Slow 7mm-08?

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Xs24-7

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I didn't have my chronograph with me today, and I wanted to test out a new load in my Tikka 7-08.
I checked my zero at 200 yards, and everything was good. I went back to 350, and ended up dialing + 4.75 moa to get zerod. in order for this to match up in my ballistic calculator, I need to enter a velocity of 2575 fps, which seams about 225 fps slow for 42 grains of varget and a 140 grain Nosler ballistic tip. Every manual, and everyone online seams to be getting around 2800-2850 with this load. Is my rifle really this slow, or is there another factor I may be overlooking?
 
Tikka t-3 stainless. 22" barrell. Nikon Monarch 3-12x42 in a low Reaper mount.
Load is a 140 grain Nosler Ballistic tip in front of 42 grains of varget in Winchester brass. It's loaded to max mag length, so just over 2.8" COAL.
 
Hi: I have the same rifle in 7-08 and have used a few powder/bullet choices and as you i too have found velocity to be low, 43.5 grs. of RE15 shooting a 140BT my avg. velocity was 2760 with an ES of 21. i even tried RE17 with 47.5 grs i achieved 2800 fps with a ES of 6 but the rifle didn't like this powder, tried RE19 but velocity was way low. the old standby of IMR 4350 gave great accuracy but velocity was around 2600FPS.. i have settled on Reloader 15 for this rifle seated at 2.816" all loads shot through my CED Chronograph and 140 gr BT bullets.let me know if i can help
 
My chronograph is at a buddies house a couple hours away...not a big deal, the rifle shoots great, and everything is sighted in...deer season opens in 2 weeks...I'll worry about building a faster load in the spring.
 
I would honestly say get some loads chronographed first and then start to dissect things.

Should still be able to get 2750-2850 ft/sec with a 7/08 and proper powder combination.

Like stated above , W760 is a good one(little more speed), H4350 (little more accurate)

I have always had best results with 140's in factory twists moving above 2800 ft/sec.
 
I wouldn't be surprised to see it running 100fps low, because rifles vary from one to another, but 225fps seems like a bit much for that alone. Maybe its a combination of a loose chamber and a long-seated bullet both working together to lower the pressure enough to drop your speeds? I dunno. Tagged for interest...
 
I just double checked the Hodgdon manual...and its showing 2675 fps with 39 grains of Varget..and 42.2 as a max load for 2825...I cant believe that Id be getting less velocity from the max load than they were getting from the min. I chorongraphed another load with IMR 4350 in the spring that were slow as well...which is why I tried the switch to varget. I found a load that shot well, and im not one to worry too much about velocity...but this is pushing it...I was thinking about trying some 162 grain but if they run as slow as the 140s in this rifle I wont see 2400 fps with them...
 
With a custom barrel on a 7/08 that I have I am getting near max book loads with near min charges, rifle dynamics can play a role.

Xs24-7 said:
I just double checked the Hodgdon manual...and its showing 2675 fps with 39 grains of Varget..and 42.2 as a max load for 2825...I cant believe that Id be getting less velocity from the max load than they were getting from the min. I chorongraphed another load with IMR 4350 in the spring that were slow as well...which is why I tried the switch to varget. I found a load that shot well, and im not one to worry too much about velocity...but this is pushing it...I was thinking about trying some 162 grain but if they run as slow as the 140s in this rifle I wont see 2400 fps with them...
Click to expand...
 
I've seen several Tikka T3's that were slow and there is talk about this on 24hr Campfire too. Additionally I had a 20" barreled Remington Model Seven that could hardly exceed 2700fps with 140gr bullets. One of Nosler's old manuals laments the proliferation of short barreled 7mm-08 rifles as the editors felt this particular chambering does much better with long barrels. I have experienced a sample size of exactly one, but that will change now as I just added a Remington M700 Compact to the stable.
 
Kelly Timoffee said:
With a custom barrel on a 7/08 that I have I am getting near max book loads with near min charges, rifle dynamics can play a role.
Click to expand...

Same experiences here, tolerance of production barrels can vary a lot, and looser will be slower as pressure is reduced due to the larger chamber/throat/bore.

But without chrony results, it's all just guessing. I can honestly say I've never had a rifle match published velocity data even within a grain or 2 of powder, taking in to account barrel length as well. Faster or slower, but never close enough to say wow...
The 2 slowest I have are a Rem 783 in 30'06 which easily is 200fps below published data, and a Browning AB3 in 270 which is a bit more then 200fps slower.
Each rifle will tell you your max load, and I think velocity over a chrony is much more valuable in determining pressure then how much powder is in the case.
 
AP said:
I wonder...would you believe your chrony? Or your observed 'drop'?
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If you know your exact altitude, temperature, barometric pressure, wind speed and direction, exact line of sight over the bore, exact horizontal distance to the target or account for incline/decline, BC of the bullets is exactly as advertised, you know 100% your scope is tracking perfectly with no variation or deadspots, and you can gather several data points (drop) from 100m out to just before your bullet goes subsonic.....then you could reliably calculate muzzle velocity using a ballistics calculator.
 
To get that additional velocity you're after you might want to try a mono like the 120 gr. TTSX. That is what I shoot out of my Sako 85 7-08 (22" barrel). I'm using 43.5 gr. of Varget which is still below max by close to a grain for my rifle. It's been giving me 2900 FPS with great accuracy. All three deer I shot with it this year dropped on the spot. Just the same, I'm going to give the 110 gr. TTSX a try next season because I know that will easily give me over 3000 FPS.
 
Faster twist barrel can produce less velocity, ie 9 twist x fps slower than a 11 twist. In my older savage 7-08 the company designed the barrel with a 11.5 twist (120-140gr pills) until heavier bullet bandwagoneers forced their hand towards the standard 9.5 twist. In my case with 43.0gr varget, 120gr TSX, 60 jump, in a 22" 11.5 twist barrel=yields 3050 fps. And they are the hammer of thor on deer.

Winter and temperature can play as well. Your sight in in the spring may not apply in November...good on ya for checking.

Remember elevation and time of day you are using the chrony can make a lot of difference. Here at 2000ft velocities are higher than say 760 ft in Winnipeg due to atmosphere density. Morning, noon, and evening light will vary your results.

So if your load shoots well I say don't get so caught up in the velocity game. No real benefit unless you are poking out beyond 300m.
My 2c.
 
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Not every load listed in a manual has been shot through a chronograph... many are estimated... and unless the loads were tested with the same make and model of firearm, there will be a discrepancy. PO Ackley once tested 2 factory 30-06 rifles with consecutive serial numbers and by all measurements exacty the same... and there was 100 feet per second difference in velocity from one rifle to the other.

Sight your rifle in, leave all the ballistic data at home and go shoot your rifle... if it shoots low, hold a little higher for the next shot...
 
guntech said:
Not every load listed in a manual has been shot through a chronograph... many are estimated... and unless the loads were tested with the same make and model of firearm, there will be a discrepancy. PO Ackley once tested 2 factory 30-06 rifles with consecutive serial numbers and by all measurements exacty the same... and there was 100 feet per second difference in velocity from one rifle to the other.

Sight your rifle in, leave all the ballistic data at home and go shoot your rifle... if it shoots low, hold a little higher for the next shot...
Click to expand...

Yes - I think this; and to add - not all chronographs agree .. not even the same one on different days and different light conditions.
 
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