What did you do in the reloading room today?

[Sinistram]

I loaded a fire forming load in 50 new Lapua 22-250 cases to get them ready for load development of a 52gr Sierra MatchKing.

The rifle is already pretty accurate for hunting and general purposes, but I'm using this opportunity to go for ultimate target precision. I'm not breaking new ground with the combo (probably with Varget) so it's only a matter of arranging the variables to what shoots best for me.

 

[Q_Sertorius]

I sighted in a new-to-me Tikka T3X in .223. And I [temporarily] rescued this little guy from the farm dogs.

 

[Q_Sertorius]

I have been struggling with my .243 116-grain TMK load this morning. As I mentioned elsewhere, I had three popped primers in around sixty shots when I was at S2H. I had not had a previous issues with this load. I think it was due to not seating them deep enough and possibly having the ammo in the sun for a while.

This is the .243 load:
Once-fired Hornady brass
H4350 - 40.0 grains
116-grain TMK
Winchester Large Rifle Primers
Loaded to 2.94” COAL (2.944” if we are being precise, although at least one round measures 2.942”)
Getting 2750 FPS

I would prefer to load them shorter, because these rounds won’t load in my nice Waters magazines. But, I don’t seem to get good accuracy seating them shorter (I’ll post up a 10-shot group at 2.89” COAL shortly).

 

[Q_Sertorius]

This is my 2.89” COAL group:

This was a typical group I shot before with 2.94” COAL.

 

[Q_Sertorius]

The 2.94” rounds are clearly too long.

 

[43.6N]

The 2.94” rounds are clearly too long.

Couple of thoughts specific to why you suddenly had pressure issues:
1. Case stretch? What’s the fired case length on your popped primer brass.
2. Humidity/Altitude change. Sun exposure is an easy answer, but maybe other environmental factors contributed. You loaded those in Va? Then travel to MT where you started noticing the pressure issue? Do you have any more of that lot of ammo? You could leave it in the sun/hot dashboard, and rapid fire a few to see if you can recreate the pressure now that you’re back home.

I’m thinking trapped humidity in the powder off gassed at the higher elevation, lower humidity, leading to a more energetic burn.

as far as the OAL: Might be worth going even shorter to see if accuracy changes. 2.825 OAL?

 

[Q_Sertorius]

Couple of thoughts:
1. Case stretch? What’s the fired case length on your popped primer brass.
2. Humidity/Altitude change. You loaded those in Va? Then travel to MT where you started noticing the pressure issue? Do you have any more of that lot of ammo? You could leave it in the sun/hot dashboard, and rapid fire a few to see if you can recreate the pressure now that you’re back home.

I’m thinking trapped humidity in the powder off gassed at the higher elevation, lower humidity, leading to a more energetic burn.

Thanks.

So, to experiment, I left 10 of the 2.94” rounds in the sun. Fired 7 shots, popped a primer. Stopped. Then another primer fell out of a pocket while I was examining it. So, not good, Bob. My group sucked too.

The 8th round is the one that shows obvious signs of hitting the lede. So, I think I am back to the drawing board with this load.

I measured some cases and I am seeing up to 0.007” difference in length. This is also clearly causing a variation in COAL, by about the same difference. So, even though it was only once-fired and full-length resized, I think I should have trimmed them all?

Or maybe I just need to buy a lot of good brass and stop screwing around?

Anyway, this is all a reminder of why I don’t love reloading. And I probably just need to get more consistent on my process…

 

[Q_Sertorius]

All the cases that show pressure signs are shorter than the ones that don’t.

 

[NWBLKTAIL]

I have been struggling with my .243 116-grain TMK load this morning. As I mentioned elsewhere, I had three popped primers in around sixty shots when I was at S2H. I had not had a previous issues with this load. I think it was due to not seating them deep enough and possibly having the ammo in the sun for a while.

This is the .243 load:
Once-fired Hornady brass
H4350 - 40.0 grains
116-grain TMK
Winchester Large Rifle Primers
Loaded to 2.94” COAL (2.944” if we are being precise, although at least one round measures 2.942”)
Getting 2750 FPS

I would prefer to load them shorter, because these rounds won’t load in my nice Waters magazines. But, I don’t seem to get good accuracy seating them shorter (I’ll post up a 10-shot group at 2.89” COAL shortly).

You’re putting forth more effort than I would for one bullet, I’d scrap it use another suitable alternative and sell the rest.

I’m sure you’ve heard that before, I’ve tried to make bullets shoot and sometimes they just won’t. Sound like yours will under specific circumstances that’s too finicky for me.

 

[43.6N]

Thanks.

So, to experiment, I left 10 of the 2.94” rounds in the sun. Fired 7 shots, popped a primer. Stopped. Then another primer fell out of a pocket while I was examining it. So, not good, Bob. My group sucked too.

The 8th round is the one that shows obvious signs of hitting the lede. So, I think I am back to the drawing board with this load.

I measured some cases and I am seeing up to 0.007” difference in length. This is also clearly causing a variation in COAL, by about the same difference. So, even though it was only once-fired and full-length resized, I think I should have trimmed them all?

Or maybe I just need to buy a lot of good brass and stop screwing around?

Anyway, this is all a reminder of why I don’t love reloading. And I probably just need to get more consistent on my process…

Gotchya. So if I’m understanding, the original OAL variation is enough to push some to kiss the lands? Going shorter seems very reasonable. And dropping the powder charge by 0.2-0.5gr also seems very reasonable.

I made a quick edit to my original response.
Going even shorter may give some accuracy. 2.825 perhaps?

 

[Q_Sertorius]

You’re putting forth more effort than I would for one bullet, I’d scrap it use another suitable alternative and sell the rest.

I’m sure you’ve heard that before, I’ve tried to make bullets shoot and sometimes they just won’t. Sound like yours will under specific circumstances that’s too finicky for me.

I agree. Back in March and early April, I had a run of about 50 shots where the groups were great (0.9-1.1” 10-shot groups), velocity was consistent, no pressure signs, etc. I thought it was on the money.

And then problems show up once the ammo gets a bit hot.

 

[NWBLKTAIL]

I agree. Back in March and early April, I had a run of about 50 shots where the groups were great (0.9-1.1” 10-shot groups), velocity was consistent, no pressure signs, etc. I thought it was on the money.

And then problems show up once the ammo gets a bit hot.

Back it down .5gr or 1 like you mentioned a few post earlier see what happens still plenty of time before fall to dial it in.

 

[Q_Sertorius]

I appreciate the replies.

I’m going to give this rifle a break and go do something else. Maybe there’s a groundhog out there with a death wish?

 

[he_lives]

The 2.94” rounds are clearly too long.

@Q_Sertorius I read the results you posted in the 116 TMK thread and was inspired to order a Tikka 243 takeoff barrel and 300-ea 116 TMK's to try out. Pushed at 2,700-fps they seem to hold a slight edge over the 108 eld-m and I'm hoping they continue to prove that they perform well terminally. So I'll be following along as you sort this out.

Initial thoughts I had:

• Approximating your load in GRT, you should only be at ~57k psi. Your thought of the bullet being into the lands, creating some added initial pressure tracks.
• How did you determine the COAL where the bullet contacts the lands?
• I'm assuming your blown primers were only with one batch of reloaded ammo using Hornady brass? Do you have other brass available to try? I ask because I've had two occasions where Hornady brass gave me issues. Once with 25-06 brass that blew primers below book max. More recently, I had a batch of 6.5cm brass that was showing pressure with 39.5gr of H4350 behind 140 eld-m's. It would occasionally blow primers with 40gr, which should have only been an estimated 55k psi. Switching brass solved the issue.