Took my new F1 Chrony to the range yesterday and checked out the 140 Grn Accubonds on top of Varget. Got the following average velocities from my Rem 700 Mtn LSS 22" barrel using the top three powder charges.

41.0Grn 2,673 FPS
41.5Grn 2,716 FPS
42.0Grn 2,752 FPS

I know it's not much of an increase, and although it's a bit nitpicky, I would like to get it up to 2,800 FPS as per my ballistics program that velocity most closely matches the bullet drop compensator notches of my Burris 3-9x40 Ballistic Plex reticle.

The Nosler 5th edition shows a velocity of 2,849 for the Ballistic Tip with 42.0Grn of Varget using a 26" barrel. I'm shooting a 22" barrel and not showing any pressure signs at 42.0Grns of Varget (shot at 84 degrees outside temp). Considering the difference in barrel length, would it be OK to edge past the 42.0Grn max at say .2 grns per increment and watching for pressure signs?

Are any of you guys getting 2,800 fps or better out of a 22" barreled 7MM-08? If so, could you please share bullet / powder / primer / brass info?

Thanks

firstshot
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Make your first shot count!

This would be the proper approach.

Bear in mind lots of factors enter into achieving that "magical" 2800 fps for your particular rifle. Bore fouling, precise seating depth, condition of brass, accuracy of scale (be sure to calibrate carefully and check often), temprature and humidity on shooting day, sensitivity of chronograph, etc.

As you've been informed, the difference between your 22" bbl and the 26" test barrel, all other things considered, can amount to about 100 - 125 fps loss on the 22" bbl.

Working up in .2 increments from the max you've tested and watching for the first pressure signs is a good idea. Watch the accuracy, also. Think you'll find the best accuracy is usually just under max manual reloading. The game you hunt really won't notice the difference between 2752 fps and 2800 fps.

Kdub

Actually, I was a little surprised that the difference in velocity from the 26" to 24" barrel was only 24.25 FPS per inch of barrel. I was expecting a difference of closer to 50 FPS per inch of barrel.

I know the game won't know the dif in 50 FPS and I can always adjust the sight in distance to match the Ballistic Plex reticle. As far as accuracy goes, one of the best groups, .495"CTC @ 100Yds, was with the max charge of 42.0 Grns Varget.

Don't know if I'll even mess with it, but if I do, I definitely Workup in .2 increments and watch pressure signs as well as loss of accuracy.

firstshot
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Make your first shot count!

What bullet, exactly, is that recticle set up for? The plastic-tipped bullets tend to fly a bit flatter than regular soft points, and your 2,750+ fps might already be very close to the recticle's predictions. You could already be shooting flatter, there is no way to know without testing it.

I'd say that rather than fret over the last few FPS, see if you can find a range to shoot at that will let you test the reticle's predictions. After all, that's what it is doing, "predicting" the downrange ballistics - there are no guarantees.

If you can find the exact B.C. that the reticle is set up for, you'd still need to measure the actual B.C. that your rifle is delivering. B.C., like predicted muzzle velocities, will vary by rifle a tad.

What bullet, exactly, is that recticle set up for?........................
I'd say that rather than fret over the last few FPS, see if you can find a range to shoot at that will let you test the reticle's predictions. After all, that's what it is doing, "predicting" the downrange ballistics - there are no guarantees.



MikeG

You're absolutely right!!! I went back and checked my ballistics program and even at 2,752FPS, sighted in dead on at 100Yds, I should be within an inch at 200 & 300 Yds. I just need to get out and shoot it at 200 & 300 and see what is "actual".

Just FYI, the reticle isn't set up for a particualr bullet, but for specific amounts of drop at the various ranges.

100Yds - sight in dead on
200Yds - calibrated for 3.1" drop
300Yds - calibrated for 13.5" drop
400Yds - calibrated for 30.1" drop
500Yds - calibrated for 55.3" drop

By the way, thanks for the advise. I'll quit spinning my wheels and get out to the range and do some shooting.

firstshot
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Make your first shot count!

So what BC does that work out to, exactly? It has to be calibrated not only for the velocity, but an exact ballistic coefficient, as well.

Good luck.

So what BC does that work out to, exactly? It has to be calibrated not only for the velocity, but an exact ballistic coefficient, as well.

Good luck.

MikeG

I don't think it was anything quite that scientific, otherwise they would have to have a different reticle for every rifle / caliber / bullet / velocity combination out there.

They basically just picked the most popular calibers and loads out there from a sales standpoint and then averaged the bullet drop at 200, 300, 400 & 500 Yds.

Here is a link to the teck notes on the Ballistic Plex Reticle.
http://www.burrisoptics.com/pdf/BALLPLEX.pdf

I haven't tried it out yet on my 7MM-08, but with my 30-06 sighted in dead on at 100Yds, I was a little less than 1/2" low at 200Yds using the first hash mark. Our gun range only has a 50, 100 & 200 Yd berms so I didn't get to check the 06 out at 300YDs before I sold it.

I like the BPlex reticle because most of my shots are between 50 & 125 Yds and I really like being able to sight in dead on at 100 Yds yet still have the 200 & 300 Yd hash marks available in the rare case where I get an opportunity for a long range shot. I may not be dead on at 200, 300 etc, but I will be within an inch or so which is plenty close for a hunting application.

Great reticle as far as I'm concerned.

firstshot
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Make your first shot count!

So what BC does that work out to, exactly? It has to be calibrated not only for the velocity, but an exact ballistic coefficient, as well.

Good luck.

Tinkering with the external ballistics calculator shows a bullet with a BC of about .450 will give this trajectory at sea level for standard atmospheric conditions.

I've never yet had a bullet behave exactly as it should according to the numbers. You gotta shoot 'em and see!

Give RL-15 a try. I was working with my M70 Classic Featherweight ( 22" bbl ) 7mm-08 last year with 140 grain bullets (North Fork) and found that for the same powder charge I was getting a consistent 40 - 50 fps more velocity with RL-15 than Varget with all other components exactly the same. I did get a chronographed muzzle velocity of 2800 fps with that powder bullet combination. No indications of high pressure with either powder, good accuracy with both. Just got a little more velocity with RL-15 than Varget. Varget is generally my preferred powder, but in this case I met my loading & accuracy goals with RL-15 instead of Varget.

Give RL-15 a try. I was working with my M70 Classic Featherweight ( 22" bbl ) 7mm-08 last year with 140 grain bullets (North Fork) and found that for the same powder charge I was getting a consistent 40 - 50 fps more velocity with RL-15 than Varget with all other components exactly the same

I found the exact same to be true with the 308... RL15 approx 50 fps faster than Varget. If you're concerned about the "temperature insensitivity" of Varget, RL15 is also "temp stable" as it is a milspec powder.

I'd also try H4350 with the 140's in the 7-08...

gldprimr / Brad A

Isn't that a hoot....the Nosler manual actually shows RL15 as runing a little slower than Varget with both at max charge. Just goes to show you that the manuals are just a guide!

Thanks for the input guys!!!! I'll definitely give RL15 at try.

firstshot
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Make your first shot count!