Barnes 200gr XPB and 275gr TSX

Talk about your 450b reloading experience, ask questions, etc...

Moderator: MudBug

Forum rules
Please try and keep it safe!

This information is the responsibility of the community, not the forum. 450bushmaster.net is not responsible if you blow yourselves up.

Re: Barnes 200gr XPB and 275gr TSX

Postby Bmt85 » Sun Sep 24, 2017 2:25 pm

Bolt thrust calculations only looks at inner case head diameter and pressure. It doesn't take into account rim diameter, case taper, dry or oiled chamber, body taper, shoulder angle, etc. Its a quick and dirty way to get a comparison. If it was the end all, be all, number, a lot of us would be breaking bolts all the time.

As to chamber friction, your correct on pressure effecting it, however, you also have surface area to consider. 450 has a lot more surface area to grab with than 5.56.

I'm not trying to argue or push you, just trying to point out a few things. If you feel you have to stay at/under 40K psi, that is your choice. You will still have a potent hunting round, and as long as your having fun, who cares.
Bmt85
 
Posts: 701
Joined: Wed May 18, 2016 11:13 am
Location: S.E. Michigan

Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Sun Sep 24, 2017 6:33 pm

There are certainly many nuance to calculating real world bolt thrust compared to the simplified calculation, but most of those nuances are second order at best, pressure times area is the first order factor.

When you look at the quick and dirty calculation (max chamber pressure times case-head or chamber area) for bolt thrust you end up with 450 BM being very similar to 556. I suspect this was a driving reason Bushmaster/Hornady set the SAAMI MAP to 38,500 psi when they created the new cartridge. This is much lower than its progenitor 450 Professional. I also suspect this is why the 30 RAR uses an AR-10 size bolt and barrel extension with its MAP of 55,000 psi. Now if you go and run your 450 BM up to 45,000 or 50,000 psi suddenly your putting loads on the bolt that are comparable to or greater than the thrust of 556 proof loads (125% or 62,366psi) put on that bolt. The lugs are at best equal to 556 lugs in strength and very likely weaker due to the larger case-head recess cut into the bolt.

It seems prudent to watch how much you over pressure 450 BM in an AR. In a bolt gun with a action that is designed to take bolt thrusts from other high pressure large case head cartridge I would think running 450 BM up to 50,000+ psi would be no problem. In an AR though the bolt is the weak link and must be considered.

I love the discussion; push, pull, and discuss this with me all you want, I don't mind. And yes my more conservative Barnes 275gr @1923fps are going to be joy to hunt deer with this year. :D
User avatar
mcb
 
Posts: 70
Joined: Fri Apr 07, 2017 10:22 pm

Re: Barnes 200gr XPB and 275gr TSX

Postby Al in Mi » Mon Sep 25, 2017 4:03 am

Texas Sheepdawg wrote:
4C1EDF7C-FC36-4605-AF6D-DC9446581D8F.jpeg

This is for my bolt action and single shot. 40.0 grains of 1680 Barnes 275 XPB
2.272”. (Would never fit an AR Mag).
I have yet to test them over a Chrony but I fired one and when it hit the steel plate at 50 yards it sounded like someone hit it with a baseball bat. BOOONNNNGG!!


Dawg, for my 700 and #1, I've seated those 275's at 2.400 OAL. and 10gr more 1680 with no problems. 300MP has really been shining with those 275's too, no chrono data on either yet but soon.

Image
User avatar
Al in Mi
 
Posts: 1982
Joined: Sat Jun 20, 2009 8:24 am

Re: Barnes 200gr XPB and 275gr TSX

Postby mcb » Mon Sep 25, 2017 7:18 am

You guys need to post some chrono data. I am curious how 1680 works with the 275gr bullet.
User avatar
mcb
 
Posts: 70
Joined: Fri Apr 07, 2017 10:22 pm

Re: Barnes 200gr XPB and 275gr TSX

Postby Texas Sheepdawg » Tue Sep 26, 2017 10:17 am

mcb wrote:You guys need to post some chrono data. I am curious how 1680 works with the 275gr bullet.

I Know.... dang. I’ve got loads piling up for testing.
-Texas Sheepdawg

http://youtube.com/c/TexasSheepdawg21
NRA Life Member
User avatar
Texas Sheepdawg
 
Posts: 4731
Joined: Fri Nov 05, 2010 10:55 am
Location: North Texas

Re: Barnes 200gr XPB and 275gr TSX

Postby Al in Mi » Tue Sep 26, 2017 1:38 pm

once these 90*+ days get out of here, I plan to. Hopefully this weekend
User avatar
Al in Mi
 
Posts: 1982
Joined: Sat Jun 20, 2009 8:24 am

Re: Barnes 200gr XPB and 275gr TSX

Postby plant_one » Tue Sep 26, 2017 10:01 pm

1680 should do well with those. it tends to gets real happy with nice full cases under heavy projo's as a general rule
User avatar
plant_one
 
Posts: 1109
Joined: Sat Mar 19, 2016 8:58 pm
Location: Oakland County, MI

Re: Barnes 200gr XPB and 275gr TSX

Postby Gifters » Tue Dec 04, 2018 12:19 pm

I'd be interested in trying 275gr but my 200 grain loads I'm getting 2600fps with the lil gun 43.5 and CCI #41. Out of an 18" AR barrel. CHG isn't above .50000 on any of my previously once fired Hornady brass. For me to switch to 275's if I could get 2400 FPS safely. I don't think that will happen. But still for expansion, its hard to make them more than 150 yard gun if they're not opening up at 1700 fps
Gifters
 
Posts: 17
Joined: Wed Aug 02, 2017 7:11 am

Re: Barnes 200gr XPB and 275gr TSX

Postby Gifters » Tue Dec 04, 2018 12:40 pm

I'd like to see Barnes come out with a 450 TTSX bullet based off the 250 Grain Spitfire TMZ. All the sudden you have a 400 yard gun. If I could get 2450 fps out of that with a .210 BC and expansion down to 1050fps.

My 10ml2 used to scream those out, I'm sure it lost its petals but still turned lungs into soup.

All you need is a couple driving bands on that.
Gifters
 
Posts: 17
Joined: Wed Aug 02, 2017 7:11 am

Re: Barnes 200gr XPB and 275gr TSX

Postby Hoot » Tue Dec 04, 2018 1:05 pm

Gifters wrote:I'd be interested in trying 275gr but my 200 grain loads I'm getting 2600fps with the lil gun 43.5 and CCI #41. Out of an 18" AR barrel. CHG isn't above .50000 on any of my previously once fired Hornady brass. For me to switch to 275's if I could get 2400 FPS safely. I don't think that will happen. But still for expansion, its hard to make them more than 150 yard gun if they're not opening up at 1700 fps


Bmt85 wrote: Excerpt from a different, recent thread: The 275’s have lower velocity thresholds. The 275 XPB have a minimum of 1400 FPS and the TSX have a minimum of 1200fps. The 200 XPB is rated for 1800fps. They also hold up very well on game when being pushed past normal 450B velocities.


My assumption that the 275 and 200 bullets XPB had the same expansion behavior was based upon how they looked externally. I never did a cross sectional comparison. Apparently, that 7 year old assumption was wrong. I should have checked with Barnes before assuming. Given the 275's expand at a lower velocity, you should be able to take them out further than the 200's and still get expansion.

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
User avatar
Hoot
 
Posts: 5083
Joined: Tue Feb 09, 2010 9:34 am
Location: Minnesota

PreviousNext

Return to Reloading for the 450b

Who is online

Users browsing this forum: No registered users and 21 guests