Jump to content
The SASS Wild Bunch Forum

Newbie curiosity--why no 250gr. RNFP


Eyesa
 Share

Recommended Posts

Just managed to join the forum last night. Took a bit since WR moved and just guessed at SASS #4 ! Wow I feel like earned joining!

 

Anyhow, I've been reading this load section and see most are using 230gr. RN bullets or 200gr. RNFP. I'm curious as to why no one seems to use 250gr. RNFP at a lower velocity? I was figuring that way I might reduce blow-by in the Marlin and reach PF easier in the pistol. Is it due to case capacity, as the 250 is about an 1/8 longer? I have lots of 200gr. RNFP that I use in CAS, but bought some 250's to try and haven't yet.

Link to comment
Share on other sites

That's what I thought at first, but saw some threads saying that they went from 200 to 230 to reduce recoil. Seemed odd to me, but more than one said it!

 

Also, is there a way to post without filling out all the questions at the bottom everytime??

Link to comment
Share on other sites

You don't make it clear, but I assume you are talking about 250 grain bullets in a .45 Colt RIFLE load.

 

That would be fine, and especially useful with a Marlin rifle with it's standard OVERSIZE chamber that is hard to seal up from the blow back of combustion gases.

 

Where a 250 grain bullet usually CANNOT be made to work is in the .45 auto case for your pistol.  If you seat most 250 grain bullets deep enough to meet the max OAL length for that cartridge, the base of the bullet swells the case enough to cause a bulge there, and some rounds will not chamber.

 

Its in reference to PISTOL loads that you saw most of the comments about using a 230 grain bullet instead of a 200 grain bullet.  There's so slight a difference there that I don't care, and I continue to shoot a 200 grain Truncated Cone slug (both in pistol and rifle).  THAT really helps ME keep things simple.

 

good luck, GJ

Link to comment
Share on other sites

Eyesa,

 

The math behind lower recoil for heavier bullets is due to the use of a minimum 150 Power Factor (PF) in WB.  PF = (bullet mass x velocity) / 1000. 

 

200 grn bullet needs a minimum velocity of 750FPS to meet power factor.  A 230grn bullets minimum velocity is 653FPS.  When you plug these numbers into the formula for kinetic energy (KE), you see the that squaring of 750FPS results in a higher KE than the 653fps. 

 

The other way to prove the difference in recoil is by looking at the powder manufactures data (I do not recommend you trust the testing data they provide using special equipment to meet PF in your weapons).  For example trail boss shows 3.5 grns provides 658fps for a 230grn bullet.  Same powder load gives 653FPS for a 200grn bullet which will not meet PF.  You actually need close to 4.8grns of TB to meet minimum PF with a 200grn bullet.  Bottom like more powder equals more recoil. 

 

Again the numbers I reference above, are for showing why a heavier bullet has less recoil than a lighter bullet for the same PF.  My examples should not be used as an actual load that will meet WB criteria.  Each weapon is different. 

 

Hope this helps.

 

EJ Waltermire

WB Ambassador SW region

 

Link to comment
Share on other sites

And most folks in the shooting industry believe it is recoil momentum, not recoil energy, that is what most folks feel.  Since power factor is a momentum calculation (mass times velocity), and both weights of bullets can be loaded to the same power factor to meet rules, it makes sense to me that they have just about the same felt recoil.  And that is what I feel when I shoot those loads side by side - just about the same recoil effects. 

 

(Yes, I have read the SAAMI definition of gun recoil ENERGY.  They start out talking about momentum being what they are concerned with, and then shift the discussion to energy.  Although their math works, I believe their shift in focus from momentum to free energy is just wrong).

 

But, what should matter to YOU is what YOU experience with recoil.  Try it out and see.  I just have found myself that there is little difference with both bullet weights loaded to the same Power Factor. 

 

BTW - why would our WB rules establish that Power Factor was the correct way to set a minimum floor for making sure folks were not shooting powder-puff loads, and then some folks want to shift to energy to talk about recoil?

 

good luck, GJ

Link to comment
Share on other sites

You don't make it clear, but I assume you are talking about 250 grain bullets in a .45 Colt RIFLE load.

 

That would be fine, and especially useful with a Marlin rifle with it's standard OVERSIZE chamber that is hard to seal up from the blow back of combustion gases.

 

Where a 250 grain bullet usually CANNOT be made to work is in the .45 auto case for your pistol.  If you seat most 250 grain bullets deep enough to meet the max OAL length for that cartridge, the base of the bullet swells the case enough to cause a bulge there, and some rounds will not chamber.

 

Its in reference to PISTOL loads that you saw most of the comments about using a 230 grain bullet instead of a 200 grain bullet.  There's so slight a difference there that I don't care, and I continue to shoot a 200 grain Truncated Cone slug (both in pistol and rifle).  THAT really helps ME keep things simple.

 

good luck, GJ

 

Joe---I knew about 250's in the rifle and why I got them, just haven't used them yet! I kinda figured the reason not in ACP was the amount they need to be seated. My question mostly of curiosity and I thank you so much for the input. As soon as my parts from Dillon get here I can start working up a load.

Link to comment
Share on other sites

Internet “experts” not withstanding, a 230 gr bullet in the 1911 at around 725 FPS is faster to shoot than a 200 gr at 800. The time clock doesn’t lie or speak opinions. After testing several thousands of rounds, split times between shots are faster with the 230 than the 200. At at match where there may be several hundred rounds fired, those minute times add up. While I have considered testing the 250 grain bullet, finding them easily on a regular basis is not worth it.
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...