strange chrono data

Northwest Cajun · October 23, 2002, 05:40 PM

Hi Gyus,
I just got back from the range and I'm a little confused.

Here's my story;
I'm loading for .45-70 two different loads one is a Plated 350 and the other is the Rem 405. Both using almost the same ammount of Varget with the same primers. The 350's are getting 55.0 and the 405's are getting 55.8. I'm using a Marlin Guide Gun.
Now for the confusing part, Which one do you think will be going faster........... Well the 405's clock 1630 FPS and the 350's are only going just under 1500!!!

I would think the lighter bullet would go faster, even though the heaver bullet has .8 gr more powder.
Both are very accurate and I can stay on a 3"x5" target out to 200 yds with my Wild West open sights....yes 200yds!

Can someone explain PLEASE

Thanks

Cajun

stans · October 23, 2002, 06:07 PM

I'll take a stab at this one. The 405 grain bullet is probably a lot longer than the 350 grain bullet, but both are probably loaded to the same OAL. This means that the round with the 405 grain bullet has less case capacity under the bullet, this raises pressures, thus increasing the velocity of the heavier round.

C.R.Sam · October 23, 2002, 08:38 PM

Stans succint stab sounds sufficient to explain the difference.

Sam

**Mal H** · October 23, 2002, 08:43 PM

I believe stans is on the right track with his pressure observation. In general lighter bullets will require more powder than heavier bullets in the same caliber to reach the same velocity. The lighter ones get going sooner (less inertia and possibly less friction) so the pressure can't build to the same levels as it does with heavier bullets when using the same amount of powder. Less pressure = lower velocity.

Northwest Cajun · October 23, 2002, 10:29 PM

Thanks guys for the explination. I understant it now.
I'll be using the plated bullets for deer and the jacketed for Elk.
The deer are only 150-175Lbs on the hoof and a 350 gr soft lead slug shouldnt need to go that fast to knock one over.

Cajun

October 23, 2002, 05:40 PM	#1
Northwest Cajun Senior Member Join Date: December 26, 1999 Location: Spanaway Wa. &Lafayette La,(Cajun Country) Posts: 189	strange chrono data Hi Gyus, I just got back from the range and I'm a little confused. Here's my story; I'm loading for .45-70 two different loads one is a Plated 350 and the other is the Rem 405. Both using almost the same ammount of Varget with the same primers. The 350's are getting 55.0 and the 405's are getting 55.8. I'm using a Marlin Guide Gun. Now for the confusing part, Which one do you think will be going faster........... Well the 405's clock 1630 FPS and the 350's are only going just under 1500!!! I would think the lighter bullet would go faster, even though the heaver bullet has .8 gr more powder. Both are very accurate and I can stay on a 3"x5" target out to 200 yds with my Wild West open sights....yes 200yds! Can someone explain PLEASE Thanks Cajun __________________ Laizzes Les Bon Temps Rouler!

October 23, 2002, 10:29 PM	#5
Northwest Cajun Senior Member Join Date: December 26, 1999 Location: Spanaway Wa. &Lafayette La,(Cajun Country) Posts: 189	Thanks guys for the explination. I understant it now. I'll be using the plated bullets for deer and the jacketed for Elk. The deer are only 150-175Lbs on the hoof and a 350 gr soft lead slug shouldnt need to go that fast to knock one over. Cajun __________________ Laizzes Les Bon Temps Rouler!

October 23, 2002, 06:07 PM	#2
stans Senior Member Join Date: November 9, 2001 Location: Virginia, USA Posts: 838	I'll take a stab at this one. The 405 grain bullet is probably a lot longer than the 350 grain bullet, but both are probably loaded to the same OAL. This means that the round with the 405 grain bullet has less case capacity under the bullet, this raises pressures, thus increasing the velocity of the heavier round.

October 23, 2002, 08:38 PM	#3
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Stans succint stab sounds sufficient to explain the difference. Sam

October 23, 2002, 08:43 PM	#4
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,955	I believe stans is on the right track with his pressure observation. In general lighter bullets will require more powder than heavier bullets in the same caliber to reach the same velocity. The lighter ones get going sooner (less inertia and possibly less friction) so the pressure can't build to the same levels as it does with heavier bullets when using the same amount of powder. Less pressure = lower velocity.