24hourcampfire.com
24hourcampfire.com
Previous Thread
Next Thread
Print Thread
Hop To
Page 3 of 3 1 2 3
Joined: Jul 2001
Posts: 59,910
M
Campfire Kahuna
Offline
Campfire Kahuna
M
Joined: Jul 2001
Posts: 59,910
Tejano,

The pressure results I've seen indicate pressures start rising when rifle bullets are seated pretty deeply, close to 1/2" deeper than out to the lands, or maximum magazine length. Probably that's when powder compression starts to play a role, but also probably varies with the type of powder, primer, etc. I can't even remember ever seating rifle bullets as much as 1/4" shorter than normal, so I've never found any need to reduce the powder charge.

Quite often velocities drop measureably as bullets are seated farther off the lands, though not always, especially when bullets are seated only a little deeper. This also depends on the particular bullet, powder, primer etc.

Crimping may have some effect, but I've never seen enough difference in velocity to assume it does. But I don't crimp rifle bullets very often, even in some cartridges where many handloaders assume it's necessary. Consistent neck tension on the bullet normally has more effect on both accuracy and pressure than crimping.


“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
BP-B2

Joined: May 2005
Posts: 7,046
A
Campfire Tracker
Offline
Campfire Tracker
A
Joined: May 2005
Posts: 7,046
MD,
Excellent point about crimping.
I have gone through stages where I have tossed dies that did not size cases enough to those that over sized in order to obtain a consistent hold on the bullet to the point that I have never crimped a .460 Weatherby load, even when using up to 550gn and 600gn bullet at full velocity in generating 8000FPE.

By contrast, I have however, crimped "some" .458 Winchester and .45/70 loads, but it was for assumed assurance, rather than need.

John


When truth is ignored, it does not change an untruth from remaining a lie.
Joined: Jun 2007
Posts: 7,854
Campfire Outfitter
Offline
Campfire Outfitter
Joined: Jun 2007
Posts: 7,854
Originally Posted by TooDogs
I look forward to that article too JB.

Currently working with a 7x57, economy A&B 21" bbl ( I was gifted several vz-24 recievers, A&B bbls in various chamberings, reamers, go/nogo gages, Timney triggers, sporter stocks, & so forth). Dyna coated the bore due to the A&B bore is very prone to copper foul.

Anyhow, worked w/ Hornady 139 IL & Nosler 150 BT. Goal is to get some background w/ Nosler BT, then work with 150 Nosler Accubonds for the final load.

Seated the Hornady to 3" oal, per Hornady book. I did the slit case neck, start bullet, push case in chamber until case shoulder butts chamber shoulder. OAL =3.080". Hornady 139IL jump is ~0.080". 2700 fps per crono, makes 1 3/4" @ 100.

Nosler 150 BT seated to 3.070" (SAMII max is 3.065" per Nosler book). I did the slit case neck, start bullet, push case in chamber until case shoulder butts chamber shoulder. OAL =3.150".

I conclude that the Nosler 150 BT is jumping ~0.080". This shoots ~1.00-1.25" @ 100 yard. W/49gr IMR 4350 makes 2815 fps per crono.

Intuition tells me to jump the Nosler BT a bit less, say 0.050" using same powder weight. Given I'm working with an A&B barrel, could be that 1" 3-5 shot groups could be all I can expect.

I've always approached seating depth (bullet jump) as trial & error. I'll say it again, looking forward to that article JB.

Pat


Seating depth experiments using new, unfired Remington case. Seating depth test where 0.050", 0.035", 0.020" cartridges assembled.

Determined the 150 BT is best with 0.020" bullet jump. Makes ~0.63" groups @ 100 yards.

Tried the Hornady 139 IL with 0.040" jump. Groups opened to ~2.50" at 100 yards (was 1.75" w/0.080" jump). Could be a powder thing with the 139, using IMR 4064. Need to work with IMR 4350 with this boolit. Maybe the Hornady likes to jump that 0.080", and that's why Hornady book suggests an OAL of 3.00".

Using once fired cases where shoulder is bumped back from chamber shoulder to allow 0.0015 headspace will tighten groups more.

Been my experience oversized cases ( where shoulder is bumped back excessively), or where successive neck size only results in case shoulder bumping chamber shoulder opens groups. My experience with what I described was from experimenting with a 95 Palma chambered f-class 308 rifle. This has translated to other rifles I work with.

Last edited by TooDogs; 11/18/17. Reason: added words

GOA
Joined: Oct 2006
Posts: 21,959
Campfire Ranger
Offline
Campfire Ranger
Joined: Oct 2006
Posts: 21,959
Originally Posted by Mule Deer
If anybody wants to keep it really simple (which is the primary reason any shooter looks for simple solutions on the Internet), start with the bullet seated as far out as possible, whether limited by the magazine or chamber throat. Then if the accuracy isn't all you expect, seat 'em deeper and see what happens. Unless rifle bullets are seated REALLY deeply (which isn't what occurs most of the time), then pressures are lower with deeper seating.

The article will go into a little more, uh, depth.

That's very helpful. Seating depth has always seemed like voodoo to me. I usually load to SAAMI specs and call it good. However, I've always known that I was "leaving something on the table" so to speak, by not learning more about the theory and practice of varying seating depth for optimal accuracy.
Looking forward to seeing your article.

Last edited by 340boy; 11/18/17.

"For joy of knowing what may not be known we take the golden road to Samarkand."
James Elroy Flecker







Page 3 of 3 1 2 3

Moderated by  RickBin 

Link Copied to Clipboard
YB23

Who's Online Now
325 members (280shooter, 204guy, 29aholic, 10gaugemag, 1beaver_shooter, 16penny, 43 invisible), 2,196 guests, and 1,059 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums81
Topics1,187,724
Posts18,400,607
Members73,822
Most Online11,491
Jul 7th, 2023


 







Fish & Game Departments | Solunar Tables | Mission Statement | Privacy Policy | Contact Us | DMCA
Hunting | Fishing | Camping | Backpacking | Reloading | Campfire Forums | Gear Shop
Copyright © 2000-2024 24hourcampfire.com, Inc. All Rights Reserved.
Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.3.33 Page Time: 0.083s Queries: 14 (0.005s) Memory: 0.8226 MB (Peak: 0.8734 MB) Data Comp: Zlib Server Time: 2024-03-29 05:08:53 UTC
Valid HTML 5 and Valid CSS