does this sound right?

[ubet]

5r, 308win. Temp 57 humidity 71.2 baro 29.18 ammo new win case, br2, ol 2.255 175smk 44.3 varget. I shot at some random, lased, distances to try to get my velocity and came up with 2605, is that to slow, does that sound about right to you guys? What are you pushing your 175s at?

 

[Lindy]

Re: does this sound right?

That's a reasonable velocity with that load. BTW, muzzle velocity does not change with either humidity or barometric pressure. It is strictly a function of temperature.

 

[ubet]

Re: does this sound right?

Ok, thanks for the tip. Should I up the charge a little, ballastics program says it'll just barely make it passed 1k.

 

[vman]

Re: does this sound right?

If you arent seeing any pressure signs (hard bolt lift, ejector marks, flattened primers) I would go a little higher with the varget.

I tested some loads yesterday, using 175smk and varget and provided the chrony was reading correctly, these are the figure I was getting.

Temp was 77 Degrees F.

42.9 - 2585 FPS
43.5 - 2618
44.1 - 2671
44.7 - 2722
45.0 - 2726
45.3 - 2738

From those figure, Im seeing very little MV spread between 44.7 to 45.3gr of varget. I will further my research within this area.

No pressure signs at any of those loads.

 

[Hummer]

Re: does this sound right?

Be aware that just because one barrel of a given length shoots at a certain velocity doesn't mean another will as there are big variations in barrels from the same manufacturer.

For instance I got two barrels from a vendor and chambered them both same day with same reamer to same headspace(snug on GO Gage) and ran an erosion gage in to record new throat spacing and one barrel went over a ring further in than the other. Rings are spaced about .100 apart on erosion gages and a bigger land diameter will allow a gage to go further in.

You might consider doing a ladder test to see what load your rifle actually likes because pedal to the metal velocity does not necessarily correlate to smallest group sizes.

I had rather have a 1/2MOA rifle shooting 2480 than a 1 MOA rifle shooting 2600. As well your barrel will last longer with a slower velocity load.

For instance I have a friend who got a Rem 700 Police Sniper and he shot it every evening six days a week 20-40 rounds at 600 yards with another friend who shot same schedule. My other friend has a Iron Brigade Armory built rifle.
The guy with the Police Sniper brought it to me and said it was shot out and only had 500 rounds on it so I pulled the barrel, cut the threads off and rechamberd with a short throat 308 reamer I have. Barrel went right back to shooting just fine and this time he made it to 1100 rounds before it went down and he ordered another barrel and brought it to me to put on for him.

I have a gunsmith friend up north who told me he had seen similar on three of them.

The other guys Iron Brigade rifle? Still shooting well at 10,000 rds +.

 

[81sfo]

Re: does this sound right?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ubet</div><div class="ubbcode-body">5r, 308win. Temp 57 humidity 71.2 baro 29.18 ammo new win case, br2, ol 2.255 175smk 44.3 varget. I shot at some random, lased, distances to try to get my velocity and came up with 2605, is that to slow, does that sound about right to you guys? What are you pushing your 175s at? </div></div>
That sound right to me. Im using exact same load for my M40a1 24" rock 5r 1-12 twist ,getting the same speed as you are. My scope is an Mst-100 which is meant to be used with the 175 s in the low 2600fps range.So yes your speeds seem right.Keep in mind Some barrels are faster than others ,some are more accurate than others aswell.Good luck.

 

[ubet]

Re: does this sound right?

Barrel length is 22". Its shooting around half moa right now. So that I didnt want to change it. I ran some numbers through my ballastics program, the atmospheric conditions I was shooting in, I would have to get it up to 2750 to just get it to 1100. So I am happy, as long as this load will consistently hold together 600yds+. I am not having any pressure signs as of right now.