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Posted: 12/21/2011 1:30:35 PM EDT
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I've been off this site for a long time, so I'm sure this topic has been beaten to death––but.
I cannot get the same level of performance, (velocity), from my 77gr SMK handloads as I get from my ever shrinking supply of BH MK262 Mod1 factory seconds. I've used Varget, Re-15, and Ramshot TAC, but I'm still about 200 fps lower on the crono than the MK262. I've been handloading for around 20 yrs, so I know better than to just keep adding powder until bad things happen, but was wondering if I've missed something powder choice wise or if I should just be happy with 2450fps out of a 18" bbl. Mk12 SPR clone. e-mail me if you don't want your loads on open post. Thanks for any insight you can provide. [email protected] |
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What's your current load? Max in the <62350 psi section in Ramshot's pdf for TAC is 24.8 grains. When I was using TAC, (I no longer do), my load was 24.5 grs. I am currently using Re-15, but would rather not state my load for fear of getting hammered. It's not that hot, but it is just slightly over the max load listed in the Sierra book. Keeping in mind that I am loading 5.56mm pressure loades, not .223. Currently, I am not seeing any pressure signs, and accuracy is good. I use only late issue L.C. cases, Fed Gold Medal Match primers. |
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There must be something wrong with your barrel to give such low velocities for that barrel length. However if "Factory ammunition" has been able to achieve MK 262 velocities in your 18" SPR type... maybe your loading needs a close evaluation. Perhaps your scale is not giving you honest charge weights. Regardless, IMR 8208 XBR is able to exceed MK 262 velocities in my 18" 1 in 8 twist melonited Rock Creek barrel with a .223 Wylde chamber and my Colt 6724 5.56 NATO 1 in 9 twist. If you have a chronograph and access to this powder, use F205 or Tula Small Rifle Magnum primers in Lake City brass. |
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You do know that you can buy the same load as the MK262 now, don't you? Straight from black hills, it was released for sale a few months ago if I remember correctly. Yes I do, but I have a hard time spending over $50.00 a box. That is robbery, but thank you for the heads-up. |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. What speed did you measure with the M262 ammunition in this rifle? That's the first bit of information we needed. Also, you're right, this is an old, tired topic, but I say we give it a pass for Christmas. |
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You do know that you can buy the same load as the MK262 now, don't you? Straight from black hills, it was released for sale a few months ago if I remember correctly. Yes I do, but I have a hard time spending over $50.00 a box. That is robbery, but thank you for the heads-up. Some good info as to a powder to try in 308Sako's post. |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. What speed did you measure with the M262 ammunition in this rifle? That's the first bit of information we needed. Also, you're right, this is an old, tired topic, but I say we give it a pass for Christmas. With the older white box Black Hills "factory seconds", I'd gotten just over 2650fps with this barrel if I remember correctly, (I don't have my log book here at work with me), and with one lot I know I was getting 2700 fps, but that was when I was using a older Wilson barrel. My handloads using Re-15 right now are only turning up 2450 fps. |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. What speed did you measure with the M262 ammunition in this rifle? That's the first bit of information we needed. Also, you're right, this is an old, tired topic, but I say we give it a pass for Christmas. With the older white box Black Hills "factory seconds", I'd gotten just over 2650fps with this barrel if I remember correctly, (I don't have my log book here at work with me), and with one lot I know I was getting 2700 fps, but that was when I was using a older Wilson barrel. My handloads using Re-15 right now are only turning up 2450 fps. Are the barrels the same length? |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. What speed did you measure with the M262 ammunition in this rifle? That's the first bit of information we needed. Also, you're right, this is an old, tired topic, but I say we give it a pass for Christmas. With the older white box Black Hills "factory seconds", I'd gotten just over 2650fps with this barrel if I remember correctly, (I don't have my log book here at work with me), and with one lot I know I was getting 2700 fps, but that was when I was using a older Wilson barrel. My handloads using Re-15 right now are only turning up 2450 fps. Are the barrels the same length? Yes, I cut the Wilson down from a 20" varmint bbl I found floating around the shop, but the accuracy was unacceptable, so I replaced it with a Chanlynne cut rifled 1-8 SS 18" bbl. (Rocky Mnt. Rifle Works), This barrel really shoots. If I told you the size of my 5 rnd groups, you'd say I was lying. |
Your email:<tt>Not to put you on the spot, but where can I find the kind of load data you've was returned for some unknown reason, so here was my response: The answer to your question is it begins here: http://data.hodgdon.com/main_menu.asp That is where I started and the rest is trial and error, or basic workup. One of my findings is that of the 6 lots of IMR 8208 XBR I have tried, the last one (I brought bulk) is the slowest and maybe not as productive regarding highest velocities as the first 5 single canisters. It would be important to consider that I have done most of my work with 5.56 NATO chambered Colt's and A custom Wylde chambered Rock Creek barrel. NOT .223 Remington chambers! You must know the limits of your rifles configuration. My rifles have Tubb CS springs and either the FA carrier or a carrier with the Tubb CWS installed using the heaviest weight possible. I also use a JP adjustable gas block to limit the gas flow somewhat, or a Noveske Switchblock. What these little things accomplish to to help the rifle system run smoother and diminish the apparent signs of over pressure which in reality are created by an unbalanced system beating up the brass. I would love to acquire a Rem 700 and see what the real top end potential is for this type of load. My loading procedure is to use Lake City brass and either Federal 205's, Wolf or Tula small rifle magnum primers and Redding bushing FL dies where I am setting the head space to only about .0015" of setback, and the neck tension to be about .0025" It is important for consistent ignition and attendant accuracy. As to powder charge, I use the above link for starting guide and a friend gave me the Quickload program which is a huge help in understanding the pressures and velocity relationships. My XBR loads do not exceed MK 262 pressures in my rifles to achieve the 2780 ft/sec average velocity in a 20" barrel. They result in a near 100% load density, and that in a nutshell that's the beauty of XBR. I use an Oehler 35P chronograph to verify my velocities. Good luck and I would give the powder a try. |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. What speed did you measure with the M262 ammunition in this rifle? That's the first bit of information we needed. Also, you're right, this is an old, tired topic, but I say we give it a pass for Christmas. With the older white box Black Hills "factory seconds", I'd gotten just over 2650fps with this barrel if I remember correctly, (I don't have my log book here at work with me), and with one lot I know I was getting 2700 fps, but that was when I was using a older Wilson barrel. My handloads using Re-15 right now are only turning up 2450 fps. Are the barrels the same length? Yes, I cut the Wilson down from a 20" varmint bbl I found floating around the shop, but the accuracy was unacceptable, so I replaced it with a Chanlynne cut rifled 1-8 SS 18" bbl. (Rocky Mnt. Rifle Works), This barrel really shoots. If I told you the size of my 5 rnd groups, you'd say I was lying. Not necessarily. I have a rifle with a 3 groove barrel from Lilja that shot like a hunter benchrest gun when it was new. Still shoots way sub minute. I read an article this morning about the NULA rifles using Bulldog Barrels; they must be pretty darn good. |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. Did you mean ' fast enough to produce the speed before filling the case but not producing excessive pressure' or am I missing something? |
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It comes down to this - you have to be willing to use a gunpowder that is fast enough to produce the speed before filling the case or producing excessive pressure. Did you mean ' fast enough to produce the speed before filling the case but not producing excessive pressure' or am I missing something? I think he worded it correctly. Full case and excessive pressure are the two limits. It's a fine balance. Fast enough (full case limit), but no too fast (pressure before desired velocity). |
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