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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
7mm RUM vs other mags
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<blockquote data-quote="Fiftydriver" data-source="post: 365179" data-attributes="member: 10"><p>I always giggle a bit reading these posts hammering away on what have been labeled "Over Bore", "Hyper Velocity" small and medium bore chamberings. Most want to throw every caliber in the book and compare then head to head and this is simply silly. Its like comparing a Toyota Tundra to my 600HP, 1000 ft/lb torque GMC Duramax as far as towing performance...... SILLY and totally impossible to compare head to head.</p><p> </p><p>With all due respect to the vast amount of knowledge on this board, I feel rather comfortable in saying i have likely burned out far more 7mm barrels then most others on this board combined. That is not bragging, its simply a fact because of the load development and testing I have done with my 7mm Allen Magnum which is on the top of the pile for performance in the 7mm bore family.</p><p> </p><p>I have posted many many times that there are things that can be done to extend barrel life and I will do it again:</p><p> </p><p>1. Use ball powders. </p><p>2. Do not overheat your barrel, never more then three shot strings</p><p>3. No high volume shooting</p><p>4. Use a barrel designed to offer longer barrel life</p><p>5. Use a bullet that has some jacket integrity</p><p>6. Use the rifle for its specialize design purpose and not for all around shooting</p><p> </p><p>Let me explain these things even more.</p><p> </p><p>1. Ball powders have been PROVEN to be less abrasive to the throat area of a barrel Then any stick powder. They have also been proven to burn at lower temps then stick powders. Ball powders ARE NOT the most stable over wide temp changed or dramatic elevation changes but when used in known conditions, every bit as good as any stick powder and they do increase barrel life noticably.</p><p> </p><p>2. Never shoot 5 shot strings, EVER. THe damange caused by the last two shots is far more then cause by the first three, never do it, no need anyway with this type of weapon. Those that believe they can not deterime the accuracy potential of their rifle without 5 or 10 shot groups, We are not BR shooting, we are hunting and if you can not do the job in three shots, you need more practice to be honest.</p><p> </p><p>3. If you want to take your 7mm RUM or 7mm AM to the prairie dog down, expect to change your barrel every year. Thats not its design purpose. Do not use these rifles for high volume shooting and they will last a long time</p><p> </p><p>4. There are barrels that are known to offer longer barrel life out there. I use Lilja 1-9, 4 groove barrels for nearly all of my 7mm AM rifles because they will take the punishment and last long enough to cover most hunters careers inspite of what some would have you believe. You can get fancy rifling designs but none have proven better then the standard Lilja 4 groove barrels and I have burned up every 5R barrel made as well as many others.</p><p> </p><p>5. The Berger bullets have a very thin jacket, even their new "thicker" jacketed hunting bullets. Use a bullet that will handle a bit of barrel wear. The two that come to mind are the 160 gr Accubond and 175 gr SMK. The 160 gr Accubond can take any velocity you want to drive it to. I have shot them to well over 3600 fps but will not pass on that load data. I will say, case life remained excellent in my 7mm AM. The 175 gr SMK is a great choice if you want better long range ballistics. Its true BC is more like 0.680 which compared very well with the Berger and it can be driven to well over 3500 fps in the 7mm AM depending on barrel length compared to the 180 gr Berger that is limited to around 3300 fps because its jacket will not handle much more then that.</p><p> </p><p>6. A 7mm RUM or 7mm AM is designed for one thing, long range, dedicated medium game hunting, nothing more, nothing less. USe it for that purpose and take care of the barrels and it will last longer then most of our hunting careers.</p><p> </p><p>I get a kick out of these guys putting numbers on barrel life and saying your barrel will be a paper weight after 450 to 600 rounds down the barrel..... Let me tell you about my current 7mm AM rifle, "Lil Green". Simple rifle, Rem 700 receiver, Lilja 1-9, 6 groove barrel, HS sporter stock, HS DM system, NF 20 moa rail base, Leupold Mk4 FFP 3.5-10x 40mm.</p><p> </p><p>I built this rifle 6 years ago, used it for three seasons, figured it was ready to have a new barrel installed but decided to take it out and range test it before doing that on the summer between its 2nd and 3rd season. I had put just over 300 rounds down this barrel in load development and ballistic testing as well as hunting. Took her out and She put first shot within 1/2 moa of point of aim from 300 to 900 yards so I left it as it was. I was shooting the 200 gr ULD at 3250 fps at that time.</p><p> </p><p>Took several big game critters that season at ranges from 450 to 800 yards.</p><p> </p><p>Between season 3 and 4 I noticed that the 200 gr ULD RBBT was not shooting as well as I wanted it to, around 1.5 moa accuracy at longer ranges. I then switched to the 160 gr Accubond loaded to 3500 fps. Accuracy was easily within 1 moa out to 900 yards although the wind drift was noticably more which limited the conditions I allowed myself to shoot in. Still, that season I took another three big game animals from 500 to 750 yards with great one shot kill performance.</p><p> </p><p>Between season 4 and 5 I repeated the range test and again, the rifle performed well enough to leave the old barrel on. Took three more big game animals at ranges from 400 to 850 yards.</p><p> </p><p>Between seasons 5 and this season, I decided to try the relatively new 175 gr SMK and developed loads for that bullet which averaged 3450 fps as well. The ballistic performance came back. This bullet has a much lower BC then the 200 gr ULD but had a dramatic velocity advantage as well so out to 1/2 mile they were basically identical. Starting the 2009 big game season, this barrel, the original barrel, never set back or anything, had 645 rounds down the barrel and would still hold first shot impacts within 1/2 moa of point of aim if I read the wind conditions correctly.</p><p> </p><p>This season I took a 16" pronghorn at 785 yards and a 5x5 mule deer at just under 700 yards and felt totally confident using this old, "worn out" barrel. </p><p> </p><p>What most of you will not believe, I have only fireformed one box of Lapua brass for this rifle since the first day I started barrel break in for this rifle.</p><p> </p><p>I have switched bullets three times. Had I started with the 175 gr SMK I would have never changed bullets once. I have never chased the lands although the lands are certainly eroded to some degree but not enough to eliminate consistant accuracy for big game hunting.</p><p> </p><p>Let me also say I use 338 magnums ALOT. I Have burned out as many 338 barrels as 7mm barrels and certainly, a 338 magnum in the same capacity class will offer a longer barrel life. Will the 338 magnum be more consistant, that has been hard to prove to me. If you measure consistancy by single digit extreme spreads in velocity, then yes, the 338 has an edge. IF you base consistancy on never shifting more then 20 fps in velocity over 60 degrees of temp change or 5000 ft elevation change then yes the 338s have an edge in consistancy.</p><p> </p><p>BUT, if you mean being able to put the bullet into and through the vitals of a big game animal at any range the shooter and rifle are capable of and the shooters knows his rifle as he should, I would like to see someone prove the 338s are more consistant for killing medium big game.</p><p> </p><p>Ballistically, the 338s are good for sure but to be honest, they are flat out spanked by the big 7mms as far as bullet drop but more importantly wind drift.</p><p></p><p>Now if you want to hunt game in the 500 to 1000 lb range, DO NOT go with any 7mm as your go to gun, get a 30 caliber and if you want to do this at 1000 yards or beyond, get a 338.</p><p> </p><p>There is no way to fairly compare a big fast 7mm to a big 338, two different beasts that are to different to compare head to head. I use them both, I love them both, in their specific uses, each are far superior to the other and its our job to educate outself and realize what those design purposes are.</p><p> </p><p>Not looking to start any fights, I respect most of the posters on here tremendously, especially the ones that have been around a long time and I know well, you know who you are, just offering my solid experience in the field of 7mm barrel life.</p><p> </p><p>Nuff said by me.</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 365179, member: 10"] I always giggle a bit reading these posts hammering away on what have been labeled "Over Bore", "Hyper Velocity" small and medium bore chamberings. Most want to throw every caliber in the book and compare then head to head and this is simply silly. Its like comparing a Toyota Tundra to my 600HP, 1000 ft/lb torque GMC Duramax as far as towing performance...... SILLY and totally impossible to compare head to head. With all due respect to the vast amount of knowledge on this board, I feel rather comfortable in saying i have likely burned out far more 7mm barrels then most others on this board combined. That is not bragging, its simply a fact because of the load development and testing I have done with my 7mm Allen Magnum which is on the top of the pile for performance in the 7mm bore family. I have posted many many times that there are things that can be done to extend barrel life and I will do it again: 1. Use ball powders. 2. Do not overheat your barrel, never more then three shot strings 3. No high volume shooting 4. Use a barrel designed to offer longer barrel life 5. Use a bullet that has some jacket integrity 6. Use the rifle for its specialize design purpose and not for all around shooting Let me explain these things even more. 1. Ball powders have been PROVEN to be less abrasive to the throat area of a barrel Then any stick powder. They have also been proven to burn at lower temps then stick powders. Ball powders ARE NOT the most stable over wide temp changed or dramatic elevation changes but when used in known conditions, every bit as good as any stick powder and they do increase barrel life noticably. 2. Never shoot 5 shot strings, EVER. THe damange caused by the last two shots is far more then cause by the first three, never do it, no need anyway with this type of weapon. Those that believe they can not deterime the accuracy potential of their rifle without 5 or 10 shot groups, We are not BR shooting, we are hunting and if you can not do the job in three shots, you need more practice to be honest. 3. If you want to take your 7mm RUM or 7mm AM to the prairie dog down, expect to change your barrel every year. Thats not its design purpose. Do not use these rifles for high volume shooting and they will last a long time 4. There are barrels that are known to offer longer barrel life out there. I use Lilja 1-9, 4 groove barrels for nearly all of my 7mm AM rifles because they will take the punishment and last long enough to cover most hunters careers inspite of what some would have you believe. You can get fancy rifling designs but none have proven better then the standard Lilja 4 groove barrels and I have burned up every 5R barrel made as well as many others. 5. The Berger bullets have a very thin jacket, even their new "thicker" jacketed hunting bullets. Use a bullet that will handle a bit of barrel wear. The two that come to mind are the 160 gr Accubond and 175 gr SMK. The 160 gr Accubond can take any velocity you want to drive it to. I have shot them to well over 3600 fps but will not pass on that load data. I will say, case life remained excellent in my 7mm AM. The 175 gr SMK is a great choice if you want better long range ballistics. Its true BC is more like 0.680 which compared very well with the Berger and it can be driven to well over 3500 fps in the 7mm AM depending on barrel length compared to the 180 gr Berger that is limited to around 3300 fps because its jacket will not handle much more then that. 6. A 7mm RUM or 7mm AM is designed for one thing, long range, dedicated medium game hunting, nothing more, nothing less. USe it for that purpose and take care of the barrels and it will last longer then most of our hunting careers. I get a kick out of these guys putting numbers on barrel life and saying your barrel will be a paper weight after 450 to 600 rounds down the barrel..... Let me tell you about my current 7mm AM rifle, "Lil Green". Simple rifle, Rem 700 receiver, Lilja 1-9, 6 groove barrel, HS sporter stock, HS DM system, NF 20 moa rail base, Leupold Mk4 FFP 3.5-10x 40mm. I built this rifle 6 years ago, used it for three seasons, figured it was ready to have a new barrel installed but decided to take it out and range test it before doing that on the summer between its 2nd and 3rd season. I had put just over 300 rounds down this barrel in load development and ballistic testing as well as hunting. Took her out and She put first shot within 1/2 moa of point of aim from 300 to 900 yards so I left it as it was. I was shooting the 200 gr ULD at 3250 fps at that time. Took several big game critters that season at ranges from 450 to 800 yards. Between season 3 and 4 I noticed that the 200 gr ULD RBBT was not shooting as well as I wanted it to, around 1.5 moa accuracy at longer ranges. I then switched to the 160 gr Accubond loaded to 3500 fps. Accuracy was easily within 1 moa out to 900 yards although the wind drift was noticably more which limited the conditions I allowed myself to shoot in. Still, that season I took another three big game animals from 500 to 750 yards with great one shot kill performance. Between season 4 and 5 I repeated the range test and again, the rifle performed well enough to leave the old barrel on. Took three more big game animals at ranges from 400 to 850 yards. Between seasons 5 and this season, I decided to try the relatively new 175 gr SMK and developed loads for that bullet which averaged 3450 fps as well. The ballistic performance came back. This bullet has a much lower BC then the 200 gr ULD but had a dramatic velocity advantage as well so out to 1/2 mile they were basically identical. Starting the 2009 big game season, this barrel, the original barrel, never set back or anything, had 645 rounds down the barrel and would still hold first shot impacts within 1/2 moa of point of aim if I read the wind conditions correctly. This season I took a 16" pronghorn at 785 yards and a 5x5 mule deer at just under 700 yards and felt totally confident using this old, "worn out" barrel. What most of you will not believe, I have only fireformed one box of Lapua brass for this rifle since the first day I started barrel break in for this rifle. I have switched bullets three times. Had I started with the 175 gr SMK I would have never changed bullets once. I have never chased the lands although the lands are certainly eroded to some degree but not enough to eliminate consistant accuracy for big game hunting. Let me also say I use 338 magnums ALOT. I Have burned out as many 338 barrels as 7mm barrels and certainly, a 338 magnum in the same capacity class will offer a longer barrel life. Will the 338 magnum be more consistant, that has been hard to prove to me. If you measure consistancy by single digit extreme spreads in velocity, then yes, the 338 has an edge. IF you base consistancy on never shifting more then 20 fps in velocity over 60 degrees of temp change or 5000 ft elevation change then yes the 338s have an edge in consistancy. BUT, if you mean being able to put the bullet into and through the vitals of a big game animal at any range the shooter and rifle are capable of and the shooters knows his rifle as he should, I would like to see someone prove the 338s are more consistant for killing medium big game. Ballistically, the 338s are good for sure but to be honest, they are flat out spanked by the big 7mms as far as bullet drop but more importantly wind drift. Now if you want to hunt game in the 500 to 1000 lb range, DO NOT go with any 7mm as your go to gun, get a 30 caliber and if you want to do this at 1000 yards or beyond, get a 338. There is no way to fairly compare a big fast 7mm to a big 338, two different beasts that are to different to compare head to head. I use them both, I love them both, in their specific uses, each are far superior to the other and its our job to educate outself and realize what those design purposes are. Not looking to start any fights, I respect most of the posters on here tremendously, especially the ones that have been around a long time and I know well, you know who you are, just offering my solid experience in the field of 7mm barrel life. Nuff said by me. [/QUOTE]
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