Home Forums Hunting & Shooting Single Shots Contender pressure sign?

I am a long time shooter of Contenders and especially like the G1 version. I recently bought a 30-30AI which with my brass holds 4 grains more powder than a regular 30-30 case. I worked up slowly using Leverevolution powder to 2.5 grains over what is listed as max for the 30-30. Accuracy is awesome, extraction is easy with velocity averaging 2597 fps. Barrel is 21 inches long. Have to say the 30-30 AI is a nice round to load for, case stretching is nothing compared to the 30-30 and I do believe the case does not have as much backthrust as the steeply tapered 30-30 case does. This said with the complete absence of any signs of pressure do I just take it for granted I am good?

I hesitate to tell anyone that their load is ‘ok’ I would offer up this caution though: With reduced taper of an Ackley Improved case body you probably should not wait for sticky extraction as a sign of approaching excessive pressures as you might with the standard case and it’s tapered case walls. Use a micrometer to measure case head diameter at the web and just forward of the web.
I like the 30/30AI but don’t, as I’ve read,...don’t try to make it a 308.

Are you using data you found somewhere or guesstimating? Sounds reasonable given the slightly larger case. You might post in the reloading forum and ask if someone will do a check with one of the loading programs. They'll need some info, but it's worth a shot.

I have read in several places that the 30-30 AI having ten percent more case capacity can be loaded with 5% more powder than the regular 30-30.

Rick: You are facing a situation of hand loading a wildcat cartridge with limited loading data with no pressure data. The second complication is the relatively low strength of the Contender action highly susceptible to frame stretching. As Alaninga mentioned if you have case extraction issues with a Contender you have all ready stretched the frame. Here is what I learned when loading for a 308 Bellm :
1, According to J. D. Jones the pressure limit for a G1 Contender action and a G2 action is the same. Mike Bellm thinks the strengthening bars on the top of the G2 action will allow a higher pressure of about 5000 psi in the G2 action.
2. The larger the cartridge case head the lower the allowable pressure before stretching. That is why T/C chambers the 223 Remington at 55,000 psi but only chambers the 30/30 instead of say a 308 Win. in the Contender.
3. Bellm told me that the Contender action was good for about 40,000 psi so I should limit to 300 Savage starting loads in the 308 Bellm.
4. There is a pretty large pressure spread between various powders in the same cartridge. The best example is how much lower the pressure is for Lil Gun compared to H110. IMR used to have pressure data for their loads in the free IMR handout. Lately pressure data for loads has gotten increasingly scarce.
5. According to Barsness case shape has little effect on back thrust. He also states that '...case stretching ...starts to occur at around 50,000 psi.' (Gun Gack II" page 100). My interpretation is that a straight case and a sloped case has no effect on the Contender at a 40,000 pound limit. If you follow his 4 - 1 Rule the 30/30 AI case will only increase velocity by 1/4 the increase in case capacity of the difference between the 30/30 and 30/30 AI loaded at equal pressures. Since you have a 30/30 AI case measure the fired case capacity in water for cases of the same manufacturer in a fired 30/30 case. If you have a chronograph just load the AI to 25% of the percentage increase in the difference between the 2 cases.
6. Sam Fadala in his book "Winchester 94" has 30/30 AI loading data. In his chapter on the 30/30 AI he shows the velocity of the same bullet with the same powder in the 30/30AI as slower than the 30/30. I was confused until I looked at the barrel length. The AI was in a 20" barrel and the 30/30 was chronographed in a 24" barrel. My conclusion is that 4" of barrel has a greater affect on muzzle velocity than the case shape.
Do not expect too much out of an AI and stretch your frame.

Speer lists 38.2 grains of LVR under a 150 grain bullet as max giving 2516 fps, my load used 41.0 grains of the same powder gives 2597 fps, pretty good really. It would seem that 10% more case capacity would give me 81 fps more with no issues. I can't say what barrel length Speer used either. I can say I have loaded these cases 6 times without having to trim them, something unheard of with the standard 30-30 case, even if you are using very mild loads. Years ago I ran into Fadala's book in a library, wish I had a copy of his data for sure but that was long before the current crop of modern powders arrived. As soon as the 17 cartridges i have left I loaded for this years hunting are shot up I may just drop the charge a bit.

Rick: How did you arrive at a 10% increase in case capacity?

With the medium pressure cartridges the Contender was designed for, I doubt you would see any of the classic pressure signs before you are above the Contender limits.

I filled a standard fired 30-30 case with LVR and weighed it then did the same with 30-30 AI case and came out with 4 grains more powder. In this particular case the AI'ing of the 30-30 case changes it more than a little. To add in my contender barrel I can seat bullets out to 2.640 instead of the standard COAL of 2.550 so that would give me a little more room in itself.

Therein lies the rub.

How does body taper and case capacity compare to the 309JDJ or 308Belm?

Re: Point #3. Mike Bellm uses 43,000 psi as a max working pressure for .30-30 cases.

Re: Point #5. P.O. Ackley fired a .30-30 Imp case sucessfully in a Win 94 WITH NO CASE HEAD SUPPORT. This supports the theory that mininal body taper cases expand and grip the chamber walls rather effectively and thus reduce rearward thrust. My experience with the .30 Gibbs further supports this premise.

bobmn, the lower pressures with LiLGun appear to be pretty cartridge-specific, according to Hodgdon data. Big winners are the .22 Hornet and .357 mag. Others, it seems, develop about the same pressure and velocity as with say, H110. You probably have noticed that yourself, but just thought I'd mention it for the other kids.

When I received my copy of Lyman 50, I was surprised and disappointed to see very little data for LiLGun and Trail Boss, both of which had been out for a good while. That, and some other things make me believe that there's someone there that has pretty fixed ideas about some stuff.

Muskeg: Barsness specifically addresses Ackley's experiment. You might find reading "Gun Gack II" enlightening.

Cas: The 308 Bellm is a 444 Marlin case necked to 30 caliber. According to Ken Howell the 444 Marlin case capacity is 102 gr water. The 30/30 Ackley improved is 68 gr water. The 30/30 Winchester case capacity is 62 gr water. A 308 bullet displaces 18.84 grains per inch and a 430 bullet displaces 36.72 grains per inch.

I read it and I'm not enlightened.

Barsness dismisses Ackley's experiment as he claims it doesn't really prove that the improved body taper is what helps the case grip the chamber wall because Ackley did not use the parent case also in the experiment. Pshaw! Mr. Barsness bases his comments on an experiment Charile Sisk did and I'm pretty sure it wasn't with a .30-30 (no mention of chambering IIRC). The testing used "pressure tape" attached to the case head. No mention of what was used to measure the pressure on the chamber walls and no mention of the actual pressures measured in the testing. If we're talking a 55 kpsi round, I'll concede that the pressures are probably equal on the case head and chamber walls. That's not what we're talking about here.

Either .30-30 case, loaded to 40 kpsi or below, will grip the chamber wall and reduce back thrust on the bolt, or as we're discussing here, the frame of a T/C Contender. The brass is working within the elastic range not the plastic range - it is not "stretching" per se. The OP is wondering about the .30-30 AI and possibly stretching his frame. Keep max pressure in the 40 - 43 kpsi range and he's good to go.

Muskeg:I am trying to understand your position and have no desire to be argumentative.. Please bear with me. Hypothetically let's assume a 30/30 case will stretch a Contender frame at 45,000 psi chamber pressure. We then load a 30/30 AI case to a chamber pressure of 45,000 psi with exactly the same components. Are you saying that the frame will not be stretched because the AI case grips the chamber walls better thereby reducing the back thrust on the frame? Thanks.

Pretty easy to stretch a Contender frame. It will happen before you suspect it.