Rifle reloading data question: starting loads.

[Ivan the Butcher]

The Hodgdon annual loading magazine have very accurate data as far as it goes! The Sierra hard bound manual tell you all the various loads you need with their bullets!

When Burger first brought out the 300 grain Hybrid, they had a recall and replaced them with a second generation with a slightly thicker jacket and a a little lower BC. I took my bullets to their booth at the NRA convention in 2010. They said that at most 338 Lapua Mag velocities their was not a problem. Then had me describe my observations. I told them I was using a Savage 110BA with a 26" barrel Hornady Match Brass, Federal 215 primer, and 104.0 grains of US869. COAL was standard to fit in Accuracy International Mags. My observation was that on 30 to 50 percent of shots under ideal weather conditions the bullets left contrails. and that of the observable bullets over 50% were going 150 to 175 yards the turning at a 60 to 90 degree angle, left, right, up or down, but more left than any other! The Berger reps admitted this fitted right in with their observations! (the 26" barrel and US869 got about 2900 fps, but a 24" barrel was 100 to 150 fps slower)

I have been sticking with the 300 grain Sierra Matching and 94.0 grains of Retumbo or 94.2 grains of H-1000 and getting 2775 0r 2800 fps but the groups have 1/4 MOA versus 3/4 MOA for US869.

A friend of mine was loading a 300 Lapua Mag (on a Savage 110 single shot action) using a solid bronze bullet around 3400 fps and US 869! His targets were at 1600 to 3400 yards. With that bullet/powder combination he was getting 1/2 MOA at 2 miles! The superior accuracy life was in the 300 shot range!

Ivan

Warning: these expensive toys, require that you have either NO Wife! or a very tolerant one, I am blessed with the later! She grew up with a dad that was a Police Combat competitor and 2 time National Champion! So in her opinion, if you merry a real man, he will have guns and will spend time and money shooting them! Most women don't see it that way!

 

[gwpercle]

Generally, if one intends to reload using a somewhat lighter-weight bullet for the caliber, a faster burning propellant may produce better results.

Not necessarily germane to your question, but the Lyman reloading handbooks of the 1960s-70s formerly provided "accuracy loads" for each available bullet weight for each rifle caliber. I don't think that's being done any longer.

It IS still done in the Lyman Cast Bullet Handbook 4th Edition (cast bullet data only) and also in the Lyman 50th Edition Reloading Handbook (some cast and some jacketed bullet data).
I have them on my desk and just checked ...still there , " potentially the most accurate load " ...shown in bold type .

I always liked that little heads up on what might be best !
Gary

 

[STORMINORMAN]

Well, finally got around to loading some 250gr bullets (Hornady SP) that has published data with US 869. The suggested OALs for 250gr jacketed bullets, however, range from 3.550 to 3.565".

When I loaded a test round (at 0.5gr over the Hodgdons START LOAD of 101.5gr) and at the longer 3.565" OAL and then chambered the round (bolt action) the OAL was shortened to 3.532". There are no marks on the bullet but it is obviously being pushed further into the case.

Since most of my reloading experience is with handgun calibers, where variances in OAL can have serious consequences I am looking for additional guidance, please.

Pressures listed at the START LOAD is 47,000 CUP, the MAX @ 108gr is 51,100 CUP. This would lead me to believe that pressure is not really the issue? A reduction of 33 thousandths vs.6 grains of powder?

The bullet is now nearer to the cannelure (well, 0.033" nearer) but I don't believe it should be loaded to actually touch the rifling? The bolt closed smoothly with no unusual resistance on the original test round.

Am I overthinking this? Should I just go a few thousandths shorter at 3.530" so the bullets are not touching the rifling?

Intended to work the load up a bit depending upon acceptable accuracy at the range: this is not designed for long range hunting nor a sniper type application, just practice.

Thanks in advance for your kind consideration!

P.S. Once-fired brass was checked for headspace & length with a Wilson's gauge.

 

[Sevens]

In the interest of full disclosure, I have a LOT of experience in handgun loading… many calibers over decades and a very high round count using many different bullets, many different powders and launched from countless handguns. And that is relevant to say because my experience in bottle neck rifle is probably 5% compared to 95% in handgun.

With that said…

I think it’s worth mentioning that as IMPORTANT as COAL is in handgun rounds, especially smallish, compact, high pressure handgun rounds (9mm, .40cal. etc), bottle neck rifle often acts opposite when it comes to COAL.

In a handgun round, shorter COAL means to absolutely expect higher pressure due to decreased combustion space. However in a bottle neck rifle round, your are reducing the combustion space very little in comparison, percentage wise, considering the volume of a typical rifle case. At the same time, you are pushing the bullet closer to the lands and you are quickly removing the start space for the bullet to move before meeting serious resistance in the lands.

If you have built a load to a COAL where merely chambering the round is pushing your bullet deeper in to the case, you are doing a poor job of building that ammo safely.

You need to start with a shorter COAL, giving your bullet room to travel before smacking in to the lands, which drives the pressure up immediately.

Please fact check me on this:

If you build four different loads, all same bullet and same powder charge, the longer COAL loads should be expected to be higher pressure in your rifle.

 

[STORMINORMAN]

This was a 1st time test round: I set the OAL to the longer of the "published" data. I had to start somewhere. I actually was a bit surprised it was still way short of the cannelure?

Loading them a bit further off the lands is what I was suggesting.

The real question was if a 0.035" (or more?) reduction of the OAL from the "published" data using an almost minimum START load would possibly create pressure issues: obviously I was not going to just use the bolt, chamber and barrel to shorten subsequent loads specifically because of the pressure issue detailed in the above post by Sevens (Thanks, BTW!)...

I would think there would be plenty of room to load shorter with 6gr of powder between START & MAX given the 4,000+ CUP pressure difference?

Correct me if my logic is faulty, please?

Cheers!