178 Amax 45gr Varget only 2550 fps?

[Cory Lee]

I just started reloading.

Hodgdon's data shows 45gr Varget and 178 Amax should be between 2661 and 2690 fps.


Remington 700 VTR .308win

178 Amax .005 off the lands
45gr Varget
Winchester Brass resized to -.003
CCI Standard Primers
22" Barrel
2550 FPS

No pressure signs but I haven't exceeded max load.

44.6gr was at 2535 fps

I'm using a Competition Electronics ProChrono Digital Chronograph at 10' to get Velocity. Iphone Ballistic App was right on at 420 and 530 yards. This is my 530 yard target 5 shot group. Its a 12" by 18" target.

Any ideas why my velocity isn't up? Or is this normal?

 

[roggom]

Re: 178 Amax 45gr Varget only 2550 fps?

Looking at my Hodgdons manuals, they have that load listed for the 175 SMK, although with the heavier bullet I would think the velocity would be higher. Though the test rifle was a 24" bbl, so you will lose about 20 fps/in. Are you shooting moly coated a-max?

 

[5RWannabe]

Re: 178 Amax 45gr Varget only 2550 fps?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cory Lee</div><div class="ubbcode-body">I just started reloading.

Hodgdon's data shows 45gr Varget and 178 Amax should be between 2661 and 2690 fps.


Remington 700 VTR

178 Amax .005 off the lands
45gr Varget
Winchester Brass resized to -.003
CCI Standard Primers
22" Barrel
2550 FPS


Any ideas why my velocity isn't up? Or is this normal?


</div></div>




The anwser lies in your own data. your not taking into consideration the pressure lost by seating the bullet long. .015 off the lands is quite alot away from where hogdon pressure tested its rounds.. the test data will show probally a COAL of 2.775 or 2.800, what im guessing you have something like 2.9xx for a remmy chamber.

this shows you that by seating a bullet long, you have more room in the case for powder (thus reducing pressure), this is why people that sit so close to the lands usually have a higher powder load than others.

 

[Niles Coyote]

Re: 178 Amax 45gr Varget only 2550 fps?

About two months ago I decided to find out what 6" of barrel length would yield with identical loads fired in both of my Remington’s, one 20" tactical and one 26" varmint. Here is what I found, FWIW...



Remington SPS Tatical20"
175smk 44.5 varget load @ 2.825oal = 2550fps
155 lapua scenar varget 46.7 load @ 2.825 = 2750fps

Remington Varmint 26" same loads as above.
175 = 2645
155 = 2850

So in my rifles you gain 100 fps +/- a couple from those extra 6"

I have a theory, I believe it is the barrel quality but more so the large chamber remington uses. I have a rock creek barreled 308 with a match chamber that is 21" and with the above loads I get 2650-2670 on the 175 and 2850-2865 with the 155.

Also I have found that a bullet that has more jump to the lands tends to run a little faster... if your bullet will handle more jump.

 

[5RWannabe]

Re: 178 Amax 45gr Varget only 2550 fps?

on average you gain or loose about 20 fps per inch of barrel length. with the standard being 24 inches. now there are makers like tack ops and gap, whose shorter barrels will not loose so much velocity at shorter lengths, i assume its because of tighter tolerances all the way around.

 

[5RWannabe]

Re: 178 Amax 45gr Varget only 2550 fps?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body">

Also I have found that a bullet that has more jump to the lands tends to run a little faster... if your bullet will handle more jump.

</div></div>

with all things being equal wouldn't this be due to a higher pressure in the cartage because of less internal volume.(because you seated the bullet into the case further)

 

[mwroseberry]

Re: 178 Amax 45gr Varget only 2550 fps?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Whisky Shot</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body">

Also I have found that a bullet that has more jump to the lands tends to run a little faster... if your bullet will handle more jump.

</div></div>

with all things being equal wouldn't this be due to a higher pressure in the cartage because of less internal volume.(because you seated the bullet into the case further) </div></div>

On my 7mm-08 I wanted to test the new 162BTHP vs my 162 A-max. Thinking the bullet was the exact same Ogive I left my press the same for my rounds on the amax (OAL 2.904). To my supprise when I removed the BTHP the OAL was 2.870. Since it's only a slight jam over the what length my reloading books are giving me and it's still .02" off the lands I decided to test it. With the exact same powder, primer, brass set up and loads I yielded 2700FPS with the longer seated A-max and 2775 with the BTHP. Both bullets have the same OAL lenght so less case capacity with the same amount of powder equals more speed. Result Push your load until you start getting a sticky bolt, ejector marks or popped primers then back it down until you find it's next accuracy node and load it up.

Good luck,
Merritt

 

[BCP]

Re: 178 Amax 45gr Varget only 2550 fps?

I've never found seating them out farther to give more velocity. Try it at 2.8.

 

[roggom]

Re: 178 Amax 45gr Varget only 2550 fps?

Niles, Thanks for the info. I am running the same 308's an SPS-V and SPS-T and was curious of the difference in velocity that 6" makes.

OP: nice grouping btw

 

[Cory Lee]

Re: 178 Amax 45gr Varget only 2550 fps?

Thanks for all the replies.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: roggom</div><div class="ubbcode-body">Looking at my Hodgdons manuals, they have that load listed for the 175 SMK, although with the heavier bullet I would think the velocity would be higher. Though the test rifle was a 24" bbl, so you will lose about 20 fps/in. Are you shooting moly coated a-max?</div></div>

Ya I looked at the 175 and the 180 grain projectiles and thought it should be somwhere between the two. 2660-2691 fps. Even losing 20fps/in I thought I'd still be around 2620-2650 fps. I'm not using Moly Coated


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Whiskey Shot</div><div class="ubbcode-body"> anwser lies in your own data. your not taking into consideration the pressure lost by seating the bullet long. .015 off the lands is quite alot away from where hogdon pressure tested its rounds.. the test data will show probally a COAL of 2.775 or 2.800, what im guessing you have something like 2.9xx for a remmy chamber. </div></div>

I'm not sure what my coal is but I'm loading 2.322" to the ogive to get -.005 from the lands. I also measured my chamber with the Sinclair chamber gauge and found it was 2.056"


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">I've never found seating them out farther to give more velocity. Try it at 2.8.</div></div>

Everything I've read is that the AMAX likes to be seated just off the lands. -.005 - -.020. I could be wrong on this.


I think I will slowly go up in powder by .1/.2 grain increments until I see pressure signs.