again with the 300g xtpmags

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Re: again with the 300g xtpmags

Postby pitted bore » Mon Aug 18, 2014 12:17 am

Hoot wrote: ... How about you Bob? You've been around the block with the different powders. ...

Hoot-

Have you been lurking in the bushes at my local range? Maybe you have a hidden wireless camera next to my reloading bench?

For the last couple of weeks I've been playing with 300-grain Hornady XTP/Mags, trying them with several appropriate (perhaps) powders. In the next post are some very preliminary results of initial exploration with the 300s. They may have to suffice for a while. I'd like to be consistent with bullet type, and the 300 XTP/Mags are hard to find these days. There is as yet no replication, and the numbers are subject to modification.

Before proceeding to the next post, I'm obligated to post the following:


* * * * Warning * * * * Warning * * * * Warning * * * * Warning * * * *

In this thread are described some handloads for the 450 Bushmaster cartridge that produce pressures well above SAAMI maximum pressures for the cartridge. Use of handloads based on the data below in your own rifle may be dangerous. Attempting to shoot similar loads in your own rifle may damage or destroy your rifle, and may cause severe bodily injury or death to the shooter or bystanders.

Please consider the description of events in this thread as being intended for entertainment purposes only.

I don't know the pressures at which I'm working. I've blown two primers this past week, which wise readers will take as proper evidence that I don't really know what I'm doing.

(Continued in next post.)
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Re: again with the 300g xtpmags

Postby pitted bore » Mon Aug 18, 2014 12:20 am

With 300-grain bullets, I've tried 296, Lil'Gun, and Enforcer, and will start 1680 and 300-MP later this week. The rifle is the Winchester Model 70 (post-64 push-feed) action with the 26-inch barrel. My chrono is placed 10 feet from the muzzle. Primers are Rem 7-1/2s. I have used only a firm taper crimp so far; no side/stab crimp.
Code: Select all
   296              Lil'Gun          Enforcer
grains  fps       grains  fps       grains  fps 
------ ----       ------ ----       ------ ----
  35   1814         37   2085         36   2050   
  36   1999         38   2087         37   2132
  37   1999         39   2139         38   2131
  38   2114         40   2270         39   2229
  39   2111         41   2244         ...
  40   2195         42   2313         45   2434   
  41   2231         43   2345
  42   2266
  43   2336
  44   2314


NOTE: For the Enforcer series, I misread one of my own tables, and skipped the increments above 39 grains, jumping directly to 45 grains. This resulted in a blown primer, with the primer pocket expanded a bit and the primer lying on the magazine follower after the case was ejected. I've read that the pressure needed to produce this effect are in excess of 75,000 psi. Fortunately, my rifle head together. At least I know the top end for that powder. My inference from the incident is that loads with other powders that approach 2400 fps are also on the ragged edge. The 43-grain load of Lil'Gun resulted in stiff opening of the bolt.

I suspect that 1680 and 300-MP, acting as slower powders than 296, Lil'Gun and Enforcer in the 450B cartridge, may allow velocities a bit higher without signs of excess pressure.

It's worthwhile checking on comparable data for these powders in the 460 S&W. That cartridge has about the same case capacity as the 450B, but it can operate safely at much higher, rifle-like pressures. Hornady lists the following as approximately max loads (60K psi?) for the 460 S&W with the 300 XTP/Mag bullet: 296--39.3 grains; Lil'Gun--38.4 grains; Enforcer--37.5 grains. This would indicate that pushing the bullet out of my 26" barrel at more than about 2100 fps is accompanied by pressure exceeding SAAMI max for even the 460 S&W.

(A further note on the subject in the next post. )
- - - - - - - - -
This post was edited on 20 Aug 2014 to correct the data shown for Enforcer powder. The primer-blowing load was 45.0 grains, not 44.0 grains as originally posted.
Last edited by pitted bore on Tue Aug 19, 2014 10:42 pm, edited 1 time in total.
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Re: again with the 300g xtpmags

Postby pitted bore » Mon Aug 18, 2014 12:26 am

Hoot in Penalty Box thread wrote:
... 300gr XTPM 40-42gr 300MP. (latter was real high pressure load) ... fully flattened primers ...

... Even 300gr FTP Mags over 42gr 300MP (2250fps) (Stout but different recoil impulse) ...

... 300gr XTP Mag over 41.5gr 300 MP, 2.08 COL Taper crimp into cannelure .476 ...

Hmmmm!

As a point of information, Alliant's 2013 Reloader's Guide shows the max load of Power Pro 300-MP powder in the 460 S&W cartridge to be 38.0 grains with a 300-grain bullet. Some of the components did differ: case was Federal, primer was Fed 210 Large Rifle, and the bullet was Speer Gold Dot hollow point. Even allowing for these differences, it's almost certain the pressures with the 42 grain load in the 450B were well above SAAMI max for the 450B and likely above the max for the 460 S&W. It's not surprising the primers were flattened.

--Bob
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Re: again with the 300g xtpmags

Postby Hoot » Mon Aug 18, 2014 3:51 am

pitted bore wrote:
Hoot in Penalty Box thread wrote:
... 300gr XTPM 40-42gr 300MP. (latter was real high pressure load) ... fully flattened primers ...

... Even 300gr FTP Mags over 42gr 300MP (2250fps) (Stout but different recoil impulse) ...

... 300gr XTP Mag over 41.5gr 300 MP, 2.08 COL Taper crimp into cannelure .476 ...

Hmmmm!

As a point of information, Alliant's 2013 Reloader's Guide shows the max load of Power Pro 300-MP powder in the 460 S&W cartridge to be 38.0 grains with a 300-grain bullet. Some of the components did differ: case was Federal, primer was Fed 210 Large Rifle, and the bullet was Speer Gold Dot hollow point. Even allowing for these differences, it's almost certain the pressures with the 42 grain load in the 450B were well above SAAMI max for the 450B and likely above the max for the 460 S&W. It's not surprising the primers were flattened.

--Bob


While I may have stumbled upon those "Stout" loads last year when I first ventured into 300 MP, I do not make them a regular diet in my 450b. I resurrected them to see just how much pressure it would take to cycle my "problem child" barrel. I knew my old rig took these without failing, so I filed the recipe away for future use, when I needed some umph. Not that it helped with my problem... :| Another thread, another time.

GL with the 1680. My 450b just could not get it cooking hard enough in 20 inches. I even loaded stab crimped Speer 300gr gold dots into the lands in an attempt to get it cooking. Still wasn't enough. Pleasant powder in terms of recoil impulse though.

Hoot
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Re: again with the 300g xtpmags

Postby BW460 » Mon Aug 18, 2014 3:29 pm

Don't know if I can really add much more to what Hoot and Pitted Bore have said. I don't have a chrony, wish I did. TSD - you asked about crimp and primers. I taper crimped only and used the Remington 7 1/2 primers. I didn't feel that the 39.5 grains of H110 was any more unpleasant in terms of recoil than factory ammo. The brass looked fine and the case heads still measured exactly 0.500 inches. The primers were flattening some. Those are interesting comments about Quickload. For anyone who has ever used it, it is very much a case of garbage in, garbage out. So, as you are aware, you always have to measure your components carefully for the input. With that said, QL predicted my load to be 2183 fps. Interpolating from Pitted Bore's chart above for 39.5 would be 2153 fps. I'm not sure what that means, if anything.

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Re: again with the 300g xtpmags

Postby wildcatter » Mon Aug 18, 2014 7:02 pm

Woody,

Just for grins. H110 and WW-296 are essentially the same powders. In fact, you can trade load data between them.

As the Factory uses WW-297 for our 450b, with is really ww-296 with a flash suppressant in it.

So, your loads are not surprising and it seems you might be doing quite well with them..

..t
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Re: again with the 300g xtpmags

Postby Texas Sheepdawg » Mon Aug 18, 2014 10:45 pm

I just want to say......
I love this forum. :mrgreen:
-Texas Sheepdawg

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