Pressure signs puzzling me.

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  • crimsoncomet6.5

    Pressure signs puzzling me.

    Hey guys. I am glad to be back to get some help from the experts. I have a 24" LW barrel with CSS chamber. I have had two grendels. A 16" Bill Alexander barrel and the 24" barrel. The LW barrel shoots amazing, but I am having trouble working up loads for it. It seems that pressure signs appear much earlier and quicker than they did with my AA barrel. Could this be because of the tighter chamber? Here is one of my loads for example.

    100 TTSX 29.5 gr of TAC with a OAL from base to ogive of 2.700. Avg speed was 2675fps. Seems a bit slow with this length barrel. 30 gr of TAC started showing pressures.

    Another- 100 TTSX 29.0 gr of 8208 xbr base to o-give length 2.700. Avg speed was 2760 fps but showed distinct extractor mark.

    I was more just curious if anyone else has seen this. My speeds dont seem on par to what most people get from this bullet.
  • bwaites
    Moderator
    • Mar 2011
    • 4445

    #2
    With that cartridge length you are in the lands very deeply. I'm not sure it's even possible to load that long.

    Comment

    • StoneTower

      #3
      With my LW 20" barrel, I loaded up 50 to 2.260. The bullet hits the lands at about 2.300. I needed a 100gr TTSX load in a hurry for a hog hunting trip in a no-lead zone in CA. I copied PA_ALLEN's load and it worked like a charm. The big old piggy took a dirt nap and never knew what hit her See the pictures in the hunting section.

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      • PA_Allen
        Warrior
        • Mar 2011
        • 333

        #4
        Originally posted by StoneTower View Post
        With my LW 20" barrel, I loaded up 50 to 2.260. The bullet hits the lands at about 2.300. I needed a 100gr TTSX load in a hurry for a hog hunting trip in a no-lead zone in CA. I copied PA_ALLEN's load and it worked like a charm. The big old piggy took a dirt nap and never knew what hit her See the pictures in the hunting section.
        Glad to hear it worked for you. That load has been deadly so far for me as well!

        Comment

        • PA_Allen
          Warrior
          • Mar 2011
          • 333

          #5
          Crimson,
          There are lots of variables at play, but one possibility is that your 24" barrel is over gassed and trying to unlock to early. Longer barrel lengths increase port pressure and can make safe loads appear "over pressure." The extractor mark indicates that your bolt was maybe trying to extract the brass before the pressure had dropped enough for the brass to contract and free itself from the chamber walls. Increasing carrier weight, increasing buffer spring tension, or an adjustable gas block are all possible fixes if this turns out to be the problem. Many high power match rifles with longer barrels have the gas port moved forward an inch or two to lower port presssure and slow down bolt unlock time for the very reasons stated above. Good luck, and I hope you find an easy fix.
          PA

          Comment

          • longdayjake

            #6
            TAC has been hit and miss with me. It is fine for heavier bullets, but the lighter ones require a faster powder to get the most out of them. Try AA2230 or H322

            Comment

            • crimsoncomet6.5

              #7
              Thanks for all the replies fellas. I made a mistake in my OAL. That is not the OAL of the cartridge, that is the OAL from the o-give with my comparator and dial calipers. So it is the OAL from base to o-give plus the comparator. I keep a record of it for reloading the exact same load over again. The OAL was 2.250" so I should have been okay on OAL. I have a heavier buffer spring, but that did not seem to help. Do you all have a suggestion for a adjustable gas block? Also PA, do you mind sharing your load with me? Of course I will work up to it like always. Thanks again guys! If the over gas is not my problem, at least the gas block will help keep my brass from being so beat up so bad.

              Comment

              • crimsoncomet6.5

                #8
                Originally posted by StoneTower View Post
                With my LW 20" barrel, I loaded up 50 to 2.260. The bullet hits the lands at about 2.300. I needed a 100gr TTSX load in a hurry for a hog hunting trip in a no-lead zone in CA. I copied PA_ALLEN's load and it worked like a charm. The big old piggy took a dirt nap and never knew what hit her See the pictures in the hunting section.
                I checked out the pig StoneTower. Very nice!

                Comment

                • PA_Allen
                  Warrior
                  • Mar 2011
                  • 333

                  #9
                  Originally posted by crimsoncomet6.5 View Post
                  ......Do you all have a suggestion for a adjustable gas block? Also PA, do you mind sharing your load with me? Of course I will work up to it like always. Thanks again guys! If the over gas is not my problem, at least the gas block will help keep my brass from being so beat up so bad.
                  Crimson,
                  Sorry, I do not have any personal experience with adjustable gas blocks, but others on the forum have reported good results.

                  The load that StoneTower was referring to is:
                  100 gr. Barnes TTSX
                  Hello All, Here is some of the data that I had posted on the old site before the crash. I thought that repeating it here might be useful. These loads were safe in my rifle, but please work up to the max loads to ensure your own safety. All of the loads were fired through my 20" Lothar Walther Barrel with the CSS


                  Best,
                  PA

                  Comment

                  • crimsoncomet6.5

                    #10
                    Thanks PA. I have an adjustable gas block heading this way. I will give it another shot. The rifles hasn't been shot in awhile and is begging to be taken out. I have some H335 that has been on my shelf for awhile now.

                    Comment

                    • RangerRick

                      #11
                      Originally posted by crimsoncomet6.5 View Post
                      Do you all have a suggestion for a adjustable gas block? Also PA, do you mind sharing your load with me? Of course I will work up to it like always. Thanks again guys! If the over gas is not my problem, at least the gas block will help keep my brass from being so beat up so bad.
                      I tried weights, but when I started using an adjustable gas block my brass dents went way down and as an unexpected side effect, the primers are not as flat. Not sure why, but I suspect the bolt was unlocking with the pressure still pretty high. There are lots of gas blocks to choose from, but I got a JP clamp on because I don't care for the set screw mounting type of blocks. They have aluminum and stainless. It has a hex nut to adjust the gas. I originally set it for 123 grain bullets and I found that I had to open it up a little for 100 grain bullets with a faster powder. I also put a little piece of stick on velcro (the fuzzy side) on the brass deflector to pad it a little. Some examples: http://www.midwayusa.com/Search/#adj..._1-2-4_8-16-32

                      Comment

                      • crimsoncomet6.5

                        #12
                        Thanks rangerick. I just installed my new adj gas block tonight. Hopefully I will get to shooting this weekend. The gas block was quite a bit taller than a standard gas block. This was from PRI. Question though. My handguard was quite a tight fit. Scrubbed the gas block a bit going back on. I am using a straight gas tube since the block is so high and it seems it may be barely touching. I could squeeze a receipt over the tube but it was snug. Will this effect accuracy? Of course the range will be the true test, but i would like to get y'alls opinion. Might have to go to a larger diameter handguard. Thanks again to all.

                        Comment


                        • #13
                          I use a JP adjustable on both of mine. If you tune pretty much any of them for a certain load, you may have to change for another. I just open mine up an extra turn and call it good. The TTSX won't come anywhere close to the lands loaded in AR-15 mags. I pulled the tips and was then able to get the ogive with in 0.030" from the lands. I've seen no significant detriment in hunting accuracy. Regular TSX will get you closer than the TTSX, but not by much. Ramshot X-terminator is a better choice forthe 100 gr than TAC. I use 30.8grs of X-terminator which gives me 2,775 FPS out of my 18" LW bbl

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                          • #14

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