Sticky Bolt with Accurate Load

5.56×250

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Yep, I read them. I had plenty of published load data that ran a lot slower too non-Tikka with factory barrel and custom barrels.
Could be that some rifles have a smoother bore out of the box and build less pressure from reduced friction. Ive always thought a slow barrel was the result of a slightly oversized bore diameter , but thats just thinking out loud and not based on any data.
 

jgs8163

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I agree. I’ve taken multiple Hornady OAL measurements with a once fired modified case and I seated 0.015 off lands so maybe it’s seating depth and charge.
Using the OAL Gauge is awesome. I use it all the time to get a baseline for load development. However, after making up some test loads it’s possible when you cam over the bolt onto the loaded round it pushes it ever so slightly further in the chamber. You may be even closer than you think.
 

jgs8163

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I’m on a learning curve. So you can get pressure spikes even off the lands like 0.010 or 0.015? I thought I was safe cause I wasn’t in the lands.
Usually the closer you are the more pressure you will have. This is why most published loads will have a COAL or CBTO measurement. .010-015 is about the thickness of 3-4 sheets of paper. COAL on the Hornady load data you mentioned earlier is 2.80 what is the COAL of your round?
 
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FEENIX

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Could be that some rifles have a smoother bore out of the box and build less pressure from reduced friction. Ive always thought a slow barrel was the result of slightly oversized bore diameter, but that's just thinking out loud and not based on any data.
Yes, differences in bore, lands, throat measurements and conditions, etc might cause velocity differences. This is why end users cannot use published load data as gospel. It is an excellent guide but the result was from their test rifle, which is different from the end-users' rifle.
 
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Seabeeken

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Yes, the more jump, the lower the start pressure. Think of it this way. If it is jammed into rifling it takes a lot more pressure to start that bullet into the rifling because there is no momentum. The longer the jump, the more momentum and lower start pressure. If you want to work at .015 off the rifling, that's all fine but you will need to find an accuracy node for that OAL with a lighter load. You also need to consider temperature. A load that is on the upper end of pressure but safe at 30*F will be way overpressure at say 70*. Many guys, me included, pick our bullet and powder, start loading at a known safe level and work up in .3 or .5 gr increments depending on case capacity until we see pressure and then back off. Do this at hot temperatures if you could be shooting in hot conditions and you will be fine at colder temps but developing a hot load in cold temps and then shooting in hot weather is going to be over pressure.
 

General RE LEE

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Usually the closer you are the more pressure you will have. This is why most published loads will have a COAL or CBTO measurement. .010-015 is about the thickness of 3-4 sheets of paper. COAL on the Hornady load data you mentioned earlier is 2.80 what is the COAL of your round?

Not with my load data journal but I believe COAL is 2.88 or 2.90. It’s up there but still fits in the Mag + Tikka magazine. I measure CBTO when seating bullets.
 

foul bore

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I am using 4451 at 40.5 gr behind a 144gr Berger , Fed 210 primer .020 off jamb with no problems very good grouping at 500 yds .899 . 4451 is very temp stable, more so than H4350 . I agree with above post on seat depth you could be closer than you think. I have done that. I am more interested in accuracy than speed.
 

RockyRandy

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My Hornady reloading manual shows IMR4451 start load 36.6-41.3 max,143 ELD-X
If you need more velocity Superformance powder start load 38.2 gr-44.7 max-velocity 2800 fps.
I know its hard to find any powder now but for the future IMR4350 can get you 42.0 max=2750 fps.
But work up to loads.
Old Rooster
Old Rooster I was wondering what you consider working up your loads slowly? Do you build your ladders at .3 gr or .5? Or what is your number?
 

Old rooster

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I recently loaded my 300 weatherby mag with a 200 gr ELD-X and this is my method and others may do it differently.
In the reloading manual you have white numbers and red numbers and I start in the white and go up in .5 until I get close to red then .4 increments.
I loaded 3 at 75.9 and 3 at 76.4 and 3 at 76.9 3 at 77.0 grs Re 22 and keep a log book with me when I shoot.
Record accuracy at each load but not velocity yet.I got positive node at 76.4
but kept going as you may get a positive node again.
At 76.7 accuracy fell off so I shot 77.0 and had hard bolt lift so I did not shoot the other 2 at 77.0.
Came home and cleaned the rifle well.I then work on bullet depth and loaded 3 at 3.510 then 3 at 3.530 and 3 at 3.560 and checked velocity at 2969 fps and hit a positive node at 3.560 and stopped there.
On a new rifle I work up in .2 grs at a time when I get close to red numbers.
That's my method and have used it since I was young.
I seen rifles over loaded and exploded on the bench with injury's 3 stations to the right,one serious so I try to stay out of red numbers but sometimes I get my best positive node at numbers in the red.
Old Rooster
 
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Old rooster

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I have to add something to the above post.
The 300 weatherby mag is a rifle that I have reloaded for since 1998 so I know about where I cross a red line.
I keep records for reloading and shooting,2 different note books (1 is for data and the other is range report) and every load gets a lot number including T L for Test Load 656R R but for proven loads I leave out T L for rifle as I reload for several handguns but EVERY load has a record that I can get to at a moments notice.
My older note books are in a stack of important papers.I know where they are but have not looked at them in years.
In 1967 I reloaded for 32 winchester special and started my reload procedure as lot number 001.
New rifles are unknown and I work up in .2 increments when even close to the red numbers.
If your reloaded cartridges blow up and cause injuries YOU are responsible for their injuries.
If a death occurs YOU are responsible.
It's impossible to be too careful.
Stay safe folks
Old Rooster
 
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