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Severely Overbore Chartidges and short barrel life myths...

 
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Old 09-26-2010, 04:02 PM
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Severely Overbore Chartidges and short barrel life myths...

To all, I just spent a few hours this morning getting my personal hunting rifles tuned in and ready to roll for the upcoming hunting season. My personal big game rifles this year will be:

6mm-06
95 gr Ballistic Tip @ 3540 fps
Win M70 push feed
Lilja #3 contour 1-8 SS barrel, 27" finish length
Boyds classic sporter laminated stock
Small PK muzzle brake
Leupold VX-3 LRT 4.5-14x 40mm with Varmint Hunter Reticle
Pronghorn hicking rifle
Weight: 10.5 lbs ready to hunt with

7mm Allen Magnum
160 gr Accubond @ 3414 fps
Rem 700
Lilja #3 SS 1-9, 26.5" Finish length
DE 1/2" brake
HS Precision sporter stock, green with black web
HS Precision DM system
Tuned Rem 700 trigger
Leupold Mk4 FFP 3.5-10x 40mm w/ TMR reticle
Anything packing rifle
Weight: 10.0 lbs ready to hunt with

338 Allen Xpress
225 gr Accubond @ 3392 fps
Raptor LRSS
Lilja Raptor barrel, 1-10 twist, 30" finish
APS Medium PK brake
Jewell trigger
McMillan A-5 w/ adj CP
HS Precision DM system
NF NXS 5.5-22x 50mm (soon to be Votrex Razor!!)
Sit and shoot rifle for ambush hunting
Weight: 16 lbs ready to hunt with.

So these are my three babies. The middle child, is the reason I am posting this story. Ya see, she has been around since the spring of 2003 when I first put her together. At that time I developed a load with the 200 gr ULD RBBT from wildcat bullets and did alot of range practice with her. It has never been an EXCEPTIONAL shooter, 3/4 moa give or take. I have many more consistant rifles but I have no rifles that have performed for me in the field like this rifle.

For the past 3 years, I have been going to put a new barrel on this rifle because its getting extremely long in the tooth. By that I mean I stopped counting at 700 rounds down the barrel and that was three seasons ago. Past that I figured it would go at any time so stopped counting.

Over the years I have had to switch to several different bullets with complete ballistic work ups and range practice to validate drop chart numbers. First there was the 200 gr ULD, then the 160 gr Accubond, then to the 175 gr SMK and this year I am going back to the 160 gr Accubond.

The reason is simply that I had a couple situations last fall with the 175 gr SMK that left me wanting for a bit more consistant bullet expansion on soft tissue impacts. The 160 gr AB does not have the ballistic performance but its much better terminally so that is why I went back to that bullet.

I also decided to use Retumbo with the 160 gr Accubond, something I had never done but I did use that powder with the 175 gr SMK with good results. After a load development session, Retumbo was driving the 160 gr Accubond out at 3414 fps average with ES in the 27 fps range. I have an old drop chart from many years ago and used that and tweaked it a bit for the different velocity average. It only took a few shots to get things on track and then I set up on my steel gong at 880 yards. About the max I have always limited myself to with this rifle on big game. Again, its always been a 3/4 to 1 moa rifle at long range from the start.

I took four shots at 880 yards. The wind was coming from my 10:30 direction at around 8 mph at the shot. This is the result



Three of the shots went into 3" ctc and all four went into 6" ctc. Things were pretty much right on top of my black aiming point on the gong other then the one shot to the right but all well within where I wanted them for big game hunting.

I bring up this simply because of all the stories I hear about severely overbored chamberings chewing up throats before you can even get one decent load developed and drop chart tested. Now, there are few combinations out there that will match the 7mm AM as far as being classified as overbore!!!

the throat on this rifle has some significant heat cracking but I clean it often, always have and most importantly, this barrel has NEVER been over heated. To my best recollection, I have never put more then three shots through this barrel in one string. As such, the barrel still produces fine accuracy, high velocity and its pretty damn easy to clean still.

So, for those that get scared off choosing an extreme performance chambering, please realize that the life of your barrel greatly depends on how you care for the barrel and how you treat it while shooting. In my opinion, these have much more to do with barrel life then what the rifle is chambered in.

It is true I do not load this rifle terribly hot. 3414 fps is a good top working load but I can easily hit 3500 fps if I want to and in a full custom rifle with stronger receiver, near 3600 fps with acceptable pressures is easy with the 7mm AM.

Still, this rifle could not use those loads or take advantage of the ballistic increase created by them simply because I can not shoot the rifle well enough past 1/2 mile to make them worth while.

3414 fps is roughly 150 fps faster then the 7mm RUM "SHOULD" be loaded to in this barrel length with the 160 gr bullet weight and thats PLENTY for me.

I have the replacement barrel sitting here and to be honest, I REALLY do want to get this old barrel off and new one on because I have been seeing some good performance with the Berger 180 gr VLD in the Lilja 1-9, 6 groove barrels being able to be pushed to nearly 3400 fps with top loads and so far good accuracy but as long as this old pipe keeps working I will keep her with me hunting.

To date, this rifle has 17 big game kills at ranges from 385 yards to 845 yards and has never missed a big game animal I have pointed it at!!!

By conventional wisdom, this barrel should be worth nothing more then a paperweight by now but it just goes to show if you take care of a barrel and especially do not over heat the bore, you will get much longer barrel life they you would expect with a chambering such as this. I hear all the time that you can not practice with one of these rifles to become proficent with it. Again, BULL. Once I get my load, which generally takes 20-25 rounds total, You can verify a drop chart in another 20-25 rounds and then its simply a matter of taking the rifle out from time to time to practice on targets of opportunity just as you would big game hunting. 10 rounds a summer is plenty once you get the drop chart figured out. NO NEED at all to run 100s of rounds down the bore.

In fact, Now that I have this load developed, I will take water filled milk jugs out and set them up at ranges from 300 to 1000 yards and shoot one shot at each. Actual rounds down the bore will be very limited and as such, barrel life will be greatly increased.

The key here, get away from load development as soon as you can, never shoot on paper once your zeroed. Tinkeritis is a bad thing. Many will develope load after load trying to find that magical load that offers sub 1/2 moa groups, single digit extreme spreads when in reality, they could likely take any load they try out in the field and have a load that would shoot better then they can shoot the rifle at long range from field conditions. I am saying this about myself.

I know this because this old 3/4 to 1 moa rifle has NEVER let me down in the field even though many would say its not accurate enough for big game hunting at long range.

So for those that are scared away from extreme performance chamberings, do not believe alot of the hype you hear about them being barrel eaters, thats greatly dependant on you, not the chambering.

Good hunting and shooting to all this season, be safe and have fun.
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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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  #2  
Old 09-26-2010, 04:14 PM
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Join Date: Jul 2004
Location: Texas
Posts: 5,627
Re: Severely Overbore Chartidges and short barrel life myths...

Quote:
Originally Posted by Fiftydriver View Post
To all, I just spent a few hours this morning getting my personal hunting rifles tuned in and ready to roll for the upcoming hunting season. My personal big game rifles this year will be:

6mm-06
95 gr Ballistic Tip @ 3540 fps
Win M70 push feed
Lilja #3 contour 1-8 SS barrel, 27" finish length
Boyds classic sporter laminated stock
Small PK muzzle brake
Leupold VX-3 LRT 4.5-14x 40mm with Varmint Hunter Reticle
Pronghorn hicking rifle
Weight: 10.5 lbs ready to hunt with

7mm Allen Magnum
160 gr Accubond @ 3414 fps
Rem 700
Lilja #3 SS 1-9, 26.5" Finish length
DE 1/2" brake
HS Precision sporter stock, green with black web
HS Precision DM system
Tuned Rem 700 trigger
Leupold Mk4 FFP 3.5-10x 40mm w/ TMR reticle
Anything packing rifle
Weight: 10.0 lbs ready to hunt with

338 Allen Xpress
225 gr Accubond @ 3392 fps
Raptor LRSS
Lilja Raptor barrel, 1-10 twist, 30" finish
APS Medium PK brake
Jewell trigger
McMillan A-5 w/ adj CP
HS Precision DM system
NF NXS 5.5-22x 50mm (soon to be Votrex Razor!!)
Sit and shoot rifle for ambush hunting
Weight: 16 lbs ready to hunt with.

So these are my three babies. The middle child, is the reason I am posting this story. Ya see, she has been around since the spring of 2003 when I first put her together. At that time I developed a load with the 200 gr ULD RBBT from wildcat bullets and did alot of range practice with her. It has never been an EXCEPTIONAL shooter, 3/4 moa give or take. I have many more consistant rifles but I have no rifles that have performed for me in the field like this rifle.

For the past 3 years, I have been going to put a new barrel on this rifle because its getting extremely long in the tooth. By that I mean I stopped counting at 700 rounds down the barrel and that was three seasons ago. Past that I figured it would go at any time so stopped counting.

Over the years I have had to switch to several different bullets with complete ballistic work ups and range practice to validate drop chart numbers. First there was the 200 gr ULD, then the 160 gr Accubond, then to the 175 gr SMK and this year I am going back to the 160 gr Accubond.

The reason is simply that I had a couple situations last fall with the 175 gr SMK that left me wanting for a bit more consistant bullet expansion on soft tissue impacts. The 160 gr AB does not have the ballistic performance but its much better terminally so that is why I went back to that bullet.

I also decided to use Retumbo with the 160 gr Accubond, something I had never done but I did use that powder with the 175 gr SMK with good results. After a load development session, Retumbo was driving the 160 gr Accubond out at 3414 fps average with ES in the 27 fps range. I have an old drop chart from many years ago and used that and tweaked it a bit for the different velocity average. It only took a few shots to get things on track and then I set up on my steel gong at 880 yards. About the max I have always limited myself to with this rifle on big game. Again, its always been a 3/4 to 1 moa rifle at long range from the start.

I took four shots at 880 yards. The wind was coming from my 10:30 direction at around 8 mph at the shot. This is the result



Three of the shots went into 3" ctc and all four went into 6" ctc. Things were pretty much right on top of my black aiming point on the gong other then the one shot to the right but all well within where I wanted them for big game hunting.

I bring up this simply because of all the stories I hear about severely overbored chamberings chewing up throats before you can even get one decent load developed and drop chart tested. Now, there are few combinations out there that will match the 7mm AM as far as being classified as overbore!!!

the throat on this rifle has some significant heat cracking but I clean it often, always have and most importantly, this barrel has NEVER been over heated. To my best recollection, I have never put more then three shots through this barrel in one string. As such, the barrel still produces fine accuracy, high velocity and its pretty damn easy to clean still.

So, for those that get scared off choosing an extreme performance chambering, please realize that the life of your barrel greatly depends on how you care for the barrel and how you treat it while shooting. In my opinion, these have much more to do with barrel life then what the rifle is chambered in.

It is true I do not load this rifle terribly hot. 3414 fps is a good top working load but I can easily hit 3500 fps if I want to and in a full custom rifle with stronger receiver, near 3600 fps with acceptable pressures is easy with the 7mm AM.

Still, this rifle could not use those loads or take advantage of the ballistic increase created by them simply because I can not shoot the rifle well enough past 1/2 mile to make them worth while.

3414 fps is roughly 150 fps faster then the 7mm RUM "SHOULD" be loaded to in this barrel length with the 160 gr bullet weight and thats PLENTY for me.

I have the replacement barrel sitting here and to be honest, I REALLY do want to get this old barrel off and new one on because I have been seeing some good performance with the Berger 180 gr VLD in the Lilja 1-9, 6 groove barrels being able to be pushed to nearly 3400 fps with top loads and so far good accuracy but as long as this old pipe keeps working I will keep her with me hunting.

To date, this rifle has 17 big game kills at ranges from 385 yards to 845 yards and has never missed a big game animal I have pointed it at!!!

By conventional wisdom, this barrel should be worth nothing more then a paperweight by now but it just goes to show if you take care of a barrel and especially do not over heat the bore, you will get much longer barrel life they you would expect with a chambering such as this. I hear all the time that you can not practice with one of these rifles to become proficent with it. Again, BULL. Once I get my load, which generally takes 20-25 rounds total, You can verify a drop chart in another 20-25 rounds and then its simply a matter of taking the rifle out from time to time to practice on targets of opportunity just as you would big game hunting. 10 rounds a summer is plenty once you get the drop chart figured out. NO NEED at all to run 100s of rounds down the bore.

In fact, Now that I have this load developed, I will take water filled milk jugs out and set them up at ranges from 300 to 1000 yards and shoot one shot at each. Actual rounds down the bore will be very limited and as such, barrel life will be greatly increased.

The key here, get away from load development as soon as you can, never shoot on paper once your zeroed. Tinkeritis is a bad thing. Many will develope load after load trying to find that magical load that offers sub 1/2 moa groups, single digit extreme spreads when in reality, they could likely take any load they try out in the field and have a load that would shoot better then they can shoot the rifle at long range from field conditions. I am saying this about myself.

I know this because this old 3/4 to 1 moa rifle has NEVER let me down in the field even though many would say its not accurate enough for big game hunting at long range.

So for those that are scared away from extreme performance chamberings, do not believe alot of the hype you hear about them being barrel eaters, thats greatly dependant on you, not the chambering.

Good hunting and shooting to all this season, be safe and have fun.

+1

A very good post worth thinking about.

J E CUSTOM
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  #3  
Old 09-26-2010, 05:04 PM
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Join Date: Sep 2009
Location: Washington
Posts: 661
Re: Severely Overbore Chartidges and short barrel life myths...

You said you use only 20-25 rounds on average to figure out your best load. I understand this is probably a new thread all together but could you explain the reloading method you use. I have heard of the ladder testing method but maybe what you do is different. I have gone through way to many rounds trying to get that load just right. I appreciate all the knowledge you share here, thank you
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  #4  
Old 09-26-2010, 06:07 PM
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Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,370
Re: Severely Overbore Chartidges and short barrel life myths...

I agree that a hunting barrel's life should be high, no matter the cartridge. This, because we should be highly focused on cold bore accuracy rather than grouping. Even a 220swift could last a lifetime of actual hunting.

Barrel life has always been subject to performance expectations though. I recently polled BR shooters about their current 6PPC barrel life expectations. This is by no stretch a barrel burner, and if used strictly for hunting, would probably last 100yrs. A link:
Barrel life of 6PPC?
Now these guys have to toss a barrel by 0.1moa of performance slip. But even at the pressures and timing they punish these barrels with, they would never have to toss one if 3/4 to 1moa was acceptable.

Personally, I would toss or set-back a hunting barrel once exceeding 1/2moa of cold bore accuracy at 500. That would be the point where it's just no use to me, as I hunt groundhogs.
So I get more out of my barrels than BR shooters, but less than you.
As implied in another thread, there is rarely anything in shooting that applies across the board.
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  #5  
Old 09-26-2010, 06:35 PM
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Location: SW MT or noVA
Posts: 985
Re: Severely Overbore Chartidges and short barrel life myths...

Excellent read! I totaly agree.
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  #6  
Old 09-26-2010, 08:12 PM
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Re: Severely Overbore Chartidges and short barrel life myths...

Nice post but I need the rifle pic.
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  #7  
Old 09-26-2010, 08:18 PM
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Location: Dayton, Nevada
Posts: 1,825
Re: Severely Overbore Chartidges and short barrel life myths...

So, is the 224 Allen Mag going to be based on the RUM or 338 Lapua?

Great explanation, thanks.
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