Newbie 308 300 wm 338 lapua ?'s

[IA Shooter]

New guy here with ?'s. Started reloading bout yr ago for my 300 wm(noreen assassin). Using imr 4831 200 grn eld-x bullets. Started experimenting between 69-74 grn powder. Didn't have chrony so I went with grouping. 74 was best 69 or 70 next best. Then read that this is way to hot in one book but others use it. So how much is to much? Got chrony recently and just did few test. at 69 grn 2740, 70grn 2790, 72 grn 2930(worst group) 74 grn 2990 best grp .75" 100 yds. Want optimum velocity but want to be safe and not damage rifle. What are you guys getting for velocity and what book or site has best advice for max loads. Rifle cycles perfect. On 338(noreen bad news) same ? how much h1000 is max? seems everyone has diff data. Currently using 89 grn(tackdriver) cause somewhere stated as top load but its little slow. Loaded 92 grn when first got it and grouped great but again read that its to hot. This rifle also cycles perfect with higher loads. On 308 just got some 178 eld-x bullets and want to know if anyone has loaded up any with 8208 xbr. Works great for 155 bullets but was told it sucks for heavier bullets. Thanks in advance

 

[Beneviolence]

A bit hard to follow what you're saying and what you're asking...but instead of going for specifics, I think people will offer general advice for good load development practices. Start with brackets (5-10 shots per bracket, 0.3-0.5gr change per increment) in the range of what your manuals say and look at the precision and velocity consistency. The ladder test is another helpful one (look at the sticky). Know pressure signs (bolt lift resistance, primer integrity, and brass lengthening are some guides) and follow the manuals.

 

[IA Shooter]

I guess what I'm saying is it seems every manual has different max loads for same powders and I don't know which one to believe. Ive never seen pressure signs or cycling issues(semi-auto) with higher loads that were accurate and with velocities i liked . Basically wanted to know how other guys know when a load is to high, either by what manuals say or what casings show. Hope that makes more sense.

 

[ehryk]

in the reloading manuals, look at the barrel length, brass manufacturer and primer manufacturer. Also, keep in mind that different lots of all components vary as do different chambers. The small variances in each thing can make what is safe in one rifle very unsafe in another.

As for your steps in increasing powder charges, way too steep. I go .5 for .308 and .300 WM and 1 for my .338LM. Once I get roughed in I do .2 grain steps in all of them to search for a final load. You very possibly skipped over a lower accuracy node entirely.

Start low, work up slow. The rifle and face you save may just be your own.

 

[Firearrow]

Well to start with look up or do a google search on what a swipe looks like. It's the mark left by the ejector when you chamber pressure gets to high when you are doing load development. When I see these marks that means I have hit Max load for that rifle, case, primer, powder, and bullet. Once I know the Max I usually back it down 1.0 grain and call that " hay stupid don't go higher because it's going to get warm". This Max will be different than loading manuals because they have a safety factor built in to keep guys from doing dumb things. Another really bad sign of a load that is way to HOT is a heavy bolt lift. This is a really HOT load.

If your using a Chronograph once you start to reach your max pressure you will also see a drop off of the increase in your Velocity, or there won't be an increase at all. I base this on a three shot average. Usually the swipes and decrease in Vel happen about the same time, then if you made a bad choice and kept going would eventually hit a heavy bolt lift. Depending on the rifle and caliber that could be as little as 1.0-1.5 grains higher from when you see swipes.

You can also start to see flattened primers when you start to reach your max, but I have found that the primers can be a little miss leading, but they are still a sign to look for.

So to sum it up, use a Reloading Manual to get a starting charge weight. From there load up a round and in crease .5 grains at a time until you have gone a couple of grains past what the Manual says max is. Fire that lowest charge weight. Record Vel, and look for flattened primers/decrease in Vel/swipes/ heavy bolt lift. Then fire the next round. Do this until swipes/decrease in Vel shows up. Record this as Max Load. As stated above drop 1.0gr for safety. Now you have your Min and Max charge weights with an idea of velocity.

I believe that most will agree that midway through your min/max is a good place to start your load development. Up to you if you wanna do the ladder method or the traditional method. You "should" find about two charge weights that shoot the best.

Please keep in mind that if you do your load development in the heart of winter and your best charge weight is near max, and summer time comes around, your near max charge weight now could actually be HOT. This is usually why I drop 1.0gr for safety.

 

[WildRose]

I guess what I'm saying is it seems every manual has different max loads for same powders and I don't know which one to believe. Ive never seen pressure signs or cycling issues(semi-auto) with higher loads that were accurate and with velocities i liked . Basically wanted to know how other guys know when a load is to high, either by what manuals say or what casings show. Hope that makes more sense.

Anytime you exceed published maximums you're literally taking your own life into your hands.

Most of us have done just that if we've been loading for very long and just accept that risk.

I just about blew up a Model 70 back in the late eighties and that was a real eye opener so I always watch for pressure signs no matter what the load tables tell me is safe.

Personally if I find that a load over listed max is my best load I'll probably stick with it but I'll be very careful in working up to it and I always proof all of my loads during the summer so that if warmer temps are going to cause a pressure spike I find out about it in the safest way possible.

You however have to be your own guide.

I can tell you from experience though, you only have to blow one up to change your life forever. I'm damned lucky I still have sight in both of my eyes.

 

[WildRose]

in the reloading manuals, look at the barrel length, brass manufacturer and primer manufacturer. Also, keep in mind that different lots of all components vary as do different chambers. The small variances in each thing can make what is safe in one rifle very unsafe in another.

As for your steps in increasing powder charges, way too steep. I go .5 for .308 and .300 WM and 1 for my .338LM. Once I get roughed in I do .2 grain steps in all of them to search for a final load. You very possibly skipped over a lower accuracy node entirely.

Start low, work up slow. The rifle and face you save may just be your own.

Always the best advice.

 

[IA Shooter]

Thanks for the advice from all. I think Ive been jumping around to much trying to get the most velocity, accuracy combo. I also didn't consider enough about barrel length for some of the velocities I read about on internet. I also realize I can't compare a semi-auto to bolt action for max pressure signs. A question I do have is does having semi-auto change what kind of optimum velocity can be acheived for a given caliber.? I admit I was loading to get to close to high end of velocity range to quickly, to big of jumps. Thanks again

 

[WildRose]

Thanks for the advice from all. I think Ive been jumping around to much trying to get the most velocity, accuracy combo. I also didn't consider enough about barrel length for some of the velocities I read about on internet. I also realize I can't compare a semi-auto to bolt action for max pressure signs. A question I do have is does having semi-auto change what kind of optimum velocity can be acheived for a given caliber.? I admit I was loading to get to close to high end of velocity range to quickly, to big of jumps. Thanks again

You're going to give up a little velocity with a semi auto just because of the gas system which relies on a hole in the barrel to channel gas back to your bolt to operate it.

It doesn't amount to much but there is a little loss in velocity as a result.

 

[alaska]

The reloading manuals changed in the late 60's ......mainly Speer. True reloading data can be found in the Speer No 7 and earlier. But the powders were mainly used were the good old standards like IMR 4350 and H4831 and IMR 4895/4064. You can still find these manuals on eBay. Current reloading manuals are a good place to start your load.

For Semi Auto unless you have a Browning BAR most others weapons use Mid Burning Powders like IMR 4064 and IMR 4895.

Browning BAR in 30-06/270/7mm Mag/300 Win Mag/338 Win Mag was designed around IMR 4350.
Win 100 and Rem 742 suggest IMR 4895/4064
M1 or M14 use IMR 4064/4895
SCAR 17 .......IMR 4064 works very well

If you need additional info send me a note