Stupid reloading question

[nidahunter]

I am working up a load for my Tikka 7mm08, and have a dumb question. The maximum load in the Nosler manual for the 140 gr accubond is 46 grains of IMR 4350. I started at 44 grains, worked my way up in 1/2 grain increments and ended up at 47 grains (which is over maximum stated.) I have always heard that one way to know if a load is too hot is if the primer "craters". Does anyone have a picture of this? The primer on the 47 grain shell looked the same as the 44 grain shell. Does this mean I am safe at 47 grains, and can I try 47.5 and 48? I got the best group at 47 grains, just want the fasted safe load I can make.

 

[Ben Lamb]

Check out this link: http://www.massreloading.com/reading_pressure_signs.html

Don't just go by the primer and don't get addicted to speed. Find the load that you shoot the most accurately and go with that.

 

[nidahunter]

Thanks for the link, I should have said I want the fasted accurate load I can get safely.

 

[Ben Lamb]

Thanks for the link, I should have said I want the fasted accurate load I can get safely.

Amen. Lord give me that perfect load that's 100 fps faster than factory and shoots .5 MOA.

 

[emrah1028]

Most experts will agree that the "cratered primer" test is a very, very poor indication of pressure. Almost useless. Do not go by this. The cratered primer thing came about in the early years of reloading before we had proper pressure measuring devices and science to tell us exactly what's going on during the firing cycle. You obviously have seen for yourself that your max load is no different (primer-wise) than the 44 grain load. In fact, forget about looking at primers altogether.

Emrah

 

[MtnWest]

Do you have a chrono? Loading to a velocity with the exact brass, primer, powder, bullet and barrel length listed is best next to having pressure equip. You may get there 2 grains sooner or .5 past max depending on your barrel. The tolerance on a barrel one way or the other will affect pressure and therefore velocity. Same with powder manufacturing lots.

Primers used in 50k psi calibers and 63k is comparing apples and oranges. There are many people shooting 70k psi I'm sure because bolt lift and primers look ok to them. I'm not immune to wanting the top accuracy/top safe velocity either but when my dad owned his shop and built rifles he told me early on if I wanted to load a 30-06 to warp speed to just by a 300 mag.

Have fun with your -08. Great great caliber, I have it's older sibling the 7x57 I passed onto my son.

 

[Ben Lamb]

Do you have a chrono? Loading to a velocity with the exact brass, primer, powder, bullet and barrel length listed is best next to having pressure equip. You may get there 2 grains sooner or .5 past max depending on your barrel. The tolerance on a barrel one way or the other will affect pressure and therefore velocity. Same with powder manufacturing lots.

Primers used in 50k psi calibers and 63k is comparing apples and oranges. There are many people shooting 70k psi I'm sure because bolt lift and primers look ok to them. I'm not immune to wanting the top accuracy/top safe velocity either but when my dad owned his shop and built rifles he told me early on if I wanted to load a 30-06 to warp speed to just by a 300 mag.

Have fun with your -08. Great great caliber, I have it's older sibling the 7x57 I passed onto my son.

Good stuff. I've got loads that are safe in one manufacturer's brass and over-pressure in another. Keeping your variables all the same leads to the best load.

 

[MtnWest]

You are absolutely right Ben, that is very overlooked. I've got a handloader mag where in the 7 mauser there was over 125fps difference just between rem, fed and win brass, the win in this case being slower due to thinner walls and a few grains more capacity.

Here is a link for those interested.... http://edoqs.com/download/97a39df894d3cf3f17a423a2e8ecf1bb

 

[nidahunter]

I do not have a chrono, but sounds like I should. I read the link from Ben and nothing shows any sign of pressure, but I think I will stop at 47 grains. It was the most accurate of them all so is a good compromise. Thanks for the replies!

 

[Biscuit Hunter]

Most experts will agree that the "cratered primer" test is a very, very poor indication of pressure.
Emrah

I was noticing some cratered primers on loads that "should" be safe, so I did some research on the subject. One cause that was mentioned was out-of-spec/overly-large firing pin holes in the bolt face. I compared the bolt from the rifle in question to all of my other bolts, and sure enough, the hole was noticeably larger.

Here's what the primer looked like:



The book data I was working with was fired through a 22" factory barrel, in Hornady +P cases. The WW +P cases I was working with were, on average about 4 grains heavier, indicating slightly less capacity. My load was producing equivalent velocity with 0.8 grains less powder, and all of this was 2.2 grains and 100 fps under book maximum for the bullet/powder combo. So... despite a bit of cratering, I feel that these loads are safe in my rifle. Hopefully I'm not missing something?


nidahunter--

Definitely get a chrono. You won't regret it.

Also, once you find a powder charge-weight that you like, you can play with seating depth to see if you can wring out a bit more accuracy. Try going in +/- 0.010 increments.

 

[idahofishnhunt]

I shoot 48 grains of H4350 with 140 accubonds in my 7-08 and get 2863 fps, thats as high as I'm going. I shot 47 grains of IMR4350 with 139gn SST's without any pressure issues, but also didn't want to go higher as the kernels are bigger with the IMR and it takes up more room in the case. It's all about your own barrel though, but I don't think I would go any higher then 47 grains with IMR4350, you're probably crunching the powder good already when seating your bullet.

 

[MtnWest]

Biscuit, I don't think you're missing anything. Sounds like you've been meticulous working up safe loads.

nida, The $100 shooting chrony (in fact $75 on amazon right now that I did a search to verify the price) has always done well for me. I've owned two (long story but I double lunged the first with a 200gr hardcast 10mm- not even from my gun!) and wouldn't hesitate to recommend them. "Better" ones can be had but for the casual reloader they are hard to beat. I shoot bows, pellet guns, you name it through them. I'd probably throw a football across it if i wasn't afraid of buying a third.

 

[Pagosa]

If you see marks on the butt of case from excess pressure you need to reduce loads. I load several grains under max in 7mm, 30 cal, and 338 and can't tell any difference in knockdown or bullet drop.

 

[MKotur325]

One last thing to consider before hunting with that load. IMR 4350 is not all that temperature stable. Before you decide 100% on a load, you should shoot it at hotter air temps. This can effect chamber pressures and could take a safe load into bad places during hot hunts. The worst case scenario is you might have to back down a half grain or so off max... I ended up having this happen with my .325 with H4350 which is more temperature stable. Started getting sticky bolt lift and some marring on the case head starting around 70-75 Degrees. Most likely will not be an issue, but never hurts to be safe.

 

[devon deer]

One last thing to consider before hunting with that load. IMR 4350 is not all that temperature stable. Before you decide 100% on a load, you should shoot it at hotter air temps. This can effect chamber pressures and could take a safe load into bad places during hot hunts. The worst case scenario is you might have to back down a half grain or so off max... I ended up having this happen with my .325 with H4350 which is more temperature stable. Started getting sticky bolt lift and some marring on the case head starting around 70-75 Degrees. Most likely will not be an issue, but never hurts to be safe.

I shoot IMR4350 in my 30-06 and this is news to me in relation to temp, not something we worry about in England, but are you saying that when i come back to Montana if the temp is well below zero i will have problems?

Cheers

Richard

 

[1_pointer]

I shoot IMR4350 in my 30-06 and this is news to me in relation to temp, not something we worry about in England, but are you saying that when i come back to Montana if the temp is well below zero i will have problems?

Cheers

Richard

Not that you 'will' but that it is quite possible. H4350 is purported to being much more temperature stable and is part of the Extreme series of powders. One well known gunwriter states that this often is more evident on the cold end of the spectrum. Generally shown by a loss in velocity, which may or may not change point of impact at close ranges and definitely will at longer ranges. He also states that nearly all powders increase in pressure above 70ºF, just some not as fast. IIRC he tries to test for this at 70º and 0º.

 

[sbhooper]

Cratering can show over pressure, but it is not foolproof. I have had two Savage 7 mags that both have shown cratered primers on safe loads. I think it is strictly the bolt face. Bolt lift is a real indicator in most circumstances. If you are getting a hard bolt lift, then you had better start backing down. As far as the primer goes, If the primer is extremely flattened, I think that is more of an indicator than an actual cratering effect.

There is really no reason to ever go beyond the safe listed max on a cartridge. You are not going to gain enough to be worth the potential danger.

 

[MKotur325]

I shoot IMR4350 in my 30-06 and this is news to me in relation to temp, not something we worry about in England, but are you saying that when i come back to Montana if the temp is well below zero i will have problems.

In all likely hood, No. With all powders there is some amount of pressure change between hot and cold temps, however small it may be. Biggest difference you may see in below zero temps is some velocity loss. Easiest way to test, next time you head out to the range with your '-06 bring a cooler full of ice and your chrono. Put a few rounds of ammo in a plastic bag, on ice for an hour or two before you leave. Shoot them over the chrono while still cold. This is as good as simulating freezing temps. Note any velocity change from ambient temp to freezing, you can extrapolate from there. Some powders can change up to 2-4fps/degree F of temperature change.

Going from cold to hot can be more dangerous as higher temps increase chamber pressures, slightly. If shooting over book loads, its worth testing before it becomes a final load.

 

[jryoung]

RL-22 has a big reputation for temp sensitivity. I didn't think it was that big of a deal until I ran into pressure signs at warmer temps. In CA this can be a big issue, and while I developed loads at 65ish degrees, 80 was too much.

Back to the drawing board. Hopefully I can find a powder that can get me back to 3,100fps with 145LRX since my CDS dial is engraved for it.

 

[Ben Lamb]

Cratering can show over pressure, but it is not foolproof. I have had two Savage 7 mags that both have shown cratered primers on safe loads. I think it is strictly the bolt face. Bolt lift is a real indicator in most circumstances. If you are getting a hard bolt lift, then you had better start backing down. As far as the primer goes, If the primer is extremely flattened, I think that is more of an indicator than an actual cratering effect.

There is really no reason to ever go beyond the safe listed max on a cartridge. You are not going to gain enough to be worth the potential danger.

Good stuff Hooper. Here's an example from yesterday. I've been working up loads for the 88 winchester in 33 wcf and have only had a few primers that were normal after firing. Those loads were Dad's from the late 60's, early 70's with cast bullets. He did have one factory load that didn't give any primer flow.

My loads have been on the high side with 49895, but not over max. I started at 43 grains and moved up to 45. Every load had primer flow. Extraction was nonproblematic at 43.5 grains but the primer was extremely misshapen. That could mean either headspace problems (which is doubtful since it's been gone over by my smith) or I'm right on the edge of pressure. Either way, it looks like I'll be aiming for 2000 fps instead of 2200.