Cold bore shot load development.

[JFrank]

I just use minimum component ladders to get a repeatable point of impact, fine tune seating, neck tension and primers etc.
clean and re - foul the barrel with a couple shots and go hunting.

Done deal.

 

[cjmac]

I just use minimum component ladders to get a repeatable point of impact, fine tune seating, neck tension and primers etc.
clean and re - foul the barrel with a couple shots and go hunting.

Done deal.

I just use minimum component ladders to get a repeatable point of impact, fine tune seating, neck tension and primers etc.
clean and re - foul the barrel with a couple shots and done ladder test ..

Iv never done a ladder test . Is it done on cold barrel ?

 

[JFrank]

Iv never done a ladder test . Is it done on cold barrel ?

Starts cold with low charges that progress incrementally to identify nodes that will repeat with a cold bore. Clean bore and cold bore are two different things. Clean bore has more friction and takes a couple shots to foul in. When in tune a cold bore shot will impact the point of aim. Here’s a super easy way to develop a load you might want to check out.

load tuning – Sierra Bullets

Posts about load tuning written by Sierra Bullets

sierrabullets.wordpress.com

 

[K22]

This is a topic that is near and dear to my heart. But let's be clear we are talking about the same issue, cold bore (fouled bore) shots, not clean bore shots. While the latter is also achievable to place a shot in the desired POI, it is beyond the scope of this discussion**.

Because I am year around hunter, mostly varmints in the summer, predators in the winter, and big game in the past, all my rifles are tuned for cold bore desired POI. This is not difficult to achieve in my experience even with my more stringent requirements of 1/2 to 5/8 moa for varmint / predator hunting.

Your requirement of a 1 1/2-inch radius (3" circle) is reasonable, and I would add, enough for big game hunting. This should be easy to achieve with a mechanically defect free rifle and scope. I would also like to compliment you on establishing an accuracy standard for your intended use and equipment. And I might add, a sensible one.

Because of the modest accuracy requirements, you do not need to make this process complicated. Choose a day that the temperatures are moderate, preferably below 80 and test three loads with 3 shot groups. Allow the barrel to cool about 5 minutes between shots or until the barrel is cool to the touch and about 10 minutes between test loads.

Once you find a promising load, retest with 5 shot groups, preferrable 3 times on different days, allowing the barrel to cool between shots. Mark the cold barrel shot for each of these groups. This should give you an idea of the cold bore capability. Unless something strange is going on, they should be within the radius you specified.

I do a lot of practical range shooting throughout the year, and I have a very definite idea of both my cold and clean bore shot capability. In addition, all my range practice is done from clean and cold (fouled) bores.


** I do not need to fire fouling shots for either cold (fouled) or clean bores. My rifles are ready to go into the field whenever the opportunity is available. I have found that the clean bore issue is primarily related cleaning but as I said, that is beyond the scope of this post.

 

[Webster]

So i have a new factory barrel hunting rifle that was given to me . Ruger American in 308 . Never worked up a load for a thin wall factory barrel before . I mentioned a few times I'd like to have a cheap light weight scouting / hunting rifle and this was given to me lol ..
I want to have a consistent cold bore shot that will land within 1.5in radius at 100 yards . I have some 165 Sierra game king btsp and varget powder . How do I work up a load that will give good cold bore shots ? Done plenty of load development on heavy barrel guns but only worried about tye groups not the cold bore shot .. thanks !

Shoot 3 in a group maybe minute apart. If it groups you don't need to worry about cold bore

 

[Coyotefurharvester]

I shoot a powder charge test starting load to max(for rifle) looking for minimal vertical dispersion, I like less than 1 caliber of the cartridge. .4-.5 gr powder charge range hopefully. Tune seating depth as needed. Shots are slow fire, cooling towel on barrel or air through the barrel between shots. Than I zero and keep the same target and shoot shots a few days to a week apart. This last procedure, is it a optics test or load test, probably both. Group should look and have same poi as your final load development 3 shot group. Decent/good barrels are usually "easy". Than I shot with a bipod to make sure no poi change. Varmint rifles need to be shots touching or better(100 yards) game rifles 3" -4" groups at 300 yards off bipod, prone on the ground no rear bag.

 

[cjmac]

This is a topic that is near and dear to my heart. But let's be clear we are talking about the same issue, cold bore (fouled bore) shots, not clean bore shots. While the latter is also achievable to place a shot in the desired POI, it is beyond the scope of this discussion**.

Because I am year around hunter, mostly varmints in the summer, predators in the winter, and big game in the past, all my rifles are tuned for cold bore desired POI. This is not difficult to achieve in my experience even with my more stringent requirements of 1/2 to 5/8 moa for varmint / predator hunting.

Your requirement of a 1 1/2-inch radius (3" circle) is reasonable, and I would add, enough for big game hunting. This should be easy to achieve with a mechanically defect free rifle and scope. I would also like to compliment you on establishing an accuracy standard for your intended use and equipment. And I might add, a sensible one.

Because of the modest accuracy requirements, you do not need to make this process complicated. Choose a day that the temperatures are moderate, preferably below 80 and test three loads with 3 shot groups. Allow the barrel to cool about 5 minutes between shots or until the barrel is cool to the touch and about 10 minutes between test loads.

Once you find a promising load, retest with 5 shot groups, preferrable 3 times on different days, allowing the barrel to cool between shots. Mark the cold barrel shot for each of these groups. This should give you an idea of the cold bore capability. Unless something strange is going on, they should be within the radius you specified.

I do a lot of practical range shooting throughout the year, and I have a very definite idea of both my cold and clean bore shot capability. In addition, all my range practice is done from clean and cold (fouled) bores.


** I do not need to fire fouling shots for either cold (fouled) or clean bores. My rifles are ready to go into the field whenever the opportunity is available. I have found that the clean bore issue is primarily related cleaning but as I said, that is beyond the scope of this post.

I figured it being a factory barrel on a ruger should produce atleast a reasonable group at 100 even with factory ammo . Iv always been a fan of varget cause it seem more temperature stable . I wonder if a light crimp would help give some more stable pressure. Not to mention i could load a few in the mag just in case . Have had times where hogs and deer will kinda stand there after a shot and was able to take one . The average shot on whitetail and hog here in this part of fl is about 100-150 yards . Normally aim for the base of the neck .

 

[cjmac]

Shoot 3 in a group maybe minute apart. If it groups you don't need to worry about cold bore

Yeah guess I didn't really think about that . If the first shot and other 2 are close . All 3 in a 1.5in bullseye . It should repeatable all the time ?

 

[K22]

I figured it being a factory barrel on a ruger should produce atleast a reasonable group at 100 even with factory ammo . Iv always been a fan of varget cause it seem more temperature stable . I wonder if a light crimp would help give some more stable pressure. Not to mention i could load a few in the mag just in case . Have had times where hogs and deer will kinda stand there after a shot and was able to take one . The average shot on whitetail and hog here in this part of fl is about 100-150 yards . Normally aim for the base of the neck .

Varget and IMR 4064 are excellent powders for the 308 Win. I have used both with outstanding results, both with the 150 and 165 Sierra grain bullets.

I am not a fan of crimping reloads for bolt action rifles. If you are using standard dies, you should have enough neck tension to hold the bullet. However, given the light weigh nature of the rifle that you are using and the significant amount of recoil with 165 bullets in this light rifle, it is not inconceivable that the bullet tips could be deformed or more importantly, the bullet could move in the case in the magazine from recoil.

In my 308 Model 700 with full power 150 grain Sierra Pro Hunters loads the bullet tips (exposed lead tips) would deform in the magazine upon recoil. For big game hunting at distance 200 yards and under, this never made a difference. Bullet movement in the case however is more significant issue since it can change pressure. You may want to test a few in the magazine and see if the bullet moves upon recoil without a crimp.

The bottom line on crimping is that at the level of performance you need, there is probably no significant negative accuracy effect crimping but it could provide an extra level of reliability for field conditions. Afterall, you do not need target or varmint grade accuracy, but you do need reliability.

 

[divingin]

Probably off-topic, but I read an article by a guy who got a military armorer (or shooting coach; don't remember) to coach him on his new hunting rifle. First session, the coach had the guy take notes of distance, all weather conditions, time of day, etc, then had him take one shot and note where it landed. Then he got sent home. Next session, same thing. And the same after that. After about 9 months, he started to complain about it to the coach. He was told to show up the next time and be ready to go through the notes he had taken. He shows up, coach tells him to read the current conditions and go through the data to find where the rifle was likely to hit based on conditions and distance, correct as needed, and fire one shot. He placed the impact on whatever he was shooting at. Coach said that, for hunting, he'd likely get one shot that mattered, and knowing where that one bullet was going to hit was paramount, hence all the one-shot days.

No idea if that story was based on actual events or making a point, but seems like it could be legit.

 

[cjmac]

Varget and IMR 4064 are excellent powders for the 308 Win. I have used both with outstanding results, both with the 150 and 165 Sierra grain bullets.

I am not a fan of crimping reloads for bolt action rifles. If you are using standard dies, you should have enough neck tension to hold the bullet. However, given the light weigh nature of the rifle that you are using and the significant amount of recoil with 165 bullets in this light rifle, it is not inconceivable that the bullet tips could be deformed or more importantly, the bullet could move in the case in the magazine from recoil.

In my 308 Model 700 with full power 150 grain Sierra Pro Hunters loads the bullet tips (exposed lead tips) would deform in the magazine upon recoil. For big game hunting at distance 200 yards and under, this never made a difference. Bullet movement in the case however is more significant issue since it can change pressure. You may want to test a few in the magazine and see if the bullet moves upon recoil without a crimp.

The bottom line on crimping is that at the level of performance you need, there is probably no significant negative accuracy effect crimping but it could provide an extra level of reliability for field conditions. Afterall, you do not need target or varmint grade accuracy, but you do need reliability.

I will try some 150 btsp game king as that's what I have on hand right now .
Always wondered if a consistent crimp would give equal pressure. and make charge weights a little less important or sensitive? I know some rifles that you can use a powder thrower without precision measuring and thay still group really good

 

[Doom]

Probably off-topic, but I read an article by a guy who got a military armorer (or shooting coach; don't remember) to coach him on his new hunting rifle. First session, the coach had the guy take notes of distance, all weather conditions, time of day, etc, then had him take one shot and note where it landed. Then he got sent home. Next session, same thing. And the same after that. After about 9 months, he started to complain about it to the coach. He was told to show up the next time and be ready to go through the notes he had taken. He shows up, coach tells him to read the current conditions and go through the data to find where the rifle was likely to hit based on conditions and distance, correct as needed, and fire one shot. He placed the impact on whatever he was shooting at. Coach said that, for hunting, he'd likely get one shot that mattered, and knowing where that one bullet was going to hit was paramount, hence all the one-shot days.

No idea if that story was based on actual events or making a point, but seems like it could be legit.

When speaking of DOPE (No, not the one pulling the trigger), but Data On Previous Engagements is a well known process and what the story is intended to show the importance of. Snipers use it because the whole idea is one shot/one kill and to do that you have to know what the rifle and ammunition will do on that first cold bore shot based on the environmental factors and at different distances. We have gotten lazy now that we have ballistic solvers and wind meters and laser rangefinders at our disposal. All are tools but they are only as good as the inputs. Ballistic calculators can lead anyone astray unless the data within is verified at actual distance.

 

[JB10]

I don't get to hunt much, but i just make sure the first 3 shots are a tight group with #1 being more important. Then let it cool for over an hour. If i dont have time i visit the range another day and recheck. Places i have hunted 1st round matters most and might not get a 2nd shot. So if the 1st round keeps hitting in same spot for me i know where it should go if i get to take a shot

 

[Doom]

I will try some 150 btsp game king as that's what I have on hand right now .
Always wondered if a consistent crimp would give equal pressure. and make charge weights a little less important or sensitive? I know some rifles that you can use a powder thrower without precision measuring and thay still group really good

A few years back the Army was having trouble with hang fires with the M80 7.62x51 ball ammunition and did some testing on what was happening. One of the test was comparing velocity/pressure/action timing with and without the cannelure crimp. What they found was the crimp did make a significant reduction in the standard deviation of velocity and pressure variance. This was with double based spherical propellents. If you think about it for general mass produced ammunition adding a crimp probably becomes the dominant factor in neck tension equation versus the neck interference and surface friction.

https://ia803106.us.archive.org/19/items/DTIC_ADA341390/DTIC_ADA341390_text.pdf

 

[NZ_Fclass]

Early on, I had a Mini Mauser in 7.62x39, which I figured for a lightweight goat - getter. Naturally, I handloaded...but soon found that the rifle was only good for the cold bore shot, as the shots moved right a couple of inches until the thing was about 7 inches off, at 100, after 5 shots. What a POS! Lesson - if the rifle moves when it gets warm - it's only useful as a trade for something better. In my case a BSA Majestic in 308. All 5 shots inside an inch from cold. It was bedded properly by a previous owner and well cared for. I confess to selling it at some point, but now I have 2 more Majestics, 2 Monarchs, 3 Hunters - the older control feed action.and a Viscount. I just don't hunt much anymore!

 

[Coyotefurharvester]

I really believe what matters with a hunting rifle is maintaining first shot poi, over time(month plus) my winter coyote/fox rifles must hold zero from Oct-March. This poi must be stable during after transport. Often my coyote rifles are in a hardcase in the bed of a pickup. Once while riding with a friend, we hit a hard finger drift. The tailgate dropped and my case/rifle slid out at 20 ish mph, onto the frozen gravel road. We didn't realize it until a couple miles later, when we spotted a bedded coyote and I was preparing to stalk it. We back tracked and found it, I took one shot to confirm zero and than went and shot the coyote(head shot at about 225 yards). Sightron stac scope, Talley lw ring/base, Blackhawk axiom stock. This rifle has went 5 winters, zero poi shift. And I have reloaded rounds for it each winter. Stability is possible, not my first rifle with multiple winter stable accuracy.

 

[cjmac]

I really believe what matters with a hunting rifle is maintaining first shot poi, over time(month plus) my winter coyote/fox rifles must hold zero from Oct-March. This poi must be stable during after transport. Often my coyote rifles are in a hardcase in the bed of a pickup. Once while riding with a friend, we hit a hard finger drift. The tailgate dropped and my case/rifle slid out at 20 ish mph, onto the frozen gravel road. We didn't realize it until a couple miles later, when we spotted a bedded coyote and I was preparing to stalk it. We back tracked and found it, I took one shot to confirm zero and than went and shot the coyote(head shot at about 225 yards). Sightron stac scope, Talley lw ring/base, Blackhawk axiom stock. This rifle has went 5 winters, zero poi shift. And I have reloaded rounds for it each winter. Stability is possible, not my first rifle with multiple winter stable accuracy.

Dang . Impressive, if mime stays within a inch I'll be surprised lol more like 1.5in is more realistic fir this factory gun

 

[K22]

I will try some 150 btsp game king as that's what I have on hand right now .
Always wondered if a consistent crimp would give equal pressure. and make charge weights a little less important or sensitive? I know some rifles that you can use a powder thrower without precision measuring and thay still group really good

I have taken many of deer with the Sierra 150 grain Pro Hunter bullet. In my experience, the 150 grain is the ideal bullet weight for white tail deer.

I cannot comment of crimp relative to accuracy since in 50+ years of reloading I never crimped bottle neck rifle reloads. From what I gathered, the crimp often induces another variable and is not conducive to the best accuracy but that is only what I have read, I have no personal experience. Again, you are not trying to load for benchrest competition of varmint grade accuracy, so you have quite a bit of accuracy margin.

Also, the bullet needs to have a cannelure to obtain a crimp with a conventional F/L die. If it does not, you will bulge the neck if you try to apply a crimp with bullets lacking a cannelure.

Many reloaders who use ball powders charge cases directly from the powder measure, verifying of course, that the measure is discharging required load. Some extruded powders are more difficult to charge accurately directly from a powder measure because of the tubular construction of the kernels. For most big game hunting situations, a few tenths of a grain variation are not going to matter as long as you are within safe pressure limits.

 

[Bill K]

I feel you are over thinking the so called "cold bore" first shot. If you work up a load that is grouping an inch or so to your satisfaction with 3-5 shot groups at 100 yrds. Take that load and run a couple groups with it on 2-3 occasions from a cold rifle like you would start a hunt with, I would almost bet you will find that first shot will be within the 1.5 inch area you want on each occasion.
In other words, keep it K.I.S.S. and enjoy your hunt.

 

[cjmac]

I have taken many of deer with the Sierra 150 grain Pro Hunter bullet. In my experience, the 150 grain is the ideal bullet weight for white tail deer.

I cannot comment of crimp relative to accuracy since in 50+ years of reloading I never crimped bottle neck rifle reloads. From what I gathered, the crimp often induces another variable and is not conducive to the best accuracy but that is only what I have read, I have no personal experience. Again, you are not trying to load for benchrest competition of varmint grade accuracy, so you have quite a bit of accuracy margin.

Also, the bullet needs to have a cannelure to obtain a crimp with a conventional F/L die. If it does not, you will bulge the neck if you try to apply a crimp with bullets lacking a cannelure.

Many reloaders who use ball powders charge cases directly from the powder measure, verifying of course, that the measure is discharging required load. Some extruded powders are more difficult to charge accurately directly from a powder measure because of the tubular construction of the kernels. For most big game hunting situations, a few tenths of a grain variation are not going to matter as long as you are within safe pressure limits.

I have tried ball powder in the past and it didn't seem to temperature stable? Maby it was just me . I have a charge master and it's pretty accurate.. as far as a crimp I have the Lee factory crimp die . Don't need a crimp ring on bullet . Probably wouldn't take much of a crimp to hole it