Broke another bolt.... your thoughts??

[Cajuntransplant]

Cajun,

Pressure signs like ejector swipes and flattened/cratered primers are clumsy indicators of overpressure. When I used to shoot F-Class those of us shooting .223 would run pressures of around 95K lbs (SAAMI peak for 223 is 55K lbs). We could not get bullets to the furthest targets at 1,000yards and still be supersonic without it. The bolt gun actions we used were typical big, solid REM700's and upwards. The cases did not look too bad coming out after that amount of pressure and were fine to reload. We used 450primers because they were extra thick and hard. The firing pins were thinner and the holes were tighter than normal so no tell-tale cratering signs. The cases were supported by properly headspaced chambers so no bulges. My point is, the signs of overpressure in spent cases are subtle, and by then in an AR it's too late.

That suppressor adds a bit to the pressure but if it's cracking bolts it likely means you were already on the raggedy edge before you fitted it.

I use 8208 for bullets under 120 and H4895 for 120 and over.
For the 107SMK it's 28.5/8208 which is 2,513 - 2,527fps (depending on the ambient temperature).
For the 123ELD it's 27.8/H4895 for 2,429 - 2,434fps.

Lapua brass
2.24" OAL
CCI450 primers.
Radar chronographed.

I'm thinking if you can match those pressures in whatever powders you have it's not going to cost you any money. It's also the solution with the least effort. See how that goes and if it cures the symptoms (chipped bolts) then whatever the problem is, or was, is moot. If you get another chipped bolt then my money is on the lugs not being square, and that is a new barrel.

Klem

Thanks again for all the info. I love learning from people that know more than me and have been doing this longer than I have. I looked through my load data and without suppressor I was actually even faster, by about 25fps on average depending on time of year. I’m guessing that adding the suppressor is compounding everything with the speeds and pressure I’m getting. Also to note I’m running faster than my friends rifle with almost same load data and he’s got a 20” barrel. Interesting to know about the pressure signs and how that when pressure shows at the casing it’s already too late. Never thought about it that way. Hoping I don’t have a bad barrel but I’m thinking the pressures are the cause and suppressor is adding to it and making the problem known.