Velocity Load Developing Part 2

H

hounddawg

New member
I am still experimenting with finding a good load for my new tactical build in .260 Remington with the Sierra 123 grain MK. This weeks test was using brand new Peterson brass with the small rifle primer with the .60 small flash hole. The only case work was measuring 15 of the cases at the shoulder datum and OAL. The case necks from the factory were nicely chamfered and deburred, OAL and base to shoulder was within .001. No measuring of case capcity or weight was checked with the exception of 10 cases were checked for volume to ensure the Peterson was within a grain or so of the Lapua from last week. I used CCI 400 small rifle primers seated using a Lee Auto Prime tool.

Varget was thrown on a Hornady Lock-N-Load Powder Measure. I threw the charges .1 low then trickled to exact weight using a modified RCBS 502 beam scale which is sensitive to a kernel of powder

The 37.6 node only had 1 shot recorded and the 37.8 node 2 shots because of an operational mistake with the chronograph on my part.


Code: 
36	36.2	36.4	36.6	36.8	37	37.2	37.4	37.6	37.8  Grains of Varget
												
2560	2593	2602	2604	2627	2636	2619	2648	2688	2674  Velocity
8	4	6	11	9	11	22	8	0	8     SD


The average velocity at 36.2 and the average at load had a spread of 11 FPS so next week I will experiment with seating depths using 36.4 grains as my load. I will load 30 rounds total with 10 rounds at .050 from the lands, a second 10 at .025, and a third 10 at .005. There is a higher node but 36.4 will get me 2600 FPS which with this bullet is cranking out 1430 FPS at 800 yards which is the most it will be shot at

I am beginning to wonder exactly how accurate my chrono is and am considering the purchase of a CED M2 which is rated as one of the most accurate chronos on the market, the much pricier Labradar being the other. I may break down and buy one in March or I may spend that money on powder and bullets. I am still deciding
 
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I'll vouch for the CED M2. It is a goodun' and the only errors that I have had was when I first got it and was learning its perks.

Interfacing with a PC helps keep all the records in order.
 
It has good reviews and reputation. My old CE is getting long in the tooth but I will test it first by starting to shoot a few batches of same load over it a few weeks in a row with a temp stable powder or some factory Lapua making sure the distance from the muzzle to the chrono is the same each time. I really don't care if the shots are running at 2600 and are really going 2650 FPS. I want to make sure the readings are consistent from session to session
 
Velocity Based Load Testing Final

Last real test was this morning. I could probably refine a bit with seating depth and primer later on but will be shooting this gun in a match in a couple of weeks with the load as is. I decided on a load of 36.3 grains of Varget and seated the 123 SMK's .010 off the lands because of past experience with this bullet in another gun. I chose 36.3 because 36.2 had a SD of 4, 36.4 had a SD of 6 and there was only 9 FPS difference between their average velocity.

Code: 
36	36.2	36.4	36.6	36.8	37	37.2	37.4	37.6	37.8
												
2560	2593	2602	2604	2627	2636	2619	2648	2688	2674
8	4	6	11	9	11	22	8	0	8

Powder was thrown on a Horandy powder measure using a home made Uncle Nick baffle made from a aluminum beverage can. Charges were thrown and popped on a electronic scale and if they were between 36.2 and 36.4 a bullet was seated @ 2.270 or about .010 off the lands for this chamber. It took about 15 minutes to load 50 rounds. Cases were on their 1st reload and were depinned, wet tumbled for 2 hours, annealed, FL sized on a Redding S die with no expander ball or bushing, then necksized with a Lee collet die. CCI 400 SRP's were seated using a Lee tool with the old square tray

Winds were from the ESE @ 10 - 15. I had wind flags set up at 100, 200, and 275. I shot 5 sighters then this 10 shot group. It scored 96% with 50% x's so I am happy with this load. I dialed it out to 600 and banged the steel a few times, and then out to 800, then back to 600 just to check my ballistics data against real world performance. Using a speed of 2600 FPS the dta was dead on. Then I let a friend who is much better shot than me show me how it is done. At 600 he put 5 shots in a 3 inch circle on the steel

Al in all I am pleased with the method it is a great way to develop a very tolerant load that gives you some leeway for temperature and powder load accuracy

The target with data analysis https://i.imgur.com/SA8qVCT.jpg

The riflehttps://i.imgur.com/JB76dEg.jpg
 
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For those who want to try this method Erik Cortina has a thread over on accurate shooter. It has been proven effective for a lot of shooters. best part of it is if done properly you don't have to sweat trickling to the kernal of powder.

I will still use the modified beam scale during development but now I can toss out 50 rounds in just a few minutes by throwing plus or minus a tenth and be assured that they will be within a few FPS of each other

Long range load development at 100 yards by Erik Cortina
 
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I am still looking for a good 600 yard load for my .223 and thought I would try some CFE .223 with some SMK 77's just to see how it shot. To make a long story short it is way too slow, and the SD's and ES's are way too large for anything over 300


The good news is it will make a great little 100 to 300 powder I think. I only did 3 shot groups since I was more interested in the velocity than the groupings so I would not read too much into the any 1 group but the overall target with 3 shots each of 23.1, 23.3,23.5,and 23.7 was only .83 MOA with a 95% CEP of .536 MOA. That is with a .6 grain spread of powder. This week I plan on loading 25 rounds or so at 23.1 measured exact and see do a 20 round group 300.

Rifle is a Savage 10 action in a Choate stock with a Criterion 8 twist 26 inch barrel . Shot from a Sinclair bipod and a squeeze sock at the back. Mid 50's temp, no wind or mirage and 200 yards

The Target

All shots are almot 3 inches low since I had been shooting some fairly warm Varget loads with 69SMK's and did not want to change zero in the middle of a test


Code: 
Name: 223 CFE223										
Notes: 24.1										
Number	of	Shots	3							
Extreme	Spread	34								
Average	2743									
Standard	Deviation	16								
					
										

Name: 223 Cfe223										
Notes: 23.9										
Number	of	Shots	3							
Extreme	Spread	54								
Average	2702									
Standard	Deviation	23								


Name: 223 Cfe223										
Notes: 23.7										
Number	of	Shots	3							
Extreme	Spread	78								
Average	2645									
Standard	Deviation	34								

Name: 223 Cfe223										
Notes: 23.5										
Number	of	Shots	3							
Extreme	Spread	11								
Average	2666									
Standard	Deviation	4								

Name: 223 Cfe223										
Notes: 23.3										
Number	of	Shots	2							
Extreme	Spread	15								
Average	2621									
						

Name: 223 Cfe223										
Notes: 23.1 										
Number	of	Shots	4							
Extreme	Spread	36								
Average	2605									
Standard	Deviation	14
 
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"I only did 3 shot groups since I was more interested in the velocity than the groupings"

Oh...... I thought the reason for shooting was to hit a target. I would be looking for repeatability, IOW can you hit the same spot with each shot? At 100 yards a 3 shot group you can cover with a quarter is good.
 
"I only did 3 shot groups since I was more interested in the velocity than the groupings"

Oh...... I thought the reason for shooting was to hit a target. I would be looking for repeatability, IOW can you hit the same spot with each shot? At 100 yards a 3 shot group you can cover with a quarter is good.
Click to expand...

for a hunting rifle yes 3 shots in a MOA is good, for a F class rifle no, you try to put 20 in a half an MOA. Read the link in post 7
 
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I use reloader 15 with 77 gr smk's, excellent accuracy at 300 yds, that is the longest range at our club
 
well here is latest test of the .260 load workup so far. I still have not had a chance to tune the bullet jump yet, and probably wont for a few weeks. But just as it is I shot a 197 6X at 300 with it yesterday which is one of my better scores. The wind/mirage bit me on the butt but I was happy with the groups CEP numbers and the group height. Or should I say groups becasue if you look there are 2 distinct groupings on that target. One centered on the X where I read the mirage correct, the other to the left where I did not. The other 2 matches were both 193 so I ended up with a 97% overall which I was quite pleased with. I still ended up as #6 out of 8 though, there were a number of excellent shooters at the match

I like this method so much I am going to rework my 4350 with 140 grain Nosler load for my FTR rifle this month

tIZOiNl.jpg
 
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