Range Report Does this seem slow to you ?

[Tun_x]

I recently had a chance to shoot through a chrony and was a bit surprised at the results.. The velocity was about a 175fps slower than I expected based on dope ..
Here are the specs on the gun.

Rem SPS V .308
21" cut and re-crowned factory barrel
BC stock
Falcon 4-14 ffp

Load
175 SMK
42.5 Varget
Neck sized 3 times fired BHA brass
Coal 2.83"

Chrony showed 2440fps to 2450fps
60 degrees
4500 ft above sea level
29.97 in
Chrony was placed 10' from muzzle
It seems slow for the dope I dial unfortunately I haven't had the chance to stretch out past 400yds
Dope is as follows
100yds -0-
200yds 1.75 MOA up
300yds 4.75 MOA up

When I put the velocity into JBM nothing matches up!! In order for me to make the dope line up I have to adjust the velocity to about 2625fps
I know that nothing replaces real world data, but would at least like to gain a good starting point for reaching out before I shoot up a bunch of ammo. The load is very accurate in my gun but the chrony leaves me wondering if I should pursue more velocity..

Thanks

Jason

 

[Grump]

Re: Does this seem slow to you ?

Just in case you have the very, very rare scope MOA calibration problem, you might want to double-verify your load's performance by shooting a 300- or 400-yard target AFTER verifying 100-yard zero... on a tall piece of paper...

without any come-up

and get the group center with a target analysis program

and then measure the drop with an accurate ruler. I have a cheap level with a half-"yardstick" on it, but the Chinese goons who made it were OFF by almost exactly 10%. I've marked it lest anyone be led astray by its false doctrine...

That's the realest real-world data I can think of.

For electronics, battery, lighting and jiggle and muzzle blast and shock wave and shadow of the gas cloud at the muzzle and who knows what else can EACH throw the readings off, and having more than one can compound the errors.

 

[Queequeg]

Re: Does this seem slow to you ?

42.5 grains of Varget is a full 2.5 grains lower than what I am running in four .308s, though OAL varies from 2.825 - 2.865 depending on the rifle.

I've only chrono'd the load once but it was right around 2725 fps and that was after finding it dovetailed well with the JBM data I downloaded while guessing at the velocity!

I think you'll find what you are looking for by bumping that load up a couple grains and tweaking from there.

 

[Tun_x]

Re: Does this seem slow to you ?

Thank you for the responses ..I'm still a little hesitant on posting as I don't want to ask the sort of question that generates negative responses. "the stupid question"

I'm going to give both suggestions a shot .


Thanks

Jason

 

[Munimula]

Re: Does this seem slow to you ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tun_x</div><div class="ubbcode-body">Thank you for the responses ..I'm still a little hesitant on posting as I don't want to ask the sort of question that generates negative responses. "the stupid question"

I'm going to give both suggestions a shot .


Thanks

Jason </div></div>

Your initial question had all the data needed and not just a "my guns crooked" or something.

It was well written and thorough. That goes along way around here. So fear no evil, just attempt a search first and you should be good to go with future questions.

 

[strambo]

Re: Does this seem slow to you ?

I like the shoot at 400 yds with 100yd dope and measure to center of group suggestion, takes all the guesswork out.

 

[ubet]

Re: Does this seem slow to you ?

I was shooting 44varget 175smk and getting 2645. If it were me, I would look between 44-44.5 of course all disclaimers apply and assuming you know damn good reloading techniques.

 

[Tun_x]

Re: Does this seem slow to you ?

Ubet,


How long is your barrel?

 

[marduk185]

Re: Does this seem slow to you ?

id be looking into a different chrono

 

[ubet]

Re: Does this seem slow to you ?

Tun, 22"

 

[Grump]

Re: Does this seem slow to you ?

IME, and from mathematical modeling calibrated to actual velocities obtained, I am convinced that no current powders can get you much more than about 2625 fps out of a 22-inch barrel with 175 SMKs.

I have a load at 2580 that seems to be working just fine.