Need help with pressure/velocity spike

[wind gypsy]

I shot 5 factory loads first to make sure my chronograph was set up exactly how i wanted it. Plus i like to shot a few times before the "real" group test. I let it cool down for 5 minutes. Then I shot my first 5 round group. Everything was great. ES of 7 and 0.5'' 5 shot group at 100y. Let it cool 5 minutes then shot the next 5 shot group. That is when all hell broke out.

If it was 63 degrees and you are shooting 5 round strings followed 5 minute breaks, I doubt your barrel is really cooling that close to ambient. A rough example:
-First 5 round string of factory - barrel heats up to 200% of ambient temp, after 5 minutes is down to 150%
-Second 5 round string (handload) barrel heats up to 250% of ambient, after 5 minutes is down to 180%
-Third 5 round string (handloads) - round in chamber has time to heat up more before firing, following rounds do the same

That scenario is a possibility. I wouldn't be surprised if it is a combination of a few items.
-Could be fouled barrel or carbon ring
-Could be barrel speeding up and creating more pressure
-Could be ammo getting hotter before shooting
-If you previously loaded a ladder with virgin brass and are now using once fired - it is likely to show pressure signs earlier and you'll need to develop load based on fired brass.

The above is why i try not to get too far into load development until I have a broken in barrel and fired brass.

 

[archp625]

If it was 63 degrees and you are shooting 5 round strings followed 5 minute breaks, I doubt your barrel is really cooling that close to ambient. A rough example:
-First 5 round string of factory - barrel heats up to 200% of ambient temp, after 5 minutes is down to 150%
-Second 5 round string (handload) barrel heats up to 250% of ambient, after 5 minutes is down to 180%
-Third 5 round string (handloads) - round in chamber has time to heat up more before firing, following rounds do the same

That scenario is a possibility. I wouldn't be surprised if it is a combination of a few items.
-Could be fouled barrel or carbon ring
-Could be barrel speeding up and creating more pressure
-Could be ammo getting hotter before shooting
-If you previously loaded a ladder with virgin brass and are now using once fired - it is likely to show pressure signs earlier and you'll need to develop load based on fired brass.

The above is why i try not to get too far into load development until I have a broken in barrel and fired brass.

Very well laid out, I like the temp idea. But like you said i think i have several things going on all at the same time. This makes it really hard to figure out whats wrong.

I will say the brass that i am doing my reloads are all once fired brass from the factory shots. I have 6 factory loads left to shoot then I'm all once fired brass.

 

[VAHunter01]

Couple oddball questions...

What dies are you using?

How far off the lands are your loads?

What is your neck tension in that brass and is it somewhat consistent?

 

[archp625]

Couple oddball questions...

What dies are you using?

How far off the lands are your loads?

What is your neck tension in that brass and is it somewhat consistent?

I’m using Hornady Dies, 0.020” off the lands. I do not know beck tension. I don’t have that kind of die.

 

[wind gypsy]

I’m using Hornady Dies, 0.020” off the lands. I do not know beck tension. I don’t have that kind of die.

You can measure neck tension by comparing diameter of sized brass necks to the necks after seating bullets.

 

[ResearchinStuff]

You're the second guy in 24 hours with crazy velocity/pressure changes on this forum, but your situation seems a bit more complicated.
You're for sure overpressure, but it's not really clear why yet. If it's a reloading issue the questions before should help sort it out. if it's a cleaning problem I can't help you.

Did anything about your loads change? New box of primers, new jug of powder, new box of bullets, new box of brass, new battery in your digital caliper, chargemaster plugged into a new outlet?

Do you anneal? If so, what's your annealing method?

Are your shells in direct sunlight before you shoot them? Is it windy or still where you're shooting? Did the fast shells feel warmer than the air when you were putting them in the gun?

Whats your case water capacity before firing, after firing, and after resizing? Is there any difference between the overpressure cases and your cases that were ok?

How far back are you moving the shoulder when you resize?

What chronograph do you have, and where is it located when you shoot?

Sent from my LM-G820 using Tapatalk

 

[VAHunter01]

You can measure neck tension by comparing diameter of sized brass necks to the necks after seating bullets.

Yep, I’d try this on a handful of them. At least you’ll be scratching that off the list.

 

[archp625]

I went out today and did a little shooting. Temperature was 37 degrees. Here is what I did and the numbers.

1) Factory ELD-X 3079 fps (very similar to what I got a couple days ago and 122 fps faster that when i did my initial ladder test)

Let cool for 10 minutes (set a timer)

2) 54.7 grains at 0.040" off lands 2954 fps
3) 54.7 grains at 0.040" off lands 2988 fps
4) 54.7 grains at 0.040" off lands 2972 fps

ES is horrible. Not sure on this one but shot a 1 hole ragged group.

Let it cool 30 minutes (set a timer)

5) 53.0 grains at 0.020" 2865 fps (64 fps faster than first ladder test)

Let cool for 5 minutes (set a timer)

6) 53.5 grains at 0.020" 2895 fps (104 fps faster than first ladder test)

Let cool for 5 minutes (set a timer)

7) 54.0 grains at 0.020" 2928 fps (56 fps faster than first ladder test)

Let cool for 5 minutes (set a timer)

8) 54.5 grains at 0.020" 2971 fps (54 fps faster than first ladder test)

Let cool for 15 minutes (set a timer)

9) Factory ELD-X 3073 fps
10) Factory ELD-X 3077 fps
11) Factory ELD-X 3072 fps

That's my last factory load so I would have enough one shot brass to reload.

mt take away from all this:

1) My barrel sped up between 50-75 fpsf from the first ladder test. I have 137 rounds down the barrel now. The first ladder test was shot shots 81-92.

2) The 54.7 grain loads that were over pressure were not once I loaded them 0.040" off the lands instead of 0.020" off the lands. ES went to crap but the group got tighter.

3) Waiting between shots looks to help cool things down.

Now my dilemma is do I drop my powder charge in the 54.0 - 54.4 grains and keep is at 0.020" off the lands or do I keep my original load of 54.7 grains and load 0.040" off the lands (the ES was bad).

Looks like my gun likes to be at the 2930 - 2970 fps range.

I'm open to any and all suggestions. Please remember I am a rookie at reloading.

 

[Justin28345]

A lot of things could be going on. With the number of rounds you have through the barrel seeing velocity climb is normal in the 100-150 round range. The barrel is “ Settling In” and it will speed up. You could have developed a carbon ring in the chamber. Give it a good cleaning shoot about 15 rounds through it and repeat your test.

 

[VAHunter01]

Sounds like you’re getting it figured out.

It very well could have just been your barrel speeding up,settling in, or whatever. I still feel like you must have been right on the edge though, if that’s true.

I would let the rifle decide what you do with your loads. I’d take it out to 300, or better yet 500 yards and see what it looks like there.

How much are you sizing your brass?

I would check you neck tension as well sometime, as Wind Gypsy described above. Also take a rough look at runout. If you don’t have a tool, and very imprecise way to check for big discrepancies,is to lay two loaded rounds on a flat surface with the bullet tips touching one another on the ends. Roll them around a bit and hopefully the tips will point directly at the other.

The more things you can prove are in line, the list of things that can be causing your woes gets smaller!

I’ll repeat myself here, and say once again, I’ve had bad luck with Hornady brass. It’s always suspect to me when someone is having strange problems.

 

[greyghostnw]

maybe a headspace problem with brass? take some para cord and a dime pull your firing pin out of your bolt, put bolt back in action, take a piece of your sized brass with no powder/bullet to be safe and load into chamber ,your handle should close with little pressure .002 is a good minimum for shoulder bump imop. if your not setting your shoulder back enough pressure increases.

 

[Rover31]

Question,
When is the last time you have cleaned your barrel?
I neglected a barrel and had problem with pressure. cleaned and all better

 

[greyghostnw]

Question,
When is the last time you have cleaned your barrel?
I neglected a barrel and had problem with pressure. cleaned and all better

After every session shooting to bare metal lately. Although i think i like every 40-50 firings with eldx’s. Neither meathod has shown much difference imop. After this weekend i think its the windage turret in my nxs. Single avg, std, es and ill shoot, zero re fire and move back to where it was. Feels like ive done my part and ill send it in to gave looked at, thanks for reply.

 

[ResearchinStuff]

After every session shooting to bare metal lately. Although i think i like every 40-50 firings with eldx’s. Neither meathod has shown much difference imop. After this weekend i think its the windage turret in my nxs. Single avg, std, es and ill shoot, zero re fire and move back to where it was. Feels like ive done my part and ill send it in to gave looked at, thanks for reply.

The windage turret is causing pressure spikes?

 

[greyghostnw]

The windage turret is causing pressure spikes?

The windage turret is causing pressure spikes?

not at all. windage turret is possibly tracking off