Author Topic: .45-70 Throater Test (Read 974 times)

Leftoverdj · « **on:** April 08, 2004, 06:51:06 AM »

Sorry about this being upside down, but I marked the target before I realized that the server logo would cover one of the holes right side up. Three five shot groups can't really prove anything, but they are some indication. I think I pulled the lowest shot (highest shot in that upside down picture) in the first "after" group.

Load was Remington cases, Win LR primers, 27.0 grains 5744, and Lee 459-405-HB as cast and Liquid Aloxed. I'll be doing some more shooting and posting before I start sending the throater out.

Deadeye47 · « **Reply #1 on:** April 08, 2004, 07:45:05 AM »

Good thing I got a laptop...that wasn't so bad but I feel for the guys that have desk tops..they could get light headed standing on a chair looking thru their legs and fall off....

Were those shot at 100 yds??? Looking good!

Haywire Haywood · « **Reply #2 on:** April 08, 2004, 10:51:50 AM »

This is kinda off topic but related. If you post your pictures at Hunt101.com, their logo is much less intrusive.

Ian

Leftoverdj · « **Reply #3 on:** April 09, 2004, 06:47:39 AM »

I'm satisfied. For me, anyway, doing the 1.5 degree throat seemed to help a little with average loads and more than a little with the loads that were already good.

Cottonwood · « **Reply #4 on:** April 09, 2004, 07:06:59 AM »

Just curious, what was the yardage to the target. I haven't throated my 45-70 barrel and am already having groups like this at 100 yards.

Leftoverdj · « **Reply #5 on:** April 09, 2004, 07:34:28 AM »

Only 50 yards, Montanan. That's all the range I have handy.

I labelled the target, but the font was too small. Still getting the hang of doing that.

Could easily be that you shoot better than me or are better at casting bullets or got a rifle that likes your bullets. All I know is that I am jumping up and down at getting one hole fifty yard groups out of my .45-70.

Cottonwood · « **Reply #6 on:** April 09, 2004, 08:31:53 AM »

Yes you did well with that group. I did forget to ask, is your rifle topped with a scope or are you using iron sights?

For ranges that we use for hunting, about 50 yards is max anyway. I hunt in thick woods most of time and your lucky to get 50 yards. Most of the time it is much, much less and not much more than 20 yards.

The most important shot is from that cold barrel on a good morning hunting what game it is we are seeking.

Leftoverdj · « **Reply #7 on:** April 09, 2004, 10:56:48 AM »

I got a 4x scope on it. My eyes won't do open irons, any more and peeps are getting iffy. That last load shoots groups close to that pretty consistently. I'm not a hunter so I don't need to worry about the cold barrel problem, but the first shot seems to be to POI if the barrel is seasoned with the same lube.

Main problem I am running into is that accuracy falls off rapidly as velocity rises. 1100 fps will do for my purposes, but I'm still looking for higher.

mag41vance · « **Reply #8 on:** April 09, 2004, 02:28:05 PM »

That 45-70 is talkin now! Good shootin dj!

That 30-06 info you sent didn't tranfer very well. Sorry to put you to all that trouble. I just get it later when I can copy it.
Thanks for the try,
vANCe

PS: 5 shot = 1.301" with the max today

Speer 158gr Sil-FMJ over 21.5 grains of H4227 cci srp
The 296 was 1.55" with 24.5 gr.
The lighter bullet did better than I thought.

Those Speer bullets vary quite a bit in weight. :x

handirifle · « **Reply #9 on:** April 09, 2004, 10:03:57 PM »

leftover
I think it is the type of rifling in the 45-70 barrels that limit the cast velocity/accuracy on these rifles. From the Marlin Big Bore forum of old, their rifles with deeper grooves seemed to not be bothered by higher velocities.

That was sure the case with my BC

Sky C. · « **Reply #10 on:** April 10, 2004, 10:40:15 AM »

leftoverdj-

The current groups look good... but how do they compare to the before groups? Any adjustments to loading, seating depth, etc. required.

Thanks for posting!

Best regards-

Sky C.

Leftoverdj · « **Reply #11 on:** April 10, 2004, 12:08:09 PM »

Sky, I was not as scientific as I would have liked to have been, but that would have required over a thousand shots. As it was, I have shot over a hundred. My sense is that the throating slightly helps marginal loads. It seems to reduce 1.5"-2" loads by a quarter inch. You get another slight improvement when you seat the bullets out slightly to engage the new throat. In my case, this is just over the width of the crimp groove.

I did increase the charge a half grain when I seated the bullet out. I am not sure if this helped or not, or if it was even meaningful since I was using metered Unique charges.

The big barrier, to which throating is nearly irrelevant. is that I can only get microgroove barrels to shoot accurately with plain base bullets at a very limited pressure/velocity level. Loads that had been shooting quite well for me at 30 degrees opened by at least half at 70 degrees. These loads had been 1250-1300fps in the colder weather. That seems to be around the accuracy barrier for PB bullets in microgroove barrels.

See my upcoming post on JPH45's Bullets for more speculation on microgroove.