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338 Allen Xpress, first load developement session....

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Unread 08-10-2007, 06:23 PM
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338 Allen Xpress, first load developement session....

To all,

Had some rifles to develope loads for this morning so I decided to throw my sporter weight 338 Allen Xpress I just finished up in for some load testing as well. This rifle will be used at the end of this month on an early season elk hunt.

The bullet I will be using if it proves up to the penetration challange and strains of impact will be the new Wildcat Bullets 265 gr AL RBBT. A bit of quick back ground on this bullet. Basically, its a 300 gr ULD RBBT with a long aluminum tip on the nose of the bullet. Because of the lighter weight of the aluminum the bullet weighs 265 grains compared to 300.

The main benefit of the tip is to dramatically increase BC over the 300 gr SMK while also allowing a higher velocity potential as well with the lighter weight. It does both very well. In my very limited BC testing so far using bullet drop numbers it looks like this bullet will have a BC in the .900 to .930 range depending on muzzle velocity. Compare this to the 300 gr SMK which will range from .780 to .810 in most cases. A significant increase. Now realize these numbers are what I need to put into my Exbal program to get the computer generated flight path to match up with actual bullet flight.

For some reason is not allowing me to upload my pics so this will be in essay form only......

My dad is starting practicing fireforming brass for me as he will be in charge of forming cases for customers when he feels comfortable taking that over. From the looks of the 50 cases of 338 Allen Xpress brass he made up for me, he is ready to go. They looked like they just came out of the Lapua box preformed in 338 Allen Xpress.

Because this rifle will be used on elk at possibly closer range I decided I would turn her into a repeater and installed a 3.900" center feed Wyatts mag box in the Rem 700 receiver.

The rifle is pretty basic:

Accurized Rem 700 CM
Gre Tan striker assembly
Badger Ord pinned in extractor
Wyatts 3.900" mag box
Lilja 27" #4 contour SS 1-10 barrel
Manners sporter stock pillar bedded
RB trigger
Holland recoil lug and QD muzzle brake
Factory Rem 700 BDL floorplate
Burris one piece standard base
Burris Signature rings
Weaver 4.5-14 Tactical

Your basic sporter rifle. She weighs in at 9 1/4 lbs ready to hunt with.

Because of the length of the barring surface on the 265 gr AL RBBT, which is basically the same as the 300 gr SMK, I figured a goal of 3000 fps was about right.

Also, because of the length of this bullet, 1.920" compared to 1.720" for the 300 gr SMK, I had to leave the throat very short so it would still function as a repeater. Normally I would not have worried about a repeater but with big critters at closer ranges, it may be nice to have a back up laying under the bolt!

The ogive on this bullet is so long(1.050") that I had to go with the very short throat and as such, the case capacity is severely impacted by the large amount of bullet below the case neck. This concerned me a bit as far as performance was concerned.

Knowing that H-1000 is about perfect in the 338 RUM and 338 Edge, I figured with the 8 to 9 grains extra case capacity of the 338 Allen Xpress that Retumbo would be just about perfect with this bullet. I was not wrong.

I started at 92.0 gr and worked up to 102.0 gr. Here were the velocity results:

92.0 gr.......................2819 fps
94.0 gr.......................2848 fps
96.0 gr.......................2883 fps
98.0 gr.......................2942 fps
100.0 gr.....................2994 fps
101.0 gr.....................3030 fps
102.0 gr.....................3055 fps

100.0 gr is roughly 100% load density with this bullet seated to an overall length of 3.850"

Extraction was perfect on all loads including the 102.0 gr load which produced 3055 fps. I stopped here because this load started to show a bit of a shiny ejector circle on the case head. Not heavy by any means but noticable and that is my stopping point with the Rem 700 receivers.

Had this receiver been a BAT, Nesika or my new Raptor receiver, I would have gone until the bolt lift just started to get sticky and then back off 2 grains and call that absolute max load but I did not want to push the Rem 700 that hard.

My velocity goals with this bullet were 3000 fps so it easily matched that and then some.

Because of the possibility we will be hunting in very hot temps I decided to load up the 98.0 gr load so I would have a bit of pressure cushion if the temps got up in the high 80 to 90 degree range which may be very possible at the end of August, hopefully not but its possible.

Accuracy of the rifle and bullets was pretty good. no group was larger then 1" at 100 yards for three shots. Average was around 0.6" with about half breaking the 1/2 moa level of accuracy. Since I have not fine tuned any load yet I think that was pretty darn good for a prototype bullet.

The 98.0 gr load by the way cut a 0.377" ctc group which is one reason I wanted to test it out more.

After the load development testing I headed back to the shop and started looking up references in different loading manuals on the performance of the 338-378 Wby. THe reason is because my design goal for the 338 Allen Xpress was to match this round with roughly 10 grains less powder.

In every instance, The manuals listed the 338-378 at around 2950 to 3000 fps with a 250 gr bullet weight in a 26 to 28" barrel length.

I was pushing a 15 gr heavier bullet to this same velocity range with very comfortable loads in the same class barrel length and with 10 grains less powder so, so far it looks like another APS wildcat that will meet or surpass all my performance goals.

If this rifle were a single shot and had the throat set up to seat this bullet to the base of the neck, I would have another 10 grains of powder capacity and I know full well 3100 fps would not be a problem at all in this 27" barrel length.

In my testing of the 265 gr AL RBBT and 300 gr SMK in my 338 Allen Magnum, I have come to find that the 265 gr can be drive to roughly 125 to 150 fps higher velocity then the 300 gr SMK with similiar pressures.

Comparing this for use in the 338 Allen Xpress, in a 27" barrel I would be surpised if I could not push the 300 gr SMK to 2900 fps which really is impressive from this class of round.

As soon as I can get pictures uploaded I will post some of the rifle, bullets and ammo. Next up is accuracy testing at 300 yards and 500 yards to fine tune the load and then start drop chart work out to 800 yards which should be farther then any range we will be shooting at.

I will also be testing penetration and expansion here in the next week. This is my only concern with this bullet. Because of the large tip, I am hoping the very heavy jacket can handle the impacts and not come completely apart.

I tested this bullet in my 338 Allen Magnum at 1000 yards on 3, 3 gallon water jugs set up in a row. The bullet punched through all three and literally ripped all three in half. The first two were thrown more then 10 feet to the left of the impact position!!!! I have never heard something pop that hard at 1000 yards before and I have shot alot of water jugs with the 338 AM and the 300 gr SMK at this range. The bullet did not stop in the jugs, I guess I need to line more up!!!!

That test was with this bullet at nearly 3500 fps however so if it will penetrate at this velocity it should at lower as well, as long as it expands well.

We will see.

Kirby Allen(50)
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:
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Unread 08-11-2007, 12:20 AM
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Join Date: Aug 2006
Location: Hatchet City, AB,Canada
Posts: 232
Keep up the good work Kirby and keep us informed please...
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Unread 08-11-2007, 02:20 AM
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Join Date: May 2001
Location: Australia
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Thanks for the report. Will be looking forward to photos and details of your testing.
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Unread 08-11-2007, 03:30 PM
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Ballistic mysteries continue....

I am not sure if this bullet is just taking us to such a different level of ballistic performance that the old ballistic calculators are not working or what but I have run into some seriously strange things again as I did with the 338 AM testing this bullet.

First off, consistancy is great, accuracy is great, getting the ballistic model to match up to actual bullet flight, nearly impossible. Let me explain.

Went out this morning with 20 rounds of test ammo. I used 98.0 gr Retumbo under the 265 gr AL RBBT which averaged right around 2965 fps this morning. Extreme spread was in the mid teens.

Bore sighted the rifle and after a couple shots was where I wanted to be. Made one more slight adjustment and then shot a three shot group at 100 yards on paper. This group was right at 0.7" with the last two touching. The center of the group was 1.9" high at 100 yards.

Went back to 450 yards, shot a three shot group. Nice group, just a hair over 2" which for a 9 lb class rifle I am plenty happy with. Group center was just a hair over 16" low. This matched up perfectly as my first mil dot down was used for the hold and the mil dot pretty much covered up the group.

I then turned the rifle on a 2.5 gallon water jug that was looking at me wrong that I had placed backed up against one of the logs on my backstop. The jug was blown forward 15 feet from the impact!!! Which was dead center using the first mil dot down.

Came back to my computer to run the numbers,

2965 fps
1.5" scope height
65 degrees
45% humidity
3300 ft altitude
26.82 Bar press
240 yard zero

I used a BC of 0.900 and ran the numbers. 100 yard impact was predicted to be +2.0". Very close, within group variations.

Then the mystery, the predicted drop at 450 yards was right at 21". It was far less then this.

I increased the BC to 1.05 and still the predicted drop at 450 yards was said to be just a hair over 20".

How in the hell is my rifle shooting nearly 4" flater then this at 450 yards????

I had to go back out and recheck the zero so I shot three more shots at 100 yards which this group measured 0.455" ctc and again right at 1.9" high for the center average of the group.

Put one more water jug up and moved back to 450 yards and again water flew with a very center hit using the first mil dot down. Now from my figuring, one mil is 3.6" per 100 yards so that comes out to 16.2" at 450 yards.......................

I think I need to come back and look at this again with fresh eyes, I must be missing something simple. What do you boys think. ARe we just dealing with a bullet with a higher BC then we have played with before and the ballistic models are not matching up.

I even tried using the G7 drag function with no more luck then the G1 out to 450 yards.

I must be missing something simple here. Open my eyes.

The rifle shoots like a dream by the way, there will be an elk in serious trouble here at the end of the month!!!

Kirby Allen(50)
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:
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Unread 08-11-2007, 04:09 PM
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Join Date: Feb 2004
Location: Pennsyltucky
Posts: 2,630
50, are you using a slanted base? they play havoc with those computer programs.

the second thing i'd do is make sure of your zero,by this i mean don't use a computer generated zero. get some bullet holes at that distance, then move out to at least 800 and shoot some holes in a target without changing the turrets and measure the drop. this eliminates all the variables of scopes that don't move what they should, reticles that aren't right and half a dozen other things that can mess numbers up. you'll simply have a very close number for the BC with those conditions.
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Unread 08-11-2007, 04:26 PM
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Join Date: Jun 2005
Location: Yakima, Washington
Posts: 3,832

I played with your numbers and you can change the weather related items as well as the BC and you can't make it work out to what you experienced, but...........if you play with the actual sighted in distance you can make it match up at the 450 yard range although it's off slightly at 100 yards.

Is it possible that your actual sighted in distance is out around 275 or 280 instead of the 240 you believe it to be??? Try it at 240 and also at 275-280 and see where it's actually zeroed at. Or better yet, pick a distance, say 300 yards and zero it. Then put that known zero in your software instead of the computed zero and see what you think.

I always zero at 300 and then try it from 100 on out to the longer ranges and it seems to work better than zeroing at a short range. I've found it really easy to get what I think is an accurate zero at 100 and then shoot with computer generated numbers at longer range and be off, but............if I zero at 300 yards, at least, then go from 100 on out to infinity my results work out better. Just my $.02 worth.
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Unread 08-11-2007, 04:46 PM
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Join Date: Jan 2005
Location: Western MI
Posts: 718

Nice write up as usual on the 338AX. Very interesting caliber indeed. In fact, you are building one for a friend of mine and no doubt, it will be a hammer.

Any chance you could post a pic comparing the 338AX to the 338 RUM?

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