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Posted: 11/14/2012 1:33:10 PM EDT
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I currently have a two stage match trigger in my 20" barreled LR308. I know how much of an improvement it was over the factory trigger. I'm hitting targets out to about 680 yards pretty consistently with my hand loads (168 SMK @2605fps). I would like the rifle to be as accurate close to the limit of my loads as it is with the closer targets. Would a Jewell trigger give me that big of an edge over the two stage trigger in the accuracy department or am I pretty much limited to 700 yards max range? JBM indicates the loads should be supersonic out to about 1000 yards.
Thanks! |
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The components that make the most as far as accuracy would be 1) Barrel 2) Trigger and 3) Glass. The component order is up for argument, this is just my opinion. If you are already using a match grade trigger, switching it out for another match grade trigger will probably not matter. You did not mention either the barrel or the glass you are using. What is the twist rate on the barrel? Who is the manufactuerer. Is it a stock DPMS? Those barrels are OK but they are not Kreigers or Shilens quality.
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When you factor in shooting from a benched position, if the rig is about 1 MOA capable or better, windage will play a larger role than your trigger.
Unless your trigger is awful, or if your range estimation is bad, windage will play a larger role at those distances. I always like a good trigger on anything I shoot, but a decent break is all that is required. If you are shooting silhouette and all your shots are offhand, then you should make sure your trigger is consistent by measuring with a gage. I would recommend the book by Bryan Litz. He does a good job of exploring the contributions of each variable in terms of hit probability. Accuracy and Precision For Long Range Shooting. |
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In order to make informed suggestions, a bit more information would be useful.
What are your average group sizes at 100, 300, and 600 yards. This will help assess whether sight error, hold error, lack of trigger control, or drift calculation error is hindering your accuracy. The more raw data you can give me, the better assessment that I can make. Weather info for the group data will be useful as well. One of the things the scope makers do not tell you is that the parallax focus knobs are calibrated for a standard air density and temperature, humidity, and barometric pressure can bring parallax issues back into the picture. Trigger control issues rarely manefest themselves at 600 yards, but give me some more complete information and I can help you get it sorted out. |
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I strongly suggest an upgrade to the Geissele High Speed National Match trigger over a Jewell.
While a Jewell breaks well the hammer spring is weak compared to the Geissele or a replacement GI spring (which can be bent to function with a Jewell); the hammer and trigger pins can walk out; and hammer lock time is longer. I shot Jewell triggers pretty extensively in three separate National Match rifles until replacing them with Krieger-Millazzo KM IIs and Geisseles. The good thing about the Jewells is three juniors got my old ones for free. Your barrel will do well for at least 3,000 rounds of casual accuracy shooting, perhaps longer if you're not shooting rapid fire. As you're in Virginia, with a 20-inch barrel and 168s you should get to around 850 yards before velocity goes trans-sonic and your bullets start doing funky things. You can try 175 Sierras or 185 Bergers to 1,000. |
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Quoted:
In order to make informed suggestions, a bit more information would be useful. What are your average group sizes at 100, 300, and 600 yards. This will help assess whether sight error, hold error, lack of trigger control, or drift calculation error is hindering your accuracy. The more raw data you can give me, the better assessment that I can make. Weather info for the group data will be useful as well. One of the things the scope makers do not tell you is that the parallax focus knobs are calibrated for a standard air density and temperature, humidity, and barometric pressure can bring parallax issues back into the picture. Trigger control issues rarely manefest themselves at 600 yards, but give me some more complete information and I can help you get it sorted out. I only have group measurements for 100 yards- 0.794" average. The only place I can shoot past 100 is where an informal tactical shoot is conducted. I was 1/2 moa high and 1/2 moa left from when I had sighted it in several days before and didn't write down wx conditions. The targets are set at varying distances and with the number of people who attend, there isn't enough time to be able to shoot for groups. It was 65 degrees, 41% humidity, 30.377 pressure and 482 feet for altitude. The wind was about 3 mph, half value from the right. Out to 683 yards, elevation was good. Bullet impact was less than a moa from center. At 800 and 847 yards, my first shots were misses. The spotter wasn't able to see the trails. I made the follow up shots, both were about 4:30 and about 3 inches in from the corner of each plate. I had 3/4 moa windage on the scope. At the next shoot, I'll try to stay until the end and try to get some groups on some of the closer targets which are past 100 yards. I've thought about going with 175 SMKs, but I still have about 1000 168s left. I'll need to go through them first. |
| I have had a Jewell and a JP trigger in a couple of varmint AR's. I decided to build another on the cheap and used a DPMS single stage trigger and it was atrocious. I sent the trigger group out to Bill Springfield and what I recieved back surpassed any trigger I have ever used with a AR, super clean and ultra crisp with absolutely no creep. I wil never purchase a highend triggergroup ever again!!! |
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I have had a Jewell and a JP trigger in a couple of varmint AR's. I decided to build another on the cheap and used a DPMS single stage trigger and it was atrocious. I sent the trigger group out to Bill Springfield and what I recieved back surpassed any trigger I have ever used with a AR, super clean and ultra crisp with absolutely no creep. I wil never purchase a highend triggergroup ever again!!! Cost? Where can I find him? Working on two more builds. I have had a Jewell for almost 10 years in a AR15 with zero problems. I also have Jewells in many bolt guns and they are flawless. |
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Quoted:
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In order to make informed suggestions, a bit more information would be useful. What are your average group sizes at 100, 300, and 600 yards. This will help assess whether sight error, hold error, lack of trigger control, or drift calculation error is hindering your accuracy. The more raw data you can give me, the better assessment that I can make. Weather info for the group data will be useful as well. One of the things the scope makers do not tell you is that the parallax focus knobs are calibrated for a standard air density and temperature, humidity, and barometric pressure can bring parallax issues back into the picture. Trigger control issues rarely manefest themselves at 600 yards, but give me some more complete information and I can help you get it sorted out. I only have group measurements for 100 yards- 0.794" average. The only place I can shoot past 100 is where an informal tactical shoot is conducted. I was 1/2 moa high and 1/2 moa left from when I had sighted it in several days before and didn't write down wx conditions. The targets are set at varying distances and with the number of people who attend, there isn't enough time to be able to shoot for groups. It was 65 degrees, 41% humidity, 30.377 pressure and 482 feet for altitude. The wind was about 3 mph, half value from the right. Out to 683 yards, elevation was good. Bullet impact was less than a moa from center. At 800 and 847 yards, my first shots were misses. The spotter wasn't able to see the trails. I made the follow up shots, both were about 4:30 and about 3 inches in from the corner of each plate. I had 3/4 moa windage on the scope. At the next shoot, I'll try to stay until the end and try to get some groups on some of the closer targets which are past 100 yards. I've thought about going with 175 SMKs, but I still have about 1000 168s left. I'll need to go through them first. 4:30 makes it seem like drop estimation error is a contributing factor. In what conditions were your velocity readings for your loads made? What BC figures are you using for 168 SMK's? What adjustments did you make for your successful follow up shots? While most ballistics programs make adjustments for field conditions, none, that I am aware of, make adjustments to account for the fact that a projectile's BC can change with its velocity. I suggest using the bullets average BC for its velocity range for a specific shot as the BC input to ballistics programs, instead of the more commonly used BC for the projectiles muzzle velocity. That alone can make up to a 10 inch difference on projected POI with a 168gr .308 on a 850 yard shot. If affects windage, too, but not as much in a 3 mph 1/2 value wind. |
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Quoted:
Quoted:
Quoted:
In order to make informed suggestions, a bit more information would be useful. What are your average group sizes at 100, 300, and 600 yards. This will help assess whether sight error, hold error, lack of trigger control, or drift calculation error is hindering your accuracy. The more raw data you can give me, the better assessment that I can make. Weather info for the group data will be useful as well. One of the things the scope makers do not tell you is that the parallax focus knobs are calibrated for a standard air density and temperature, humidity, and barometric pressure can bring parallax issues back into the picture. Trigger control issues rarely manefest themselves at 600 yards, but give me some more complete information and I can help you get it sorted out. I only have group measurements for 100 yards- 0.794" average. The only place I can shoot past 100 is where an informal tactical shoot is conducted. I was 1/2 moa high and 1/2 moa left from when I had sighted it in several days before and didn't write down wx conditions. The targets are set at varying distances and with the number of people who attend, there isn't enough time to be able to shoot for groups. It was 65 degrees, 41% humidity, 30.377 pressure and 482 feet for altitude. The wind was about 3 mph, half value from the right. Out to 683 yards, elevation was good. Bullet impact was less than a moa from center. At 800 and 847 yards, my first shots were misses. The spotter wasn't able to see the trails. I made the follow up shots, both were about 4:30 and about 3 inches in from the corner of each plate. I had 3/4 moa windage on the scope. At the next shoot, I'll try to stay until the end and try to get some groups on some of the closer targets which are past 100 yards. I've thought about going with 175 SMKs, but I still have about 1000 168s left. I'll need to go through them first. 4:30 makes it seem like drop estimation error is a contributing factor. In what conditions were your velocity readings for your loads made? What BC figures are you using for 168 SMK's? What adjustments did you make for your successful follow up shots? While most ballistics programs make adjustments for field conditions, none, that I am aware of, make adjustments to account for the fact that a projectile's BC can change with its velocity. I suggest using the bullets average BC for its velocity range for a specific shot as the BC input to ballistics programs, instead of the more commonly used BC for the projectiles muzzle velocity. That alone can make up to a 10 inch difference on projected POI with a 168gr .308 on a 850 yard shot. If affects windage, too, but not as much in a 3 mph 1/2 value wind. I didn't write down the wx conditions when I sighted it in, but it was about 10- 12 degrees warmer, no wind, and probably about 15% higher humidity. I used the JBM smart phone app to determine the MV the day it was sighted in and used that with the wx conditions of the day of the shoot to get my drop and wind corrections. The ballistic program uses a variable BC. On the follow up shots I only had a 1/4 moa windage correction but no elevation corrections. Experienced shooters say the wind can be tricky as there are several factors affecting the bullet's path, ie: a pond about 3 acres in size, a tree line running right behind most of the targets under 600 yards, an "alley" formed by a cut made through the woods for 700- 900 yard targets, plus the overall terrain is gently rolling land. I do have much better results with my bolt gun, maybe I just need to use 175 SMKs and get more practice with the AR? (I do realize the bolt gun is a true tack driver and will always out shoot the AR.) |
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