So, I just ordered a chronograph and was wondering what is acceptable when it comes to spread? I'm shooting a Tikka CTR in 260rem with a 20" barrel. Will the shorter barrel show a larger spread? I do reload, and like to think I know what I'm doing there, but am always up for constructive criticism also.
Acceptable spread
- Thread starter CKshooter
- Start date
Thanks for the post Rsadam. The chrono should be here tomorrow, and plan on trying it out this weekend. I'll post some numbers then. Look forward to hearing what you think. As far as the reloads go, I'm paying very close attention to the necks on the cases to insure that they have uniform release of the projectile as possible. I guess my thinking on the short barrel was would it be more suseptable to inconsistent powder burn?
hogpatrol
Silver $$ Contributor
What will be your maximum shooting distance? I wouldn't get hung up on spreads being the final determination of a load. Your target will tell you what works.
I would like to be accurate out to 600yds, with potentially going to 1000.
That twenty inch barrel will have some limitations. Bullet weight and subsequently powder burn rate will definitely come into the picture. A heavier bullet with a slower powder burn rate is going to produce somewhat greater extreme spreads. Choose wisely.
I think the 1000 with a 20 inch barrel might be pretty tough.. I also think the 1000 yard mark gets thrown out there a lot. 600 yards is a long ways with a stock setup.. People that shoot 1000 use scopes that cost more than most peoples whole setup.. Ranges these days seem to be shortening range not increasing them.
Most people don't shoot over 200 yards down here in S. Texas becouse of the terrain... At my local range which goes to 300 most people never go that far.. I would say in almost 4 years I have seen about 3 people useing the 300 yard targets but the 100 yard backboard stays shot up.
Because of this most are not going to install a 20 MOA rail etc, thats needed to get to extream distance.. It is also hard to find a place that goes to 500 much less 1000.. The game has become like car racing, its a battle of wallets.. Very fat wallets... Shooting should be fun and relaxing,not hair pulling out stress.. Don't get cought up in the 1000 yard stuff , just go out and shoot your best groups with your reloads and improve and enjoy it..
Most people don't shoot over 200 yards down here in S. Texas becouse of the terrain... At my local range which goes to 300 most people never go that far.. I would say in almost 4 years I have seen about 3 people useing the 300 yard targets but the 100 yard backboard stays shot up.
Because of this most are not going to install a 20 MOA rail etc, thats needed to get to extream distance.. It is also hard to find a place that goes to 500 much less 1000.. The game has become like car racing, its a battle of wallets.. Very fat wallets... Shooting should be fun and relaxing,not hair pulling out stress.. Don't get cought up in the 1000 yard stuff , just go out and shoot your best groups with your reloads and improve and enjoy it..
Right now it's favorite is h4350 with 43.8 gr. No pressure signs so moving up to 44gr. It seems to like 130 Berger vld pills the best about .005 off lands.
CharlieNC
Gold $$ Contributor
Use the OCW or ladder type method to minimize the sensitivity of POI to velocity differences, making harmonic tuning your friend. Both my 223 and 6.5x47 have 22in barrels and shoot fine at 1000yd; pick a 140gr high bc bullet and you should be fine. Not a record setting setup but as a LR newcomer you will have plenty of fun.
Jarhead6870
Gold $$ Contributor
Acceptable spread is a relative term and depends on your shooting discipline and distance. You mentioned neither. Ballistic programs are your friend and can give you projected data and give you a picture of what to expect. I just ran a few numbers through one of my programs to show you an example. These were for a 6.5 Creedmoor shooting a 140 ELD-M at 2000 ft density altitude. In the first example, I used an extreme spread of 50 fps, which most would consider a very extreme example, but it gives a picture of how spread is effected by distance and the reason it depends on your shooting goals, target size and the distances being shot.
Extreme Spread of 50 fps
2725 fps - at 600 yards, drop is 81.2 inches and at 1000 yards, drop is 312.3 inches
2750 fps - at 600 yards, drop is 79.4 inches and at 1000 yards, drop is 305.7 inches
2775 fps - at 600 yards, drop is 77.7 inches and at 1000 yards, drop is 299.2 inches
This shows us an extreme vertical spread at 600 yards of 3.5 inches and an extreme vertical spread of 13.1 inches at 1000 yards. If we based our ballistics on the 2750 fps, we would see a vertical spread on the target of these numbers divided by two, i.e. at 600 yards our impacts could be as much as 1-3/4 inches above or below our POA (Point Of Aim). At 1000 yards, our impacts could be as much as 6.55 inches above or below our POA.
In the second example, I used an extreme spread of 20 fps to show what an average reloader using normal reloading methods should be able to attain.
Extreme Spread of 20 fps
2740 fps - at 600 yards, drop is 80.2 inches and at 1000 yards, drop is 308.2 inches
2750 fps - at 600 yards, drop is 79.4 inches and at 1000 yards, drop is 305.7 inches
2760 fps - at 600 yards, drop is 78.8 inches and at 1000 yards, drop is 302.8 inches
This shows us an extreme vertical spread at 600 yards of 1.4 inches and an extreme vertical spread of 5.4 inches at 1000 yards. If we based our ballistics on the 2750 fps, we would see a vertical spread on the target of these numbers divided by two, i.e. at 600 yards our impacts could be as much as 0.7 inches above or below our POA (Point Of Aim), and at 1000 yards, our impacts could be as much as 2.7 inches above or below our POA.
For the above data, you can see that the small extreme spread makes a difference BUT it depends on the targets you're shooting. F-Class guys are shooting a very small X-Ring and 10 ring for score while a guy shooting at a 12" piece of steel, where a hit is a hit, have different objectives and base their success accordingly. For my shooting purposes (steel), extreme spreads under 20 fps are adequate. If you're shooting paper for score, then you'll have to decide what is good enough for your shooting needs and how far "down the hole" you'll want to go to improve your extreme spreads.
Hope this helps...Semper Fi
Wow!! Man i really appreciate your knowledge on this. Amazing stuff there. Also thank you so much for taking the time to put this together.
I the beginning of your thread you mentioned shooting discipline and ballistics. As far as ballistics go that's the main reason I'm getting the chrono. Its tough to find any consistent info for a 20" barrel. I realize I'm losing speed with the short barrel but would like to know how much. Some say as much as 50fps per inch. Others say 17-25fps is the norm. The chrono should eliminate this guesswork correct?
Jarhead6870
Gold $$ Contributor
Every barrel is different and changes in velocity between barrel lengths and calibers are not linear. I think shooters use a "general" rule of thumb of 20-25 fps per inch. The chrono will give you exact numbers for your barrel and load which will give you input for your ballistics program AND tell you how good your reloading practices are, as will the target. As I mentioned in my previous post, I'm mainly a steel shooter but will occasionally go out and play with the F-Class guys. My reloading methods are not as involved as some on this forum as I don't do any case/bullet sorting or neck turning or seating with an arbor press or measure concentricity and yet my extreme spreads are between 10-15 fps with SDs between 3-6 for the 4 rifles I shoot. I do anneal after each firing and weight each charge but that's the extent of my reloading, everything else is the normal sizing, priming and seating.
I guess my point is, with the results on the target and the numbers from the chronograph I have empirical information that tells me how well my loads are performing. This also allows me to modify or tweak a load by changing primers or powder or charge weight or seating depth and use the numbers from the chrono as well as the results downrange on the target to verify whether the change, or changes, make a difference.
The chronograph is a great tool. I know many here use their's to monitor/record each and every shot downrange but my shooting needs do not find that to be necessary. I shoot Berger Hybrids, which are "jump tolerant" vs the VLDs which I find to be "jump sensitive". This gives me a little more freedom with velocity and accuracy as the throats erodes. I do check my velocities every few hundred rounds to maintain the inputs in my ballistic programs but dialing a little more elevation is easy enough as long as accuracy is maintained. Once accuracy starts to degrade I do another load work-up, chronograph the most accurate load and go shoot.
Hope this helps, enjoy the journey...Semper Fi
Some chronographs have an accuracy window of plus or minus 25fps. Something you should take into consideration. One big thing you have not mentioned is this rifle a repeater and can you get close to the rifleing loading to mag length? Being able to load to a length that will reduce extreme spread is going to be critical.
I can jam them id needed but .005 off seems to be the sweet spot. It is a bolt action but at .005 i can still fit them in the mag for hunting purposes if needed.
Remember that if you shoulder the rifle testing ammo for velocity, the extreme spread and standard deviation numbers will often be 3 to 4 times greater than those obtained if the barreled action was bolted to a 2 by 4 clamped solid on a bench top so it stayed fixed in place and doesn't recoil.
Rifles fired when shouldered shoot bullets slower through chrono screens than their barreled action does when fixed in place.
Rifles fired when shouldered shoot bullets slower through chrono screens than their barreled action does when fixed in place.
Well, got to test the chrono today. Shooting 5 sets of 3 shot groups my worst spread was 43fps. My best was 19fps. On the paper my worst group was 1.5in @ 200yds. That was 46.3gr of h4831. This also had the highest spread, and was the slowest. My best was 44gr of h4350. All three were touching@ 200yds. Spread was 19fps. Also 43.8gr of h4350 were really close to all 3 touching@ 200yds. these had a spread of 25fps. It seems the hotter the charge, the tighter the groups, but in my reloading book max for this round is 42.7gr. I'm at 44 with no pressure signs. Do I get nervous or just continue to go up in minor increments till my groups show signs of falling apart or pressure signs appear?
Lapua40X
California Hunter Education Instructor
Getting back to your original question, ES tolerances are relative to your own requirements. A hunter may be satisfied with an ES greater than a competition shooter. My own competition goals are < 12 fps. That's very difficult to achieve. Regardless of your goals, the accuracy and reliability of the chronograph you select are of primary importance. GIGO applies to ballistics as much as computer science. Whether or not MV is affected by what you have behind the stock's butt plate is irrelevant. As long a that element is consistent your MV data should remain pretty much the same. Always use the same method, shot to shot, when collecting data.
Good luck ......
I'm shooting 130 vld out of a 20in tikka ctr. Harrell radial brake, pillar bedded. MV is 2800 with 44gr h4350. 4895 i think would burn too fast and at 36.5 gr wouldn't fill the case enough to get a consistent burn. Just my opinion. 4895 is my 22-250 favorite powder. I'm seating the pills .005 off lands. Gonna try 300 and 400yds in the morning.
Lapua40X
California Hunter Education Instructor
Sorry CK; wrong thread. My bad ......
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