primer seating depth

hounddawg said:
The only possible benefit I can see of having primers seated perfectly would be consistent lock times. Bear in mind here we are dealing in milliseconds when discussing lock times. A millisecond could affect of difference could affect the POA in a minor way on a unsupported rifle. When using a bipod or front rest I seriously doubt there would be any effect at all since the rifle is being held perfectly steady.
Click to expand...
Interesting info on lock times:

https://en.wikipedia.org/wiki/Lock_time

As compressed springs weaken over time, lock time increases over time. Primers are struck with less force.

First indicator is easily seen shooting at long ranges. Primers have less fire and wider spread and average muzzle velocity is less. Need to increase sight elevation. Watched one person replace a weak Win 70 striker spring and his 308 Win vertical spread at 1000 yards went from 2 MOA to 1 and needed about 1.5 MOA less sight elevation.
 
Last edited:
cptjack
If your interested in target shooting accuracy but not a serious competition shooter . Just make sure your primers bottom and are below the base of the case , capable of shooting a ragged hole group if you have a good rifle and you do your part . If your looking for that one hole group then your in for a long ride . I like shooting benchrest but I'm not capable of shooting that one hole group , a half inch group yes at 200 yards better a 1/2" ragged hole . Now I stopped going down that rabbit hole , stick with the same load and enjoy shooting more , some days more then others . That's on me , not the round or rifle . I do enjoy sharing information on this site , good group of guys .

Chris
 
It's too easy to cut the pocket to the same depth and set the primers to the same depth below the case head. This is just one many little tricks I have experimented with.
My goal in this exercise to lower SD was to form procedures that would give the best results every time with any brass of one brand.
 
cw308 said:
Just make sure your primers bottom and are below the base of the case , capable of shooting a ragged hole group if you have a good rifle and you do your part.
Click to expand...
Does doing ones part mean pointing the LOS a half MOA out at 8 o'clock as the firing pin starts moving when the round that's destined to go a half MOA out at 2 o'clock out finally does?

Both the LOS and LOF angles and direction are constantly changing while the bullet goes through the barrel.
 
Last edited:
Bart B
Your question reminds me of the questions asked in one of those defensive driving classes to lower your insurance. I just want to bang my head on the table.
 
@ CW308

I think what Bart is wondering if do you wiggle the gun around as the bullet travels down the barrel to compensate for a weak firing pin :confused::rolleyes:
 
cw308 said:
Bart B
Your question reminds me of the questions asked in one of those defensive driving classes to lower your insurance. I just want to bang my head on the table.
Click to expand...
Last time I did an extensive investigation on this popular claim of what happens to make some group sizes the smallest, I came to the same conclusion as previously looked into.

We always do our part with every group we shoot. The smallest group happens as often as the largest group: once.

Who's holding, aiming, pulling the trigger then pointing the barrel before the bullet leaves?
 
I don't compensate for anything , as far as lock time I changed the firing pin and spring for a faster lock time but I didtn't see any improvement in my groups . I think for me at my age I'm OK with it , only shoot for fun . I want to share this , I take a walk every day in my neighborhood with my wife , after seeing this older chinese couple on our walk all the time , we started talking and he was a target shooter . I aasked what did you shoot , he said 30BR . He's walking with a walker and problems with speach do to Parkinson's . Anyway , when I got home I looked up 30BR and there he was , Clark Shen , even holds world records , I was blown away . He showed me his trophies and a wall covered with plaques for 1st and 2nd place 100 , 200 and 600 yard matches.
 
Last edited:
hounddawg said:
post # 9 of this thread
Click to expand...
I don't think lock time will always be the same with all primers seated equal distance from the case head. Striker pin tip travel distance to primer will still vary a couple thousandths or more. Case heads have at least that much spread in clearance to the bolt when rounds fire. A couple housandths more is common.
 
Last edited:
On group size do you really think by seating primers at different depths leaving different distance from primer to bolt face and how light your firing pin or how strong your FP spring is makes a different in your group size . We're not talking about your rifle locked in place and pinching off on the trigger but real shooting , make a difference in group size ? I rather use my new excuse that rounds loaded in the 80's were more accurate .
 
cw308 said:
On group size do you really think by seating primers at different depths leaving different distance from primer to bolt face and how light your firing pin or how strong your FP spring is makes a different in your group size . We're not talking about your rifle locked in place and pinching off on the trigger but real shooting , make a difference in group size ?
Click to expand...
Yes. If you can shoot your stuff no worse than 3/4 MOA.

Shoot through a chronograph several 10 shot groups with the firing pin spring cut one turn off after each until primers no longer fire. Don't change the sight settings.
 
Last edited:
Why would you do that , That's like saying , trim down the firing pin until the primer fails to fire . Both would sure screw up a 10 shot group. During normal primer seating maybe a difference of one thousandth but the round would go off , in that case would that make a big difference , I don't think so , to be fair , I'm not that good of a shot.
 
I once had a spring get so weak I had to jerk the rifle back when I pulled the trigger to get it to fire :eek::p:D:rolleyes:

joking of course
 
cw308 said:
What would be the round count for the spring to fail to that degree?
Click to expand...
A few to several thousand depending on its metal quality, where in its load range is it operated in and how much it's compressed when the rifle's stored.

It's easy to measure firing pin spring force in cocked and fired lengths. Then compare that to factory specs. Some folks use stronger springs.

https://www.gunsprings.com/Rifles & Shotguns/cID2

Pins also have to dent primer cups sufficiently to uniformly fire them.
 
Last edited:
No.

Seat the primer to firmly bottom out. (period)
Just don't crush it.

^^This^^

Too many people who don't know what they are doing overthink what they don't know.
 
You must log in or register to reply here.
Back
Top