Ladder test for military rifles
- Thread starter BJung
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Really depends on the rifle in question, some rifles require a given amount of tension of the barrel bands which have direct contact with the stock/barrel to shoot accurately. Other rifles simply have bands that just hold the hand guard in place which has no direct contact with the barrel at all.
When I was reworking my 1933 M91 / 30 I free floated the barrel per say as the only place the stock touches the barrel is at the front where the barrel rest on a cork pad which doesn't put any direct upward pressure on the barrel it just gives it a place to rest.
After working on some test loads using my 215 gr. FN cast bullet I found a sweet spot, but it shoots several cast bullets very well.
Ladder test are always a good choice if you want to find the most accurate node or nodes regardless of if the rifle is modern or an old military surplus.
When I was reworking my 1933 M91 / 30 I free floated the barrel per say as the only place the stock touches the barrel is at the front where the barrel rest on a cork pad which doesn't put any direct upward pressure on the barrel it just gives it a place to rest.
After working on some test loads using my 215 gr. FN cast bullet I found a sweet spot, but it shoots several cast bullets very well.
Ladder test are always a good choice if you want to find the most accurate node or nodes regardless of if the rifle is modern or an old military surplus.
Nice group! I like seeing results like this. Comparing military surplus rifle results to aftermarket rifle results is like comparing Seabiscuit the horse to a thoroughbred. The first being a mere workhorse yet the ability to be that much special because of its pedigree.
I'm shooting a 7.7 Arisaka,
I'm shooting a 7.7 Arisaka,
I've shot a good number of different Garands that belonged to clubs I joined. Some of these as-issued rifles were only good for 3½ moa with surplus M72 National Match ammo, while I would occasionally see one that cleaned enough 10's and X's at 600 yards to be no worse than 1½ moa. So the parts can just happen to go together in a favorable way and the chamber size and throat wear be just right for a particular load or lot of ammunition.
Stock contact is not automatically a bad thing. There are stock tuners that intentionally contact the barrel to produce good muzzle displacement timing with average ammo. Remingtons accuracy bumps in their stocks are an example. "O'Connor" bedding is another example, where you jam paper matchstick between the stock and barrel at different locations until your load tunes in, and then later mix up some epoxy and glue them permanently to the stock with a little paste wax or other mold releases on the barrel. So tuning weights on the muzzle aren't the only thing that can help.
Since this applies to different bullet types, I'll move the thread to the general handloading forum.
Stock contact is not automatically a bad thing. There are stock tuners that intentionally contact the barrel to produce good muzzle displacement timing with average ammo. Remingtons accuracy bumps in their stocks are an example. "O'Connor" bedding is another example, where you jam paper matchstick between the stock and barrel at different locations until your load tunes in, and then later mix up some epoxy and glue them permanently to the stock with a little paste wax or other mold releases on the barrel. So tuning weights on the muzzle aren't the only thing that can help.
Since this applies to different bullet types, I'll move the thread to the general handloading forum.
It was in the early 1960's the USN Match Conditioning Unit tested Garand lower band pull down force by the stock ferrule needed to be 30 to 35 pounds for best accuracy. This was made possible by putting a spacer ring on the barreled action as its receiver was epoxy bedded in the stock resting on the stock ferrule previously epoxied in place. That spacer positioned the barrel about 2/10ths inch higher than when the barrel group was installed. The barreled action was removed, cleaned then the barrel was knurled there and the lower band seated in place. When the ferrule was fit into the lower band and trigger group clamped to the receiver, that down force bent the stock fore end a little as it pushed the barrel down. The bore axis was bent down a little.
Best match grade 7.62 NATO barrels tested handloads with new cases near half MOA at 300 yards, 2/3rds MOA at 600 with complete rifles clamped in free recoiling test cradles.
Remember that any contact of stock fore end parts to the barrel transfers external forces on the fore end to the barrel and bends the barrel at that place in the force direction. This doesn't happen with totally free floating barrels in stock fore ends. No wonder Garands shoot bullets different directions depending on how they're held and aimed slung up in sitting and prone.
Best match grade 7.62 NATO barrels tested handloads with new cases near half MOA at 300 yards, 2/3rds MOA at 600 with complete rifles clamped in free recoiling test cradles.
Remember that any contact of stock fore end parts to the barrel transfers external forces on the fore end to the barrel and bends the barrel at that place in the force direction. This doesn't happen with totally free floating barrels in stock fore ends. No wonder Garands shoot bullets different directions depending on how they're held and aimed slung up in sitting and prone.
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Yep, I've got the Brownells spacer for setting the pulldown tension and have done a couple of Garands that way. I floated my first one because I didn't know about that at the time. But considering the barrel was the as-issued GI barrel, I wasn't unhappy with how it shot. I got the front handguard to center by sleeving the lower band to give it a snug fit over that part of the barrel contour. The sleeve is held in by Loctite and has a T profile so it extends slightly forward to cover the whole barrel contour for better stability. Seems to work OK.
Doesn't the barrel resting on that cork pad put a downward pressure on that pad?
Won't that cause the barrel to vibrate different while bullets go through it depending on how the fore end is supported?
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If the barrel vibrations are dampened the same for every shot, then yes, ladder tests will work. Providing each loads average velocity and test groups spread doesn't overlap each other too much.
I'm not a fan of ladder tests. Several people doing the same ladder test with the same stuff won't get the same results. Are your ladder tests with the same stuff repeatable?
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The beginning of my testload
I don't have much time to shoot and want to develop test loads within the shortest time period. And so, I'm putting a lot of faith in the ladder test. Here is what I have and plan to do. First, I resized, weighed, fireformed, and measured the concentricity of military 30-06 brass. Groups were separated by headstamp too and the necks were turned. I then made these test loads separated by .3gr increments using 150gr. Barnes 150gr. Hornady, 150gr. Speer, 174gr. Hornady, and 180gr. Hornady. I'll shoot them and find the node by MV. Afterwards I'll buy some different primers and adjust the powder to match the mode MV. Then, I'll make lots of 5 reloads by different seating depth and measure the MV for SD and accuracy. After I find the best load I'll shoot at distances to find a ballistic chart for the load. All this will take time but for reloaders it's fun. Sorry, my photo wouldn't upload.
I don't have much time to shoot and want to develop test loads within the shortest time period. And so, I'm putting a lot of faith in the ladder test. Here is what I have and plan to do. First, I resized, weighed, fireformed, and measured the concentricity of military 30-06 brass. Groups were separated by headstamp too and the necks were turned. I then made these test loads separated by .3gr increments using 150gr. Barnes 150gr. Hornady, 150gr. Speer, 174gr. Hornady, and 180gr. Hornady. I'll shoot them and find the node by MV. Afterwards I'll buy some different primers and adjust the powder to match the mode MV. Then, I'll make lots of 5 reloads by different seating depth and measure the MV for SD and accuracy. After I find the best load I'll shoot at distances to find a ballistic chart for the load. All this will take time but for reloaders it's fun. Sorry, my photo wouldn't upload.
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The velocity ladder, the OCW ladder or an Audette ladder, and a seating depth ladder all have to be done to completely optimize a load. Before that, you need to choose a powder for your bullet, though that can often be done by reputation.
The velocity ladder, the OCW ladder or an Audette ladder, and a seating depth ladder all have to be done to completely optimize a load. Before that, you need to choose a powder for your bullet, though that can often be done by reputation.
I've only used the ladder test a couple times, but, the test is to determine the best powder charge for a given gun. The condition of the gun will have little to do with the test, but will affect accuracy. So I would say "yes, a ladder test will work with military rifles"...
I believe it's for testing the load, not the gun...
I believe it's for testing the load, not the gun...
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All that stuff hanging of those service rifle's barrels in 7.62 NATO helped rebuilt ones test under 4 inches at 600 yards, under 1.5 inches at 300. Their barrels vibrate as repeatable as those in bolt action rifles.
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