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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
260 Rem AI
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<blockquote data-quote="twh731" data-source="post: 957830" data-attributes="member: 53716"><p>As promised, I will describe my fireform load procedure. The caveat is that I am not a gunsmith or professional ballistician so your rifle may require a different approach. I had some old IMR 4064 on the shelf and decided to utilize that for the fireforming procedure and save my "good" powder for working up actual accuracy loads. I used Hornady 120 AMax bullets and Federal GMM primers throughout. I did not bother to run the Lapua 260 Remington brass thru any dies before loading them. The Hornady reloading manual that I have (I think 7th volume) gives 37 gr. of 4064 as the only load listed (and maximum load at that) for the 120 gr bullet. My Sierra manual (don't know the vintage, but it's not more that 15 years old) lists over 40 gr of 4064. I decided to use the lower Hornady load as adequate for my application. So, 37 gr of IMR 4064, and 120 gr AMax, standard Lapua 260 Remington cases, Fed GMM primers. I determined my bullet seating depth by inserting a bullet in an unprimed, empty piece of brass and inserted into my chamber and closed the bolt. I extracted the dummy cartridge and measured the OAL and recorded it in my log book. I screwed the bullet seating die into my Rockchucker and ran the ram up and bottomed the die body onto the shell holder. I unscrewed the bullet seating portion until it was almost all the way out of the die. I put the dummy cartridge in my reloading press and ran it up into the die body and then screwed the bullet seater down onto the bullet. I then extracted the cartridge, remeasured it to make sure it hadn't changed. Put it back in and screwed the bullet seater down a tiny amount and ran the cartridge back into the die. I did this until I had achieved .004" shorter OAL. I loaded 10 rounds with the above recipe and carefully cycled them all thru the rifle (outside in a safe area, of course) to make sure that they would all function before heading out to the range. The cartridges all fit VERY snug in the chamber and I had to lock the bolt with alot of resistance. </p><p>At the range my first round struck 2" high and 5" left at 25 yards. I made a scope correction and dialed the wrong direction for my next shotlightbulb. I made the appropriate scope corrections and my next 3 rounds went exactly into the center square. Since I wanted to be sighted on at 100 yards I dialed in about 6 MOA lower correction and my next 3 rounds went into a single hole, literally. I had 2 rounds left for a 100 yard verification and they didn't disappoint me, landing .23" I know a 2 shot group isn't really a group but man was I stoked. Now to fireform the rest of my stash of Lapua 260 Remington brass! By the way, the fireformed brass chambers in the rifle beautifully with no hard bolt work. I think I have achieved my goal. My next step is to find a killer load using the Lapua 136 Scenar-L that I have. I am going to try H4831 first. Tom</p></blockquote><p></p>
[QUOTE="twh731, post: 957830, member: 53716"] As promised, I will describe my fireform load procedure. The caveat is that I am not a gunsmith or professional ballistician so your rifle may require a different approach. I had some old IMR 4064 on the shelf and decided to utilize that for the fireforming procedure and save my "good" powder for working up actual accuracy loads. I used Hornady 120 AMax bullets and Federal GMM primers throughout. I did not bother to run the Lapua 260 Remington brass thru any dies before loading them. The Hornady reloading manual that I have (I think 7th volume) gives 37 gr. of 4064 as the only load listed (and maximum load at that) for the 120 gr bullet. My Sierra manual (don't know the vintage, but it's not more that 15 years old) lists over 40 gr of 4064. I decided to use the lower Hornady load as adequate for my application. So, 37 gr of IMR 4064, and 120 gr AMax, standard Lapua 260 Remington cases, Fed GMM primers. I determined my bullet seating depth by inserting a bullet in an unprimed, empty piece of brass and inserted into my chamber and closed the bolt. I extracted the dummy cartridge and measured the OAL and recorded it in my log book. I screwed the bullet seating die into my Rockchucker and ran the ram up and bottomed the die body onto the shell holder. I unscrewed the bullet seating portion until it was almost all the way out of the die. I put the dummy cartridge in my reloading press and ran it up into the die body and then screwed the bullet seater down onto the bullet. I then extracted the cartridge, remeasured it to make sure it hadn't changed. Put it back in and screwed the bullet seater down a tiny amount and ran the cartridge back into the die. I did this until I had achieved .004" shorter OAL. I loaded 10 rounds with the above recipe and carefully cycled them all thru the rifle (outside in a safe area, of course) to make sure that they would all function before heading out to the range. The cartridges all fit VERY snug in the chamber and I had to lock the bolt with alot of resistance. At the range my first round struck 2" high and 5" left at 25 yards. I made a scope correction and dialed the wrong direction for my next shotlightbulb. I made the appropriate scope corrections and my next 3 rounds went exactly into the center square. Since I wanted to be sighted on at 100 yards I dialed in about 6 MOA lower correction and my next 3 rounds went into a single hole, literally. I had 2 rounds left for a 100 yard verification and they didn't disappoint me, landing .23" I know a 2 shot group isn't really a group but man was I stoked. Now to fireform the rest of my stash of Lapua 260 Remington brass! By the way, the fireformed brass chambers in the rifle beautifully with no hard bolt work. I think I have achieved my goal. My next step is to find a killer load using the Lapua 136 Scenar-L that I have. I am going to try H4831 first. Tom [/QUOTE]
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