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

 
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  #8  
Old 05-28-2007, 10:14 AM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Dave,

From the Carbon Wrapped barrels I have built on, it seems they tend to run pretty quick as far as velocity potential compared to other barrels.

To be honest, I will admit that Lilja barrels are probably about the slowest barrels out there I have built on but some of the most accurate as well. That is why I am fine to give up some top end velocity potential for accuracy.

I suspect that is why you are seeing the velocity you are getting in that very short barrel. If that were a Lilja barrel you would probably be running a full 75 to 100 fps less then what your seeing but I am sure accuracy would be great.

I have been thinking about getting a wrapped barrel for another lightweight project. I have 7 on order right now for customer rifles if they ever show up and then I will be able to provide definate velocity comparision numbers between the two but in all my testing of different barrels, the wrapped barrels are running around 75 to 100 fps more then what the same lenght Lilja will get with same pressures.

I would suspect that a carbon wrapped barrel of 33" on this rifle would be producing 3400 fps easily without any ejector marks of any kind.

I do not see any ejector marks until I hit 146.0 gr of H-50BMG. And those are very faint. At 148.0 gr they are more defined. Not as heavy as I have seen with some handloads used by other shooters on a regular basis but more then I like to see in one of my rifles or that I would recommend to a customer.

For now, 3350 to 3370 fps is plenty for me at comfortable, long case life pressures.

As far as your powder testing. I have found similiar results. US-869, at least the lots I have is much more similiar to Retumbo in burn rate then H-50BMG. In fact its far to fast in burn rate for my needs with my 338 Allen Magnum except perhaps with 250 gr bullet weights.

That is just my lots of powder however but I have been hearing similiar reports from my customers using this powder in my other more conventional Allen Magnums. For heavy weight bullets, in my opinion, a bit slow in burn rate and not apporiate in my Allen Magnums for the most part. It works but there are better choices out there.

As far as WC872 is concerned. It is a great burn rate for any bullet in the 338 Allen Magnum over 300 grains. It has a relatively narrow pressure window where it works well. On the bottom end you can see some hangfires. On the upper end it works very well but can be temp change sensitive. I do like this powder however and all of my lots of WC872 has been measureable slower in burn rate then H-50BMG. Generally taking 3-4 gains more powder to match muzzle velocity as H-50BMG in most cases.

With the 266 gr tipped Wildcat Bullets, I think you will be much better served still using H-50BMG. When I tested these bullets I used 145.0 gr and that was a very mild load in my heavy rifle which shows pressure signs dramatically sooner then my lightweight Heavy Sporter Xtreme rifle seems to.

I personally feel that H-50BMG will offer about the perfect burn rate for this bullet when you take into consideration that the baring surface is similiar to the 300 gr SMK but the overall length is longer then the SMK and the weight is 44 grains less.

As such, you need a slightly quicker burn rate powder then would be optimum for the 300 gr SMK but not significantly faster like you would get with US869.

In my testing with this bullet, I suspect that in my HSX 338 AM I will top out at around 150-151 grains under this bullet which when using H-50BMG will give me right around 98-99% load density, what more could you ask for???

WIth US869, again I would predict there will be around 5 grains less powder used when you reach top pressures, at least from what I am seeing with my lot of powder.

Combine this with the much denser powder column produced by the ball powder, you will have much lower load densities which is not the best thing with a ball powder.

In spite of what has been advertised about US869, it is no better in changing temps then any other ball powder I have tested, at least not in my small to medium bore Allen Magnums and Allen Xpress rounds.

The advertisements are all for the results Hodgdon got testing with the 50 BMG so to be fair to them, this powder may have a totally different personallity in the big 1/2" bore but it is still sensitive to temp changes in smaller bore, large capacity round.

I think you will see from your tests that H-50BMG will be THE best powder for the new lighterweight 266 gr bullet from Wildcat. You will get the most velocity with the tightest velocity spreads and should be the most stable under temp changes.

When I get my big order of 266 gr pills, H-50BMG will be the only powder I test unless it does not offer me what I have already seen with this powder and this bullet.

In my lightweight 338 AM HSX I suspect that I will be pushing 3500 fps very hard with this bullet!!!

More to come soon.

Kirby Allen(50)
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #9  
Old 05-28-2007, 10:19 AM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Festus,

I know you were probably joking with your comments about the flier but those are the statements that start rumors about ones honesty reporting accuracy results.

I thought it was obvious that that covered bullet hole was a 30 cal hole instead of a 338 cal hole but just to clear things up, here is a pic with my calipers measuring that covered bullet hole.



It is pretty clear that the hole measures 0.2915" which is about right for a 308 cal bullet. A bit tight for a 338 cal.

Just wanted to clear that up before some one else started accusing me of being selective in my group measurements!!

By the way, the long tears on the target to the right and down from the covered bullet hole are prototype 311 grain Aluminum tipped 338 Cal Wildcat Bullets that I obviously did not have enough twist for and they landed full profile. Not to bad of a group though at 100 yards, one hole group making an "X"!!! [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

Kirby Allen(50)
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #10  
Old 05-28-2007, 11:51 AM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Kirby,
I agree the BMG50 powder is the best overall! My personal gun loves the WC872, 145.5 grns = 3350fps 33" barrel, Lawton 11.25" twist. The BMG50 also shoots just as good, but $$$ wise the 872 is nice, bit dirty however.

I haven't had to much to compare the carbon barrels to, my Lawton is the only other barrel i have used to date. The Rock bbls and ABS/Rock seem to shoot about 70fps slower than the Lawton, but they have all been the 9.4 twist barrels.

Any where from 3200 up to 3400 is just amazing as to the power these guns have.

Good shootin

Dave
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  #11  
Old 05-28-2007, 06:56 PM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Kirby,

I'm glad you recognized my comment about the "flier" as total tongue in cheek. To be honest I had not considered the possibility of anyone interpreting it as a challenge of your integrity. I appologize for that. I thought the graemlin would have tagged my comment as tugging on your leg. Your integrity and honesty has never been in question to me. Just wanted to clear that up for anyone reading this post.

Festus
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  #12  
Old 05-28-2007, 10:07 PM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Festus,

From our dealings in the past, I knew exactly where your comments were coming from and that they were only ment in good natured ribbing. I certainly have no problem with that!!!

I just wanted to make the point for those that do not know either of use much and may read your post and not know you were joking and then take that to another board and start spouting off. I am sorry to say it would not be the first time things have been taken out of context from LRH and posted on other chat rooms and used as fodder against us here.

My comments were not really directed at you in any way, just covering our rears here on LRH from those snakes that may be lurking. Unfortunately there are more then we realize!!!

Nothing negative even considered by your comments. Good shooting as always!!! [img]/ubbthreads/images/graemlins/grin.gif[/img]

Kirby Allen(50)
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #13  
Old 05-28-2007, 11:49 PM
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Re: More range testing with 338 Allen Magnum XHS rifle....

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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  #14  
Old 05-29-2007, 06:31 AM
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Re: More range testing with 338 Allen Magnum XHS rifle....

Festus,

You put near 150 grains of any powder in a 338 bore and you will be looking at 1000 rounds of accurate barrel life at most. I have not seen a real difference between the two in this chambering.

H-50BMG makes it alot easier to get tighter extreme spreads for what this round is designed for that is probably my preferred powder for most applications.

Most critical thing to barrel life in this round is not shooting more then three shots without letting the barrel cool completely before shooting again. That is as far as bench shooting.

The occasional longer string will not destroy a barrel in 10 shots but those that feel only 5 shot groups tell you anything about the accuracy of a rifle will be getting new barrels sooner then later!! [img]/ubbthreads/images/graemlins/grin.gif[/img]

My 375 AM version will be much more barrel friendly but bullet selection is the key there.

Kirby Allen(50)
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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