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#6481891 - 10/05/16 10:36 AM Determining pressure of reloads?
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
I am currently doing some load work up for 6.5 cm. I am loading 43 grains of H4350, CCI 200, topped with 140 Berg VLD, but would like to increase my velocity for better results long range (1000 yards plus). Is there a way to estimate pressure using load data combined with velocity or other inputs? I would greatly appreciate any insight. I am also curious the degree that higher pressure (even under max) effects throat erosion and barrel life? I have 2 good loads with 40.8 and 41 grains using different primers, but they only chrono at 2679 fps and 2636 fps respectively. Thanks for the help / suggestions.

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#6481910 - 10/05/16 10:45 AM Re: Determining pressure of reloads? [Re: Burton Ranch]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9393
Loc: Lewisville, TX
In a simple answer, no. H4350 has large swings between lot to lot. The newer lots of H4350 has been running slow, requiring more powder to equal the max speeds of the 6.5 CM. I have not run any loads hotter than about 43 grains, so any more than that, and I will guarantee you will be getting higher pressures, or a hot load. Plus, Hornady brass has a semi soft primer pocket, and you will wear out the primer pocket very quickly with the max or over max loads. I've seen in as few as 2-3 reloads. If you want more speed, go to a bigger round. But the 6.5 CM with a 140 VLD is great medicine for 1K yards. More pressure = more throat erosion and reduced barrel life. I would agree that the 2670 and 2636 speeds are fairly slow. There is a higher accuracy node around the 42 to 43 grain powder charges. But IMO, it's not worth the hassle to gain a few fps for a hot round in a 6.5 CM.
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#6481935 - 10/05/16 10:59 AM Re: Determining pressure of reloads? [Re: Burton Ranch]
Rustler Offline
Veteran Tracker

Registered: 03/01/07
Posts: 3211
Loc: Carrollton/ Young, Blanco coun...
I use an Oehler 43, some folks like the PressureTrace 2.

Just me, I wouldn't 'estimate' pressure, measure it or stay below max.

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#6481940 - 10/05/16 11:03 AM Re: Determining pressure of reloads? [Re: ChadTRG42]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
Thanks, I have considered loading Varget, but have not found any reliable data for bullets > than 123 grain. Some even discourage using it with 140 grain bullets. This seem strange due to the fact I use Varget for my 7-08 with 140's and it shoots very well. Any suggestions regarding powder, primer, bullet combination for this application (shooting Savage LRP 10BA)? I have not been reloading long and hate to ask so many questions, but damn I have a lot to learn. Thanks again

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#6481945 - 10/05/16 11:06 AM Re: Determining pressure of reloads? [Re: Rustler]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
Thank you

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#6482319 - 10/05/16 02:26 PM Re: Determining pressure of reloads? [Re: Burton Ranch]
Creedmoor Offline
Tracker

Registered: 09/12/16
Posts: 607
Loc: Soon to be Hudson Oaks
I'll echo what Chad said about Hornady brass. I use it exclusively in my Creedmoor, but it does tend to have a short life if you load near max published data. For some reason my rifle likes a load that is conservative and my brass has lasted 8 cycles with no signs of fatigue so far. As for H4350, some are loading over published max data and are having good results with it. I loaded H4350 for a long time, and then switched to IMR4451 and am a bit more pleased with it. It is a bit cleaner than H4350 and is only a teeny amount slower. Varget is a great powder but it didn't show me anything in the CM. I didn't fool with it for very long as H4350 is obviously the powder of choice.

If you desire you can go to www.65creedmoor.com and research their site. I have a lot of friends there who eat, sleep, and breath the cartridge. Tons of CM info if you go and read a bit.

EDIT TO ADD: I just went back and re-read your initial post. At 43 grains of H4350 I am assuming you know that you are WAY over any published max load. And I also know that some folks are loading the CM over published data and having satisfactory results. But asking for a 140 grain bullet pushing 3000fps you are dreaming. You can get that with a 120 grain load, but I don't want to be anywhere around if you try to push a 140 to that speed. The creedmoor is very adequate and accurate out to 1000 yards without having to push the speeds up in that area. Just saying ......
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#6483948 - 10/06/16 01:57 PM Re: Determining pressure of reloads? [Re: Burton Ranch]
JTPinTX Online   content
Woodsman

Registered: 04/01/15
Posts: 182
Loc: TX Panhandle
43 would be too hot in my 6.5 Creedmoor, at that point it is blowing primer pockets in just a few loadings. I use 42.3 with a 140 or 136L Scenar. Granted, that is an older lot of H-4350. I have some newer stuff but haven't gotten into it yet. My rifle has a 22" Bartlein barrel and I am getting right at 2775 fps with 42.3 and a 140. It took 45 grains of H-4350 to get 3000 fps with a 123 SMK, and that was a blistering hot load in my rifle.

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#6484895 - 10/07/16 07:53 AM Re: Determining pressure of reloads? [Re: Creedmoor]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
Thanks. I would be satisfied if I could find a load that groups well around 2800 fps. I am currently shooting out to 1200, but hope to clear some more brush when I get time which would allow me to shoot out past 1450. I think I will have to have the higher velocity to be accurate at that range and beyond. I do have some IMR 4451, but only 4 lbs. and I was saving I for a 6.5 cm I am having built with an 18" barrel. Thanks again

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#6485070 - 10/07/16 09:31 AM Re: Determining pressure of reloads? [Re: Burton Ranch]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
2670 fps, MV @ 40.8 gr of H-4350, but what is your barrel length?

My 6.5 Creedmoor barrel is 25". Old lot of powder shot best at 42.4 gr and made a 140 gr leave the muzzle at 2800 fps. With the new lot of powder, the charge is 42.8 gr, and is making 2800 MV.

That's about as fast as it'll go out of that barrel length. If that's not fast enough, you'll have to go to a different cartridge.

And BTW, 1430 yards is as far as I've pushed that combo, but it is repeatable.
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#6485179 - 10/07/16 10:27 AM Re: Determining pressure of reloads? [Re: Burton Ranch]
JTPinTX Online   content
Woodsman

Registered: 04/01/15
Posts: 182
Loc: TX Panhandle
I have played with a lot of bullet weight/BC/velocity combinations in my Creedmoor. For about 90% of them the reality is that it is going to go subsonic somewhere in the 1200-1300 yard range. The exception to that is the 140 Berger (either VLD or Hybrid, take your pick). Either of those 2 bullets run hard can make 1400+ supersonic. Some bullets fly through trans-sonic better than others. The Berger Hybrid does good, the 140 AMAX isn't too bad. I know the Hornady 140 BTHPM doesn't fly though it for crap.

Bottom line is that to get 1400+ out of the Creedmoor you are going to have to load a specific way to either keep it supersonic, or fly though it. 140 Berger Hybrid will do both. I know several folks who shoot it to 1700 out of one of the mid-capacity 6.5's.

Other than that, like JG said, you are going to have to step up to a more capable cartridge.

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#6485242 - 10/07/16 11:05 AM Re: Determining pressure of reloads? [Re: FiremanJG]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
24" with 1:8 twist. I also run an aac can (if that makes a difference). Thanks for your insight.

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#6485252 - 10/07/16 11:19 AM Re: Determining pressure of reloads? [Re: JTPinTX]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
Thanks. I appreciate the info. Seems hard to find relevant data on shooting past 1000 (maybe I'm just not looking in the right places). The good information I do find is predominantly for wildcat rounds or .338, 375, etc. and is hard to apply to what I am looking for (that may be a sign). I am really just getting stared and trying to educate myself as quickly as I can. Thanks again.

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#6485396 - 10/07/16 01:26 PM Re: Determining pressure of reloads? [Re: Burton Ranch]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
www.jbmballistics.com

Plug in BC, MV, and bullet weight. It'll tell you what you need to know. Sure some bullets do well trans-sonic, however Chad went to Brian Litz's seminar and learned that 1340 fps is the line to look for. Bryan says the bullet has plenty of stability at that speed, and faster (that's the short version). So plug in your numbers into jbm and see where you drop below 1340 fps down range.
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#6485588 - 10/07/16 03:54 PM Re: Determining pressure of reloads? [Re: FiremanJG]
Burton Ranch Offline
Light Foot

Registered: 05/21/12
Posts: 37
Wow, that is an extremely useful tool. I am so impressed by Bryan Litz,Todd Hodnett, and the like. There understand of ballistics and its application at long range is extraordinary. Thank you sir.

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