Author Topic: 45-70 32" barrel actual speed? (Read 498 times)

mattparliament · « **on:** August 17, 2005, 10:37:38 AM »

Hello all. I've been loading for my 45-70 with the 32" BC barrel. I've been using 60gr of H4198 with 300gr Hornady hollow points which is top load according to the Hodgdon manual for the Marlin guns, observe, it is the load on the bottom of the left column, not the circled one. Sorry about the size, you may have to zoom in a bit on the pic to read it:

This load is stout but I like it. Shoots 1.25" groups at 100 yards and does a number on bowling balls! I have the barrel on my 270 action with the synthetic stock with a sock full of 8 shot in it, works great for dampening recoil. Only a big "push" not a sharp crack like necked-down cartridges. My question is this: what would the expected increase in velocity be due to the 32" barrel? I know that Tim has been working with 4198 and getting "diminishing returns". I have read on other forums that a 150-200 fps gain can be expected. What are some of the experiences here? According to the pic on this post this load measured 2424fps from a 24" barrel. Any input fellas or should I just go drop the cash and get a chrony?

quickdtoo · « **Reply #1 on:** August 17, 2005, 10:50:18 AM »

I think the H4198 burns too fast for the 32" barrel, I only get around 2450fps in the BC, get just over 2400fps in the 22" Handi barrel with 56.2grs shooting the 300gr Nosler partition. H4895 is going to be my powder of choice to attempt at better use of the 32" barrel, it's a fair bit slower burning and I prefer to stay with the extreme powders for consistency within temperature changes.

http://www.reloadbench.com/burn.html

Matt, how much case growth are you getting with the 60gr loads? I'm getting about .010" using the remington nickel cases.

Thanks

mattparliament · « **Reply #2 on:** August 17, 2005, 11:07:21 AM »

Tim~

I also use remington nickel brass though I don't measure them pre and post firing. I can say that there aren't any noticable pressure signs.

quickdtoo · « **Reply #3 on:** August 17, 2005, 11:15:40 AM »

Matt,

Straight wall cases don't show pressure signs like a bottleneck case will, measuring the case after full length resizing is the only way to check to see how much growth there is. That and checking for case head separation with the bent wire which shouldn't show up for a few firings.

mattparliament · « **Reply #4 on:** August 17, 2005, 11:24:25 AM »

Tim, I actually did the bent wire trick with no abnormalaties detected.

Longcruise · « **Reply #5 on:** August 17, 2005, 01:14:06 PM »

Quote

Any input fellas or should I just go drop the cash and get a chrony?

Get the chrony. It's like giving a reloading manual a shot of sodium Pentathol!

quickdtoo · « **Reply #6 on:** August 17, 2005, 01:21:48 PM »

LC is 100% right on with that suggestion, I haven't used my chrony much, but it sure seems to be an invaluable aid....you don't have to spend an arm and a leg to get one that is serviceable, the F-1 Shooting Chrony can be had for $50-$80, I have a Master that has the remote display, that and pencil and paper is all ya need!! If ya got good eyes, you don't even need the remote display!!!! :-D

handirifle · « **Reply #7 on:** August 17, 2005, 03:52:38 PM »

Get one, otherwise you don't know the whole story. I had some 243 loads that were actually giving me a spread of less than 10fps for 10 shots. Never would have known otherwise.

Mac11700 · « **Reply #8 on:** August 17, 2005, 07:19:58 PM »

I've had both the original Chrony...with the paper sky screens...and my new Beta master with the remote...it is nice just to look down at the bench and get all the data...I say...spend a-little more...you'll be glad you did...

Mac