks. I knew I needed to add powder to the load for coated bullets. I didn't realize how much more was needed. Looks like I will have to go over 53 grains to get near 2950 fps.

Thanks again!
FD

 

[BarryL]

I tried shooting for the "magic" 2950 and accuracy deteriated. Im using a 29" Gaillard barrel with 8.5 twist. So far Im doing best with 50.8gr. of H4831sc, Lapua brass, 142gr. MK's and Fed 210m primers. Velocity is 2890 and change.

 

[demarpaint]

I got some IMR4350 to try, and will also try increasing the 4831SC charge a little more. What I have is an accurate 100 yard load, but feel that I am not taking advantage of the wind bucking ability with my current load and speed of 2780 FPS. If I can get a little closer to 2900 FPS and still have accuracy I'll be GTG.

FD

 

[Raptor]

FD,
Your shooting nearly 260 velocities with your 6.5x284. I used a 6.5x284 for tactical shooting and used 53grs of H4831SC and I was pushing 140AMAXs at around 2975 out of a 26" Pac Nor barrel.

I used the Norma brass and had some first and then 3rd generation brass and there was nearly a grain difference in the loads for the two batches of brass. So your brass may dictate your load also. You need to be up around the 2900+ to take advantage of the 6.5x284s.

 

[BarryL]

For a 1K load its hard to tell if accuracy at 100yds is going to be good at 1000. SD and ES is a major factor once your past the 600yd line. Another consideration is a boat tail will take 200yds or better to stabalize. Get your ES under 20 and your SD into single digits then tweek for accuracy with seating depth and/or jam after that. Let your 1K target tell you whats the best velocity for your rifle.

 

[demarpaint]

FD,
Your shooting nearly 260 velocities with your 6.5x284. I used a 6.5x284 for tactical shooting and used 53grs of H4831SC and I was pushing 140AMAXs at around 2975 out of a 26" Pac Nor barrel.

I used the Norma brass and had some first and then 3rd generation brass and there was nearly a grain difference in the loads for the two batches of brass. So your brass may dictate your load also. You need to be up around the 2900+ to take advantage of the 6.5x284s.

Thanks I was thinking that if I had 260 Velocities I might get 260 barrel life too. I was going to try and load up 53 gr of 4831 SC and see what happens.

For a 1K load its hard to tell if accuracy at 100yds is going to be good at 1000. SD and ES is a major factor once your past the 600yd line. Another consideration is a boat tail will take 200yds or better to stabalize. Get your ES under 20 and your SD into single digits then tweek for accuracy with seating depth and/or jam after that. Let your 1K target tell you whats the best velocity for your rifle.

Thanks for the info. The problem I am having is the only range time I have before my first 1K outing is at 100 yards. I might be a little too hung up on the 2950 fps, but I needed something to go by.

Frank D

 

[Spotcheck_Billy]

Frank D,

You won't get 260 barrel life with 260 velocities in your 6.5-284 because it's taking more powder to reach those velocities in that larger case.

My advice is to increase your powder charge to compensate for the coated bullets that you're using. Get those 142SMK's going about 2900-2950 MV and grouping under .5MOA for five shot groups at 100yds and it'll do just fine at 1K. It shouldn't be hard to do, and you won't have to push chamber pressures into the stratosphere to do it with that combination.

I don't subscribe to the theory that it takes 200yds for boattail bullets to stabilize. If you can shoot small groups with those SMK's at 100yds at a decent velocity what happens at 1K is gonna be strictly up to the shooter

 

[demarpaint]

Frank D,

You won't get 260 barrel life with 260 velocities in your 6.5-284 because it's taking more powder to reach those velocities in that larger case.

My advice is to increase your powder charge to compensate for the coated bullets that you're using. Get those 142SMK's going about 2900-2950 MV and grouping under .5MOA for five shot groups at 100yds and it'll do just fine at 1K. It shouldn't be hard to do, and you won't have to push chamber pressures into the stratosphere to do it with that combination.

I don't subscribe to the theory that it takes 200yds for boattail bullets to stabilize. If you can shoot small groups with those SMK's at 100yds at a decent velocity what happens at 1K is gonna be strictly up to the shooter

Thanks for the info Billy, I had a feeling there was more to it about the 260 barrel life. My current load was amazingly accurate at 100, but I am going to push for the extra velocity as you mentioned. No point in having a hot rod if you're stuck in third gear.

Take care,
Frank D

 

[BarryL]

Ive had quarter inch bug holes at 200yds and 18" vertical spreads at 1K. Sometimes a 200yd group will be half the size of a 100yd group due to the boattail needing the extra distance to get it together. Other times and in other guns it will have no problem. Im not lucky enough to have one of those guns. If you have a chronograph and your doing development at 100yds go with the load with the smallest ES as opposed to group and it will be the one that shows best at 1K. My best load didnt start grouping nice until past the 200yd mark then shot a 3.836" at 1049yds.
http://usera.imagecave.com/moosehunter/5shot3.836.jpg

 

[Spotcheck_Billy]

Ive had quarter inch bug holes at 200yds and 18" vertical spreads at 1K. Sometimes a 200yd group will be half the size of a 100yd group due to the boattail needing the extra distance to get it together. Other times and in other guns it will have no problem. Im not lucky enough to have one of those guns. If you have a chronograph and your doing development at 100yds go with the load with the smallest ES as opposed to group and it will be the one that shows best at 1K. My best load didnt start grouping nice until past the 200yd mark then shot a 3.836" at 1049yds.
http://usera.imagecave.com/moosehunter/5shot3.836.jpg

Respectfully, your advice as to choosing accurate loads by using the ES figure from a chronograph is not scientifically correct.
The facts are:
1) ES is not a reliable statistical indicator.
2) The best indicator of velocity variation is SD.
3) In the sample sizes we commonly chronograph both figures have very little meaning.

I don't want to start a pie fight on this forum, nor did I intend to hijack this thread, but I thought that some of the advice presented required a rebuttal, if just for scientific accuracy. I am providing a link to an excellent paper dealing with this specific topic. I urge anyone interested in this subject to partake of this offering -

http://www.shootersjournal.com/Features/Haps/EnglemanChronographStatistics.pdf

The information contained is scientific fact and not merely 'conventional wisdom' which is most often misused and likely flawed.

 

[BarryL]

Your right. We may have hijacked the forum to discuss apples and oranges. Ive printed that paper and Im going to give it a go over. I understand SD and see its application. My only statement is a poor ES will look great at 100yds and down right ugly at 1K. Thanks for the link.

 

[Forum Boss]

I want to point out that Barry and Billy are not necessarily in disagreement. SD can be the most important statistical predictor.

However, a large Extreme Spread, if you confirm it is happening with your match loads, can be the "group killer" at long range. If you have one bullet launching at, say, 40 fps slower Vel than another, you just won't be able to hold a tight vertical at long range. For the score shooters that can be critical, because it will mean you're in a lower value ring, no matter how well you call the wind.

 

[AlanPF]

I agree with increasing,incrementally and carefully) the H4831SC powder charge if you're getting under 2800fps - there will be plenty of room to add more powder. I'm wondering if DANZAC is more slippery than moly, because I can get 2950fps with 51.2 in all my barrels. With naked SMKs I get 3100fps with about 52.0, although preferred match loads are always somewhere in the 2900s.

On the second subject in this thread, you can't expect good 100yd,or even 300yd) groups alone to guarantee similar results at long range. Short range groups hide velocity variations, and also bullet BC variations. So if you can't test at the long range distance you compete at, then minimising your SD or ES,whichever turns you on) and sorting bullets would be my advice.

Alan

 

[demarpaint]

Thanks for the replies. I think the Danzec is more slick than moly. I understand what you guys are saying about the testing at 100 yards. Around where I live the furthest I can shoot is 200 yards, an hours drive away. I had access to a Chronograph and indoor 100 yard range where I was able to test my loads. Now I won't be able to get there for a while. It looks like I am blind now and won't even be able to test again before the 1 K shoot. Not sure what to do now?

Again thanks for all the replies!

Frank D

 

[BarryL]

I hear you. I got a shoot on the 5th and 6th of May and my range is under 3 feet of snow. Very good paper and a good read, thanks. A small SD is still the answer to small groups at 1K though. My chrony has a 15fps accuracy either way so if I can keep them in that its as good as its going to get.

 

[demarpaint]

Well I got to shoot with this rifle at 1K at Bodines this past weekend, my first time out with it. I was unable to test any loads so what I ended up doing was took the original load 51.5 gr of 4831 SC, and upped it to 53.5 grains. Guessed at the velocity,based on 2780 fps with 51.5 gr load). Then I asked my shooting buddy to calculate how many more MOA I needed from my 100 yard zero. I dialed in 28 MOA first shot was on paper about 1 foot high at 1000 yards. I was shocked since I am new at this 1 K game.

First relay I shot was a 180, my second try was a 170 in some pretty tough winds. I was happy. Now I have to get some kind of adapter to get my PSS stock to stop rolling in the rest. Sinclair has one, I have to check out.

Thanks for all the replies.

Frank D