Load issues today

[Proarc]

Shooting my .260 today I noticed my long range shots were not grouping like normal(800yds).

Looking at my cases there is a small trace of black smoke residue like a leaking primer. This was on 7 of the 30 rounds I fired.

Load is 43g of H4350 in a winchester case and FGMM 210M primers.
Bullets are 139 Scenars Seated 10 tho off the lands.
Rifle is a Terry Cross built .260 that has been flawless. This is kind of a standard load for the .260's and I have shoot about 900 of this load with no issues. I load 500 rounds at a time so primers and powder are from same lot.

Temps were 90degs today but that is normal for Florida in June. Unfired rounds were kept in the shade. 3rd time loading on this batch of cases and primers were not loose going in. Kind of stumped on what is happening and need to figure it out before I load another 500 round batch.

100yd group was good with 10 shots going inside a inch.

Any ideas or suggestions?

Thanks,

Greg

 

[Paladin2147]

Re: Load issues today

Bolt sticky? Other signs of pressure? How did the "leaky" primers feel when you knocked them out? Did a new primer feel loose going back into these questionable ones? Have you messed with the primer pockets - at all during prep.? From 100 to 800 yards - a lot of things can take a crap on you.

 

[Proarc]

Re: Load issues today

Bolt lift was like other rounds, very easy. Primers looked the same as unsmoked primers and had not even started to flatten.

I would not have looked at them if I had not had a shot gun grouping. Target was a 8 inch plate at 835 yds, usually with a good wind call not a hard target and shoot it 3-4 times a week. With these rounds was hitting off the plate randomly. One would be high right. then the next low left. <span style="font-weight: bold">I </span>have always been the defect when this has happen in the past, but the primer leakage has me looking at load/case?

 

[Aimsmall55]

Re: Load issues today

Not sure if your load is hot bc I don't shoot a .260 but in my experience win brass has horrible primer pocket longevity. If you are loading hot this is possibly the problem. My .300 win mag gets 2 to 3 at most before I toss em. Just thin brass all the way around. I wouldn't worry about your load, just your brass. I know lapua is expensive but it pays for itself. All I shoot for the calibers it manufactures in which I own. Or maybe it was just a bad day. Hell everbody has em. If you have a hand primer you'll be able to feel the loose pockets. Good luck... I'm sure you'll figure it out

 

[Proarc]

Re: Load issues today

I would love to use Lapua brass, but most comp chambers wont accept it. Cant even find .260 brass at all these days.

 

[Aimsmall55]

Re: Load issues today

Comp chambers...??? Elaborate if you would. Do you mean the weapon??

 

[Proarc]

Re: Load issues today

Sorry, Seems like most match chambers from Gap, Terry Cross and others are cut with a reamer thats to tight to use the Lapua brass in .260. I belive Lapua is made to a different spec. This is from my experence from a lot of .260 shooters at matches. I am not speaking for any gunsmiths just my own experence.

 

[Aimsmall55]

Re: Load issues today

Interesting. I have a GAP Crusader in .308 and it & I love lapua brass. Nice to know. Fixing to build a .260 or a 6.5 creedmore & was planning on using lapua brass. Wonder whats going on. Got a buddy whose a damn encyclopedia on GAPs. Hell he owns 6 or 7 of them. He'll know. I'll pm you with what he says. That just doesn't make sense to me and I know your frustrated.