Well I want to give a little back round first. I am a tacticalrifleman for the department of corrections here in ohio. I have been doing this for nine years. We recently changed our duty rounds to the hornady 110 TAP, due to concerns about over penetration. Our rifles were for the most part 15 to 30 year old remington 700 varmints, and P's. Some of these have been rebuilt over the years but even these have many, many rounds through them. We are also using the 1/12 twist of the factory rifles.
We switched to the TAP rounds a couple of two or three years ago, and have found that when the weather is fair, and the shooter does his part they shoot tiny little groups at 100, 200, and will usually equal Fed. Gold match 168 at 300. They fell off rapidly after that. We also found that the weather had a huge effect on them. We used to have a 1-1.5O minutes varience in adjustments from Jan. to Aug. with the old gold match. The TAP rounds we are seeing something like an extreme spread of 6-8 minutes from Jan-Aug.
We originally thought it was just the way it was with TAP, but after some discussion with Hornady, and some guys here (thanks sobrbiker) I got to thinking maybe it was the extremely long throats. Obviously the stock remingtons had long throats to begin with and after many years of use they are all the way out to an inch in some cases. The rebuilt ones are for the most part between .080 and .270 of throat erosion.
We were also getting flyers occasionally so couldn't tell if that was the shooter or the rifle. I had several ideas I wanted to try to maximize our duty round. Some of you will probably find fault with this as it will limit us to one round. Unfortunately that is the way the state works, we have ONE duty round and will only have that until it is proved inferior. So I wanted to optimize it.
I wanted to slow the twist down because at the velocity it was going it seemed to be excessive for such a short light bullet, and the chamber obviously would be enormously better using a reamer for the TAP round. I had a testing and evaluation rifle built by Predator Custom Shop in Tenn. to try out my theory.
They blueprinted the action, bedded it to the HS precision stocks we use, set the trigger, chambered and threaded a Rock 1/17 twist M24 contour in 20 inches, and coated it. I used all the same gear that the state rifles do, same stock, scope, mount and rings.
I got this back in early January, we zeroed it in 40 degree weather. So far that setting has held true for the cold bore since in all the different temps I have shot it in. Some of those were at zero, to 20 degrees, up to a little over fifty. On the old rifles that would have required adjustment of probably a little over a minute. This one is still right on.
My partner actually shot the first 100 or so rounds out of it as his rifle is shot out and ready to retired. He instantly improved his cold bores, shrunk his follow up group size significantly, and was able to hit 11 out of 16 1/2 inch dots at 100 yards. He tried that with his duty rifle first and hit 1!
I started shooting it one cold day in late january it was 8 degrees, and I wanted to try it at 200, 300, 400, and 500. I used a ballistic chart for the adjustments and found I was under the recommended all the way to 500, for instance we had been using 7-9 clicks at 200 from 100, with the new setup with a 6 inch shorter barrel at 8 degrees it was only 5 clicks. This trend continued all the way to 500.
I know three shot groups are unpopular here but when you only have twenty rounds and need to try to get all these distances in you do what you have to. 200 resulted in .260 for the first group of three, .243 for the second, moving to 300 netted 1.5, and 1.7, 400 resulted in 2.25, and 3.15, then 500 got 3.5 and 3.25.
These were all fired from a rutted up corn field in the cold with walking back and forth all morning between to measure groups, so not the best conditions, but consistantly under MOA and close to half. I have been doing this frequently since and have yet to have one that went as big as MOA. Last wednesday conditions were almost perfect, so I shot 300 and 500. This got me a couple of 1 inch groups at 300, with one at 5/8", and the last 10 shots were at 500. After walking 500 down and back the first group was 3.15, the second was 2.25, and the third was four shots in a nice round group that measured .75 from center to center at the widest point! I actually have shot some tighter groups with another rifle that Predator built for me using gold match, at 600 but only by an 1/8".
So my goals with this project were;
1. more consistent cold bores, with fewer flyers
2. fewer adjustments for the weather in ohio
3. a more forgiving setup that wouldn't require the shooter to be perfect
4. flatter shooting with more wind resistance, through higher velocity
5.to be able to extend our range to 500 if needed accurately
My results so far are that;
1. it is vastly more consistent, with no flyers
2. haven't made an adjustment yet due to temp
3. extremely forgiving-some of these groups I shot would have resulted in over MOA with the duty rifles in the conditions I was shooting in, and my condition at the time (pulse up from walking, cold, etc.)
4. It is flatter shooting, but only increased the wind resistance a small degree.
5. I think the groups at 500 are spectacular, and it is shooting flatter than the gold match at that distance, definately giving us more capability than before.
So I think in the long run everything worked out, and I would expect that we will experience better barrel life with the slower twist, as well as slower throat erosion. With the history of the state that is a huge factor. As I said some of these are 30 years old! The only negative I can come up with is the fact that we are locked into the 110 TAP round, but as I said we are locked into it anyway. Frankly the more testing we do, as far as car glass, and building glass the more impressed we are. For pinpoint instantaneous stop of all activity, this appears to be the best there is, with the absolute minimum danger of overpenetration.
Sorry for the long post, I just wanted to share some of the stuff I found out with this little excercise.
We switched to the TAP rounds a couple of two or three years ago, and have found that when the weather is fair, and the shooter does his part they shoot tiny little groups at 100, 200, and will usually equal Fed. Gold match 168 at 300. They fell off rapidly after that. We also found that the weather had a huge effect on them. We used to have a 1-1.5O minutes varience in adjustments from Jan. to Aug. with the old gold match. The TAP rounds we are seeing something like an extreme spread of 6-8 minutes from Jan-Aug.
We originally thought it was just the way it was with TAP, but after some discussion with Hornady, and some guys here (thanks sobrbiker) I got to thinking maybe it was the extremely long throats. Obviously the stock remingtons had long throats to begin with and after many years of use they are all the way out to an inch in some cases. The rebuilt ones are for the most part between .080 and .270 of throat erosion.
We were also getting flyers occasionally so couldn't tell if that was the shooter or the rifle. I had several ideas I wanted to try to maximize our duty round. Some of you will probably find fault with this as it will limit us to one round. Unfortunately that is the way the state works, we have ONE duty round and will only have that until it is proved inferior. So I wanted to optimize it.
I wanted to slow the twist down because at the velocity it was going it seemed to be excessive for such a short light bullet, and the chamber obviously would be enormously better using a reamer for the TAP round. I had a testing and evaluation rifle built by Predator Custom Shop in Tenn. to try out my theory.
They blueprinted the action, bedded it to the HS precision stocks we use, set the trigger, chambered and threaded a Rock 1/17 twist M24 contour in 20 inches, and coated it. I used all the same gear that the state rifles do, same stock, scope, mount and rings.
I got this back in early January, we zeroed it in 40 degree weather. So far that setting has held true for the cold bore since in all the different temps I have shot it in. Some of those were at zero, to 20 degrees, up to a little over fifty. On the old rifles that would have required adjustment of probably a little over a minute. This one is still right on.
My partner actually shot the first 100 or so rounds out of it as his rifle is shot out and ready to retired. He instantly improved his cold bores, shrunk his follow up group size significantly, and was able to hit 11 out of 16 1/2 inch dots at 100 yards. He tried that with his duty rifle first and hit 1!
I started shooting it one cold day in late january it was 8 degrees, and I wanted to try it at 200, 300, 400, and 500. I used a ballistic chart for the adjustments and found I was under the recommended all the way to 500, for instance we had been using 7-9 clicks at 200 from 100, with the new setup with a 6 inch shorter barrel at 8 degrees it was only 5 clicks. This trend continued all the way to 500.
I know three shot groups are unpopular here but when you only have twenty rounds and need to try to get all these distances in you do what you have to. 200 resulted in .260 for the first group of three, .243 for the second, moving to 300 netted 1.5, and 1.7, 400 resulted in 2.25, and 3.15, then 500 got 3.5 and 3.25.
These were all fired from a rutted up corn field in the cold with walking back and forth all morning between to measure groups, so not the best conditions, but consistantly under MOA and close to half. I have been doing this frequently since and have yet to have one that went as big as MOA. Last wednesday conditions were almost perfect, so I shot 300 and 500. This got me a couple of 1 inch groups at 300, with one at 5/8", and the last 10 shots were at 500. After walking 500 down and back the first group was 3.15, the second was 2.25, and the third was four shots in a nice round group that measured .75 from center to center at the widest point! I actually have shot some tighter groups with another rifle that Predator built for me using gold match, at 600 but only by an 1/8".
So my goals with this project were;
1. more consistent cold bores, with fewer flyers
2. fewer adjustments for the weather in ohio
3. a more forgiving setup that wouldn't require the shooter to be perfect
4. flatter shooting with more wind resistance, through higher velocity
5.to be able to extend our range to 500 if needed accurately
My results so far are that;
1. it is vastly more consistent, with no flyers
2. haven't made an adjustment yet due to temp
3. extremely forgiving-some of these groups I shot would have resulted in over MOA with the duty rifles in the conditions I was shooting in, and my condition at the time (pulse up from walking, cold, etc.)
4. It is flatter shooting, but only increased the wind resistance a small degree.
5. I think the groups at 500 are spectacular, and it is shooting flatter than the gold match at that distance, definately giving us more capability than before.
So I think in the long run everything worked out, and I would expect that we will experience better barrel life with the slower twist, as well as slower throat erosion. With the history of the state that is a huge factor. As I said some of these are 30 years old! The only negative I can come up with is the fact that we are locked into the 110 TAP round, but as I said we are locked into it anyway. Frankly the more testing we do, as far as car glass, and building glass the more impressed we are. For pinpoint instantaneous stop of all activity, this appears to be the best there is, with the absolute minimum danger of overpenetration.
Sorry for the long post, I just wanted to share some of the stuff I found out with this little excercise.
