How much difference do you think there is tween 12 and 14 twist

[gatorman]

What I mean is most loading manuals call for 14 twist for
this bullet and this powder..
And you have a 12 twist..There has got to be some pressure
difference as well as muzzle valicity,etc
When trying to develope an MOA load for mt 22-259 I found no
manuals that had data for the 12 twist...The loads for the 14 were
ok but not MOA like I like to get.So I had to change the data to work
for me by slowing them down
There should be loading data for all twist rate as long as they make the
bullets....Just wanted to whine about it..I am sure others wonder as well...John

 

[gatorman]

you all stumped on this one?

 

[gunsandgunsmithing]

There is little or no pressure difference between different twist rates. Of course, heavier bullets that the faster twist will stabilize will make a substantial difference in pressures. What are you wanting to shoot in it? I'm sure someone here can give you a starting point.

 

[skeetlee]

I would say dont sweat the small stuff. keep this simple. Start with the lowest powder listing per given bullet weight and tune your rifle from there. Dont worry about your twist, other than matching your twist to the proper bullet weight. Keep it simple and have fun. Lee

 

[bheadboy]

going with a faster twist by 12/14 is a modest change, the pressure increase realised would be accounted for in the normal process of CAREFUL reloading by starting with mid recomended loads and working up in small increases, watching for signs of pressure, etc.

Bob

 

[gatorman]

SO your saying that if a loading manual has loads for
a 22-250 with 1 in 14 twist,I am not able to use
the data in my rifle with the 1 in 12 twist..There has got
to be something different there..
Sorta of piss's me off that there isn't more data for
different twist rates..

 

[Cort]

I don't have the ability to measure chamber pressure but my guess is that there is little pressure change due to the change in twist alone. The weight of the bullet that the twist will stabilize is a bigger deal. If you chose a bullet that would stabilize in both twists, then chamber pressure is likely a function of the individual chamber and barrel characteristics rather than the twist. In any event, you will need to start your load 10% below max and work up with both barrels.

Cort

 

[gunsandgunsmithing]

Once more....THERE IS VERY LITTLE OR NO DIFFERENCE IN PRESSURE BETWEEN TWISTS. The answer to your question comes from physics. Each barrel/chamber have their own pressure characteristics that are of much greater significance. Start with starting loads or 10% under max with book data...but keep in mind, as a reloader, it's up to YOU to know when to say when. Things like this are why there are starting and max loads. If you're not comfortable with the process, or anything it entails, seek guidance from someone that can help one on one.

 

[gatorman]

So you saying to start at a 10 percet load reduction and work up....

I have never seen this mentioned in the loading manuals..Not doubting
your word....Seems this would be mentioned in the manuals..

I have ofter wondered if there was any possible danger using data for
a different barrel twist...I know with my savage 22 -250 I started
blowing primers with using data for the 1 in 14 twist...I even sent it
back to Savage to have the chamber polished some...

Anyway,thanks for the information guys....John

 

[gunsandgunsmithing]

So you saying to start at a 10 percet load reduction and work up....

I have never seen this mentioned in the loading manuals..Not doubting
your word....Seems this would be mentioned in the manuals..

I have ofter wondered if there was any possible danger using data for
a different barrel twist...I know with my savage 22 -250 I started
blowing primers with using data for the 1 in 14 twist...I even sent it
back to Savage to have the chamber polished some...

Anyway,thanks for the information guys....John

What I'm saying is get someone to help if you're not completely comfortable. The responsibility is YOURS!
Polishing the chamber would have nothing to do with high chamber pressures. Got any pics of your "blown" primers? Did they have a hole in them or were they pushed back...and what did the primer pockets look like after firing them? How 'bout ejector marks or hard bolt lift?

 

[gatorman]

Not saying I am afraid of using the loading data...Just saying there has got to be
some pressure difference in the two...Even though I have no way to measure it..
Oh well,,,What the hell...Let it be

 

[CanusLatransSnpr]

The pressure differences are so small that they are insignificant or have no relevance. I've used "published" loading data for a 22-250 with a 14 twist barrel to make loads for my 22-250 with a 9 twist barrel and guess what? The rifle shot well with the published loading data! No two rifles are the same. That is why you have to watch for pressure signs while working up a load. Excessive pressure signs are: flattened primers, cratered primers, loosening of primer pockets, heavy bolt lift. High pressure signs are: ejector marks on the head stamp of the cartridge, pierced primers, blown primers out of the cartridge, split case necks, having to beat the bolt open with a hammer! I hope none of the latter ever happen to you because it is scary and I wouldn't wish that on anyone! Long story short, shoot an appropriate bullet for the rate of twist in the barrel. Start load development at the published starting load or 10% below the published max load for that given powder. In all honesty, bullet seating depth has more effect on chamber pressure than a change in twist rate. You should concern yourself with safe and proper loading procedures more so than an insignificant change in twist rate!

Mike

 

[BoydAllen]

If you were blowing primers with a load that you got from a reloading manual, you need to figure out the cause, and I am pretty sure that you are looking in the wrong place....seriously. Loading manuals are pretty conservative with their top loads these days, due to liability issues. Was the rifle that started blowing primers a new one? The reason that I ask is that I once saw a .22-250 that had so much hard carbon in its throat ( after a lot of shooting) that it acted as a partial obstruction. What powder are you using, and how are you measuring it for each load? If you are using a balance scale, have you checked it for accuracy? A friend has 6 BRs that he shoots hot, one each in 12 and 14 twist. He has never mentioned any difference in pressure signs related to the differences in twist. The short version is that you are barking up the wrong tree.

 

[gatorman]

aarff aarf bark bark...
meow meow.........Seriously this savage was blowing primers using Varget loaded with
an RCBS electronic scale which I check befor use every time..Sometimes I weigh a bullet
or two just to see how close it is...I think what was happening,was I might have had
the bullets into the lands to tight.....As I said...I think.....And it was with a slightly
below max load in the manual....????????????????

 

[BoydAllen]

I don't think that you can get to blown primers with a book load, from bullet seating depth. Do you, have (or anyone you know) have a bore scope? Are the primers pierced, or are the pockets made larger?

 

[TheSnake]

Gatorman,
The guys above have given you some good advice and they are very respected shooters here. The reason they don't publish different loads for different twists is because it would be a waste of paper as the velocity and pressure is almost identical. The difference in pressure from a 14 and 12 twist is most likely less than 20 psi in chamber pressure an probably not more than 1 or 2 fps in velocity. The loading manual companies use twist rates for testing that are the most popular for standard common factory rifles so they can cater to the largest number of customers. They don't publish for custom rifles with custom barrels and twist rates.

If your barrel is 1-14 twist, what weight bullet are you loading that you can get to the lands with it? I shoot a standard chamber 22-250 in 14 twist and my 50 to 55gr bullets fall out of the case long before I get to the lands. I too think you have/had something else going on to blow your primers.

 

[gatorman]

NO bore scope....And I don't know anyone who has one either,,,,,
This was a new rifle with only 243 rounds...How I know is
cause I log everything down..
The primers where blow clean out..There was no pierceing...

 

[jo191145]

The primers where blow clean out..There was no pierceing...

I'm confused, what exactly does that mean?
What primer are you using?

 

[BoydAllen]

Two ideas:
Is the same powder performing normally in one rifle but not the other? If that is the case, it is definitely the rifle.
Factory chambers may not be cut with a single reamer. If the one that cut the neck was out of spec. on the short side, and their gauging did not catch it, you could be forcing the neck into the bullet as you chamber the round, and that will definitely raise pressure by a significant amount. If I were testing for this, I would shorten a couple of cases .050 under spec. start low, and work up. looking for pressure signs. If the short cases did not present the same problem, I would have found my problem.

 

[matorre]

My word,

how on EARTH do you blow out a primer on a bolt gun ?

M-