What?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jmden, Jun 4, 2004.

  1. jmden

    jmden Well-Known Member

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    Hi,

    I'm in need of some advice/ideas in regards to some "issues" I'm having with my stock Rem. 700 LSS 300RUM. It's got about 170 rounds through it. Last year I worked up a load for it using 200g Swift A-frames and 94.4g RL25, (FED 215 primer and 3.677 COL using Sinclair bullet comparator because of magazine lenth) at just under 3100fps MV with little to no pressure signs. All Remington brass is carefully prepped by trimming, primer pocket uniforming, flash hole reaming, then weighing and sorting cases into the 1 grain lots.

    This year I'm working up a load for the 200 Accubond. I've played with RL25, Retumbo, H870, AA8700, VV N560 and have settled for the moment on RL25 again with FED 215M primers. (BTW, is RL25 really temp insensitive?)

    The other day I went to shoot over the Oehler chrono at the range with rounds from 93.0 to 95.0g of RL25 in .2g increments, hoping I would find a sweet spot of several sequential .2g increment increased rounds by noting several at the same or nearly same velocity--this is kind of shortcut of the "ladder method". I had ejector pin marks right away but velocities of about 3185fps MV with the 200g Accubond. (Hmmm...Why was I at 94.4g RL25 last year with the 200g Swift A-frame at an MV of just under 3100fps with little or no pressure signs?)

    So, I went home and reloaded in .2g increments from 91.0 to 93.0g of RL25. Back at the range I got pressure signs again and velocities with the first couple of round at about 3125fps MV.

    These cases have been mostly full-length resized using the +.010 Redding competition shellholder and die about 4 times (may have been neck sized only a couple of times as that seems to work just fine in my rifle) and shot about 3 times. It almost seems like that with each subsequent firing, pressure signs come on earlier and earlier. From my limited knowledge, this does not make sense. However, with my careful record keeping and with nearly every round fired over the Oehler and with most if not all conditions and parameters recorded...this data doesn't lie or there is some piece of the puzzle I'm missing. Arghhh! Bad brass? What is it?

    It's quite difficult to come up with a consistently workable load when each subsequent firing seems to give different results. Ideas?

    The barrel seems to copper foul pretty badly even though I did a regimented break-in procedure I read out of Sinclair's book. I still need to do several laborious rounds with Sweets and Shooter's Choice before no more blue comes out--even after only 4 or 5 rounds have been fired throught it. I finally gave in and had my way with the JB bore paste the other day in hopes of some improvement. Some folks swear by it and some folks are repelled by it--each seemingly equally qualified. Dan Lilja, for instance, hates JB but doesn't need it on his fine barrels. I've got a dime a dozen stock barrel--maybe it can make a difference on a cheap barrel, I don't know. ???

    Thanks,

    Jon Denham
     
  2. orwapitihunter

    orwapitihunter Well-Known Member

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    Jon,
    Just a thought but have you compared bearing surface between the Nosler and the Swift? I have played with some 180 and 160 Accubonds and noticed they come up to pressure a little quicker than the Partitions I was shooting. Try a few more Swifts I bet the problem disappears and it is the Accubond that is the reason. That's my guess anyway.

    Luck

    m
     
  3. Guest

    Guest Guest

    It's like Birdshooter said, check the length of both bullets and you will see that the Accubond is about 0.150" longer than the A-Frame. So, if you seat them both to the same OAL, you will encounter a significant increase in pressure since the Accubond will be seated deeper into the case. Your load for the A-Frame is already at the upper end for Re-25 according to Alliant's site.

    You might want to try seating the Accubonds further out of the case as that will reduce the pressure. The throats on the Remington chambers are usually long by comparison to other manufacturers, especially with the UltraMags. Take a Dremel tool with a cut off wheel and cut a slot in an empty case (no primer or powder) from the top of the case mouth down and just into the shoulder. Sand off any burrs and then seat a bullet lightly into the neck by hand. Then chamber the dummy carefully but completely. Withdraw the bolt and the case which now will serve as a dummy cartridge which represents the OAL of that chamber with that bullet seated to touch the lands. Use a tool that measures the length from the ogive and you will be all set for that bullet and that chamber. Be sure to start your first tests with the bullets seated just off of the lands so that you don't start out by running the pressures up right away.

    Retumbo and V V N-170 are showing good results with the heavier bullets in the 300 RUMs that I'm working with, right now.

    Best.
     
  4. jmden

    jmden Well-Known Member

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    Hi Birdshooter and Crispin Goodall,

    Thanks for your advice. Bearing surface length and seating depth could make a difference. I'll have to check the bearing surface length. I thought that the A-frame actually had a longer bearing suface. And yes, since the Accubond is considerably longer than the A-frame, it is seated further down into the case which could affect pressure, depending on who you talk to again... Both bullets are seated to 3.677 COL to fit the magazine. This puts me .106 off the lands with the A-frame and .150 (using Sinclair OAL tool and bullet comparator) off the lands with the Accubond. I'll just have to keep playing with this.

    What do you guys think of the copper fouling issue?

    Also, what experience to people have with shooting a few rounds with a certain powder at the range and then shooting a few more rounds of a different powder without cleaning? Can this result in some type of abnormal powder fouling that could affect pressures?

    Crispin, I've got some Retumbo and it has seemed to pressure out before RL25 in my rifle, but perhaps I haven't given it a fair test because I've always shot it after shooting some other powder for awhile(see above paragraph) without cleaning in between powders. Ideas?

    Crispin, what kind of performance have you gotten out of VV 170? What is your load with VV 170? This seems like it might be a good powder for the 300RUM. I've also tried H50BMG, but can't cram enough in the case to get a decent velocity with my stock 26" tube.

    Does anybody know if RL25 is sold as a temp insensitive powder?

    Thanks for your help and ideas,

    Jon Denham
     
  5. jmden

    jmden Well-Known Member

    Messages:
    2,725
    Joined:
    Nov 2, 2003
    Hi Birdshooter and Crispin Goodall,

    Thanks for your advice. Bearing surface length and seating depth could make a difference. I'll have to check the bearing surface length. I thought that the A-frame actually had a longer bearing suface. And yes, since the Accubond is considerably longer than the A-frame, it is seated further down into the case which could affect pressure, depending on who you talk to again... Both bullets are seated to 3.677 COL to fit the magazine. This puts me .106 off the lands with the A-frame and .150 (using Sinclair OAL tool and bullet comparator) off the lands with the Accubond. I'll just have to keep playing with this.

    What do you guys think of the copper fouling issue?

    Also, what experience to people have with shooting a few rounds with a certain powder at the range and then shooting a few more rounds of a different powder without cleaning? Can this result in some type of abnormal powder fouling that could affect pressures?

    Crispin, I've got some Retumbo and it has seemed to pressure out before RL25 in my rifle, but perhaps I haven't given it a fair test because I've always shot it after shooting some other powder for awhile(see above paragraph) without cleaning in between powders. Ideas?

    Crispin, what kind of performance have you gotten out of VV 170? What is your load with VV 170? This seems like it might be a good powder for the 300RUM. I've also tried H50BMG, but can't cram enough in the case to get a decent velocity with my stock 26" tube.

    Does anybody know if RL25 is sold as a temp insensitive powder?

    Thanks for your help and ideas,

    Jon Denham
     
  6. Guest

    Guest Guest

    Jon,

    Here is the burn rate the way that Hodgdon sees it. I've also seen it flopped. So, it's anybody's game at that point. Fast barrels, fast lot number, slow barrels, slow lot numbers. My Retumbo runs just a bit slower than the Re-25.

    97. Alliant Reloder 25
    98. Hodgdon Retumbo
    _____________________________________________

    I had to look back in my notes to see if I had written anything down regarding the shooting of one powder over another. I guess that I avoided that problem by getting good advice before I committed that error. I have a note that says never shoot a test of one powder over another without cleaning the barrel thoroughly first. The note states that this situation has the potential to create higher pressures. Needless to say, I clean my barrels before I switch powders or bullets. It's such an old habit that I don't even think about it anymore, that's why I had to look it up. The Benchrest guys have discussed this on occasion with the same answer.
    _____________________________________________

    I'm sure that you've seen this infomation but I thought that I would post it for some of the others if they are interested.

    200 GR. BAR XFB (1.475")(Starting Loads)
    DIA. .308" COL: 3.575"
    RETUMBO 81.0 2852 56,200 PSI (start)

    200 GR. BAR XFB (1.475")(Maximum Loads)
    DIA. .308" COL: 3.575"
    RETUMBO 86.0 2988 62,800 PSI (end)
    _____________________________________________

    V V N-170 gives good results in my 300 RUMs.
    I am getting ready to start some shooting at 300 yards to see if the accuracy holds up from 200 yards. These targets were averaging about 1-3/4" for 5 shots, paced (cooling the barrel), at the 200 yard mark. There have been some exceptional targets sprinkled into the mix but they are not the norm, merely the tease. I have a bad time with wind this time of the year, it blows pretty much non-stop most of the day then the temps go up and the mirage kicks in. I'm seriously
    thinking about camping out where I test and start shooting at first light which is about 5:10AM here. The wind can be fairly calm at that time of the day. Besides, the bullets that I'm shooting aren't supposed to perform well at short ranges. I had Dave Kiff grind me a reamer specifically for VLD Match bullets and a minimum throat length. I have 4 barrels that I'm working with right now, with various bullet weights.
    22" / 12 twist
    26" / 15 twist
    28" / 12 twist
    30" / 10 twist.

    210 Berger VLD's @ ~3000 fps.
    190 Berger VLD's @ ~3150 fps.
    185 Lapua Scenars @ ~3200 fps.
    _____________________________________________

    You might want to do a quick test with some of your brass to see if it has any effect on pressure.

    <BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> It almost seems like that with each subsequent firing, pressure signs come on earlier and earlier. <HR></BLOCKQUOTE>

    Take a few pieces and anneal the necks, then reload and fire as usual. See if you notice any lessening of the signs of high pressure. I've had to do this with some other cartridges that show signs of work hardening.
    _____________________________________________

    It's been a long time since I worked with a factory barrel. Lapping it with JB is a good idea to smooth it out the best that you can. But keep in mind that it may just be a poor example of a factory barrel. It happens. Find someone that has a borescope or visit your gunsmith if he has one, but be prepared to reimburse him if he does and see if he will let you look through the 'scope. It's time out of his day and it is billable.

    Dan Lilja doesn't recommend JB because he goes to a great effort to lap each and every one of his barrels before they leave his shop. I have never had to lap one of his barrels. On the other hand, I have had to lead lap some other brands before they could even be threaded, chambered and crowned.

    That's the best that I can do for tonight. Long, but I hope a little bit helpful.
     
  7. jmden

    jmden Well-Known Member

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    Thank you, Crispin. I will keep this in mind.

    Jon Denham
     
  8. BountyHunter

    BountyHunter Writers Guild

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    Almost all custom barrel mftrs will warn against lapping barrels AFTER they have been crowned and chambered. All you are going to do is open up both ends of the barrel and worsen accuracy.

    Some barrel mftrs are also require you to relap the barrel after fluting as that will leave high spots in the bore.

    As for the coppering. Two things to try Wipeout (foam that sets in the bore), check BR central for advertisers

    Sinclair www.sinclairintl.com sells the Montana Extreme Copper Cream. Works great but requires the use of hard bristle brush. Sinclari also sells. I use the Kleen Bore brush, has the hardest bristles I have found.

    pressure variations will come from three areas.

    1. different bearing surface lengths

    2. difference in actual bullet diameters or pressure rings for each bullet

    3. work hardening of necks

    BH
     
  9. jmden

    jmden Well-Known Member

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    Bounty Hunter,

    I haven't progressed to annealing yet. Maybe it's time? The brass in question is 300RUM Remington brass that has been shot 2-3 times and sized 3-4 times. Have folks found that this Remington brass requires annealing earlier than other brass? Like I said, I've not annealed and don't know terribly much about it, but having to anneal after 3 firings seems strange to me from what I've heard. If I need to do it, no problem, I'm just looking for answers/advice.

    Thanks,

    Jon Denham
     
  10. BountyHunter

    BountyHunter Writers Guild

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    Jon

    every lot of brass is a beast unto itself.

    However, many 1k guys are now annealing every time.

    two major annealing machines, Leonard Baity at Baity custom guns in NC(336) 667-8785

    and Ken Light at www.kenlightmfg.com

    both machines are same. I use Leonards at $300 and $80 per caliber wheel. You can hand anneal if you use the 700 degree templac from welding supplies to put on the brass. Changes color when gets 700 degrees.

    BH
     
  11. Duff

    Duff Well-Known Member

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    I use JB in my new factory barrels as part of a break in process (if there is such a thing [​IMG] I don't get too gung ho, but I definately think it helps to "polish" the bore a little bit. I certainly hope that if I pay $250.00 or more on a custom barrel that I don't need to do any lapping or black magic to make it shoot right.