More range testing with 338 Allen Magnum XHS rifle....

[Aragorn50]

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Kirby,

Thanks for the insight, I'll try to remember that before I post in the future.

On the subject of barrel life, and maybe you've addressed this in the past, have you found that sherical double-based (hotter but less abrasive) or extruded (cooler but more abrasive) powders effect throat erosion to a greater degree? In other words, does one erode the throat faster than the other?

Festus

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Festus,

I was always of the understanding that Ball powders were "cooler" burning and that extruded powders tended to burn "hotter." The military tends to spec extruded powders for tracer rounds for this reason. W872 tends to burn "dirtier" as it has a higher graphite content. Any other info on this?

Kirby- The next issue of the VHP will have 3 separate tests of the US869, which demonstrates that it is also temperature sensitive in the BMG case as well. In the BMG loads were running similar to VV20N29, which is slower than the H50BMG. Difference of case volume and bore diameter I guess.

Scott Nye

 

[Fiftydriver]

Scott,

Good to see you on LRH!!! I tested US869 in my 510 Allen Magnum and I believe Kieth Pagel did an article for the upcoming VHP about this wildcat and also my 50 Allen Tactical as well for those not interested in an improved 50 BMG style round.

I tested WC872, US869, H-50BMG and VV 20N29 in my 510 AM and found that all worked very well in this chambering which has roughly 30 grains more usible powder capacity then the standard 50 BMG.

All powders worked much more consistantly with the heavy bullets then the standard 750 gr A-Max at least from a velocity consistancy stand point.

You are correct that WC872 has a very high graphite content compared to other ball powders. IF you do not run it to its upper end pressure ranges, it burns very dirty. It works well in the BMG and 510 AM but again, you can not get working pressures up high enough for it to burn cleanly, well, as clean as it will burn anyway!! /ubbthreads/images/graemlins/grin.gif

In my testing with my lots of US869, the burn rate in the BMG was slightly faster then average for H-50BMG. I am sure there are some lot to lot variations with the new powder as there generally is. This happened when Hodgdon brought Retumbo to the market as well and now that seems to have settled down to where lot to lot variations are pretty tight with Retumbo.

In my smaller bore Allen Magnums US869 often resembles a burn rate much closer to Retumbo then the slower burning powders.

In the 50 cal rounds on the BMG case it seems that it has a slower burn rate personality.

I have not tested it in my 50 BMG or 510 AM for temp change variation but I have in my 257 Allen Mag, 270 Allen Mag, 7mm Allen Mag and 338 Allen Mag and in every case it was nearly identical to that of WC872.

WC872 also has a much more apporpriate burn rate for these chambering as well and dramatically cheaper to shoot so I have dropped US869 in favor of WC872.

Do not read that as saying I do not think its a good powder. I believe it will be about the best powder there is for my new 300 Allen Xpress as early tests have proven very impressive with that round and this powder easily pushing slighly over 3200 fps with the 240 gr SMK.

As far as the best powders for my 510 AM, right now for the 750 gr A-Max it looks like H-50BMG loaded to around 2770 fps is about the best load. For the heavier Wildcat 835 gr pills, WC872 and VV 20N29 are getting more velocity with VV 20N29 having an edge in velocity spreads, I am sure because of the higher load density.

I am interested to read the tests in my next issue of VHP. I hope they include lot numbers for the tests as well to see how they compare lot to lot.

Again, good to have you here on LRH, your knowledge with the big 50s will be very valuable.

Kirby Allen(50)

 

[Festus]

lrs50bmg,

Wouldn't be the first time I got something wrong. I thought that the nitroglycerin content of the ball powders made them burn hotter. I realize that some extruded powders contain nitroglycerin as well but most of them are of the single-base genre.

Thanks for straightening me out on this, and welcome to LRH.

Festus

 

[shorty]

Kirby, I'd read your post about your 338AM as having a barrel life of approx 1000 rounds which isn't bad all things considered. I am very new to this however and have been reading this website for a while now in hopes of learning something, time very well spent,my thanks to all. I am wondering what kind of barrel life I'd get with a 338 edge? Thank's, Shorty

 

[Fiftydriver]

Just an estimate, if you take really good care of it, I would say 1500-1750 rounds at least in an edge, maybe 2000 if you did not load it to red line and and never overheated the barrel.

My idea if accurate barrel life is being able to hit a big game animal in the vitals at whatever range you are proficent at shooting to.

Some would rebarrel sooner then I would but I build my rifles for long range big game hunting, not paper punching so I would rather have the performance then extreme barrel life.

The 338 Edge is a good combo of both, good barrel life, great performance.

Kirby Allen(50)

 

[Aragorn50]

Kirby,

Thanks for the kind words and load data experiences. I was pleasantly surprised to see Keith's article, as it was nice to actually see the photo's of your wildcats. I have used a shortened/improved case in my competition 50's, which was designed by Lynn McMurdo. It is .375 shorter with an "improved" shoulder. I typically get 75-100 fps more velocity using the same 800 gr. projo, with 5-10 gr. less of the same VV20N29 powder than I do in the standard BMG case, and it is right at 100% load density. It even sounds different than the standard case, with the muzzle blast shorter/sharper that the long booooom with the standard case. Having the sharper shoulder and the base of the projo sitting on top of the powder column certainly seems to get the slow powders to burn more efficiently.

Since Illinois is making the climate for 50 owners so tenuous, I have been playing with a custom .338LM built off a Nesika action, an Obermeyer barrel on an A5 stock.

My next project will be on the 408CT case, but I haven't decided if I want to go the .375 route or not.

Scott Nye